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Dissertations / Theses on the topic 'Small-Signal Stability Analysis'
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1
McIlhagger, David. "Acceleration of power system small signal stability analysis." Thesis, Queen's University Belfast, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.486529.
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Electric power networks comprise large complex interconnections of generation and loads. The generators, and their controllers, are non-linear dynamic systems which on interconnection form a very complex control problem. Traditionally the models used to capture the small signal Rtability of these systems were not highly detailed. This waR jURtified Rince the generation was provided by large centralized power Rtations, however with the current trend towards small scale and diRtributed generation, as provided by.wind farmR and diesel genRetR, the power system modelR require a greater level of detail. This means that the stability assessment of theRe models involves greater detail and requires greater computation time, thus rendering near future predictions obsolete. ThiR thesis studies the methods that are Ilsed to determine • power system small signal stability, in order to provide acceleration to this analysis. A method based on wavelet approximations to provide an approximate solution was developed and its effectiveneRs against the traditional QR algorithm waR investigated. The method was applied to a four generator RyRtem and the IEEE New England 39 bus Rystem. Alternative methods to form accelerating polynomials for eigenvalue methodR were developed and evaluated against the IEEE New England 39 bus system. A new algorithm, called the polygon polynomial Arnoldi method (PPAM) was developed and tested against the implicitly restarted Arnoldi method (IRAM), from the linear algebra literature. The effectiveness of both theRe methods was tested against the IEEE New England 39 bus system and the one area IEEE reliability test system along with that for the QR algorithm.
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Rudraraju, Seetharama raju. "SMALL SIGNAL AND TRANSIENT STABILITY ANALYSIS OF MVDC SHIPBOARD POWER SYSTEM." MSSTATE, 2009. http://sun.library.msstate.edu/ETD-db/theses/available/etd-11052009-170217/.
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Recent developments in high power rated Voltage Source Converters (VSCs) have resulted in their successful application in Multi-Terminal HVDC (MTDC) transmission systems and also have potential in the Medium Voltage DC (MVDC) distribution systems. This work presents the findings of stability studies carried out on a zonal MVDC architecture for the shipboard power distribution system. The stability study is confined to rotor angle stability of the power system, i.e. the transient and small signal stability analysis. The MTDC ring structure similar to MVDC shipboard power system was implemented in MATLAB/Simulink to look at the transient behavior of the MVDC system. Small signal stability analysis has been carried out with the help of Power System Toolbox (PST) for both MVAC as well as MVDC architectures. Later, Participation Analysis has been carried out to address the small signal instability in the case of MVAC architecture and methods for enhancement were also presented.
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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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Mudau, Dovhani Selby. "Comparison of three power system software packages for small-signal stability analysis." Master's thesis, University of Cape Town, 2009. http://hdl.handle.net/11427/8935.
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Includes bibliographical references (leaves 131-133).Many power system simulation tools exist for small-signal stability analysis. This is due to the rapid development of computer systems, higher industrial growth and the need for reliable power system simulation tools for efficient planning and control of electric power systems. Three power system small-signal stability simulation tools have been selected for comparison and these are: PSAT 2.1.2, MatNetEig and PacDyn 8.1.1. These combine both open and closed source code industrial-grade power system analysis tools. The objective of this thesis is to compare three simulation tools on power system small-signal stability analysis. Input formats, data output flexibility, dynamic components and synchronous machine saturation modelling in all three simulation tools were amongst other features investigated for comparative studies.
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Aree, Pichai. "Small-signal stability modelling and analysis of power systems with electronically controlled compensation." Thesis, University of Glasgow, 2000. http://theses.gla.ac.uk/2600/.
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Flexible AC Transmission Systems (FACTS) equipment is currently being incorporated into the power system for controlling key networks parameters aiming at improving the power system steady-state and dynamic performances. The vast array of power system analysis tools used by planners and system operators, on a daily basis, for the successful running of the network are to be upgraded to include comprehensive modelling for FACTS plant components. Commensurate with this global objective, this research work is aimed at developing comprehensive power system models of FACTS devices suitable for small-signal stability studies. The FACTS components covered in this research are the Static Var Compensator (SVC) and the Thyristor-Controlled Series Capacitor (TCSC). More specifically, the modelling of these devices combined with advanced modelling of synchronous generators has positioned the current work in the area of small-signal stability modelling and analysis of power systems with electronically controlled compensation. The work has been developed within the framework of the block-diagram methodology because it yields physical insight and offers the opportunity to gain fundamental knowledge of the dynamic interactions taking place between synchronous generators and FACTS plant components. The key issues of synchronous generator modelling, from the viewpoint of small-signal stability analysis, are addressed in this thesis. In particular, the impact of synchronous generator modelling order, with emphasis on system damping, is discussed in depth. Various representations of salient-pole synchronous generators are used to enable a variety of models suitable for small-signal stability studies. The models range from synchronous generators with no danger windings, to cases when one damper winding is included in each of the rotor axes, i.e. d and q-axis. The drive behind the study is to settle the issue of what is a suitable number of machine damper windings to be used in small-signal stability analysis that adequately represents the system model with a good level of reliability while keeping engineering complexity manageable.
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Li, Chi. "Impedance-Based Stability Analysis in Power Systems with Multiple STATCOMs in Proximity." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/85053.
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Multiple STATCOM units in proximity have been adopted in power transmission systems in order to obtain better voltage regulation and share burdens. Throughout stability assessment in this dissertation, it is shown, for the first time, that STATCOMs could interact with each other in a negative way in the small-signal sense due to their control, causing voltage instability, while loads and transmission lines showed small effects. Since this voltage stability problem is induced by STATCOMs, d-q frame impedance-based stability analysis was used, for the first time, to explore the inherent power system instability problem with presence of STATCOMs as it provides an accurate understanding of the root cause of instability within the STATCOM control system.
This dissertation first proposes the impedance model in d-q frame for STATCOMs, including dynamics from synchronization, current and voltage loops and reveals the significant features compared to other types of grid-tied converters that 1) impedance matrix strongly coupled in d and q channel due to nearly zero power factor, 2) different behaviors of impedances at low frequency due to inversed direction of reactive power and 3) coupled small-signal propagation paths on the voltage at point of common coupling from synchronization and ac voltage regulation.
Using the proposed impedance model, this dissertation identifies the frequency range of interactions in a viewpoint of d-q frame impedances and pinpointed that the ac voltage regulation was the main reason of instability, masking the effects of PLL in power transmission systems. Due to the high impedance of STATCOMs compared to that of transmission lines around the frequency range of interactions, STATCOMs were seen to interact with each other through the transmission lines. A scaled-down 2-STATCOM power grid was built to verify the conclusions experimentally.Ph. D.
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Lin, Qing. "Small-Signal Modeling and Stability Specification of a Hybrid Propulsion System for Aircrafts." Thesis, Virginia Tech, 2021. http://hdl.handle.net/10919/103515.
