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Xue, Chang-Fei. "Modelling and control of flexible AC transmission systems (FACTS)." Thesis, University of Warwick, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.425979.
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Fuerte, Esquivel Claudio Rubén. "Steady state modelling and analysis of flexible AC transmission systems." Thesis, University of Glasgow, 1997. http://theses.gla.ac.uk/4616/.
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As electric utilities move into more competitive generation supply regimes, with limited scope to expand transmission facilities, the optimisation of existing transmission corridors for power transfer becomes of paramount importance. In this scenario, Flexible AC Transmission System (FACTS) technology, which aims at increasing system operation flexibility, appear as an attractive alternative. Many of the ideas upon which the foundations of FACTS rest were conceived some time ago. Nevertheless, FACTS as a single coherent integrated philosophy is a newly developed concept in electrical power systems which has received the backing of the major manufacturers of electrical equipment and utilities around the world. It is looking at ways of capitalising on the new developments taking place in the area of high-voltage and highcurrent power electronics in order to increase the control of the power flows in the high voltage side of the network during both steady state and transient conditions, so as to make the network electronically controllable. In order to examine the applicability and functional specifications of FACTS devices, it is necessary to develop accurate and flexible digital models of these controllers and to upgrade most of the software tools used by planners and operators of electric power systems. The aim of this work is to develop general steady-state models FACTS devices, suitable for the analysis of positive sequence power flows in, large-scale real life electric power systems.Generalised nodal admittance models are developed for the Advance Series Compensator (ASC), Phase Shifter (PS), Static Var Compensator (SVC), Load Tap Changer (LTC) and Unified Power Flow Controller (UPFC). In the case of the ASC, two models are presented, the Variable Series Compensator (VSC) and the Thyristor Controlled Series CapacitorFiring Angle (TCSC-F A). An alternative UPFC model based on the concept of Synchronous Voltage Source (SVS) is also developed. The Interphase Power Controller (IPC) is modelled by combining PSs and VSCs nodal admittance models. The combined solution of the power flow equations pertaining to the FACTS devices models and the power network is described in this thesis. The set of non-linear equations is solved through a Newton-Rapshon technique. In this unified iterative environment, the FACTS device state variables are adjusted automatically together with the nodal network state variables so as to satisfy a specified nodal voltage magnitudes and specified power flows. Guidelines and methods for implementing FACTS devices and their adjustments within the Newton-Rapshon algorithm are described. It is shown that large increments in the adjustments of FACTS devices and nodal network state variables during the backward substitution may dent the algorithm's quadratic convergence. Suitable strategies are given which avoid large changes in these variables and retain the Newton-RapshRapshon method's quadratic convergence. The influence of initial conditions of FACTS devices state variables on the iterative process is investigated. Suitable initialisation guidelines are recommended. Where appropriate, analytical equations are given to assure good initial conditions.
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Farsangi, Malihe Maghfouri. "Robust control of flexible AC transmission systems for damping power system oscillations." Thesis, Brunel University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.269400.
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Hasanovic, Azra. "Modeling and control of the unified power flow controller (UPFC)." Morgantown, W. Va. : [West Virginia University Libraries], 2000. http://etd.wvu.edu/templates/showETD.cfm?recnum=1633.
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Thesis (M.S.)--West Virginia University, 2000.Title from document title page. Document formatted into pages; contains viii, 78 p. : ill. Includes abstract. Includes bibliographical references (p. 61-63).
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Perez, Hugo Ambriz. "Flexible AC transmission systems modelling in optimal power flows using Newton's method." Thesis, University of Glasgow, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301856.
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Zeraatzade, Mahbube. "Transmission congestion management by optimal placement of FACTS devices." Thesis, Brunel University, 2010. http://bura.brunel.ac.uk/handle/2438/4710.
