Dissertations / Theses: 'Power System Stabilizer (PSS)'

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Mensah, Kwaku Sarpong. "Improving Stability of Ghana's Power System Using Power System Stabiliser(PSS)." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for elkraftteknikk, 2009. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-12884.

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Stability of a power system is vital for its reliable operation and maintaining system stability has been a big challenge for engineers over the years. One way of improving system stability is the use of power system stabiliser (PSS). Its main function is to add damping to the generator rotor oscillation by modulating the generator excitation so as to develop a component of electrical torque in phase with the rotor speed deviation. In Ghana, two power stations have their generators equipped with PSS but none of the PSS are activated. The main objective of this study is to assess how the stability of the power system of Ghana can be improved by activating the power system stabilizers (PSS) on the excitation system of some of the generating units. To effectively perform the study the following questions had to be answered.To what extent will the activation of the PSS on some generating units affect the overall system dynamic performance?Where in the power system should the PSS be activated?To what extend can the PSS reduces system oscillation? What improvement can be made to the power system to optimise the performance of the PSS?Data of Ghana and the interconnected systems were first collected, reviewed and all the systems were modelled using PSSE program. Steady state stability studies were then performed to identify the inadequacy in the system during steady state operations. Five base cases including peak and average load condition with and without contingency were used for this study. Dynamic stability studies were also carried out by selecting appropriate dynamic models for generators, exciters and governors that best fit the dynamic behaviour of the generating units in the PSSE program. Appropriate PSS models were selected for units equipped with PSS based on manufacturers recommendation. Series of dynamic simulations were carried out to identify the best location and parameter settings for the PSS. Small signal stability studies were also carried out to complement the results obtained from the transient studies using NEVA. There was however a defect in the NEVA program and full results could not be obtained.In conclusion, Ghanas system is likely to experience voltage collapse during a transmission outage on some critical lines at peak period unless some loads are shed. This risk can be reduced by improving the power factor to 0.95 using more reactive power compensating devices (capacitor bank) at the local substation. Transient stability results also show that the best location for the PSS to effectively damped oscillation is Akosombo GS. Inter-area oscillations of 0.5Hz between Ghana and Ivory Coast systems, local-area oscillation of 0.8Hz between the Akosombo units and Aboadze units in Ghana, were effectively damped within 7sec with PSS at Akosombo GS. It is highly recommended that PSS at Akosombo generation station be activated since their application has a positive impact on the dynamic performance of Ghanas system. Steady state stability be improved by correcting the power factor at the local stations and line relay settings reviewed to accommodate the present operating condition. It is also recommended that the PSS be coordinated effectively with the protection and control devices for optimal performanc

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Sanchez, Ayala Gerardo. "Centralized Control of Power System Stabilizers." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/51754.

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This study takes advantage of wide area measurements to propose a centralized nonlinear controller that acts on power system stabilizers, to cooperatively increase the damping of problematic small signal oscillations all over the system. The structure based on decision trees results in a simple, efficient, and dependable methodology that imposes much less computational burden than other nonlinear design approaches, making it a promising candidate for actual implementation by utilities and system operators. Details are given to utilize existing stabilizers while causing minimum changes to the equipment, and warranting improvement or at least no detriment of current system behavior. This enables power system stabilizers to overcome their inherent limitation to act only on the basis of local measurements to damp a single target frequency. This study demonstrates the implications of this new input on mathematical models, and the control functionality that is made available by its incorporation to conventional stabilizers. In preparation of the case of study, a heuristic dynamic reduction methodology is introduced that preserves a physical equivalent model, and that can be interpreted by any commercial software package. The steps of this method are general, versatile, and of easy adaptation to any particular power system model, with the aggregated value of producing a physical model as final result, that makes the approach appealing for industry. The accuracy of the resulting reduced network has been demonstrated with the model of the Central American System.
Ph. D.

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Tiako, Remy. "Optimal design of power system stabilizer (PPS) using multi-power flow conditions." Master's thesis, University of Cape Town, 2007. http://hdl.handle.net/11427/5096.

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Abhyankar, Shounak. "Application of wide area frequency information from FNET to Power System Stabilizer (PSS) a thesis presented to the faculty of the Graduate School, Tennessee Technological University /." Click to access online, 2009. http://proquest.umi.com/pqdweb?index=0&did=2000377691&SrchMode=1&sid=4&Fmt=6&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1277473349&clientId=28564.

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Ahmed, Sheikh. "PMU based PSS and SVC fuzzy controller design for angular stability analysis." Thesis, Kansas State University, 2015. http://hdl.handle.net/2097/20547.

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Master of Science
Department of Electrical and Computer Engineering
Shelli Starrett
Variability in power systems is increasing due to pushing the system to limits for economic purposes, the inclusion of new energy sources like wind turbines and photovoltaic, and the introduction of new types of loads such as electric vehicle chargers. In this new environment, system monitoring and control must keep pace to insure system stability and reliability on a wide area scale. Phasor measurement unit technology implementation is growing and can be used to provide input signals to new types of control. Fuzzy logic based power system stabilizer (PSS) controllers have also been shown effective in various studies. This thesis considers several choices of input signals, composed assuming phasor measurement availability, for fuzzy logic-based controllers. The purpose of the controller is to damp power systems’ low frequency oscillations. Nonlinear transient simulation results for a 4-machine two-area system and 50 machine system are used to compare the effects of input choice and controller type on damping of system oscillations. Reactive power in the system affects voltage, which in turn affects system damping and dynamic stability. System stability and damping can be enhanced by deploying SVC controllers properly. Different types of power system variables play critical role to damp power swings using SVC controller. A fuzzy logic based static var compensator (SVC) was used near a generator to damp these electromechanical oscillations using different PMU-acquired inputs. The goal was again improve dynamic stability and damping performance of the system at local and global level. Nonlinear simulations were run to compare the damping performance of different inputs on the 50 machine system.

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Wu, Zhongyu. "Wide Area Analysis and Application in Power System." Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/36427.

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Frequency monitoring network (FNET) is an Internet based GPS synchronized wide-area frequency monitoring network deployed at distribution level. At first part of this thesis, FNET structure and characteristics are introduced. After analysis and smoothing FDR signals, the algorithm of event trigger is present with Visual C++ DLL programming. Estimation of disturbance location method is discussed based on the time delay of arriving (TDOA) in the second part of this work. In this section, author shows the multiply method to calculate event time, which is important when deal with pre-disturbance frequency in TDOA part. Two event kinds are classified by the change of frequency and the linear relationship between change of frequency and imbalance of generation and load power is presented. Prove that Time Delay of Arrival (TDOA) is a good algorithm for estimation event location proved by real cases. At last, the interface of DLL module and the key word to import and export DLL variables and function is described.

At last, PSS compensation optimization with a set of nonlinear differential algebraic equations (DAE) is introduced in detail. With combining the bifurcation theory of nonlinear system and the optimization theory, the optimal control of small-signal stability of power electric systems are solved. From the perspective of stability margin, global coordination of controller parameters is studied to ensure the stable operation of power grids. The main contents of this thesis include:

ï¼ 1ï¼ Models of power systems and test power electric systems. Tht5e dynamic and static models of the elements of power systems, such as generatorbbs, AVRs, PSSs, loads and FACTS controllers are presented. Method of power system linearization modeling is introduced. Three test power systems, WSCC 9-bus system, 2-area system, New England 39-bus system, are used in thesis.

ï¼ 2ï¼ Multi-objective optimizations based on bifurcation theory. The optimization models, damping control-Hopf bifurcation control, voltage control-damping control, are presented. Pareto combined with evolutionary strategy (ES) are used to solve multi-objective optimizations. Based on traditional PSS parameters optimizations, it can be formulated as a multi-objective problem, in which, two objectives should be taken into account. The minimum damping torque should be identified.
Master of Science

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Costa, Filho Raimundo Nonato Diniz. "ANÁLISE TÉCNICO-ECONÔMICA DO IMPACTO DOS PSS E CONTROLADORES FACTS NA ESTABILIDADE ELETROMECÂNICA DE SISTEMAS DE ENERGIA ELÉTRICA." Universidade Federal do Maranhão, 2014. http://tedebc.ufma.br:8080/jspui/handle/tede/512.

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Made available in DSpace on 2016-08-17T14:53:27Z (GMT). No. of bitstreams: 1 Dissertacao Raimundo Nonato Diniz.pdf: 3599082 bytes, checksum: 5e6a5df5d6046a848205e71a3d63c95f (MD5) Previous issue date: 2014-02-21
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
In this work the influence of FACTS (Flexible AC Transmission Systems) Controllers and power system stabilizers (PSS) on electromechanical stability of electrical power systems (EPS) is analyzed considering their technical and economic impact in the operation and planning. FACTS Controllers most employees in practical applications were considered in this study, the Static VAr Compensator (SVC) and Thyristor Controlled Series Capacitor (TCSC), in addition to the PSS. For the technical and economic evaluation of the impact of FACTS and PSS in power systems a methodology based on indices of electromechanical small-signal and transient stability has been developed. Software packages PacDyn and ANATEM, including ANAREDE, all produced by CEPEL (Centro de Pesquisas de Energia Elétrica), were used to analyze the technical impact of SVC, TCSC and PSS on electromechanical stability enhancement. The economic analysis was based on the use of software package PSAT (Power Systems Analysis Toolbox). As part of the technical evaluation, coordination and tuning of the parameters of PSS and FACTS Controllers were conducted using artificial intelligence techniques in order to obtain the best optimal values. The proposed methodology was applied to test systems and a configuration of the Brazilian Interconnected System (SIN - Sistema Interligado Nacional) modeled with 50 generators and 616 buses.
Neste trabalho é analisada a influência dos Controladores FACTS (Flexible AC Transmission Systems) e dos estabilizadores de sistemas de potência ou PSS (Power System Stabilizers) na estabilidade eletromecânica dos sistemas de energia elétrica (SEE), considerando o seu impacto técnico e econômico na operação e planejamento. Os Controladores FACTS mais empregados na prática foram considerados nesta pesquisa, o compensador estático de potência reativa ou SVC (Static VAr Compensator) e o capacitor série controlado a tiristores ou TCSC (Thyristor Controlled Series Capacitor), além dos PSS. Para a avaliação técnico-econômica do impacto dos FACTS e PSS nos SEE foi desenvolvida uma metodologia baseada em índices de estabilidade eletromecânica a pequenas perturbações e de estabilidade transitória. Na análise técnica foram utilizados os programas PacDyn e ANATEM, além do ANAREDE, todos desenvolvidos pelo CEPEL (Centro de Pesquisas de Energia Elétrica). A análise econômica baseou-se no uso do aplicativo PSAT (Power Systems Analysis Toolbox). Como parte da avaliação técnica a coordenação e sintonização dos parâmetros dos PSS, SVC e TCSC foram conduzidas utilizando métodos de inteligência artificial de forma a obter os melhores valores ótimos. A metodologia proposta foi aplicada a sistemas teste e a uma configuração do Sistema Interligado Nacional (SIN) modelado com 50 geradores e 616 barras.

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Carbonera, Luis Felipe Bianchi. "Comparação de funções objetivo para seleção de PSS pelo amortecimento de oscilações em sistemas multimáquinas." Universidade Federal de Santa Maria, 2015. http://repositorio.ufsm.br/handle/1/8575.