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This work utilizes the small-signal impedance-based stability analysis method to develop stability assessment criteria for a single-aisle turboelectric aircraft with aft boundary-layer propulsion (STARC-ABL) system. The impedance-based stability analysis method outperforms other stability analysis methods because it does not require detailed information of individual components for system integration, therefore, a system integrator can just require the vendors to make the individual components meet the impedance specifications to ensure whole system stability. This thesis presents models of a generator, motor, housekeeping loads, and battery all with power electronics interface which form an onboard electrical system and analyzes the relationship between the impedance shape of each component and their physical design and control loop design. Based on the developed small-signal model of the turbine-generator-rectifier subsystem and load subsystem, this thesis analyzes the impact of electromechanical dynamics of the turbofan passed through the generator on the dc distribution system, concluding that the rectifier can mitigate the impact. Finally, to ensure the studied system stable operation during the whole flying profile, the thesis provides impedance specifications of the dc distribution system and verifies the specifications with several cases in time-domain simulations.M.S.
Electric aircraft propulsion (EAP) technologies have been a trend in the aviation industry for their potential to reduce environmental emissions, increase fuel efficiency and reduce noise for commercial airplanes. Achieving these benefits would be a vital step towards environmental sustainability. However, the development of all-electric aircraft is still limited by the current battery technologies and maintenance systems. The single-aisle turboelectric aircraft with aft boundary-layer (STARC-ABL) propulsion concept is therefore developed by NASA aiming to bridge the gap between the current jet fuel-powered aircraft and future all-electric vehicles. The plane uses electric motors powered by onboard gas turbines and transfers the generated power to other locations of the airplane like the tail fan motor to provide distributed propulsion. Power electronics-based converter converts electricity in one form of electricity to another form, for example, from ac voltage to dc voltage. This conversion of power is very important in the whole society, from small onboard chips to Mega Watts level electrical power system. In the aircraft electrical power system context, power electronics converter plays an important role in the power transfer process especially with the recent trend of using high voltage dc (HVDC) distribution instead of conventional ac distribution for the advantage of increased efficiency and better voltage regulation. The power generated by the electric motors is in ac form. Power electronics converter is used to convert the ac power into dc power and transfer it to the dc bus. Because the power to drive the electric motor to provide distributed propulsion is also in ac form, the dc power needs to be converted back into ac power still through a power electronics converter. With a high penetration of power electronics into the onboard electrical power system and the increase of electrical power level, potential stability issues resulted from the interactions of each subsystem need to be paid attention to. There are mainly two stability-related studies conducted in this work. One is the potential cross-domain dynamic interaction between the mechanical system and the electrical system. The other is a design-oriented study to provide sufficient stability margin in the design process to ensure the electrical system’s stable operation during the whole flying profile. The methodology used in this thesis is the impedance-based stability analysis. The main analyzing process is to find an interface of interest first, then grouped each subsystem into a source subsystem and load subsystem, then extract the source impedance and load impedance respectively, and eventually using the Nyquist Criterion (or in bode plot form) to assess the stability with the impedance modeling results. The two stability-related issues mentioned above are then studied by performing impedance analysis of the system. For the electromechanical dynamics interaction study, this thesis mainly studies the rotor dynamics’ impact on the output impedance of the turbine-generator-rectifier system to assess the mechanical dynamics’ impact on the stability condition of the electrical system. It is found that the rotor dynamics of the turbine is masked by the rectifier; therefore, it does not cause stability problem to the pre-tuned system. For the design-oriented study, this thesis mainly explores and provides the impedance shaping guidelines of each subsystem to ensure the whole system's stable operation. It is found that the stability boundary case is at rated power level, the generator voltage loop bandwidth is expected to be higher than 300Hz, 60˚ to achieve a 6dB, 45˚ stability margin, and load impedance mainly depends on the motor-converter impedance.
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Chompoobutrgool, Yuwa. "Concepts for Power System Small Signal Stability Analysis and Feedback Control Design Considering Synchrophasor Measurements." Licentiate thesis, KTH, Elektriska energisystem, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-103032.
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In the Nordic power network, the existence of poorly damped low-frequency inter-area oscillations (LFIOs) has long affected stability constraints, and thereby, limited power transfer capacity. Adequate damping of inter-area modes is, thus, necessary to secure system operation and ensure system reliability while increasing power transfers. Power system stabilizers (PSS) is a prevalent means to enhance the damping of such modes. With the advent of phasor measurement units (PMUs), it is expected that wide-area damping control (WADC), that is, PSS control using wide-area measurements obtained from PMUs, would effectively improve damping performance in the Nordic grid, as well as other synchronous interconnected systems. Numerous research has investigated one ``branch'' of the problem, that is, PSS design using various control schemes. Before addressing the issue of controller design, it is important to focus on developing proper understanding of the ``root'' of the problem: system-wide oscillations, their nature, behavior and consequences. This understanding must provide new insight on the use of PMUs for feedback control of LFIOs. The aim of this thesis is, therefore, to lay important concepts necessary for the study of power system small signal stability analysis that considers the availability of synchrophasors as a solid foundation for further development and implementation of ideas and related applications. Particularly in this study, the focus is on the application addressed damping controller design and implementation. After a literature review on the important elements for wide-area damping control (WADC), the thesis continues with classical small signal stability analysis of an equivalent Nordic model; namely, the KTH-NORDIC32 which is used as a test system throughout the thesis. The system's inter-area oscillations are identified and a sensitivity analysis of the network variables directly measured by synchrophasors is evaluated. The concept of network modeshapes, which is used to relate the dynamical behavior of power systems to the features of inter-area modes, is elaborated. Furthermore, this network modeshape concept is used to determine dominant inter-area oscillation paths, the passageways containing the highest content of the inter-area oscillations. The dominant inter-area paths are illustrated with the test system. The degree of persistence of dominant paths in the study system is determined through contingency studies. The properties of the dominant paths are used to construct feedback signals as input to the PSS. Finally, to exemplify the use of the dominant inter-area path concept for damping control, the constructed feedback signals are implemented in a PSS modulating the AVR error signal of a generator on an equivalent two-area model, and compared with that of conventional speed signals.
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Jiao, Yu Ming. "MPI parallel computing on eigensystems of small signal stability analysis for large interconnected power grids." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=95151.