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This thesis describes the implementation of the Flexible AC Transmission Systems (FACTS) devices to develop a market-based approach to the problem of transmission congestion management in a Balancing Market. The causes, remedies and pricing methods of transmission congestion are briefly reviewed. Balancing Market exists in markets in which most of the trading is done via decentralized bilateral contracts. In these markets only final adjustments necessary to ensure secure system operation is carried out at a centralized Balancing Market. Each market player can participate in the Balancing Market by submitting offers and bids to increase and decrease its initially submitted active generation output. In this research a method is proposed to reduce costs associated with congestion re-dispatch in a Balancing Market by optimal placement of FACTS devices, and in particular Thyristor Controlled Phase Shifter Transformers (TCPST). The proposed technique is applicable to both Mixed Integer Linear Programming (MILP) and Mixed Integer Non-Linear Programming (MINLP). In the MILP a power system network is represented by a simplified DC power flow under a MILP structure and the Market participants' offers and bids are also represented by linear models. Results show that applications of FACTS devices can significantly reduce costs of congestion re-dispatch. The application of the method based on the MINLP creates a nonlinear and non-convex AC OPF problem that might be trapped in local sub-optima solutions. The reliability of the solution that determines the optimal placement of FACTS devices is an important issue and is carried out by investigation of alternative solvers. The behavior of the MINLP solvers is presented and finally the best solvers for this particular optimization problem are introduced. The application of DC OPF is very common in industry. The accuracy of the DC OPF results is investigated and a comparison between the DC and AC OPF is presented.
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Huang, Han. "Analysis and control of modular multilevel cascaded converter-based flexible AC transmission systems." Thesis, University of Leeds, 2018. http://etheses.whiterose.ac.uk/22886/.
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Mok, Tsz-kin, and 莫子建. "Modeling, analysis and control design for the UPFC with fuzzy theory and genetic algorithm application." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2000. http://hub.hku.hk/bib/B31224969.
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Masuda, Mario. "Aplicação do dispositivo FACTS (Flexible AC Transmission Systems) em sistema de distribuição -simulação de desempenho." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/3/3143/tde-08122006-161400/.
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As novas tecnologias FACTS aplicadas ao sistema de transmissão, com base em eletrônica de potência, podem também ser úteis à distribuição. Para tal é preciso conduzir um procedimento de consolidação da utilização e do desempenho destas, para sua aplicação sem riscos. Neste trabalho, dois aspectos serão contemplados. O primeiro se refere à aplicação do dispositivo FACTS atuando como um capacitor série. Em se tendo controle de módulo e da fase da tensão inserida em série com a linha pode-se fazê-la comportar-se como uma queda em uma reatância série capacitiva ou indutiva. O controle dessa reatância série (aumentando/diminuindo) permitirá a aplicação do conceito de compensação série em qualquer ponto do sistema de distribuição, provendo benefícios de um controle contínuo da tensão e também do controle do fluxo de carga no sistema independente da corrente. O segundo aspecto refere-se ao uso dos dispositivos na conexão de alimentadores controlando a potência ativa entre eles. Para esta operação outro dispositivo UPFC, com conceito similar ao descrito acima, entretanto atuando na fase da tensão entre 2 barras, comporta-se como um transformador defasador com variação contínua de ?taps?, podendo controlar a potência ativa entre os alimentadores. A aplicação destas tecnologias propiciarão vários benefícios para a expansão da distribuição tais como, flexibilização do uso da rede, interligação de alimentadores permitindo manobras de blocos de energia sem ?pisca?, ajuste contínuo do suporte de reativos durante a operação, controle dinâmico do fluxo de potência. O objetivo deste trabalho é estudar a aplicabilidade da tecnologia FACTS e estender este conceito para aplicação em sistemas de distribuição e conduzir simulações digitais em redes de distribuição (15kV) identificando o desempenho e os benefícios atingidos. O programa de simulação utilizado é o ATP (Alternative Transients Program).The new FACTS technologies applied to the transmission system, based on power electronics, can also be useful to the distribution. For that, it is necessary to drive a procedure to consolidate the use and the performance for their application without risks. In this work two aspects will be approached. The first refers to the application of a FACTS device acting as series compensator. This device will be able to control the voltage in module and phase in order to act as a voltage drop in a serie reactance with capacitive or inductive features. The control of this series reactance (increasing/ decreasing) will allow the application of series compensation concept to any point of the distribution system, providing the benefits of continuous control of the voltage added to the load flow control in the system independent of the current. The second aspect refers to its use in the connection of two feeders controlling the active power between them. For this operation other device, UPFC, with similar concept as described previously, acts mainly in the phase of the injected voltage in the line, performing as a phase-shift with continuous taps variation and is able to control the active power flow between feeders. The application of this technology will provide several benefits for the distribution expansion, such as, a greater flexibility in the use of the network, connection of feeders without load flow interruption, continuous adjust of reactive power during the operation and dynamic control of power flow. The purpose of this work is to study the applicability of the FACTS technology, to extend this concept for the application in the distribution system by using digital simulations in distribution network up to 15kV identifying the performance and the reached benefits.