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Small disturbances occur continuously in electrical systems mainly due to load and generation variations. This ends up causing low frequency voltage fluctuations that are usually observed in systems whose lines have weak connections. In addition to damaging loads connected to the same bus, they can even damage equipment and incurring in costs to the energy distributors. Moreover, such oscillations can resonate with the system parameters and cause a general collapse in energy supplies. In the literature, there are methods for the development of stabilizers for power systems that are implemented to counteract these perturbations. In this dissertation, we compared some objective functions and identified points that can be optimized for parameterization of power system stabilizers IEEE models: PSS2B, PSS4B and conventional Delta w PSS, by computer simulations. The adjustment methodology used in this dissertation is based on the genetic algorithm (GA) held in Simulink® with the aid of the Matlab toolbox Gatool®. The effectiveness of the suggested technique and stabilizers are checked using simulation results, where it is noticeable that the PSSs managed to dampen oscillations in almost all cases. The only one who did not realize the optimization was the Delta W PSS with ITSE objective function in the hydraulic turbine, which failed to dampen oscillations even for the best results. Moreover, it was also possible to notice that the same Delta W PSS with ITAE objective function had the best results for the two types of turbine.
Pequenas perturbações ocorrem continuamente em sistemas elétricos principalmente devido às variações de cargas e da geração. Isto acaba acarretando oscilações de tensão de baixa frequência que são normalmente observadas em sistemas cujas linhas possuem conexões fracas. Além de prejudicar as cargas conectadas no mesmo barramento, elas podem até danificar aparelhos e incorrer em ônus para as distribuidoras de energia. Além do mais, tais oscilações podem entrar em ressonância com os parâmetros do sistema e causar um colapso geral no abastecimento de energia. Na literatura encontram-se metodologias para o desenvolvimento de Estabilizadores para Sistemas de Potência que são implantadas para se contrapor a estas perturbações. Nesta dissertação, foram comparadas algumas funções objetivo para a parametrização dos estabilizadores de sistemas de potência modelos IEEE: PSS2B, PSS4B e convencional Delta w PSS, a partir de simulações computacionais. A metodologia de ajuste utilizada nesta dissertação é baseada no algoritmo genético (AG) realizada em Simulink® com auxílio do toolbox Gatool® do Matlab®. A eficácia da técnica sugerida e dos estabilizadores é verificada com os resultados de simulação, em que é possível perceber que os PSSs conseguiram amortecer oscilações em quase todos os casos. O único que não realizou a otimização foi o Delta W PSS com a função objetivo ITSE na turbina hidráulica, o qual não conseguiu amortecer as oscilações com seu melhor resultado encontrado. Por outro lado, foi possível perceber também que o mesmo Delta W PSS com a função objetivo ITAE teve o melhor resultado para os dois tipos de turbina.

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Borges, Rafael Cruz. "Um algoritmo para sintonia de controladores robustos para amortecimento de modos intra-planta em sistemas de potência." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/18/18154/tde-10082009-114735/.

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O problema de modos intra-planta em sistemas de potência é caracterizado pela oscilação dos geradores de uma mesma usina uns contra os outros. Estes modos são geralmente bem amortecidos, mas uma sintonia inadequada dos parâmetros dos PSSs (Power System Stabilizers), visando fornecer um amortecimento aos modos locais, por exemplo, pode reduzir o amortecimento dos modos intra-planta. Esta possibilidade pode ser evitada por uma sintonia cuidadosa dos estabilizadores, em um modelo que seja capaz de representar os modos intra-planta. Este processo de sintonia pode ser tedioso e demorado, exigindo muitas horas de trabalho de um especialista. Neste trabalho, apresentamos um algoritmo computacional capaz de realizar esse processo, com uma intervenção mínima do projetista (reduzindo, portanto, o esforço do engenheiro projetista na sintonia do PSS e deixando que o computador faça de maneira eficiente) e aplicamos este algoritmo para encontrar uma sintonia adequada de PSSs para o amortecimento dos modos local e intra-planta coexistentes no mesmo sistema. Como mostrado neste trabalho, o algoritmo é capaz de sintonizar os PSSs para varias condições de operação de uma só vez, o que pode também resultar em uma melhor sintonia quando comparado com abordagens seqüenciais de projeto.
The problem of intra-plant modes is characterized by the oscillation of the machines within a power station against each other. These modes are usually well-damped, but improper settings for the parameters for power system stabilizers (PSSs), aiming at enhancing the damping of local modes, for example, can reduce the damping of the intra-plant modes. This possibility must be avoided by a careful tuning of the stabilizers, over a model that is able to represent the intra-plant modes. This tuning process may be involved and time-consuming, requiring many hours of work from a specialist. In this paper, we present a computerized algorithm that is capable of performing this process with minimum intervention of the human designer (therefore alleviating the burden of PSS tuning for the engineer and placing most of it on the computer) and apply it to find a PSS tuning to damp both local and intra-plant modes of the same plant. As shown in the paper, the algorithm is capable of tuning PSSs for several operating conditions at once, which may also result in better tuning when compared to sequential approaches.

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Tai-Cheng, Yang. "Power system stabilizer design." Thesis, University of Manchester, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245278.

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Mallem, Badis. "Modélisation, analyse et commande des grands systèmes électriques interconnectés." Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2010. http://tel.archives-ouvertes.fr/tel-00557829.

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Cette thèse porte sur la modélisation, la réduction et la commande des grands systèmes électriques.En terme de modélisation et de réduction, l'objectif principal est de développer une méthode de réduction des modèles dynamiques des systèmes électriques. Cette réduction a pour objet de répondre à une situation particulière dans laquelle toutes les données du système à réduire ne sont pas connues.En terme de commande, l'objectif est la conception de commandes robustes coordonnées pour répondre aux nouvelles contraintes des grands systèmes électriques. Ces approches doivent respecter trois niveaux de coordination et deux nouvelles contraintes. Les trois niveaux de coordination concernent la prise en compte simultanée des oscillations électromécaniques interzones et locaux, la coordination de la synthèse de régulateurs pour plusieurs alternateurs, et la coordination du réglage des paramètres (gains et constantes de temps) des régulateurs de tension (les boucles stabilisatrices PSS) avec le réglage des paramètres des régulateurs de turbine des alternateurs. Les contraintes sont liées à la stabilité et la robustesse des régulateurs proposés.

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Shamsollahi, Payman. "Neural adaptive power system stabilizer." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq24562.pdf.

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Soos, Antal. "An optimal adaptive power system stabilizer." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0027/MQ31404.pdf.

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Hammer, Anders. "Analysis of IEEE Power System Stabilizer Models." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for elkraftteknikk, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-14035.

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Student:Anders HammerSupervisor:Kjetil UhlenContact:Daniel MotaCollaboration with:Voith HydroProblem descriptionIEEE (Institute of Electrical and Electronics Engineers) presented in 2005 a new PSS structure named IEEE PSS4B (Figure 0 1). Voith Hydro wants to analyse the pros and cons of using this new type compared to older structures. The PSS4B is a multi-band stabilizer that has three separate bands and is specially designed to handle different oscillation frequencies in a wide range. Until now, Voith Hydro has used the common PSS2B in their installations, but in the future they will probably start to implement the new PSS4B. This master thesis will seek to find an answer on following questions:•How should the PSS4B be tuned to give the best damping of the local and inter-area oscillation mode?•Will an implementation of PSS4B give a better result compared to PSS2B?•What are the pros and cons of PSS2B and PSS4B? Figure 0 1: The multi-band stabilizer, IEEE PSS4B [1].MethodIn order to test and compare different PSS models, a simple two-area network model is created in a computer simulation programme (SIMPOW). One of the generating units is a hydro generator, which has a model of a static excitation system made by Voith Hydro. This network is characterised by a poorly damped inter-area oscillation mode, and in addition some local oscillation modes related to each machine. Different PSS structures (PSS2B and PSS4B) are then tuned and installed in the excitation system of the hydro generator, in order to improve the stability of the network. Different tuning methods of the PSS4B are designed, tested and later compared with the more common stabilizer the PSS2B. Simplifications are made where parts of the stabilizer is disconnected in order to adapt the control structure to the applied network and its oscillations. Totally 5 different tuning methods are presented, and all these methods are based on a pole placement approach and tuning of lead/lag-filters. ResultsInitial eigenvalues of the different setups are analysed and several disturbances are studied in time domain analysis, in order to describe the robustness of the system. Figure 2 illustrates the rotor speed of the generator, where the different PSS’s are implemented. PSS4B is clearly resulting in increased damping of all speed oscillations in this network. The same results can also be seen in an eigenvalue analysis.Conclusion The best overall damping obtained in this master thesis occurs when the high frequency band of the PSS4B is tuned first, and in order to maximize the damping of the local oscillation mode in the network. The intermediate frequency band is then tuned as a second step, according to the inter-area oscillation mode. Results of this tuning technique show a better performance of the overall damping in the network, compared to PSS2B. The improvement of the damping of the inter-area oscillation mode is not outstanding, and the reason is that the applied machine is relative small compared to the other generating units in the network. The oscillation modes in the network (local and inter-area) have a relative small frequency deviation. A network containing a wider range of oscillation frequencies will probably obtain a greater advantage of implementing a multi-band stabilizer.

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Hariri, Ali. "An adaptive fuzzy logic power system stabilizer." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq20741.pdf.

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Chen, Lian. "A novel method for power system stabilizer design." Doctoral thesis, University of Cape Town, 2003. http://hdl.handle.net/11427/5261.

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Word processed copy.
Includes bibliographies.
Power system stability is defined as the condition of a power system that enables it to remain in a state of operating equilibrium under normal operating conditions and to regain an acceptable state of equilibrium after being subjected to a finite disturbance. In the evaluation of stability, the focus is on the behavior of the power system when subjected to both large and small disturbances. Large disturbances are caused by severe changes in the power system, e.g. a short-circuit on a transmission line, loss of a large generator or load, loss of a tie-line between two systems. Small disturbances in the form of load changes take place continuously requiring the system to adjust to the changing conditions. The system should be capable of operating satisfactorily under these conditions and successfully supplying the maximum amount ofload. This dissertation deals with the use of Power System Stabilizers (PSS) to damp electromechanical oscillations arising from small disturbances. In particular, it focuses on three issues associated with the damping of these oscillations. These include ensuring robustness of PSS under changing operating conditions, maintaining or selecting the structure of the PSS and coordinating multiple PSS to ensure global power system robustness.

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Behbehani, Hussain M. "Enhancement of power system stability using fuzzy logic based supervisory power system stabilizer." Thesis, University of Edinburgh, 2008. http://hdl.handle.net/1842/10778.

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Maintaining power system stability has become a challenging task for engineers. A consequence of such factors is that power system damping of electro-mechanical oscillations is often reduced which could sometimes destabilise the power systems if the electro-mechanical oscillations are poorly/lightly damped. Decentralised power system stabilisers are often used to increase damping of local oscillation modes and to some extent to increase damping of inter-area oscillation modes. However, damping of inter-area oscillations modes by the local PSS is not quite effective as for local oscillation modes. Therefore, it is necessary to implement a new control strategy to enhance damping of inter-area oscillation modes. With today’s advancement of phasor measurement units (PMUs), global information, which contains valuable information about the existence of inter-area oscillation modes, could be possibly used as inputs to mitigate inter-area oscillations as the literature suggests. The aim of this thesis is to propose supervisory power system stabilisers (SPSS) which are based on Fuzzy Logic to improve damping of such electro-mechanical oscillations in particular inter-area oscillation modes. Three different structures of supervisory power system stabilisers are presented in this thesis. The inputs to the proposed supervisory damping controllers will use global signals, speeds and their derivatives; however, the structure of the inputs to the supervisory power system stabilisers is different depending on the structural design of SPSS. The uniqueness of each SPSS type proposed is that they all make use of the same control rules regardless to which power system is applied. The robustness of such control rules and proposed SPSS are verified on three different test systems as the results of the case studies demonstrate. The time domain simulations will highlight the impact of each SPSS type on the system response.