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Eigenanalysis is widely used in power system stability study. With PC technologies available today, it takes long time to compute the entire eigensystems of large interconnected power grids. Since power transmission lines are connected & disconnected and line loads keep changing frequently, tracking eigensystems in real-time requires parallel computation. Recently, a parallel eigensystem computation method, the Break and Bind (B & B) method, has been proposed by Dr. H. M. Banakar in McGill University. This method is viewing connection of two isolated sub-networks as being equivalent to a rank-one modification (ROM) of the stiffness matrix and considering the two sub-networks as a single entity. Research of this thesis consists of implementing the B & B method based on Message Passing Interface (MPI) parallel programming in #C. The developed MPI codes were executed on super-computers - Krylov cluster of CLUMEQ and Mammouth Series II cluster of RQCHP. The testing results have demonstrated that the eigensystem of a power system composed of around 4,000 generators can be updated within two seconds.L'analyse des valeurs propres est largement utilisée dans les études de stabilité des réseaux électriques. En utilisant les ordinateurs personnels disponibles aujourd'hui, le calcul de la totalité des valeurs propres de plusieurs grands réseaux électriques interconnectés requiert beaucoup de temps. Étant donné que les lignes de transport d'électricité sont connectées et déconnectées et que les charges ne cessent de varier, le suivi des valeurs propres en temps réel nécessite des calculs en parallèles. Récemment, une méthode de calcul en parallèle des valeurs propres, la Break et Bind (B & B), a été proposée par le Dr. H. M. Banakar à l'Université McGill. Cette méthode voit la connexion de deux sous-réseaux isolés comme étant équivalent à une modification de rang un de la matrice de raideur et considère les deux sous-réseaux comme une entité entière. La recherche de cette thèse consiste à implanter la méthode B & B avec une programmation parallèle en #C basé sur l'interface Message Passing Interface (MPI). Le code de programmation développé en MPI a été exécuté avec des superordinateurs - Krylov de CLUMEQ et Mammouth série II de RQCHP. Les résultats des tests ont démontrés que les valeurs propres d'un système composé d'environ 4,000 alternateurs peuvent être calculées à l'intérieur de deux secondes.
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Shah, Shahil. "Small and Large Signal Impedance Modeling for Stability Analysis of Grid-connected Voltage Source Converters." Thesis, Rensselaer Polytechnic Institute, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10786614.
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Interactions between grid-connected converters and the networks at their terminals have resulted in stability and resonance problems in converter-based power systems, particularly in applications ranging from wind and PV farms to electric traction and HVDC transmission networks. Impedance-based modeling and analysis methods have found wide acceptance for the evaluation of these resonance problems.
This thesis presents small and large signal impedance modeling of grid-connected single and three phase voltage source converters (VSC) to enable the analysis of resonance conditions involving multiple frequency components, and both the ac and dc power systems at the VSC terminals. A modular impedance modeling approach is proposed by defining the VSC impedance as transfer matrix, which captures the frequency cross-coupling effects and also the coupling between the ac and dc power systems interfaced by the VSC. Ac and dc impedance models are developed for a VSC including the reflection of the network on the other side of the VSC. Signal-flow graphs for linear time-periodic (LTP) systems are proposed to streamline and visually describe the linearization of grid-connected converters including the frequency cross-coupling effects. Relationships between the impedance modeling in dq, sequence, and phasor domains are also developed. The phasor-domain impedance formulation links the impedance methods with the phasor-based state-space modeling approach generally used for bulk power systems. A large-signal impedance based method is developed for predicting the amplitude or severity of resonance under different grid conditions. The small-signal harmonic linearization method is extended for the large-signal impedance modeling of grid-connected converters. It is shown that the large-signal impedance of a converter is predominantly shaped by hard nonlinearities in the converter control system such as PWM saturation and limiters.
This thesis also deals with the problem of synchronizing a generator or microgrid with another power system. A VSC-based synchronizer is proposed for active phase synchronization and a distributed synchronization method is developed for microgrids.
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Bu, Siqi. "Probabilistic small-signal stability analysis and improved transient stability control strategy of grid-connected doubly fed induction generators in large-scale power systems." Thesis, Queen's University Belfast, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.580121.
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Growing numbers of large-scale wind farms have been recently established and connected to conventional power grid. With the rising level of penetration, the impact of wind power sources on the grid has extended from simple power quality problems to power grid security and stability, frequency and peak regulation, and economic dispatch issues. Therefore, it has significant theoretical and practical values to comprehensively investigate the effect of grid-connected wind power sources on the power system stability. In order to study the influence of considerable stochastic characteristic of wind power generation, probabilistic analysis of power system small-signal stability has been implemented. An analytical method of probabilistic analysis based on Gram-Charlier expansion is proposed to deal with the stochastic uncertainty and spatial correlation of multiple grid-connected wind power sources. Results of probabilistic stability analysis of the example power system demonstrate that the stochastic fluctuation of wind power generation certainly affects small-signal stability of the power system especially in a stressed load condition. Probabilistic stability changes significantly with the variation of wind power penetration level. Focusing on the examination of mechanism of terminal voltage dip during the grid fault, this thesis then develops an improved flux magnitude and angle control (IFMAC) strategy to enhance the grid fault ride-through (FRT) capability of grid-connected doubly fed induction generators (DFIGs). It is indicated by analysis that the significant increase of DFIG power angle stimulated by grid faults during the transient is the essential reason of DFIG voltage dip. IF MAC scheme is proposed with the aim to control the DFIG power angle. The theoretical analysis has also illustrated that the surrounding power system may benefit prominently in terms of transient stability margin by applying the proposed control strategy. Simulation results of the example system have validated the effectiveness and robustness of IF MAC controller in different operating conditions.
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Whitlock, Rogers Jr. "Identification of Power System Stability Using Relevant Modes." ScholarWorks@UNO, 2011. http://scholarworks.uno.edu/td/1384.
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The purpose of this investigation is to identify appropriate location of capacitor banks and sources of reactive power by studying power system stability in the vicinity of system equilibrium states. The locations for reactive power sources are determined by identifying those modes of the system that participate most in the system behavior in general and in dictating the final state of the system after experiencing faults or disturbances. To identify the relevant modes of the system that participate most in the system dynamic, we shall make use of modal and participation analysis for different system conditions. We also apply modal and participation analysis to a system in order to identify the components of greatest impact that result in the most efficient system control. The ideas developed in this study are used to analyze and identify weak boundaries of the IEEE 39- Bus system that contribute to the system’s instability.
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Kopcak, Igor. "Uma plataforma unificada para analise de estabilidade de sistemas eletricos de potencia." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/261196.