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Li, Peng. "New types of voltage source converters applied in flexible AC transmission system devices." Thesis, University of Strathclyde, 2015. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=25774.
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The uses of flexible alternating current transmission system (FACTS) controllers in next generation smart grids are encouraged by the increased uses of decentralized and highly meshed grid structures that may affect the stability of power systems. Voltage source converter (VSC) based FACTS devices have reduced footprint and offer increased control flexibility, extended range and faster reaction time than line commutated thyristor based equivalent solutions. The performance of commonly used FACTS devices that employ a two-level converter is summarized. Then, multilevel converters and direct AC-AC converters which are viable for FACTS applications are reviewed. The outcomes of the literature surveys are refined to identify new features that may be critical for future centralised and decentralized smart grids such as: control range extension, improved efficiency and power density at reduced hardware cost. To pursue these features, three novel VSC topologies are proposed and analysed: An AC voltage-doubled (ACVD) topology with an internal inverting buck-boost cell in each phase-leg, is able to synthesize twice the output voltage of a conventional two-level VSC for the same dc link voltage, is proposed. A number of new modulation and control strategies that aim to further increase DC utilization of the ACVD converter and to manage its internal dynamic interaction to prevent the appearance of low-order harmonics in the output currents, are presented. With its high DC-rail utilization and sophisticated control strategies, the ACVD converter offers an extended power control range, which is increasingly important for shunt and series type FACTS devices. The controlled transition full-bridge hybrid multilevel converter (CTFB-HMC) with chain-links of full-bridge cells is proposed to combine the advantages of improved wave-shaping ability, reduced footprint and high efficiency, which promote its applications in medium and high voltage FACTS devices. An AC hexagonal chopper using heterodyne modulation to decouple the control of AC voltage amplitude from that of the phase-angle is proposed. For scalability to medium and high voltage, a modular multilevel AC hexagonal chopper (M2AHC) is developed. With adoption of a quasi-two-level transitional mode for reduced cell number and minimized footprint, dv/dt is limited and reliability is improved. Simulation and experimentation are used to validate the modulation, control and FACTS implementation of the three proposed converters.
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Griffin, Julie. "A study of the impact of flexible AC transmission system devices on the economic-secure operation of power systems." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=23263.
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This thesis examines how Flexible AC Transmission Systems (FACTS) devices can improve the secure-economic operation of a power system. More specifically, the benefits of FACTS devices in a network are evaluated in terms of four areas of power system study: system security, economic dispatch operation, maximum network loadability and electric industry deregulation. Simulations of a simple network are made to evaluate how a FACTS device can be used to increase the security region of a network. Based on this analysis, simulations are performed using the 24-bus IEEE reliability test network to assess the possible savings in generation costs, the increase in maximum network loadability and the improvements in flexibility of exchanges resulting from the use of a FACTS device in this network. The results demonstrate that FACTS devices can be used effectively to increase the security region of a network thereby allowing for a better optimum operating point in any optimization problem performed over such a region.
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Gama, Carlos Aparecido. "Utilização de equipamentos com tecnologia FACTS-flexible AC transmission systems-em sistemas de potencia-compensação serie controlada." reponame:Repositório Institucional da UFSC, 1995. https://repositorio.ufsc.br/handle/123456789/111583.
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Athanasiadis, Nikolaos P. "Modelling, control and design of Flexible AC Transmission Systems (FACTS), custom power devices and variable speed drives for transmission and distribution architectures." Thesis, University of Strathclyde, 1999. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21441.