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He, Jian. "Adaptive power system stabilizer based on recurrent neural network." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0008/NQ38471.pdf.

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Mulumba, Tshina Fa. "Application of differential evolution to power system stabilizer design." Master's thesis, University of Cape Town, 2012. http://hdl.handle.net/11427/12026.

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Includes synopsis.
Includes bibliographical references.
In recent years, many Evolutionary Algorithms (EAs) such as Genetic Algorithms (GAs) have been proposed to optimally tune the parameters of the PSS. GAs are population based search methods inspired by the mechanism of evolution and natural genetic. Despite the fact that GAs are robust and have given promising results in many applications, they still have some drawbacks. Some of these drawbacks are related to the problem of genetic drift in GA which restricts the diversity in the population. ... To cope with the above mentioned drawbacks, many variants of GAs have been proposed often tailored to a particular problem. Recently, several simpler and yet effective heuristic algorithms such as Population Based Incremental Learning (PBIL) and Differential Evolution (DE), etc., have received increasing attention.

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Singh, Ravindra. "A Novel Approach for Tuning of Power System Stabilizer Using Genetic Algorithm." Thesis, Indian Institute of Science, 2004. https://etd.iisc.ac.in/handle/2005/3913.

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The problem of dynamic stability of power system has challenged power system engineers since over three decades now. In a generator, the electromechanical coupling between the rotor and the rest of the system causes it to behave in a manner similar to a spring mass damper system, which exhibits an oscillatory behaviour around the equilibrium state, following any disturbance, such as sudden change in loads, change in transmission line parameters, fluctuations in the output of turbine and faults etc. The use of fast acting high gain AVRs and evolution of large interconnected power systems with transfer of bulk power across weak transmission links have further aggravated the problem of low frequency oscillations. The oscillations, which are typically in the frequency range of 0.2 to 3.0 Hz, might be excited by the disturbances in the system or, in some cases, might even build up spontaneously. These oscillations limit the power transmission capability of a network and, sometimes, even cause a loss of synchronism and an eventual breakdown of the entire system. The application of Power System Stabilizer (PSS) can help in damping out these oscillations and improve the system stability. The traditional and till date the most popular solution to this problem is application of conventional power system stabilizer (CPSS). However, continual changes in the operating condition and network parameters result in corresponding change in system dynamics. This constantly changing nature of power system makes the design of CPSS a difficult task. Adaptive control methods have been applied to overcome this problem with some degree of success. However, the complications involved in implementing such controllers have restricted their practical usage. In recent years there has been a growing interest in robust stabilization and disturbance attenuation problem. H∞ control theory provides a powerful tool to deal with robust stabilization and disturbance attenuation problem. However the standard H∞ control theory does not guarantee robust performance under the presence of all the uncertainties in the power plants. This thesis provides a method for designing fixed parameter controller for system to ensure robustness under model uncertainties. Minimum performance required of PSS is decided a priori and achieved over the entire range of operating conditions. A new method has been proposed for tuning the parameters of a fixed gain power system stabilizer. The stabilizer places the troublesome system modes in an acceptable region in the complex plane and guarantees a robust performance over a wide range of operating conditions. Robust D-stability is taken as primary specification for design. Conventional lead/lag PSS structure is retained but its parameters are re-tuned using genetic algorithm (GA) to obtain enhanced performance. The advantage of GA technique for tuning the PSS parameters is that it is independent of the complexity of the performance index considered. It suffices to specify an appropriate objective function and to place finite bounds on the optimized parameters. The efficacy of the proposed method has been tested on single machine as well as multimachine systems. The proposed method of tuning the PSS is an attractive alternative to conventional fixed gain stabilizer design as it retains the simplicity of the conventional PSS and still guarantees a robust acceptable performance over a wide range of operating and system condition. The method suggested in this thesis can be used for designing robust power system stabilizers for guaranteeing the required closed loop performance over a prespecified range of operating and system conditions. The simplicity in design and implementation of the proposed stabilizers makes them better suited for practical applications in real plants.

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21

Singh, Ravindra. "A Novel Approach for Tuning of Power System Stabilizer Using Genetic Algorithm." Thesis, Indian Institute of Science, 2004. http://hdl.handle.net/2005/65.

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The problem of dynamic stability of power system has challenged power system engineers since over three decades now. In a generator, the electromechanical coupling between the rotor and the rest of the system causes it to behave in a manner similar to a spring mass damper system, which exhibits an oscillatory behaviour around the equilibrium state, following any disturbance, such as sudden change in loads, change in transmission line parameters, fluctuations in the output of turbine and faults etc. The use of fast acting high gain AVRs and evolution of large interconnected power systems with transfer of bulk power across weak transmission links have further aggravated the problem of low frequency oscillations. The oscillations, which are typically in the frequency range of 0.2 to 3.0 Hz, might be excited by the disturbances in the system or, in some cases, might even build up spontaneously. These oscillations limit the power transmission capability of a network and, sometimes, even cause a loss of synchronism and an eventual breakdown of the entire system. The application of Power System Stabilizer (PSS) can help in damping out these oscillations and improve the system stability. The traditional and till date the most popular solution to this problem is application of conventional power system stabilizer (CPSS). However, continual changes in the operating condition and network parameters result in corresponding change in system dynamics. This constantly changing nature of power system makes the design of CPSS a difficult task. Adaptive control methods have been applied to overcome this problem with some degree of success. However, the complications involved in implementing such controllers have restricted their practical usage. In recent years there has been a growing interest in robust stabilization and disturbance attenuation problem. H∞ control theory provides a powerful tool to deal with robust stabilization and disturbance attenuation problem. However the standard H∞ control theory does not guarantee robust performance under the presence of all the uncertainties in the power plants. This thesis provides a method for designing fixed parameter controller for system to ensure robustness under model uncertainties. Minimum performance required of PSS is decided a priori and achieved over the entire range of operating conditions. A new method has been proposed for tuning the parameters of a fixed gain power system stabilizer. The stabilizer places the troublesome system modes in an acceptable region in the complex plane and guarantees a robust performance over a wide range of operating conditions. Robust D-stability is taken as primary specification for design. Conventional lead/lag PSS structure is retained but its parameters are re-tuned using genetic algorithm (GA) to obtain enhanced performance. The advantage of GA technique for tuning the PSS parameters is that it is independent of the complexity of the performance index considered. It suffices to specify an appropriate objective function and to place finite bounds on the optimized parameters. The efficacy of the proposed method has been tested on single machine as well as multimachine systems. The proposed method of tuning the PSS is an attractive alternative to conventional fixed gain stabilizer design as it retains the simplicity of the conventional PSS and still guarantees a robust acceptable performance over a wide range of operating and system condition. The method suggested in this thesis can be used for designing robust power system stabilizers for guaranteeing the required closed loop performance over a prespecified range of operating and system conditions. The simplicity in design and implementation of the proposed stabilizers makes them better suited for practical applications in real plants.

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22

Fourie, Gert. "Power system stabilizer and controlled series capacitor small-signal stability performance analysis." Thesis, Stellenbosch : Stellenbosch University, 2002. http://hdl.handle.net/10019.1/53013.

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Thesis (MScEng)--University of Stellenbosch, 2002.
ENGLISH ABSTRACT: This thesis presents results of a study on the small-signal stability of a single-machine infinite-bus power system. Conditions of generator loading and network impedance are identified that require additional stability support. Two methods of stability enhancement are investigated, namely the power system stabilizer and the controlled series capacitor. Both stabilizers employ the conventional (classic) control structure, and parameters are evaluated for optimum performance using an integral-of-the-squared-error-based method. Results for damping capability versus generator loading and system impedance were generated. The ability of the power system stabilizer and controlled series capacitor to provide stability support is compared. This comparison is based on (a) the ability to provide more damping torque when needed, and (b) the amount of damping torque contributed by the stabilizer.
AFRIKAANSE OPSOMMING: Hierin word die resultate van 'n studie op die klein-sein stabiliteit van 'n enkel-masjien oneindige-bus kragstelsel weergegee. Kondisies van generator belasting en netwerk impedansie waar dempings-ondersteuning benodig word, word geïdentifiseer. Twee metodes van stabiliteits-verbetering word ondersoek, naamlik die kragstelstel stabiliseerder en die beheerde serie kapasitor. Beide stabiliseerders maak gebruik van die konvensionele (klassieke) beheerstruktuur, waarvan parameters geëvalueer word deur gebruik te maak van 'n integraal-van-die-vierkant-fout-gebaseerde metode. Resultate vir dempingsvermoë teenoor generator belasting en stelsel impedansie word verkry. Die vermoë van die kragstelsel stabiliseerder en beheerde serie kapasitor om stabiliteits-ondersteuning te verskaf, word vergelyk. Hierdie vergelyking is gebasseer op (a) die vermoë om meer dempingswrinkrag te voorsien wanneer benodig, en (b) die hoeveelheid dempingswrinkrag deur die stabiliseerder bygedra.

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23

ALBUQUERQUE, MARCOS ANTONIO. "DYNAMIC AGGREGATION OF DUAL-INPUT POWER SYSTEM STABILIZER MODELS TO CALCULATE DYNAMIC EQUIVALENTS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2002. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=3278@1.

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FURNAS CENTRAIS ELÉTRICAS S.A
Esta dissertação trata do problema da agregação dinâmica de modelos de estabilizadores com dupla entrada, aplicados em reguladores de tensão de unidades geradoras coerentes, visando o cálculo de equivalentes dinâmicos precisos para estudos de estabilidade transitória de sistemas de energia elétrica. A metodologia utilizada para o cálculo de equivalentes dinâmicos é baseada em coerência de geradores, e apresenta três etapas básicas: a identificação de unidades geradoras coerentes, a redução estática da rede externa, e a agregação dinâmica dos geradores de cada grupo formado. A agregação dinâmica de um grupo de unidades geradoras coerentes permite a formação de uma ou mais unidades geradoras equivalentes. Haverá um modelo equivalente para cada componente da unidade geradora, ou seja, modelos equivalentes de máquina síncrona, sistema de excitação, estabilizador, turbina e regulador de velocidade. O ajuste numérico dos parâmetros lineares da função de transferência equivalente é feito pelo método de Levenberg-Marquardt, de modo a minimizar o erro entre a resposta em freqüência desta função e a da função de transferência agregada, que representa a soma das funções de transferência individuais das unidades de cada grupo. Isto caracteriza um problema de otimização multivariável. As respostas em freqüência são apresentadas em diagramas de Bode (módulo e fase). A avaliação do desempenho dinâmico dos equivalentes é feita no sistema teste New England, comparando-se as curvas de oscilação dos geradores do sistema interno obtidas em simulações com a rede completa e com o equivalente. Os modelos de estabilizadores com dupla entrada utilizados são do banco de dados do sistema elétrico brasileiro.
This dissertation deals with the problem of dynamic aggregation of dualinput stabilizer models applied on voltage regulators of coherent generating units to calculate dynamic equivalents for power system transient stability studies. The methodology used for the calculation of coherency-based dynamic equivalents has three basic steps: the identification of the coherent groups of generating units, the network reduction and the dynamic aggregation of coherent generator models. The dynamic aggregation of a group of coherent generating units attached to a common busbar consists of the representation of this group by one or more equivalent generating units. There will be an equivalent model for each component of the generating unit, i.e., an equivalent model for the synchronous machine, other one for the excitation system, and so on. The linear parameters of the equivalent transfer function are numerically adjusted to match the frequency response of the corresponding aggregated transfer function which represents the sum of the individual transfer functions for each coherent group. This characterises a multivariable optimization problem. The frequency responses are presented in Bode diagrams (magnitude and phase). The dynamic equivalents are evaluated in the New England system. The swing curves of the internal system generators obtained with the complete system are compared with those obtained with the equivalent system. The dual-input power system stabilizer models considered in this work are in the Brazilian system stability database.