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Orientadores: Vivaldo Fernando da Costa, Luiz Carlos Pereira da SilvaTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação
Made available in DSpace on 2018-08-08T18:53:13Z (GMT). No. of bitstreams: 1 Kopcak_Igor_D.pdf: 1188245 bytes, checksum: e1912d198506d0fd20e05f9202486e80 (MD5) Previous issue date: 2007
Resumo: O estressamento dos sistemas elétricos tem voltado o interesse de engenheiros e pesquisadores para a definição e avaliação de margens de segurança relacionadas a critérios dinâmicos. Neste trabalho é proposta uma ferramenta que permite a avaliação de quatro diferentes critérios de estabilidade: margem de amortecimento, margem oscilatória, margem de estabilidade de tensão e o ponto de máximo carregamento. A metodologia baseia-se em um fluxo de carga expandido que incorpora as características de regime permanente de dispositivos dinâmicos, fornecendo pontos de equilíbrio precisos e mais condizentes com a resposta "real" dos sistemas elétricos quando sujeitos a perturbações. As margens são calculadas através da análise modal aplicada aos pontos de equilíbrio de curvas PV. Além disso, estudos preliminares são conduzidos objetivando a expansão da análise modal estática, fornecendo fatores de participação para todas as barras do sistema, dos pontos de vista das potências ativa e reativa. Portanto, a plataforma não só permite a identificação dos pontos onde ocorreria o colapso do sistema, como fornece a indicação das medidas corretivas mais efetivas para evitar problemas de instabilidade
Doutorado
Energia Eletrica
Doutor em Engenharia Elétrica
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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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Louganski, Konstantin P. "Modeling and Analysis of a Dc Power Distribution System in 21st Century Airlifters." Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/35514.
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A DC power distribution system (PDS) of a transport aircraft was modeled and analyzed using MATLAB/Simulink software. The multi-level modeling concept was used as a modeling approach, which assumes modeling subsystem of the PDS at three different levels of complexity. The subsystem models were implemented in Simulink and combined into the whole PDS model according to certain interconnection rules. Effective modeling of different scenarios of operation was achieved by mixing subsystem models of different levels in one PDS model. Linearized models were obtained from the nonlinear PDS model for stability analysis and control design.
The PDS model was used to examine the system stability and the DC bus power quality under bidirectional power flow conditions. Small-signal analysis techniques were employed to study stability issues resulting from subsystem interactions. The DC bus stability diagram was proposed for predicting stability of the PDS with different types of loads without performing an actual stability test based on regular stability analysis tools. Certain PDS configurations and operational scenarios leading to instability were identified. An analysis of energy transfer in the PDS showed that a large energy storage capacitor in the input filter of a flight control actuator is effective for reduction of the DC bus voltage disturbances produced by regenerative action of the actuator. However, energy storage capacitors do not provide energy savings in the PDS and do not increase its overall efficiency.Master of Science
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Wang, Hongjie. "Design and Control of Series Resonant Converters for DC Current Power Distribution Applications." DigitalCommons@USU, 2018. https://digitalcommons.usu.edu/etd/7160.
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With the growth of renewable energy usage and energy storage adoption in recent decades, people have started to reevaluate the possible roles of dc systems in current and future electrical systems. The dc voltage distribution has been applied in various applications, such as data centers and aircraft industry, for high efficiency and power density. However, for some applications such as subsea gas and oil fields, and ocean observatory systems, the dc current distribution is preferred over dc voltage distribution for its low cost and robustness against cable faults. Design and control of dc power distribution systems for different applications is an emerging research area with complex technical challenges. This dissertation solves the technical challenges in analysis, design, modeling, control and protection of series resonant converters (SRCs) for dc current distribution applications. An optimum design that has high efficiency, high reliability, and minimum required control efforts for the SRC with constant input current has been achieved and demonstrated by applying the analysis and design procedures developed in this dissertation. The modeling and analysis presented in this dissertation represents an operating condition that has not been studied in the literature and could be easily extended to other resonant converter topologies. Explicit analytical expressions have been provided for all key transfer functions, including input impedance and control-to-output, offering valuable resources to design feed-back regulation and to evaluate system stability. Based on the control strategies and control design presented in this dissertation, stable and reliable operation of dc current distribution systems with long distance cable has been achieved and demonstrated. The proposed analysis, design procedure, stability evaluation, control strategy and protection techniques in this dissertation can be applied to a wide range of similar scenarios as well, which greatly increases their value.
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Pataca, Liciane Cândida. "Identificação modal a partir de dados ambiente em sistemas com geração síncrona distribuída." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/18/18154/tde-09112015-160322/.
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O crescimento da demanda por eletricidade tem promovido a diversificação da matriz energética em termos de fontes primárias, porte de geração e alocação dos geradores. Neste cenário, a inserção de geradores de pequeno porte nos sistemas de distribuição tem causado a descentralização da produção de energia elétrica e, no contexto nacional, o alto potencial para geração de eletricidade através de pequenas centrais hidrelétricas e usinas de cogeração tem dado destaque aos geradores síncronos distribuídos. Contudo, é necessário avaliar as implicações da presença dos geradores síncronos em sistemas de distribuição e avaliar se as metodologias já consagradas de análises, operação e normalização técnica estão adequadas. Dentre as principais peculiaridades dos sistemas de distribuição estão a proximidade dos geradores às cargas e a presença de eventos aleatórios de maior amplitude, tais como variações de carga que ocorrem natural e intermitentemente no sistema. Além disso, problemas relacionados a oscilações eletromecânica mal amortecidas podem agora ocorrer em níveis de distribuição e deve-se estabelecer um procedimento para identificação destes modos. Entretanto, o procedimento usual para o estudo de estabilidade a pequenas perturbações pode se tornar inviável, pois a construção do modelo completo é de extrema complexidade e os parâmetros dos elementos em níveis de distribuição são de difícil obtenção. Para reverter estes problemas citados, esta pesquisa oferece um procedimento alternativo para a obtenção dos modos de oscilação eletromecânica em sistemas de distribuição, sugerindo a estimação modal através de dados ambiente.The electricity demand increase has promoted the energy matrix diversification in terms of primary sources, generation size and allocation of generators. In this scenario, the insertion of small sized generators in distribution systems has caused the power production decentralization and, in the national context, a high potential for generating electricity through small hydroelectric power plants and cogeneration plants has drawn attention to distributed synchronous generators. However, it is necessary to assess the implications of synchronous generators presence in distribution systems and evaluate if the current methodologies of analysis, operation and technical standards are appropriate to this context. Among the main distribution systems particularities, there are the proximity of generators to loads and more significant random perturbations conceptualized as load switching. In addition, problems related to lightly damped modes can occur in distribution and there is a need to establish a procedure for modal identification. However, the usual procedure for the small-signal stability analysis is not adequate to this problem, because the model construction is very complex and the parameters in distribution are very difficult to obtain. To face the challenges, this research provides an alternative procedure for obtaining electromechanical modes in distribution systems, suggesting modal estimation techniques that use measured ambient data.
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Qoria, Taoufik. "Nouvelles lois de contrôle pour former des réseaux de transport avec 100% d’électronique de puissance." Thesis, Paris, HESAM, 2020. http://www.theses.fr/2020HESAE041.