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The main tasks of power electronics in power transmission and distribution systems is to process and control the flow of electric energy by supplying voltages and currents in a form that is suitable for user loads. In recent years, the field of power electronics has experienced a large growth. Electric utilities expected that by the year 2000 over half of the electrical load may be supplied through power electronic systems. In order to take advantage of this highly developed technology a number of detailed modelling procedures and simulation facilities are needed. The work in this thesis is concentrated on modelling, control and design of various power electronic based models for use within transmission and distribution systems. The overall objective is to provide effective methods and tools for assessing the impact of the latest technology based on power electronic devices in the reinforcement of power system networks. The thesis clarifies modelling and control of various variable speed drive models, such as the six-step, PWM and vector control and gives a detailed account of the systematic derivation of equations that are necessary for the dynamic and transient analysis of a multi-machine multi-node power system with associated adjustable speed drives. Simulation of Flexible AC Transmission Systems (FACTS) models has also been developed for a number of devices including: the SVC (Static Var Compensator), the STATCON (Static Condenser) and the UPFC (Unified Power Flow Controller). The methodologies for development of the models are described and a number of case studies are included in order to give a broad overview of the applications and to prove the usefulness of the results. The last part of the thesis includes simulation, control and design of Custom Power Devices for use within distribution system architectures. It starts with a complete control system strategy for the modelling of a solid-state switch and continues with the modelling of a Dynamic Voltage Restorer model, using an innovative control system. The creation of the power electronics models library provides several opportunities for future developments, which are discussed in the concluding sections of the thesis.
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Kalyani, Radha Padma. "A nonlinear optimization approach for UPFC power flow control and voltage security." Diss., Rolla, Mo. : University of Missouri-Rolla, 2007. http://scholarsmine.mst.edu/thesis/pdf/Kalyani_completeThesis_09007dcc80438f59.pdf.
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Thesis (Ph. D.)--University of Missouri--Rolla, 2007.Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed November 29, 2007) Includes bibliographical references.
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Bésanger, Yvon. "Etude des FACTS (Flexible AC Transmission System) et de leur comportement dans les réseaux de transport et d'interconnexion." Grenoble INPG, 1996. https://hal.archives-ouvertes.fr/tel-01147005.
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Les systèmes FACTS (Flexible AC Transmission system) sont pressentis pour l'amélioration des performances des réseaux de transport et d'interconnexion. De nombreuses études ont été faites récemment sur ces systèmes concernant l'augmentation de la vitesse de contrôle des paramètres des lignes (tension, impédance et déphasage). Les compensations shunt et série utilisant des systèmes d'électronique de puissance sont des concepts FACTS et permettent aux réseaux d'être plus flexibles. La compensation shunt réalise de préférence le support de la tension alors que la compensation série est employée pour réduire l'impédance des lignes et donc pour augmenter la capacité de transfert de puissance ainsi qu'améliorer la répartition des transits de puissance dans le réseau, aussi bien que les stabilités statiques et dynamiques. Plusieurs systèmes ont été développés ces dernières années. Ce rapport décrit une étude comparative concernant le comportement statique et dynamique de trois systèmes FACTS dans les réseaux de transport : le SVC (static var compensator), le Statcon (static condenser) et le TCSC (thyristors controlled series compensator). Ce travail est axé sur la stabilité de tension et les capacités de transfert de puissance et inclu l'étude de l'action des LTC (load tap changers). Les effets des PSS (power system stabilizers) sont également analysés dans le but de les comparer ultérieurement aux systèmes FACTS. Les résultats ont été obtenus à l'aide de différents réseaux tests (réseau 14 nœuds IEEE, réseau UHV français simplifié, réseau new-england 39 nœuds) et ont montré l'impact de chaque système FACTS sur les réseaux de puissanceFACTS Systems (Flexible AC Transmission System) are approached to improve performance transport networks and interconnection. Many studies have been done recently on these systems for increasing the speed of parameter control lines (voltage, impedance and phase shift). The shunt and series compensation using systems power electronics are FACTS concepts and enable networks to be more flexible. Shunt compensation is preferably carried out the tension carrier while the series compensation is used to reduce the impedance of the lines and thus to increase the transfer capability power and improve the distribution of power flows in the network, as well as Static and dynamic stability. Several systems have been presented in recent years. This report presents a comparative study of the static and dynamic behavior of three FACTS systems in transport networks: the SVC (Var Compensator Statie), the STATCON (ST condense ATIC) and the TCSC (Thyristor Controlled Series Compensator). This work focuses on voltage stability and power transfer capacity and undue study of the action of L TC (Load Tap Changers). The effects of PSS (Power System Stabilizers) are also analyzed in the purpose of later compare them with FACTS systems. The results were obtained using different tests networks (network 14 noeus IEEE, Simplified French UHV network, New England network 39 knots) and showed the impact of each FACTS system on power networks
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Nguyen, Van Liem. "Modeling and control coordination of power systems with FACTS devices in steady-state operating mode." University of Western Australia. School of Electrical, Electronic and Computer Engineering, 2008. http://theses.library.uwa.edu.au/adt-WU2009.0036.