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24

Hrag, Margossian. "VALIDATION OF THE PSS/E MODEL FOR THE GOTLAND NETWORKR." Thesis, KTH, Elektriska energisystem, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-119577.

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The aim of the project is to revise the load flow and dynamic PSS/E models of the Gotland network and validate them against a set of measurements collected during a major disturbance, a three phase short circuit in the 70 kV system. The main task in revising the model is to convert the induction machine models of the wind turbines into user and manufacturer wind turbine models. The validation of the model is divided into two phases. The first is to use the measurements as well as some assumptions on the wind power generation and load distribution from the time of the fault to validate the dynamic behaviour of the system. The second is to use new measurements during a normal operation day. The latter would not be very helpful to illustrate the dynamic behaviour of the system, because of the lack of a major fault that would drastically affect the system, but it would nevertheless be useful to validate the load flow with greater accuracy.

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25

Delport, Jacques. "Synchronized Measurement of Machine Rotor Angle and Its Application." Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/51242.

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The internal voltage angle of a generator is an important parameter that indicates the stability, both transient and steady-state, of the generator. This paper proposes a method of measuring and synchronizing the internal angle using a microprocessor and an optical encoder installed on the shaft of a generator. With a synchronized angle measurement, accurate stability studies and wide-area controls can be implemented. The experimental setup for measuring the rotor angle of a generator is explained in this work. A wide-area power system stabilizer implementing the synchronized angle measurement is then investigated using a four machine, two-area system. A synchronized remote feedback rotor angle signal is included in a traditional stabilizer design. It is shown that this remote signal helps increase the stability of the system while also having the benefit of being able to be predicted accurately. This capability makes bad data detection and communication delay compensation possible.
Master of Science

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26

SOUZA, FABIO LUIZ DE. "DYNAMIC AGGREGATION OF POWER SYSTEM STABILIZER MODELS APPLIED IN VOLTAGE REGULATORS AND CALCULATION OF DYNAMIC EQUIVALENTS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1999. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=7314@1.

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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
O cálculo de equivalentes dinâmicos baseados em coerência apresenta três etapas básicas: a identificação de geradores coerentes, a redução estática da rede e a agregação dinâmica dos modelos das unidades geradoras coerentes. Esta dissertação trata do problema da agregação dinâmica de modelos de estabilizadores aplicados em reguladores de tensão de geradores coerentes, visando o cálculo de equivalentes dinâmicos precisos para estudos de estabilidade transitória de sistemas de energia elétrica. A determinação de um critério de escolha do melhor modelo equivalente, para uma dada composição de modelos de estabilizadores num grupo de geradores coerentes, é o objetivo principal. O ajuste dos parâmetros dos modelos equivalentes de estabilizadores dos grupos coerentes é realizado, a partir das respostas em freqüência dos modelos individuais de cada grupo, utilizando-se o método de Levenberg-Marquardt, o que caracteriza um problema de otimização multivariável. O desempenho dinâmico dos equivalentes calculados com a metodologia adotada é avaliado em um sistema teste.
The calculation of coherency-based dynamic equivalents has three main steps: the identification of coherent generators, the network reduction and the dynamic aggregation of the coherent generating unit models. This dissertation deals with the problem of dynamic aggregation of power system stabilizer models to calculate coherency-based dynamic equivalents for power system transient stability studies. The determination of a criteria to choose the best equivalent model for a given composition of power system stabilizer models in a group of coherent generators is the main objective. The parameters of the power system stabilizer equivalent models for each group of coherent generating units are adjusted to match the frequency response of the individual models. This multivariable optimization problem is solved using the Levenberg-Marquardt method. The dynamic performance of the equivalents is evaluated in a test system.

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27

Eriksson, Joel, and Englund Simon Gozdz. "Wind Power and Its Impact on the Moldovan Electrical System." Thesis, Uppsala universitet, Elektricitetslära, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-173725.

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The master thesis project has been executed with the cooperation of Borlänge Energi, with the aim of reducing the high electric energy dependency which Moldova has on Ukraine, Transnistria and Russia. The project examines what reduction that would be possible by wind power installations on the existing electrical grid of Moldova. The installations should not surpass the capacity of the transmission lines or the voltage levels according to regulation. The southern regions of Moldova proved to have the best wind conditions and the locations of Besarabeasca, Zarnesti, Leovo, Ciadyr and Cimislia in the southern region were chosen for wind power installations. For the analysis a model over the Moldovan electrical system is constructed. Each of the five chosen locations is modelled with a generator symbolizing the wind power installation. The power flow software PSS/E is used to construct the model. To examine possible wind power installations different scenarios are created. The scenarios are executed with the southern regions 110 kV system as a focus area. All scenarios are analysed with a contingency analysis, where transmission lines in the focus region are tripped. The contingency analysis and the scenarios are automated using the programming language Python. An economic analysis shows payback periods for wind power investments in Moldova, the analysis also shows the sensitivity of the electricity price and discount rates. The project concludes that wind power installations are possible with the Moldovan electric grid as it looks today. The installations would result in reducing the high dependency of imported electrical energy.

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28

Andersson, Stefan, and Andreas Johansson. "Tillämpning av effektstabilisering i PLC." Thesis, Karlstad University, Faculty of Technology and Science, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-1717.

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Syftet med examensarbetet är att digitalt tillämpa en stabilisering av pendlingar i den aktiva effekten hos en synkrongenerator för vattenkraft kopplad till ett distributionsnät.

Implementeringen är tänkt att ske i en PLC som redan hanterar andra delar av magnetiseringen.

Effektstabiliseringen görs genom att en motverkande styrsignal skickas till magnetiseringsutrustningen vilken i sin tur påverkar generatorns uteffekt. Denna motverkande styrsignal kan tas fram på olika sätt.

Två modeller, av IEEE standardiserade, för effektstabilisering undersöks, PSS1A och PSS2B.

En Simulink-modell över ett distributionsnät med generator byggs upp för att testa effektstabiliseringen.

Diskretisering av den ena standarden utförs för att digital implementering ska kunna ske. Tester utförs även på denna modell för att kunna validera dess funktion i jämförelse med den kontinuerliga.

Den tidsdiskreta modellen görs om till ett matematiskt uttryck tillämpbart i PLC:n.

Jämförelse sker mellan simuleringarna och den tillämpade modellen genom mätningar.

The purpose of the degree project is to make a digital realization of a stabilizer for oscillations in the active power from a hydropower synchronous generator, connected to a power network.

The implementation is supposed to be done in a PLC which already handles part of the excitation system.

The power stabilization is achieved by sending a counteracting reference signal to the excitation system which controls the generator’s output power. This counteracting signal can be achieved in several ways.

Two existing models, standardized by IEEE, for power system stabilizing will be examined, PSS1A and PSS2B.

A Simulink-model of a distribution net with a generator is constructed to test the stabilizers.

To perform a digital implementation a discrete transformation of one continuous model is done. This discrete model is also tested to verify the function in comparison to the continuous one.

The discrete model is reorganized in a form possible to implement in the PLC.

Comparison between the simulated and the implemented model is made by measurement.

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Gianto, Rudy. "Coordination of power system controllers for optimal damping of electromechanical oscillations." University of Western Australia. School of Electrical, Electronic and Computer Engineering, 2008. http://theses.library.uwa.edu.au/adt-WU2009.0056.

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This thesis is devoted to the development of new approaches for control coordination of PSSs (power system stabilisers) and FACTS (flexible alternating current transmission system) devices for achieving and enhancing small-disturbance stability in multi-machine power systems. The key objectives of the research reported in the thesis are, through optimal control coordination of PSSs and/or FACTS devices, those of maintaining satisfactory power oscillation damping and secure system operation when the power system is subject to persisting disturbances in the form of load demand fluctuations and switching control. Although occurring less frequently, fault disturbances are also considered in the assessment of the control coordination performance. Based on the constrained optimisation method in which the eigenvalue-based objective function is minimised to identify the optimal parameters of power system damping controllers, the thesis first develops a procedure for designing the control coordination of PSSs and FACTS devices controllers. The eigenvalue-eigenvector equations associated with the selected electromechanical modes form a set of equality constraints in the optimisation. The key advance of the procedure is that there is no need for any special software system for eigenvalue calculations, and the use of sparse Jacobian matrix for forming the eigenvalue-eigenvector equations leads to the sparsity formulation which is essential for large power systems. Inequality constraints include those for imposing bounds on the controller parameters. Constraints which guarantee that the modes are distinct ones are derived and incorporated in the control coordination formulation, using the property that eigenvectors associated with distinct modes are linearly independent. The robustness of the controllers is achieved very directly through extending the sets of equality constraints and inequality constraints in relation to selected eigenvalues and eigenvectors associated with the state matrices of power systems with loading conditions and/or network configurations different from that of the base case. On recognising that the fixed-parameter controllers, even when designed with optimal control coordination, have an inherent limitation which precludes optimal system damping for each and every possible system operating condition, the second part of ii the research has a focus on adaptive control techniques and their applications to power system controllers. In this context, the thesis reports the development of a new design procedure for online control coordination which leads to adaptive PSSs and/or supplementary damping controllers (SDCs) of FACTS devices for enhancing the stability of the electromechanical modes in a multi-machine power system. The controller parameters are adaptive to the changes in system operating condition and/or configuration. Central to the design is the use of a neural network synthesised to give in its output layer the optimal controller parameters adaptive to system operating condition and configuration. A novel feature of the neural adaptive controller is that of representing the system configuration by a reduced nodal impedance matrix which is input to the neural network.

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30

Taddia, Antonio. "Analisi modale per lo studio della stabilità alle piccole oscillazioni nei sistemi elettrici di potenza." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020.

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La tesi affronta il tema della stabilità dei sistemi elettrici di potenza, in particolare concentrandosi sullo studio della stabilità alle piccole oscillazioni e sul ruolo che i modi oscillatori elettromeccanici giocano in essa. Lo strumento principe per tale studio è l’analisi modale del sistema, che in questa tesi viene effettuata tramite il toolbox per MATLAB “Power System Toolbox” (PST). Oltre all’analisi dei modi di oscillazione, questo pacchetto di funzioni permette di eseguire simulazioni nel tempo dei sistemi in esame, per poterne osservare il comportamento in seguito a guasti o a particolari transitori. La tesi tratta anche il miglioramento della stabilità tramite dispositivi denominati Power System Stabilizer (PSS) che agiscono sui sistemi di eccitazione degli alternatori. Per questa analisi viene impiegato lo “State Space Toolbox” (SST), compatibile con PST. In particolare, viene descritta e implementata la tecnica di dimensionamento dei PSS basata sullo studio dei fattori di partecipazione delle velocità dei rotori nei modi oscillatori elettromeccanici e i risultati ottenuti sono verificati tramite simulazioni nel tempo. Nell’ambito della tesi sono state sviluppate nuove funzioni che, operando in armonia con quelle dei pacchetti software sopramenzionati, permettono di espandere le funzionalità di PST e SST e ne facilitano l’uso.

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31

Ekstrand, Christian, and Farsad Mansori. "Stability Related Issues for High Wind Power Penetration : Exploring possibilities to enhance grid stability from synthetic inertia in a future scenario." Thesis, Linnéuniversitetet, Institutionen för fysik och elektroteknik (IFE), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-96442.