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Le développement rapide de la production d'énergie renouvelable intermittente et des liaisons HVDC entraîne une augmentation importante du taux de pénétration des convertisseurs statiques dans les réseaux de transport. Aujourd'hui, les convertisseurs statiques ont pour fonction principale d'injecter une puissance dans le réseau tout en s'appuyant sur des machines synchrones qui garantissent tous les besoins du système électrique. Ce mode de fonctionnement est appelé «Grid-following». Les convertisseurs contrôlés en Grid-following ont plusieurs limitations: leur incapacité à fonctionner en mode autonome, leurs problèmes de stabilité dans des réseaux faibles et en cas de défaut ainsi que leur effet négatif sur l'inertie équivalent du système. Pour relever ces défis, le contrôle en Grid-forming est une bonne solution pour répondre aux besoins du système électrique et permettre un fonctionnement stable et sûr du système même avec un taux de pénétration des convertisseurs statique de 100%. Tout d'abord, trois stratégies de contrôle en Grid-forming sont proposées pour garantir quatre fonctionnalités principales: contrôle de tension, contrôle de puissance, émulation d'inertie et le support de la fréquence. La dynamique et la robustesse du système basées sur chaque contrôle ont été analysées et discutées. Ensuite, selon la topologie du convertisseur, la connexion avec le réseau AC peut nécessiter des filtres et des boucles de contrôle supplémentaires. Dans le cadre de cette thèse, deux topologies de convertisseur ont été envisagées (VSC à 2-niveaux et VSC-MMC) et l'implémentation associée à chacune a été discutée. Enfin, les questions de la protection des convertisseurs Grid-forming contre les surintensités et leur synchronisation post-défaut ont été étudiées, puis, des algorithmes de limitation de courant et de resynchronisation ont été proposés pour améliorer la stabilité transitoire du système. Un banc d'essai a été développé pour confirmer les approches théoriques proposéesThe rapid development of intermittent renewable generation and HVDC links yields an important increase of the penetration rate of power electronic converters in the transmission systems. Today, power converters have the main function of injecting power into the main grid, while relying on synchronous machines that guaranty all system needs. This operation mode of power converters is called "Grid-following". Grid-following converters have several limitations: their inability to operate in a standalone mode, their stability issues under weak-grids and faulty conditions and their negative side effect on the system inertia.To meet these challenges, the grid-forming control is a good solution to respond to the system needs and allow a stable and safe operation of power system with high penetration rate of power electronic converters, up to a 100%. Firstly, three grid-forming control strategies are proposed to guarantee four main features: voltage control, power control, inertia emulation and frequency support. The system dynamics and robustness based on each control have been analyzed and discussed. Then, depending on the converter topology, the connection with the AC grid may require additional filters and control loops. In this thesis, two converter topologies have been considered (2-Level VSC and VSC-MMC) and the implementation associated with each one has been discussed. Finally, the questions of the grid-forming converters protection against overcurrent and their post-fault synchronization have been investigated, and then a hybrid current limitation and resynchronization algorithms have been proposed to enhance the transient stability of the system. At the end, an experimental test bench has been developed to confirm the theoretical approach
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Nasri, Amin. "On the Dynamics and Statics of Power System Operation : Optimal Utilization of FACTS Devicesand Management of Wind Power Uncertainty." Doctoral thesis, KTH, Elektriska energisystem, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-154576.
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Nowadays, power systems are dealing with some new challenges raisedby the major changes that have been taken place since 80’s, e.g., deregu-lation in electricity markets, significant increase of electricity demands andmore recently large-scale integration of renewable energy resources such aswind power. Therefore, system operators must make some adjustments toaccommodate these changes into the future of power systems.One of the main challenges is maintaining the system stability since theextra stress caused by the above changes reduces the stability margin, andmay lead to rise of many undesirable phenomena. The other important chal-lenge is to cope with uncertainty and variability of renewable energy sourceswhich make power systems to become more stochastic in nature, and lesscontrollable.Flexible AC Transmission Systems (FACTS) have emerged as a solutionto help power systems with these new challenges. This thesis aims to ap-propriately utilize such devices in order to increase the transmission capacityand flexibility, improve the dynamic behavior of power systems and integratemore renewable energy into the system. To this end, the most appropriatelocations and settings of these controllable devices need to be determined.This thesis mainly looks at (i) rotor angle stability, i.e., small signal andtransient stability (ii) system operation under wind uncertainty. In the firstpart of this thesis, trajectory sensitivity analysis is used to determine themost suitable placement of FACTS devices for improving rotor angle sta-bility, while in the second part, optimal settings of such devices are foundto maximize the level of wind power integration. As a general conclusion,it was demonstrated that FACTS devices, installed in proper locations andtuned appropriately, are effective means to enhance the system stability andto handle wind uncertainty.The last objective of this thesis work is to propose an efficient solutionapproach based on Benders’ decomposition to solve a network-constrained acunit commitment problem in a wind-integrated power system. The numericalresults show validity, accuracy and efficiency of the proposed approach.The Doctoral Degrees issued upon completion of the programme are issued by Comillas Pontifical University, Delft University of Technology and KTH Royal Institute of Technology. The invested degrees are official in Spain, the Netherlands and Sweden, respectively.QC 20141028
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Paiva, élcio Precioso de. "Uma proposta de controle de paralelismo de inversores com a rede elétrica utilizando-se a técnica de realimentação de fase." Universidade Federal de Uberlândia, 2006. https://repositorio.ufu.br/handle/123456789/14311.
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Fundação de Amparo a Pesquisa do Estado de Minas GeraisThe purpose of this work is to present an active and reactive power flow controller applied to inverter paralelism with the stiff AC system. An additional loop is implemented into a conventional control loop based on the characteristic curves of active power versus frequency and reactive power versus voltage. This loop uses the active power variation as feedback to generate the load angle of the voltage reference of the inverter, when it is connected in parallel with the electric network. As a consequence, the active and reactive transitory power oscillations are atenuated, without producing undesirable colateral effects as significative voltage and reactive power variations presented in the utilization of PSS (Power System Stabilizer), another technique used to improve the system damping, [Martins, M. P., 2004]. A dynamic model of the system based on the small signal analysis is presented. The root locus graphics, showing the system poles under parametric variations are also presented, allowing the analysis of the system stability. The simulation results and the experimental ones using a laboratory prototype with and without the additional loop are showed, which validate the obtained small signal model.