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This thesis is devoted to the development of new models for a recently-implemented FACTS (flexible alternating current transmission system) device, the unified power flow controller (UPFC), and the control coordination of power systems with FACTS devices in steady-state operating mode. The key objectives of the research reported in the thesis are, through online control coordination based on the models of power systems having FACTS devices, those of maximising the network operational benefit and restoring system static security following a disturbance or contingency. Based on the novel concept of interpreting the updated voltage solutions at each iteration in the Newton-Raphson (NR) power-flow analysis as dynamic variables, the thesis first develops a procedure for representing the unified power flow controllers (UPFCs) in the steady-state evaluation. Both the shunt converter and series converter control systems of a UPFC are modeled in their dynamical form with the discrete time variable replaced by the NR iterative step in the power-flow analysis. The key advantage of the model developed is that of facilitating the process of UPFC constraint resolution during the NR solution sequence. Any relative priority in control functions pre-set in the UPFC controllers is automatically represented in the power-flow formulation. Although the developed UPFC model based on the dynamic simulation of series and shunt converter controllers is flexible and general, the number of NR iterations required for convergence can be large. Therefore, the model is suitable mainly for power system planning and design studies. For online control coordination, the thesis develops the second UPFC model based on nodal voltages. The model retains all of the flexibility and generality of the dynamic simulation-based approach while the number of iterations required for solution convergence is independent of the UPFC controller dynamic responses. Drawing on the constrained optimisation based on Newtons method together with the new UPFC model expressed in terms of nodal voltages, a systematic and general method for determining optimal reference inputs to UPFCs in steady-state operation is developed. The method is directly applicable to UPFCs operation with a high-level line optimisation control (LOC) for maximising the network operational benefit. By using a new continuation technique with adaptive parameter, the algorithm for solving the constrained optimisation problem extends substantially the region of convergence achieved with the conventional Newtons method. Having established the foundation provided by the comprehensive models developed for representing power systems with FACTS devices including the UPFC, the research, in the second part, focuses on real-time control coordination of power system controllers, with the main purpose of restoring power system static security following a disturbance or contingency. At present, as the cost of phasor measurement units (PMUs) and wide-area communication network is on the decrease, the research proposes and develops a new secondary voltage control where voltages at all of the load nodes are directly controlled, using measured voltages.
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Underwood, Ryan C. "An open framework for highly concurrent hardware-in-the-loop simulation." Diss., Rolla, Mo. : University of Missouri-Rolla, 2007. http://scholarsmine.mst.edu/thesis/pdf/Underwood_09007dcc8042c7c7.pdf.
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Thesis (M.S.)--University of Missouri--Rolla, 2007.Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed February 14, 2008) Includes bibliographical references (p. 37-40).
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Smith, Johan. "High voltage direct current strategy solving power delivery shortages to localized area of national grid." Thesis, Cape Peninsula University of Technology, 2009. http://hdl.handle.net/20.500.11838/1102.