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The future global energy transition favour renewables such as wind power, which is predicted to be one of the predominant sources harvesting abundant amounts of energy onwards. Consequently, causing several conventional synchronous generators to be decommissioned in a near future to achieve an overall reduction in greenhouse gases related to electricity generation. However, this evolution comes with new challenges regarding power system stability that could jeopardize the reliability of the grid as we today know it. Therefore, this thesis will examine how high penetrations of wind power are impacting each fundamental criterion regarding power system stability. For this purpose, are two different scenarios being carried out in Siemens PSS/E, representing a futuristic case as well as a present one. The simulation results themselves are being compared with analogies drawn from previous studies conducted within the field to determine if it can be improved.

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32

Kook, Kyung Soo Soo. "Dynamic Model Based Novel Findings in Power Systems Analysis and Frequency Measurement Verification." Diss., Virginia Tech, 2007. http://hdl.handle.net/10919/27761.

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This study selects several new advanced topics in power systems, and verifies their usefulness using the simulation. In the study on ratio of the equivalent reactance and resistance of the bulk power systems, the simulation results give us the more correct value of X/R of the bulk power system, which can explain why the active power compensation is also important in voltage flicker mitigation. In the application study of the Energy Storage System(ESS) to the wind power, the new model implementation of the ESS connected to the wind power is proposed, and the control effect of ESS to the intermittency of the wind power is verified. Also this study conducts the intensive simulations for clarifying the behavior of the wide-area power system frequency as well as the possibility of the on-line instability detection. In our POWER IT Laboratory, since 2003, the U.S. national frequency monitoring network (FNET) has been being continuously operated to monitor the wide-area power system frequency in the U.S. Using the measured frequency data, the event of the power system is triggered, and its location and scale are estimated. This study also looks for the possibility of using the simulation technologies to contribute the applications of FNET, finds similarity of the event detection orders between the frequency measurements and the simulations in the U.S. Eastern power grid, and develops the new methodology for estimating the event location based on the simulated N-1 contingencies using the frequency measurement. It has been pointed out that the simulation results can not represent the actual response of the power systems due to the inevitable limit of modeling power systems and different operating conditions of the systems at every second. However, in the circumstances that we need to test such an important infrastructure supplying the electric energy without taking any risk of it, the software based simulation will be the best solution to verify the new technologies in power system engineering and, for doing this, new models and better application of the simulation should be proposed. Conducting extensive simulation studies, this dissertation verified that the actual X/R ratio of the bulk power systems is much lower than what has been known as its typical value, showed the effectiveness of the ESS control to mitigate the intermittence of the wind power from the perspective of the power grid using the newly proposed simulation model of ESS connected to the wind power, and found many characteristics of the wide-area frequency wave propagation. Also the possibility of using the simulated responses of the power system for replacing the measured data could be confirmed and this is very promising to the future application of the simulation to the on-line analysis of the power systems based on the FNET measurements.
Ph. D.

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33

Tomaszewski, Michal. "Reactive power management capabilities of Swedish sub-transmission and medium voltage level grid." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-240411.

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Rising penetration of renewable energy sources in electric power grids isboth a challenge and an opportunity to optimally utilize the potential of eitherwind or PV energy sources, to stabilize operation of future power systems.Bi-directional ows between distribution and transmission system operatorscause signicant problems with keeping the voltages in the grid within admissiblelimits. This paper contains description of Oland's island mediumandlow-voltage electric power grid, ranging from 0.4 kV to 130 kV in thepurpose of quasi-static analysis of active and reactive power ows in the system.Goal of the analysis is to optimize reactive power exchange at the pointof connection with the mainland grid. In the analyzed grid system, thereis an enormous, 190 % penetration of wind sources. Capacity of the windparks connected to dedicated buses totals to 136.1 MW, that supply up to90.5 MW of load. With industry-wise reactive power capability limits, totalcontribution of wind parks reaches almost 66 MVAr, enabling to compensatedecits and extra surpluses of the reactive power in the grid. Presentedsystem is connected to the mainland's grid through one point of connection,which is simulated as Thevenin equivalent circuit. Main objective of thethesis is to test and analyze viable solutions to minimize reactive power exchangeat the point of connection at Stavlo substation connecting Oland'sand Sweden's electric grid keeping valid all necessary contingencies enforcedby current grid codes applied in Sweden as well as thermal limits of the linesand voltage limits of the system. Furthermore, state of the art of currentreactive power compensation methodologies and most promising techniquesto eciently and eectively control reactive power ow are outlined. Droopcontrol methodologies, with focus on global and local objectives, and smartgrid solutions opportunities are being tested and modeled by the authors andare comprehensively presented in this paper. Moreover, economic costs ofcontrol methods are compared. Analysis of active power losses in the systemas well as cost of implementation of alternative solutions is presented, wheremost nancially viable solutions are outlined, giving brief outlook into futureperspectives and challenges of electric power systems. It is shown that controllabilityof reactive power support by wind turbine generators can enhanceoperation of electric power grids, by keeping the reactive power ow minimizedat the boundary between grids of distribution and transmission systemoperators. Furthermore, results indicate that extra reactive power supportby wind turbine generators can lead to diminishment of active power losses inthe system. Presented system is being modeled in the PSS/E software dedicatedfor power system engineers with use of Python programming languages.Analysis of data was done either in Python or R related environments. Thesiswas written with cooperation between KTH and E.On Energidistribution AB.
Hogre genomslagskraft av förnyelsebara energikällor i elnäteten är bådeen utmaning och möjlighet för att optimalt kunna utnyttja potentialen av vindkraft och PV källor, med avseende på att stabilisera driften av framtida elkraftsystem. Tvåvägsflöden mellan distributionoch transmissionsoperatörer orsakar betydande problem att hålla spänningen i nätet inom tillåtna gränsvärden.Denna uppsats innehåller en beskrivning av Ö lands mellanoch lågspänningsnät,på 0.4 kV till 130 kV i syftet att utföra en kvasistatisk analys av aktiva och reaktiva effektflöden i systemet. Målet med analysen är att optimera det reaktiva effektutbytet i kopplingspunkten med fastlandets nät. I det analyserade systemet, finns det en enorm potential på 190% genomslagskraft av vindkraft. Kapaciteten på vindkraftsparker kopplade till medtagna samlingsskenor i systemet uppgår till 136,1 MW, som tillgodoser upp till 90.5 MW last. Med industrimässigt begränsad reaktiv effektkapabilitet, uppgår vindkraftsparkernas bidrag till nästan 66 MVAr, vilken möjliggör kompensation för underskott och överskott av reaktiv effekt i nätet. Det presenterade systemet är kopplat till fastlandet genom en kopplingspunkt, där fastlandet är simulerat som en Thevenin ekvivalent. Huvudsakliga målet med denna uppsats är att testa och analysera gångbara lösningar för att minimera det reaktiva effektutbytet vid kopplingspunkten i Stävlö, som kopplar ihop Ö land med resterande nät i Sverige, samtidigt som alla nödvändiga villkor enligt nuvarande nätkoder i Sverige bibehålls, liksom termiska gränser för ledningarna och spanningsgränser för systemet. Ytterligare beskrivs den bästa tillgängliga tekniken som finns idag för reaktiv effektkompensation, och de mest lovande teknikerna för att effektivt och verkningsfullt kontrollera reaktiva effektflöden. Droop-kontroll-metodologier, med fokus på globala och lokala tillämpningar, och smarta nät-möjligheter testas och modelleras av författarna och presenterar djupgående i detta arbete. Dessutom jämförs ekonomiska kostnader för olika kontrollmetoder. Analyser av aktiva effektförluster i systemet samt kostnader för implementation av alternativa lösningar presenteras, där de flesta gångbara losningar behandlas, och ger en överskådlig bild av framtida perspektiv och utmaningar i elkraftsystemet. Det visas att vindturbiners kontroll av reaktiv effekt, kan förbättra driften av elnäten, genom att minimera det reaktiva effektflödesutbytet i gränsen mellan distributionoch transmissionsoperatörers nät. Ytterligare pekar resultat på att extra understöd av reaktiv effekt från vindturbiner kan leda till förminskning av aktiva förluster i systemet. Det presenterade systemet modelleras i mjukvaruprogrammet PSS/E dedikerat för elkraftsingenjörer med hjälp av Python. Analys av data gjordes antingen i Pythoneller R-relaterade miljöer. Detta arbete har gjorts tillsam-mans med KTH och E.ON Energidistribution AB.

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34

Zanchin, Volnei Tonin. "Projetos de controladores para sistemas de potência utilizando LMI'S." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2003. http://hdl.handle.net/10183/6000.

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A presente dissertação tem como objetivo estudar e aprimorar métodos de projetos de controladores para sistemas de potência, sendo que esse trabalho trata da estabilidade dinâmica de sistemas de potência e, portanto, do projeto de controladores amortecedores de oscilações eletromecânicas para esses sistemas. A escolha dos métodos aqui estudados foi orientada pelos requisitos que um estabilizador de sistemas de potência (ESP) deve ter, que são robustez, descentralização e coordenação. Sendo que alguns deles tiveram suas características aprimoradas para atender a esses requisitos. A abordagem dos métodos estudados foi restringida à análise no domínio tempo, pois a abordagem temporal facilita a modelagem das incertezas paramétricas, para atender ao requisito da robustez, e também permite a formulação do controle descentralizado de maneira simples. Além disso, a abordagem temporal permite a formulação do problema de projeto utilizando desigualdades matriciais lineares (LMI’s), as quais possuem como vantagem o fato do conjunto solução ser sempre convexo e a existência de algoritmos eficientes para o cálculo de sua solução. De fato, existem diversos pacotes computacionais desenvolvidos no mercado para o cálculo da solução de um problema de inequações matriciais lineares. Por esse motivo, os métodos de projeto para controladores de saída buscam sempre colocar o problema na forma de LMI’s, tendo em vista que ela garante a obtenção de solução, caso essa solução exista.
The current work aims to study and improve the power system controllers design methods. And we are interested in the dynamic stability of power systems, and thus, in the design of electromechanical oscillations damping controllers. The design methods studied here were chosen to fill the requirements that a power system stabilizer (PSS) must obey, that are robustness, decentralization and coordination. And the characteristics of some of these methods were improved and extended in order to meet these requirements. The approach of the studied methods is restricted to the time domain analysis because of the easiness to model the parametric uncertainties, to meet the robustness requirement, and because it also simplifies the formulation of the decentralized control problem. Moreover the time domain approach allows one to use linear matrix inequalities (LMI’s) to formulate the design problem, which has the advantages that the solution set is always convex, and that there exists efficient algorithms to compute its solution. There are several software packages developed, in the market, to solve the problem of linear matrix inequality. So that the design methods using output controllers always try to formulate this problem in the form of an LMI, because it guarantees that one can obtain a solution for the problem, in the case that this solution exists.

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35

Sochor, Tomáš. "Návrh systému chránění distribuční sítě VN." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2019. http://www.nusl.cz/ntk/nusl-400597.

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The master´s thesis deals with the design of medium voltage power line protection and the calculation of reliability indicators. First, it deals with the possibilities of power system operation. Subsequently, it divides the networks according to the grounding of the transformer node and the switching elements and devices occurring in the MV distribution network are mentioned. It presents the basic classification of power line protection and its use, especially it focuses on overhead and cable MV power lines. It also discusses the reliability of the power supply and lists the basic reliability indicators and their possible calculation. The practical part describes the changes in the considered area of the distribution network, where the reconstruction of the power line VN872 and a new way of powering the village Drnholec will take place. The impact of this change on the reliability of the supplied energy is also calculated. Furthermore, the protection of the power line is designed and the correctness of its setting is then verified on the model in the PSS Sincal software.