Este trabalho apresenta um controlador de fluxos de potência ativa e reativa aplicado ao paralelismo de um inversor com a rede elétrica. Uma malha adicional de controle é inserida a um controlador convencional, o qual é baseado nas curvas características de potência ativa versus freqüência e potência reativa versus tensão. Essa malha utiliza a realimentação da própria variação da potência ativa para a geração do ângulo de carga da tensão de referência do inversor, quando o mesmo é conectado em paralelo com a rede elétrica. Como resultado as oscilações transitórias das potências ativa e reativa são melhor atenuadas, sem produzir efeitos colaterais indesejáveis tais como as variações de tensão e potência reativa presentes na utilização do PSS (Power System Stabilizer Estabilizador de Sistemas de Potência), outra técnica usada para melhorar o amortecimento do sistema, [Martins, M. P., 2004]. Um modelo dinâmico do sistema baseado na análise para pequenos sinais é apresentado. Gráficos do lugar das raízes, mostrando os pólos do sistema diante de variações paramétricas também são apresentados, permitindo a análise de estabilidade do sistema. Resultados de simulação e resultados experimentais utilizando-se um protótipo de laboratório, com e sem a malha de realimentação adicional são mostrados, os quais validam o modelo para pequenos sinais obtido.
Doutor em Ciências
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Freytes, Julian. "Analyse de stabilité en petit signaux des Convertisseurs Modulaires Multiniveaux et application à l’étude d'interopérabilité des MMC dans les Réseaux HVDC." Thesis, Ecole centrale de Lille, 2017. http://www.theses.fr/2017ECLI0022/document.
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Ces travaux de thèse portent essentiellement sur la modélisation, l’analyse et la commande des convertisseurs de type MMC intégrés dans un contexte MTDC. Le premier objectif de ce travail est d’aboutir à un modèle dynamique du convertisseur MMC, exprimé dans le repère $dq$, permettant d’une part, de reproduire avec précision les interactions AC-DC, et d’exprimer, d’autre part, la dynamique interne du convertisseur qui peut interagir également avec le reste du système. Le modèle développé peut être linéarisé facilement dans le but de l’exploiter pour l’étude de stabilité en se basant sur les techniques pour les systèmes linéaires à temps invariant. Ensuite, selon le modèle développé dans le repère dq, différentes stratégies de contrôle sont proposées en fonction de systèmes de contrôle-commande existantes dans la littérature mis en places pour le convertisseur MMC. Étant donné que l’ordre du système est un paramètre important pour l'étude des réseaux MTDC en présence de plusieurs stations de conversion de type MMC, l’approche de réduction de modèles à émerger comme une solution pour faciliter l’étude. En conséquence, différents modèles à ordre réduit sont développés, et qui sont validés par la suite, par rapport au modèle détaillé, exprimé dans le repère dq. Finalement, les modèles MMC développés ainsi que les systèmes de commande qui y ont associés sont exploités, pour l’analyse de stabilité en petits signaux des réseaux MMC-MTDC. Dans ce sens, la stratégie de commande associée à chaque MMC est largement évaluée dans le but d’investiguer les problèmes majeurs qui peuvent surgir au sein d’une configuration MTDC multi-constructeursThis thesis deals with the modeling and control of MMCs in the context of MTDC. The first objective is to obtain an MMC model in dq frame which can reproduce accurately the AC- and DC- interactions, while representing at the same time the internal dynamics which may interact with the rest of the system. This model is suitable to be linearized and to study its stability, among other linear techniques. Then, based on the developed dq model, different control strategies are developed based on the state-of-the-art on MMC controllers. Since the order of the system may be a limiting factor for studying MTDC grids with many MMCs, different reduced-order models are presented and compared with the detailed dq model. Finally, the developed MMC models with different controllers are used for the MTDC studies. The impact of the chosen controllers of each MMC is evaluated, highlighting the potential issues that may occur in multivendor schemes
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Li, Chao-Chun, and 李昭俊. "Critical Eigenvalue Analysis for Power System Small Signal Stability." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/17567802273373541320.
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博士國立臺灣海洋大學
電機工程學系
101
The small signal stability of power systems is to investigate whether or not the system can be kept at stable operation under minor disturbances. Frequency domain analysis has been widely adopted in the study of power system small signal stability, in which the original nonlinear system is linearized around the operating point to obtain the linear model and the system matrix of which the eigenvalues can be calculated for determining the stability of the system. However, the numbers of generating units or electric apparatus in most power systems are rather large thus leading to rather high orders of system matrix such that it can be very time consuming to solve all eigenvalues and the associated eigenvectors, and it can be not easy to analyze them. So the small signal stability on power system are the critical eigenvalue calculation, and at the solving method of corresponding eigenvector. Through the analysis of eigenvalues and eigenvectors, we can understand more deeply about the system dynamic behaviors. Based on the S-matrix, shifting method, order reduction and power method, this dissertation proposes an approach for calculating the critical eigenvalues in conjunction with a flexible strategy for threshold selection. The main feature is the capability of directly solving the most unstable eigenvalue (or that with the lowest damping) and all unstable eigenvalues, as well as the corresponding eigenvectors, in order to determine the system stability while avoiding the inconvenience of time-consuming calculation of all eigenvalues. The proposed calculation method has been tested by the analysis of critical eigenvalues of the study systems which can be divided into two categories of typical power system and shipboard power system. The study results demonstrate that the proposed algorithm for critical eigenvalue calculation can indeed find both the most unstable eigenvalue and all unstable eigenvalues of system matrix, and the approach is suitable for the analysis of power system small signal stability.
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Chang, Chee-Shang, and 張集翔. "Analysis of Small Signal Stability on Marine Power System." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/21211178322477026725.
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碩士國立海洋大學
電機工程學系
90
The marine power system is an independent system of which the required reliability is higher than that of the onshore power system. A sample marine power system is taken as the study system and the method of eigenanalysis is employed to investigate the small signal stability of the system. The damping and frequency of the electromechanical oscillation mode are calculated and verified through time domain simulations.
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Huang, Hung-Chi, and 黃宏綺. "Small Signal Stability Analysis Method for Large Scale Power Systems." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/80480679003571554794.
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碩士國立海洋大學
電機工程學系
87
Power system small signal stability concerns the ability of the power system to maintain stability subject to small disturbances. The method of frequency domain analysis, i.e. to linearize the system to obtain a system linear model as well as the system matrix of which the eigenvaluses can be calculated to determine the system stability, has been widely employed in the study of power system small signal stability. However, we often have high order of system matrix due to the large number of generating units and thus it will be undesirable to calculate and analyze all the system eigenvalues. The main purpose of this thesis is to study the problem of power system small signal stability. The contents include two parts: the derivation of the linearized system model and the system matrix, and the determination of system stability using an eigenvalue calculation method to figure out those eigenvalues of critical oscillatory modes, i.e. the eigenvalues associated with the worst-damped mode or all the unstable system eigenvalues, to alleviate the effort for computing and analyzing all the system eigenvalues. Based on the parallel structure of connection networks, the eigenvalue calculation method takes the advantages of the power method, the inverse power method, and the method of approaching/shift-approaching. Numerical results from performing eigenvalue analyses on some practical power systems are demonstrated to verify the proposed method.
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Yang, Cheng-Chung, and 楊正中. "Small Signal Stability Analysis of a Commercial DC Distributed Power System." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/87455611740679482494.