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36

Sohn, Alexandre Prodóssimo. "Estudos de estabilidade de sistemas elétricos de potência na presença de diferentes modelos de unidades eólicas." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/18/18154/tde-18032014-132419/.

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Diante da crescente penetração da energia elétrica gerada por unidades eólicas no sistema elétrico de inúmeros países, a presente dissertação de mestrado investiga os problemas de estabilidade transitória, para geradores síncronos, de estabilidade de tensão, para geradores síncronos e aerogeradores e de estabilidade de velocidade, para aerogeradores, em sistemas de transmissão de energia elétrica, frente a grandes perturbações. São estabelecidas comparações entre os diferentes comportamentos dinâmicos de cada tipo de unidade eólica, referentes aos tipos A, B, C e D. Também, são verificados os efeitos de contingências aplicadas a sistemas teste, na presença de sistemas de geração convencionais dotados de geradores síncronos e parques eólicos compostos pelos tipos de unidades eólicas citadas, a fim de verificar a relação entre os diferentes sistemas de geração. As simulações realizadas contemplam aspectos dinâmicos de modelos genéricos de aerogeradores. São estudadas as partes constituintes de aerogeradores, realizadas as modelagens e discutidos os métodos de controle usuais. As principais características dos modelos genéricos de unidades eólicas, assim como os respectivos diagramas de bloco para cada modelo são apresentados. As simulações são realizadas no programa computacional PSS/E, cujos modelos, já validados, representam aerogeradores reais de fabricantes distintos. É observado que as diferentes características dos modelos de unidades eólicas e as estratégias de controle empregadas para atenuar os efeitos negativos de contingências impostas ao sistema, influenciam significativamente o perfil da tensão e o fluxo de potência na rede elétrica. Este fato é refletido em diferentes respostas dos sistemas de geração. As unidades eólicas mostram-se resistentes à perderem a estabilidade e apresentam-se capazes de estabilizar um sistema elétrico de potência, devido aos mecanismos de controle de velocidade e potência dos mesmos. A violação da curva LVRT mostra-se a principal causa da desconexão de aerogeradores da rede elétrica. Verifica-se neste trabalho que os aerogeradores somente tornam-se instáveis quando os geradores síncronos perdem o sincronismo, ou quando o controle do torque aerodinâmico é desconsiderado.
Considering the growing penetration of electrical energy generated by wind turbines in the power system of numerous countries, the present masters dissertation investigates the problems of transient stability, for synchronous generators, voltage stability, for synchronous generators and aerogenerators, and velocity stability, for aerogenerators, in transmission systems, before large disturbances. Comparisons are made between the different dynamic behaviors of each type of wind energy conversion system, namely types A, B, C and D. The effects of contingencies in some test systems in the presence of wind farms with different types of aerogenerators and conventional synchronous generators are verified, whose aim of the simulations is to analyze the relation between the different generation systems. The simulations performed contemplate dynamic aspects of generic models of wind turbines. The components of wind turbines are studied, the modeling of these components is elaborated and the usual control methods are discussed. The main characteristics of generic wind models and the diagram blocks are presented. The simulations were performed in software PSS/E, whose models already validated, represent real machines. The different characteristics of aerogenerator models and the control strategies employed to mitigate the negative consequences, from several contingencies, significantly influence the voltage profile and the power flow network. This fact implies in different responses of generation systems. It is verified that wind generators are very robust to perturbations and contribute to the stabilization of synchronous generators in a power system, increasing the average critical clearing times. Unstable modes related to the acceleration of the wind generator rotor are hardly ever observed due to the existing mechanisms of control of speed and generated power. It is observed that violation of the LVRT curve is the main cause of disconnection of wind turbines from the grid and it consists of the main cause of power system collapse triggered by problems in this type of generators.

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37

JÃnior, JosÃ Nilo Rodrigues da Silva. "Sintonia Ãtima de Regulador AutomÃtico de TensÃo e Estabilizador de Sistema de PotÃncia Utilizando Algoritmo de OtimizaÃÃo por Enxame de PartÃculas." Universidade Federal do CearÃ, 2012. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=8831.

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nÃo hÃ
Este trabalho apresenta a aplicaÃÃo do algoritmo de OtimizaÃÃo por Enxame de PartÃculas (PSO â Particle Swarm Optimization) para sintonia Ãtima de controladores associados Ã regulaÃÃo de tensÃo e ao aumento do amortecimento de geradores sÃncronos utilizados em plantas termelÃtricas de ciclo combinado. Para representaÃÃo matemÃtica do gerador sÃncrono, utiliza-se o modelo linearizado de terceira ordem do sistema mÃquina conectada a uma barra infinita, vÃlido para estudos de estabilidade a pequenos sinais. Os parÃmetros do regulador automÃtico de tensÃo (AVR â Automatic Voltage Regulator) e do estabilizador de sistema de potÃncia (PSS â Power System Stabilizer) sÃo determinados de maneira Ãtima pela ferramenta computacional proposta. Os parÃmetros obtidos para o AVR e PSS sÃo comparados com valores calculados por tÃcnicas de sintonia convencionais, baseadas em aproximaÃÃes das equaÃÃes que descrevem o sistema. Os resultados de simulaÃÃes a variaÃÃes na tensÃo de referÃncia, considerando a anÃlise da resposta temporal do sistema controlado, demonstram que o PSO Ã uma tÃcnica eficiente na sintonia dos parÃmetros do AVR e PSS, destacando-se sua simplicidade, baixo esforÃo computacional e boa caracterÃsticas de convergÃncia.
This work presents the application of the Particle Swarm Optimization (PSO) algorithm for optimal tuning of controllers associated with voltage regulation and damping enhancement of synchronous generators used in combined cycle power station. For mathematic representation of the synchronous generator, the third order linearized model of a single machine connected to an infinite bus, valid for small signal stability studies, is used. The Automatic Voltage Regulator (AVR) and Power System Stabilizer (PSS) parameters are optimally determined by the proposed computational tool. The parameters obtained for AVR and PSS are compared with values calculated by conventional tuning techniques based on approximations of the equations that describe the system. The simulations results to reference voltage disturbances, considering the time response analysis of the controlled system, show that PSO is an efficient technique in the tuning of AVR and PSS parameters, with emphasis on its simplicity, low computational effort and good convergence characteristics.

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38

Munukuntla, Sowmya. "Sensitivity Analysis of Synchronous Generators for Real-Time Simulation." ScholarWorks@UNO, 2016. http://scholarworks.uno.edu/td/2172.

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The purpose of this thesis is to validate generator models for dynamic studies of power systems using PSS/E (Power System Simulator for Engineering), EMTP (ElectroMagnetic Transient Program), and Hypersim. To thoroughly evaluate the behavior of a power system in the three specified software packages, it is necessary to have an accurate model for the power system, especially the generator which is of interest. The effect of generator modeling on system response under normal conditions and under faulted conditions is investigated in this work. A methodology based on sensitivity analysis of generator model parameters is proposed aiming to homogenize the behavior of the same power system that is modeled in three software packages. Standard IEEE 14-Bus system is used as a test case for this investigation. Necessary changes in the exciter parameters are made using the proposed methodology so that the system behaves identical across all three software platforms.

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39

Rajak, Suman Kumar. "Design of Power System Stabilizer (PSS) for small signal stability analysis of Power system." Thesis, 2017. http://ethesis.nitrkl.ac.in/8905/1/2017_MT_SKRajak.pdf.

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The modern power system is large network consisting of various types of interconnected electrical components. The main intention of installing such components is to produce and deliver with optimum efficiency and uninterruptedly. Now along with electrical components their also present fast behaving electronic components like components present in excitation system of alternator. This leads to mechanical & electrical resonances end up with oscillations in the network. This low frequency oscillations or often referred as small signal disturbances is to be reduced in order to get better overall performance. Here the PSS comes into picture which provide addl. signal to VR to damp out this oscillations. Here different design aspects of PSS & AVR has been presented. These design are broadly classified as conventional(CPSS) and non-conventional technique. Although many design approaches are there in conventional techniques here only three out of them is presented. They are Root Locus Technique, Bode Plot Technique, State space techniques. Among non-conventional approaches only ANFIS based controller design is presented here. The conventional approaches uses transfer function model applicable for highly linearized system whereas the non-conventional approach is also applicable for nonlinear systems. In each case the Automatic Voltage Regulator (AVR) and Power System Stabilizer (PSS) design method is presented separately and results are shown separately.

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40

Gurrala, Gurunath. "Power System Stabilizing Controllers - Multi-Machine Systems." Thesis, 2010. https://etd.iisc.ac.in/handle/2005/1986.

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Electrical Power System is one of the most complex real time operating systems. It is probably one of the best examples of a large interconnected nonlinear system of varying nature. The system needs to be operated and controlled with component or system problems, often with combinatorial complexity. In addition, time scales of operation and control can vary from milliseconds to minutes to hours. It is difficult to maintain such a system at constant operating condition due to both small and large disturbances such as sudden change in loads, change in network configuration, fluctuations in turbine output, and various types of faults etc. The system is therefore affected by a variety of instability problems. Among all these instability problems one of the important modes of instability is related to dynamic instability or more precisely the small perturbation oscillatory instability. Oscillations of small magnitude and low frequency (in the range of 0.1Hz to 2.5Hz) could persist for long periods, limiting the power transfer capability of the transmission lines. Power System Stabilizers (PSS) were developed as auxiliary controllers on the excitation system to improve the system damping performance by modulating the generator excitation voltage. However, the synthesis of an effective PSS for all operating conditions still remains a difficult and challenging task. The design and tuning of PSS for robust operation is a laborious process. The existing PSS design techniques require considerable expertise, the complete system information and extensive eigenvalue calculations which increases the computational burden as the system size increases. Conventional automatic voltage regulator (AVR) and PSS designs are based on linearized models of power systems which fail to stabilize the system over a wide range of operating conditions. In the last decade or so, a variety of nonlinear control techniques have become available. In this thesis, an attempt is made to explore the suitability of some of these design techniques for designing excitation controllers to enhance small perturbation stability of power systems over a wide range of operating and system conditions. This thesis first proposes a method of designing power system stabilizers based on local measurements alone, in multi-machine systems. Next, a method has been developed to analyze and quantify the small signal performance benefits of replacing the existing AVR+PSS structure with nonlinear voltage regulators. A number of new nonlinear controller designs have been proposed subsequently. These include, (a) a new decentralized nonlinear voltage regulator for multi machine power systems with a single tunable parameter that can achieve effective trade of between both the voltage regulation and small signal objectives, (b) a decentralized Interconnection and Damping Assignment Passivity Based Controller in addition to a proportional controller that can achieve all the requirements of an excitation system and (c) a Nonlinear Quadratic Regulator PSS using Single Network Adaptive Critic architecture in the frame work of approximate dynamic programming. Performance of all the proposed controllers has been analyzed using a number of multi machine test systems over a range of operating conditions.

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41

Gurrala, Gurunath. "Power System Stabilizing Controllers - Multi-Machine Systems." Thesis, 2010. http://etd.iisc.ernet.in/handle/2005/1986.

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Electrical Power System is one of the most complex real time operating systems. It is probably one of the best examples of a large interconnected nonlinear system of varying nature. The system needs to be operated and controlled with component or system problems, often with combinatorial complexity. In addition, time scales of operation and control can vary from milliseconds to minutes to hours. It is difficult to maintain such a system at constant operating condition due to both small and large disturbances such as sudden change in loads, change in network configuration, fluctuations in turbine output, and various types of faults etc. The system is therefore affected by a variety of instability problems. Among all these instability problems one of the important modes of instability is related to dynamic instability or more precisely the small perturbation oscillatory instability. Oscillations of small magnitude and low frequency (in the range of 0.1Hz to 2.5Hz) could persist for long periods, limiting the power transfer capability of the transmission lines. Power System Stabilizers (PSS) were developed as auxiliary controllers on the excitation system to improve the system damping performance by modulating the generator excitation voltage. However, the synthesis of an effective PSS for all operating conditions still remains a difficult and challenging task. The design and tuning of PSS for robust operation is a laborious process. The existing PSS design techniques require considerable expertise, the complete system information and extensive eigenvalue calculations which increases the computational burden as the system size increases. Conventional automatic voltage regulator (AVR) and PSS designs are based on linearized models of power systems which fail to stabilize the system over a wide range of operating conditions. In the last decade or so, a variety of nonlinear control techniques have become available. In this thesis, an attempt is made to explore the suitability of some of these design techniques for designing excitation controllers to enhance small perturbation stability of power systems over a wide range of operating and system conditions. This thesis first proposes a method of designing power system stabilizers based on local measurements alone, in multi-machine systems. Next, a method has been developed to analyze and quantify the small signal performance benefits of replacing the existing AVR+PSS structure with nonlinear voltage regulators. A number of new nonlinear controller designs have been proposed subsequently. These include, (a) a new decentralized nonlinear voltage regulator for multi machine power systems with a single tunable parameter that can achieve effective trade of between both the voltage regulation and small signal objectives, (b) a decentralized Interconnection and Damping Assignment Passivity Based Controller in addition to a proportional controller that can achieve all the requirements of an excitation system and (c) a Nonlinear Quadratic Regulator PSS using Single Network Adaptive Critic architecture in the frame work of approximate dynamic programming. Performance of all the proposed controllers has been analyzed using a number of multi machine test systems over a range of operating conditions.

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42

Ajit, Kumar *. "Design Of Robust Power System Damping Controllers For Interconnected Power Systems." Thesis, 2010. https://etd.iisc.ac.in/handle/2005/1653.

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Small signal oscillation has been always a major concern in the operation of power systems. In a generator, the electromechanical coupling between the rotor and the rest of the system causes it to behave in a manner similar to a spring mass damper system, which exhibits an oscillatory behaviour around the equilibrium state, following any disturbance, such as sudden change in loads, ﬂuctuations in the output of turbine and faults etc. The use of fast acting high gain AVRs and evolution of large interconnected power systems with transfer of bulk power across weak transmission links have further aggravated the problem of these low frequency oscillations. Small oscillations in the range of about 0.1Hz to 3.5Hz can persist for long periods, limiting the power transfer capability of the transmission lines. Power System Stabilizers (PSS’s) were developed as auxiliary controllers on the generators excitation system to produce additional damping by modulating the generator excitation voltage. Designing eﬀective PSS for all operating conditions specially in large interconnected power systems still remains a difficult and challenging task. The conventionally designed Power System Stabilizer (CPSS) is the most cost-eﬀective electromechanical damping controller till date. However, continual changes in the operating condition and network parameters in large systems result in corresponding large changes in system dynamics. This constantly changing nature of power system makes the design of CPSS a diﬃcult task. The design and tuning of PSS for robust operation is a laborious process. The existing PSS design techniques require considerable expertise, the complete system information and extensive eigenvalue calculations which increases the computational burden as the system size increases. This thesis proposes a method for designing robust power system damping controllers that ensures a minimum robustness under model uncertainties. The minimum performance required for the PSS is set a priori and accomplished over a range of operating conditions. A generalized robust controller design methodology has been ﬁrst implemented on a Single Machine Inﬁnite Bus (SMIB) power system model. The robust controller places the closed loop rotor modes of the system to the desire location while keeping the electrical modes intact. Unlike conventional lead/lag PSS design, the proposed PSS design is based on pole assignment technique which takes into account of various model uncertainties. For the proposed stabilizer design in a multi-machine systems a new decentralized method has been used which requires system data only upto secondary bus of the unit transformer in a generating station. The proposed robust controller design based on modiﬁed Nevanlinna-Pick theory has been designed and tested extensively on SMIB and multi-machine systems to establish the eﬃcacy of the controller in damping small signal oscillations. The thesis is organized in four chapters as follows. The ﬁrst chapter discusses the basic concepts related to the rotor angle stability in power system. The conventional and other methods of countering this instability by power system stabilizers have been described. The relative merits of the various stabilization techniques have been discussed. The scope of present work, i.e design of decentralized robust power system controllers has been deﬁned. In second chapter a modiﬁed robust power system stabilizer for SMIB system is developed. It has been shown that under speciﬁc conditions the modiﬁed Nevanlinna-Pick theory can also be applied for designing damping controllers in system with lightly damped rotor modes. Third chapter proposes a decentralized approach based on modiﬁed Nevanlinna-Pick theory for designing a power system stabilizer for interconnected power systems. The performance of the controller which is not based on external system information has been investigated on three widely used multi-machine test systems to established its eﬃcacy in damping out low frequency oscillations. The fourth chapter gives a brief summary of the work done and also includes a section on the scope of future work relating to design of power system stabilizers.

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43

Ajit, Kumar *. "Design Of Robust Power System Damping Controllers For Interconnected Power Systems." Thesis, 2010. http://etd.iisc.ernet.in/handle/2005/1653.

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Abstract:

Small signal oscillation has been always a major concern in the operation of power systems. In a generator, the electromechanical coupling between the rotor and the rest of the system causes it to behave in a manner similar to a spring mass damper system, which exhibits an oscillatory behaviour around the equilibrium state, following any disturbance, such as sudden change in loads, ﬂuctuations in the output of turbine and faults etc. The use of fast acting high gain AVRs and evolution of large interconnected power systems with transfer of bulk power across weak transmission links have further aggravated the problem of these low frequency oscillations. Small oscillations in the range of about 0.1Hz to 3.5Hz can persist for long periods, limiting the power transfer capability of the transmission lines. Power System Stabilizers (PSS’s) were developed as auxiliary controllers on the generators excitation system to produce additional damping by modulating the generator excitation voltage. Designing eﬀective PSS for all operating conditions specially in large interconnected power systems still remains a difficult and challenging task. The conventionally designed Power System Stabilizer (CPSS) is the most cost-eﬀective electromechanical damping controller till date. However, continual changes in the operating condition and network parameters in large systems result in corresponding large changes in system dynamics. This constantly changing nature of power system makes the design of CPSS a diﬃcult task. The design and tuning of PSS for robust operation is a laborious process. The existing PSS design techniques require considerable expertise, the complete system information and extensive eigenvalue calculations which increases the computational burden as the system size increases. This thesis proposes a method for designing robust power system damping controllers that ensures a minimum robustness under model uncertainties. The minimum performance required for the PSS is set a priori and accomplished over a range of operating conditions. A generalized robust controller design methodology has been ﬁrst implemented on a Single Machine Inﬁnite Bus (SMIB) power system model. The robust controller places the closed loop rotor modes of the system to the desire location while keeping the electrical modes intact. Unlike conventional lead/lag PSS design, the proposed PSS design is based on pole assignment technique which takes into account of various model uncertainties. For the proposed stabilizer design in a multi-machine systems a new decentralized method has been used which requires system data only upto secondary bus of the unit transformer in a generating station. The proposed robust controller design based on modiﬁed Nevanlinna-Pick theory has been designed and tested extensively on SMIB and multi-machine systems to establish the eﬃcacy of the controller in damping small signal oscillations. The thesis is organized in four chapters as follows. The ﬁrst chapter discusses the basic concepts related to the rotor angle stability in power system. The conventional and other methods of countering this instability by power system stabilizers have been described. The relative merits of the various stabilization techniques have been discussed. The scope of present work, i.e design of decentralized robust power system controllers has been deﬁned. In second chapter a modiﬁed robust power system stabilizer for SMIB system is developed. It has been shown that under speciﬁc conditions the modiﬁed Nevanlinna-Pick theory can also be applied for designing damping controllers in system with lightly damped rotor modes. Third chapter proposes a decentralized approach based on modiﬁed Nevanlinna-Pick theory for designing a power system stabilizer for interconnected power systems. The performance of the controller which is not based on external system information has been investigated on three widely used multi-machine test systems to established its eﬃcacy in damping out low frequency oscillations. The fourth chapter gives a brief summary of the work done and also includes a section on the scope of future work relating to design of power system stabilizers.

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44

Φωτόπουλος, Ευριπίδης. "Έλεγχος μεταβατικής ευστάθειας συστήματος ισχύος." Thesis, 2009. http://nemertes.lis.upatras.gr/jspui/handle/10889/3866.

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Η παρούσα διπλωματική εργασία έχει ως στόχο την αντιμετώπιση των ηλεκτρομηχανικών ταλαντώσεων οι οποίες εμφανίζονται σε μία σύγχρονη γεννήτρια παραγωγής Ηλεκτρικής Ενέργειας μετά από διαταραχές. Ο συμβατικός έλεγχος για τη διατήρηση της μηχανής σε συγχρονισμό μετά από ξαφνικές αλλαγές φορτίου, βραχυκυκλωμάτων, κλείσιμο διακοπτών ή οποιασδήποτε κατάστασης που μπορεί να προκαλέσει αστάθεια στο Σύστημα της Ηλεκτρικής Ενέργειας, γίνεται με χρήση ελεγκτικών διατάξεων Σταθεροποιητών Συστημάτων Ισχύος σε συνδυασμό με τον Αυτόματο Ρυθμιστή Τάσης (ΑΡΤ/ΣΣΙ). Σκοπός της εργασίας αυτής είναι να σχεδιαστούν και να ρυθμιστούν κατάλληλα οι διατάξεις αυτές, ώστε να εξασφαλίζεται η απόσβεση των ηλεκτρομηχανικών ταλαντώσεων που εμφανίζονται ανάμεσα στην γεννήτρια και το υπόλοιπο σύστημα. Στην εργασία αυτή, αρχικά γίνεται μια εισαγωγή στα είδη των ηλεκτρομηχανικών ταλαντώσεων και την ευστάθεια για δυναμικά Συστήματα Ηλεκτρικής Ενέργειας. Στη συνέχεια αναπτύσσεται το δυναμικό μοντέλο ενός απλού συστήματος μιας γεννήτριας άπειρου ζυγού βασισμένο στο απλοποιημένο μοντέλο 4ης τάξης της σύγχρονης μηχανής. Επειδή το μοντέλο αυτό είναι μη γραμμικό προχωράμε στην εξαγωγή του γραμμικοποιημένου μοντέλου που θα μας βοηθήσει για τον σχεδιασμό του κατάλληλου ελεγκτή. Αξιοποιώντας ιδιότητες του μοντέλου παρουσιάζεται μια συστηματική μέθοδος σχεδίασης του Σταθεροποιητή Συστήματος Ισχύος που είναι βασισμένη στη λογική των ολοκληρωτικών υπολοίπων. Τέλος με τη βοήθεια του λογισμικού SIMULINK του MATLAB προσομοιώνεται το σύστημα σύγχρονης γεννήτριας συνδεδεμένης σε άπειρο ζυγό, που ελέγχεται με την χρήση του Αυτόματου Ρυθμιστή Τάσης και του Σταθεροποιητή Συστήματος Ισχύος σε κατάσταση τυπικής φόρτισης. Εφαρμόζοντας διαταραχές στο σύστημα παρατηρείται η απόκριση του συστήματος και εκτιμάται η λειτουργία του ελεγκτή.
This thesis aims to address the electromechanical oscillations which appear in a synchronous generator after disturbances. The conventional control for maintaining the machine synchronized after sudden load changes, short circuits, switching or any condition which may cause instability phenomena, is achieved by the use of control circuits such as Power System Stabilizers combined with the Automatic Voltage Regulator ( PSS / AVR). The purpose of this work is to design and configure properly these control circuits to ensure the reduction of electromechanical oscillations that occur between the generator and the rest of the system. In the beginning this thesis, an introduction of the types of power system electromechanical oscillations and stability is being discussed. Afterwards, the dynamic model of a simple system of a generator infinite-bus based on simplified 4th order of synchronous machine is being developed. Due to the model nonlinearities, we export the linearized model which helps us to design a suitable controller. Taking into account the model properties, we provide a systematic method for designing a Power System Stabilizer based on the residues method. Finally, using the MATLAB-SIMULINK software, the synchronous generator infinite-bus system is simulated which is controlled by an Automatic Voltage Regulator and a Power System Stabilizer. After applying disturbances, the system response is driven and analyzed along with the controller functioning.