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碩士國立臺灣大學
電機工程學研究所
94
An intermediate bus architecture (IBA), consisting of a bus converter (BC) and point of loads (POLs), has become very popular in dc-dc distributed power system applications. When a BC modules are connected with POLs, system interactions may cause system instability or performance degradation. It was previously reported that by comparing the output impedance of the source impedance and the input impedance of a single POL, one can avoid system instability and alleviate potential performance degradation. Therefore impedance of individual subsystems must be analyzed carefully before the system coordinated. In this thesis, this theory was applied to a commercial IBA with multiple POLs. Impedance characteristics of POL section and BC modules were used with Nyquist theorem to define the limitation of impedances and ensure the IBA system stability margin. Test results and mathematical calculations were compared with good agreement.
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Huang, Wei-Lun, and 黃瑋倫. "Analysis and Measurement of Small Signal Stability for a Commercial PFC Circuit." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/68412289360386947346.
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碩士國立臺灣大學
電機工程學研究所
95
The theme of this thesis is focused on the measurement and analysis in the small signal model of a power factor correction circuit (PFC). By the design of a system feedback compensator, the analysis of system stability is achieved. In this thesis, several PFC models and control methods are introduced, and the operating theory of PFC is illustrated in detail. In further, the small signal models in average current mode of both current and voltage loops are derived so that the transfer functions can be applied to the design of the system feedback compensator. In order to validate the feasibility, the MATHCAD and MATLAB programs are applied to test the accuracy. By utilizing TI commercial PFC control IC “UCC3817”, the control loop compensator is implemented and completed. The measurement results of frequency response analyzer are in accord with the mathematical computation. In the end, the practical techniques and approaches to measure both current and voltage loops, which can be an important reference for the industry, are advanced and come to a conclusion.
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Chen, Chih-Wei, and 陳志偉. "Fast Analysis of Power System Small Signal Stability by Critical Eigenvalue Calculation." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/55970321675497325834.
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碩士國立海洋大學
電機工程學系
89
Power system small signal stability (or dynamic stability), of which the purpose is to explore the system behavior under small disturbance, is a major concern in power system planning and operation. The frequency domain approach of the linear system theory, namely the method of calculation and analysis of eigenvalues and eigenvectors, has been widely employed in small signal stability studies. Calculation of system critical eigenvalues, eigenvalues of the most unstable mode or of the mode with worst damping, plays the key step for assessment of system small signal stability. The main objective of this thesis is to propose a new algorithm, which is synthesized based on the parallel structure of neural networks as well as the techniques of shifting and inverse shifting, to calculate the eigenvalues associated with the most unstable oscillation mode or with the oscillation mode with worst damping for fast assessment of system small signal stability. Several typical study systems, including a practical shipboard electrical system, have been used to test the proposed algorithm and computer program and the results have verified the validity of the algorithm and computer program in the fast analysis of power system small signal stability.
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Chou, Cha-Min, and 周嘉明. "Small Signal Stability of Time-Frequency Analysis for Power System base on HHT." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/yb5qhy.
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碩士聖約翰科技大學
電機工程系碩士在職專班
104
This study simulates system with the Empirical Mode Decomposition (EMD) of Hilbert-Huang Transform (HHT), Intrinsic Mode Function, Hilbert Transform (HT), Hilbert Spectrum, and Hilbert Marginal Spectrum for analyzing power response waveform of electric power system.In order to find out the generator with the greatest impact on system stability. The power system stabilizer (PSS) will be placed at the location of this generator such that the system can be promptly stabilized from the disturbance.
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LI, YONG-XUN, and 李永勳. "Small signal stability analysis of power systems with superconducting magnetic energy storage units." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/87447438940034895600.
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Lin, Shih-Chun, and 林士鈞. "Small Signal Stability Analysis of a Doubly Fed Induction Generator Equipped with Wind Turbine." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/21954400351418946933.
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碩士國立臺灣大學
電機工程學研究所
101
The goal of this thesis is to analyze the small signal stability of a double fed induction generator (DFIG) equipped wind turbine under maximum power tracking using the frequency domain analysis method, time domain simulation method, and the Prony method. In the frequency domain analysis method, the steady state operating point and linearized model were first searched by MATLABR/SIMULINK software. Then the eigenvalues were computed for small signal stability analysis. In the time domain simulation method, the mathematical model of DFIG was created by MATLABR/SIMULINK software for time domain simulation. Dynamic response curves for the system subject to disturbance were employed to evaluate small signal stability. In the Prony method, the eigenvalues were computed from the time domain response curves based on the concepts from digital signal processing. Based on the results for four different cases include full generator model, reduced-order generator model neglecting stator transients, transmission line of short length, and transmission line of long length, it is concluded that the three methods give consistent results for small signal stability.
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Chien, Shih-En, and 簡士恩. "Real-Time Power System Small Signal Stability Monitoring and Analysis Using Synchronized Phasor Measurements." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/74542202735907473579.
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碩士國立臺灣大學
電機工程學研究所
92
This thesis presents how to use synchronized phasor measurements to do power system small signal stability monitoring and analysis. Take the Taiwan power system of year 2003 as the study system. First, the eigenvalue analysis and frequency response of the study system are performed using SSSP(Small Signal Stability Program). Then simulate the time domain dynamic response under some small perturbations using PSS/E(Power System Simulator/Engineering). These simulation results offered by SSSP and PSS/E draw a picture of how small signal stable the Taiwan power system of year 2003 is and can be relied on to decide where to locate the phasor measurement units (PMUs) and verify the computation results of small signal stability evaluation indices afterward. Next some buses to locate PMUs and parameters to measure are selected for simulation and the measured low-frequency oscillation data is simulated by PSS/E. Finally, given the measured data, use PRONY method to calculate the small signal stability evaluation indices. After verification, comparison and analysis of these computation results of small signal stability evaluation indices, it is shown that the evaluation indices observed especially from some parameters measured at some buses are quite accurate. Also the program execution speed is pretty fast. Both the accuracy and speed can all meet the requirements of real-time monitoring and analysis systems. So this thesis concludes that the idea of real-time power system small signal stability monitoring and analysis using synchronized phasor measurements is feasible. This study can also act as a reference for the power company to plan the dynamic security monitoring system in the future to improve the power system dynamic stability.
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Shah, Masood Hussain. "Small signal model of an HVDC terminal for stability analysis of AC-DC power systems." 2009. http://hdl.handle.net/1993/21566.
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Ngoma, Louwrance Jack. "Real-time application of synchronised phasor measurement units in power system small-signal stability analysis." 2014. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1001015.