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Moodley, Devandren. "Robust power system stabilizer design." Thesis, 2002. http://hdl.handle.net/10413/4785.

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This thesis investigates the design of damping controllers to alleviate the problem of low frequency electro-mechanical oscillations in power systems. The operating point and network parameters of power systems are continually changing, resulting in changes in system dynamics. The conventional controller design methodology has therefore come under increasing scrutiny for its lack of considerations for robustness. The thesis first outlines the conventional design of a power system stabilizer (PSS) and then applies two robust techniques (Hoo and Quantitative Feedback Theory, QFT) to the design problem. The single machine infinite bus (SMIB) model is used to illustrate the procedure for all three design techniques. The final design is undertaken to illustrate the more important problem of robust multi-machine PSS design using QFT. The design requires linearised models of the multi-machine system. A brief discussion is given on how these can be obtained. An introduction to decentralized control design in QFT is included to support the multi-machine design. Chapter three proceeds through the design steps required to generate a conventional PSS. The technique is shown to be simple for a given set of operating conditions. The controller is shown to be adequately robust over the given set of operating conditions albeit not by design. Chapter four introduces a design technique that directly addresses robustness issues during the controller design. For a restricted range of operating conditions the designed controller demonstrates the desired robustness and performance characteristics. The inherent difficulties with Hoo in PSS design become more apparent as the operating range is extended. Chapter five introduces the second robust controller design technique. QFT is shown to be more adept at dealing with increased operating ranges and changing specifications in the single-machine infinite-bus case. The controller is easy to generate and performs well over the entire range of operating conditions. QFT is also applied to the controller design for a four-machine study system. The design is a marginally more complex than in the single machine case but is still easily accomplished. This thesis confirms previous attempts at solving the design problem using the methods outlined above. The performance of all controllers is assessed for small and large disturbances using non-linear time domain simulations with models developed using PSCAD/EMTDC and MATLAB.
Thesis (M.Sc.)-University of Natal,Durban, 2002.

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Panicker, K. S. Mohanachandra. "Microprocesser based power system stabilizer." Thesis, 1986. http://localhost:8080/xmlui/handle/12345678/5394.

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47

Swain, Ashit Kumar, Arya Kumar Swagat Ranjan Swain, and Abinash Mohapatra. "Design of Power System Stabilizer." Thesis, 2012. http://ethesis.nitrkl.ac.in/3683/1/DESIGN_OF_POWER_SYSTEM_STABILIZER.pdf.

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A power system stabilizer (PSS) installed in the excitation system of the synchronous generator improves the small-signal power system stability by damping out low frequency oscillations in the power system. It does that by providing supplementary perturbation signals in a feedback path to the alternator excitation system. In our project we review different conventional PSS design (CPSS) techniques along with modern adaptive neuro-fuzzy design techniques. We adapt a linearized single-machine infinite bus model for design and simulation of the CPSS and the voltage regulator (AVR). We use 3 different input signals in the feedback (PSS) path namely, speed variation(w), Electrical Power (Pe), and integral of accelerating power (Pe*w), and review the results in each case. For simulations, we use three different linear design techniques, namely, root-locus design, frequency-response design, and pole placement design; and the preferred non-linear design technique is the adaptive neuro-fuzzy based controller design. The MATLAB package with Control System Toolbox and SIMULINK is used for the design and simulations.

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48

Ψυλλάκης, Χαράλαμπος. "Κριτήρια ενεργειακής ισορροπίας και νέες τεχνικές προηγμένου ελέγχου στη διαχείρηση συστημάτων ηλεκτρικής ενέργειας." Thesis, 2006. http://nemertes.lis.upatras.gr/jspui/handle/10889/1406.

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In this thesis new advanced nonlinear control methods that solve the power system stabilization problem in a more efficient and integrated manner are considered. The proposed methods mainly concern with the primary level control of a power system that plays a central role in maintaining transient stability and obtaining a desired system performance. To this end, several new nonlinear control schemes mainly applicable on power system stabilizers (PSS) have been designed and extensively analyzed. For a theoretical assessment of the system operation the concepts of passivity and passivity margin are analyzed while the concept of Ω--passivity is introduced. Using partial feedback linearization and backstepping design techniques on suitable models of the system under consideration (power system) the Ω--passivity property of the system is proved. This property is further improved through the control in the closed-loop design. To this end, several control schemes are developed and a series of different theoretical problems have been solved on using simple output feedback and advanced nonlinear control methods like sliding mode control, adaptive control or a combination of them. A significant breakthrough has been achieved with the use of fuzzy techniques in these schemes yielding designs with combined advantages of both fuzzy and adaptive control methods. A detailed stability analysis, based on Lyapunov functions, has been used to prove that the proposed controllers guarantee either uniform ultimate boundedness or asymptotic stability for the closed-loop system. The proposed schemes are examined assuming that the system operates under parameter uncertainties as well as external disturbances. The theoretical analysis indicates that regulating some design parameters of the proposed controllers one can significantly improve the robustness and the disturbance attenuation capability of the system. Extensive simulations on a two machines infinite bus test system have been carried out to evaluate the effectiveness of the proposed schemes as these are applied on the PSS of each machine. Hard cases of three phase faults or significant power demand changes have been simulated. The simulation results show that the proposed nonlinear controllers enhance the damping of the electromechanical oscillations with respect to classical AVR/PSS and improve their robustness to parameter uncertainties and disturbance attenuation capability. Using similar techniques, speed governor controls (SGC) are also designed. An adaptive control scheme is proposed that ensures asymptotic stabilization of the closed-loop system as proved by standard Lyapunov techniques. Simulations are carried out for the one generator system connected to infinite bus. The simulation results confirm a significant improvement in the electromechanical oscillations damping compared to conventional speed governor controls. An important contribution of the thesis involves the coordination and management of the controls at the primary level. The design is carried out so that each control is not competing with the action of the other and it is cooperating to complement the action of the other. In this frame, first, the coordinated operation of the designed nonlinear power system stabilizers with the classical AVR/PSS is proposed. Particularly, the sequential operation of these controllers is considered in the following way: immediately after a fault, only the nonlinear controller operates but when the fault attenuates the classical AVR/PSS takes over. In this way, significant transient enhancement and voltage regulation after the large transients can be achieved. To implement this kind of operation a soft-switching logic from the one controller to the other is proposed by using a fuzzy logic mechanism to determine which controller will act each time period. In this way, it is avoided a discontinuous switching that can create a number of problems and may even lead to instabilities. The analysis and the simulation results confirm the validity of this approach since it is shown that the coordinated control scheme has an almost identical transient performance with the nonlinear controllers ensuring simultaneously the voltage regulation at the desired set-point. The same approach is used for the coordinated operation of FACTS with the excitation controllers. To this end, a static var compensator (SVC) controller is developed which, during a fault, acts to improve the transient stability. During the transient period, the SVC uses as inputs not the voltage at the connecting point but suitable signals from neighbor stations in order to contribute to the electromechanical oscillations damping; in the sequel, it returns to its normal operation maintaining the voltage level at the connecting point at a specified value. A soft switching scheme is also applied while signal transmission delays are taken into the account. The simulation results of a three phase short-circuit in a system with a single machine connected to infinite bus through a bus that has a SVC attached, indicate that this coordinated control scheme improves the transient stability even more (in comparison to the previous coordinated scheme). Finally, coordinated control logic is used for the design of both the speed governor control and the PSS. This is needed when the operation of the PSS cannot be considered completely independent and decoupled from the speed governor dynamics (in the case of fast valve operation). In this combined system a parallel design of both the SGC and the PSS ensures the uniform ultimate boundedness of the complete closed-loop system. Moreover, the use of continuous switching through fuzzy logic, as mentioned before, between these controllers and the classical AVR/PSS (for the excitation system) and a PID control (for the SGC) is proposed. The simulation results on the two machines infinite bus system clearly confirm the superiority of the coordinated control scheme with respect to the classical AVR/PSS excitation controllers and PID speed governor controllers. As a conclusion, new combined advanced nonlinear control schemes are analyzed and proposed for power systems. From the stability analysis and the simulation results it is clearly confirmed that the application of these nonlinear controls can be effectively improve the transient behavior as well as the robustness and disturbance attenuation of a power system. It is also proved that, without extreme cost, coordinated control schemes implemented through the proposed soft-switching techniques further enhance the transient and dynamic performance of the system.

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Huang, Chia-Yang, and 黃家揚. "Variable Structure Power System Stabilizer Design." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/17752889008251149326.

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碩士
國立臺北教育大學
資訊科學系碩士班
101
As technology advances, the demand for electricity is increased and the scale of the power system continues to expand. The system state is also becoming increasingly complicated. In many challenges of the power system, one of the most important issues is “power system stability”. Power system stabilizers (PSSs) have been extensively used to improve the transient stability of generator in power system. This thesis proposes an approach of variable structure control method to design the power system stabilizers. First, we use the optimal reduced models to reduce the power system model into two state variables system by each generator. The control signal of the generator can be found by using variable structure control method, and the parameter of feedback gain can be found by applying genetic algorithms. The result of the proposed method are verified through numerical simulations of the multi-machine infinite-bus system, and it prove the dynamic stability of the power system can be enhanced.

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50

Jackson, Gregory A. "Design of an adaptive power system stabilizer." 2007. http://hdl.handle.net/1993/319.

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Modern power networks are being driven ever closer to both their physical and operational limits. As a result, control systems are being increasingly relied on to assure satisfactory system performance. Power system stabilizers (PSSs) are one example of such controllers. Their purpose is to increase system damping and they are typically designed using a model of the network that is valid during nominal operating conditions. The limitation of this design approach is that during off-nominal operating conditions, such as those triggered by daily load fluctuations, performance of the controller can degrade. The research presented in this report attempts to evaluate the possibility of employing an adaptive PSS as a means of avoiding the performance degradation precipitated by off-nominal operation. Conceptually, an adaptive PSS would be capable of identifying changes in the network and then adjusting its parameters to ensure suitable damping of the identified network. This work begins with a detailed look at the identification algorithm employed followed by a similarly detailed examination of the control algorithm that was used. The results of these two investigations are then combined to allow for a preliminary assessment of the performance that could be expected from an adaptive PSS. The results of this research suggest that an adaptive PSS is a possibility but further work is needed to confirm this finding. Testing using more complex network models must be carried out, details pertaining to control parameter tuning must be resolved and closed-loop time domain simulations using the adaptive PSS design remain to be performed.
May 2007

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