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M. Tech. Electrical Engineering.Discusses that most real-time applications of synchronised phasor measurement units in power system stability studies are done using RTDS simulator, hardware PMUs and PTP hardware modules with GPS providing the time reference. The major drawbacks of this configuration are both technical and economical. The technical limitations are related to the possible number of outputs that can be used to interface PMU devices, which can be very limited; and also the possible limits on small-time step computation due to the big number of output signals. The economic constraints are mainly due to cost: for a research laboratory, only a limited number of units can be acquired due to budgeting issues. To overcome these difficulties, the realisation of an entirely software-based synchrophasor measurement unit, presents an attractive approach. Such a unit will be capable of deliveringreal-time data by acquiring the voltage and current signals from the Matlab/Simulink simulator, low cost software environment PMUs computing real-time phasors of voltage and current and software only PTP synchronisation protocol. The unit delivers synchrophasors for the application of power system SE and small signal stability analysis, but also taking into consideration the accuracy of the synchronisation protocol on the application of power system SE and small signal stability analysis.
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Shiu, Ruei-Wen, and 徐睿彣. "Small-Signal Stability and Frequency Control Analysis of Power Systems with High-Penetrated Wind Power Systems." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/08630008655730463805.
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碩士國立清華大學
電機工程學系
99
Energy problems are one of the most important issues in 21st century. The advantages of wind power generation is zero-pollution and not cause environmental impacts, so the global wind power generation of capacity is increasing in recent years. However, the impacts of wind power on the power systems is very important, the wind power stability is discussed in the thesis. The major of power simulators are EMTP-RV、PSS/E、DSA、PSCAD/EMTDC and DigSILENT, however the major drawback of these simulators is that it can realize by connecting hardware. So the OPAL-RT software corporation develops a software which is called RT-LAB. The RT-LAB software can use software to do real-time simulations and realize the simulation by Hardware-in-Loop. The real-time simulation is built by RT-LAB software, and the impacts of wind power and traditional synchronous generator to power systems is researched. The aim of thesis is to develop the RT-LAB software implements of the wind power on the power systems stability .The main contribution of thesis is listed through the following steps： 1. Because the rotor speed mode of conventional synchronous generator affects system stability , the thesis first describes the conventional synchronous generator on the power system impacts, and the induction generator coefficients is derived, and the current control of doubly fed induction generator model the strengths and weaknesses is be compared. Finally, one-machine-infinite-bus system and three-machine system are performed by calculating the eigenvalues and simulating transient stability. 2. Conventional synchronous generator for power system frequency of accidents, the real power will be significantly affected, but the response is very slow wind turbines. In order to enhance the frequency stability of wind turbines, wind turbines must be added on the control loop.The relationship between frequency and load is be derived in the thesis, it indicates that the load will affect the frequency. And simulations of one-machine-infinite-bus system and three-machine system are performed to verify, which in order to enhance frequency stability the thesis add fuzzy control and fuzzy neural control. Secondly, the double-fed induction generator frequency control strategy is described , and three-machine system is performed to do verification.
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Balibani, Siva Kumar. "Small Signal Stability Analysis of a Power System with a Grid Connected Wind Powered Permanent Magnet Synchronous Generator (PMSG)." Thesis, 2015. http://etd.iisc.ernet.in/2005/3835.
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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. Following any disturbance, such as sudden change in loads, actuations in the output of turbine and faults etc. it exhibits an oscillatory behaviour around the equilibrium state. 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. These oscillations can be reduced by incorporating auxiliary controllers on generator excitation system.
Power System Stabilizers (PSSs) were developed to produce additional damping by modulating the generator excitation voltage. Designing effective PSS for all operating conditions especially in large interconnected power systems still remains a difficult and challenging task.
More and more power electronic based controllers have been and will be used in power systems. Many of these controllers such as Static Var Compensators (SVCs), Static Synchronous Compensators (STATCOMs) and Unified Power Flow Controllers (UPFCs) etc., are incorporated in power transmission networks to improve its operational capability. In addition, some of the energy storage systems such as Battery Energy Storage systems (BESS), Super conducting Magnetic Energy Storage System (SMES) as well large non-conventional energy sources are also increasingly being integrated with the power grid. With large integration of these devices, there is a significant impact on system stability, more importantly on small signal oscillatory instability of the power system.
This thesis primarily focuses on impact of such devices on small signal oscillatory stability of the power systems. More specifically in this thesis small signal stability analysis of a Single Machine Infinite Bus (SMIB) system with a grid connected wind powered Permanent Magnet Synchronous Generator (PMSG) has been presented. A SMIB system has been purposely chosen so that general conclusions can be obtained on the behaviour of the embedded STATCOM/Energy Source (ES) system on system stability. With a better understanding of the impact of such a system it would be probably possible to analyze more complicated multimachine power system and their impact on system stability. Small signal model of the complete system which comprises the generator, transmission network, inter connecting STATCOM, the wind power generator and all associated controllers has been developed. The performances of the system following a small disturbance at various operating conditions have been analyzed.
To obtain quantitative estimates of the damping and synchronizing torques generated in the system, expressions for damping and synchronizing torque clients have been developed.
With these analyses, the relative impact of the STATCOM and STATCOM with ES on system performance have been assessed. It is shown that with active and reactive power modulation capabilities effective and efficient control of small signal oscillations in power systems can be achieved.
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Tsai, Shao-Hong, and 蔡少宏. "Application of the Real Variant of the Jacobi-Davidson Method to the Small-Signal Stability Analysis of Large Power Systems." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/mxw23v.
Full textAbstract:
博士國立臺北科技大學
機電科技研究所
98
This dissertation is aimed at exploring issues relating to the analysis of the small-signal stability of large power systems. An improved numerical method incorporated with a comprehensive selection strategy for the calculation of critical eigenvalues of the system state matrix has been proposed. The real variant of the Jacobi-Davidson QR (RJDQR) method is a novel and efficient subspace iteration method to find a selected subset of eigenvalues of a real unsymmetric matrix and is favorable to eigenanalysis for the power system small-signal stability. Compared with the original JDQR method, the RJDQR method utilizes real arithmetic to keep the search subspace real and construct a partial real Schur form iteratively. Moreover, the RJDQR method can be practically implemented on highly sparse power system dynamical models. These techniques significantly accelerate iteration convergence and completely avoid repeated computations of the detected eigenvalues, as well as numerical robustness can be guaranteed. In addition, the RJDQR method in conjunction with a flexible selection strategy of critical eigenvalue detection criteria is presented in this dissertation. The selection strategy provides three options for critical eigenvalue detection criteria: (a) detection of the low damped eigenvalues, (b) detection of values in the immediate neighborhood of the specified target value, and (c) detection of the rightmost eigenvalues. By using this selection strategy, the low damped oscillatory modes and/or unstable oscillations in power systems can be found effectively. Numerical experiments demonstrate the efficiency of the RJDQR method adopting the proposed selection strategy for pursuing eigenanalysis tasks based on 89- and 120-machine systems. The results show that the proposed method is capable of effectively finding critical eigenvalues in large power systems.