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Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2009The industrial and population growth of a nation can cause power delivery problems to localized areas of a national grid through their increased demand for electrical energy. One reason for these power shortages is the insufficient current carrying capacity of existing high voltage alternating current, (HVAC), transmission lines supplying the area. High voltage direct current (HVDC) transmission lines are a possible solution as they provide better power delivery than HVAC lines. New or upgraded HVAC lines, or HVDC lines or combinations of HVAC and HVDC lines are possible solutions to improve power delivery. This research investigates the various line possibilities using theory. and cutting edge frequency and time domain software tools. The challenge is how to approach this problem. What methodology or structure should be used? Thus one of the contributions of this work is the development of a strategy (flow chart), for solving power delivery problems to localized areas of a national grid through individual or combinations (e.g. parallel operation) of HVAC and/or HVDC transmission lines. The main contribution is the evaluation of a HVDC system as a solution to overcoming power delivery shortages to a localized area of a national grid. Three different software packages (two industrial and one academic) namely, PSCAD/EMTDC (time domain), DlgSILENT PowerFactory (frequency domain) and MathCAD software are evaluated for their capability to perform the simulation studies necessary to prove the possible solutions given in the developed flow chart. The PSCAD/EMTDC software package is evaluated for integrated HVAC/HVDC load flow analyses, DlgSILENT for individual and parallel combinations of HVAC lines and MathCAD to prove hand calculations to software results. Five case studies are conducted. The first case study demonstrates a healthy system with no delivery shortcomings, the second case study portrays the delivery shortcoming due to increased localized area demand, and the remaining three case studies explore possible solutions to solve the problem. The first possible solution is to construct an identical HVAC line in parallel to the existing line.
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Li, Qiang. "ANALYSIS, DESIGN, AND LABORATORY EVALUATION OF A DISTRIBUTED UNIFIED POWER FLOW CONTROLLER CONCEPT." UKnowledge, 2006. http://uknowledge.uky.edu/gradschool_diss/347.
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A single-phase, buck-boost based, dual-output AC-DC converter is studied in this thesis. The converter has two DC outputs with opposite polarities, which share the same ground with the input power line. The power stage performance, including the input filter, is studied and procedure to select power components is given. The circuit model is analyzed to develop appropriate control. Zerocrossing distortion of the source input current is addressed and a solution is proposed. Experimental results are satisfactory in that a high power factor line current results for steady-state operation.
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Lakkireddy, Jahnavi. "Steady State Voltage Stability Enhancement Using Shunt and Series FACTS Devices." ScholarWorks@UNO, 2014. http://scholarworks.uno.edu/td/1881.
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It is specifically important to focus on voltage stability analysis of the power system to avoid worst case scenarios such as voltage collapse. The purpose of this thesis is to identify methods for enhancing the steady-state voltage stability using FACTS devices and determining their impact on real and reactive power losses, improvement of bus voltage magnitude, and transmission line loadability. To achieve this, FACTS devices such as Static VAR Compensator (SVC), Static Synchronous Compensator (STATCOM), and Thyristor Controlled Series Capacitor (TCSC) are used in the test system as three separate test cases. The results obtained assist in drawing conclusions on the effectiveness of each FACTS devices at generator, load and swing buses, on lines between two load buses, and between a load bus and a generator bus, in terms of metrics such as voltage magnitude profile, PV curves, and active and reactive power losses.
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Qiao, Wei. "Integrated control of wind farms, facts devices and the power network using neural networks and adaptive critic designs." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/29716.
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Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009.Committee Chair: Ronald G. Harley; Committee Member: David G. Taylor; Committee Member: Deepakraj M. Divan; Committee Member: Ganesh Kumar Venayagamoorthy; Committee Member: Thomas G. Habetler. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Domingues, Adriana Favaro. "Um modelo de espaço de estados com representação de segunda ordem para a analise das oscilações de modo interarea em sistemas de energia eletrica." [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/260320.
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Orientador : Vivaldo Fernando da CostaTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação
Made available in DSpace on 2018-08-04T02:42:32Z (GMT). No. of bitstreams: 1 Domingues_AdrianaFavaro_D.pdf: 789245 bytes, checksum: 9ca2b124a01cd871aa7f4bbb4c63c57a (MD5) Previous issue date: 2005
Resumo: Este trabalho aborda o problema das oscilações eletromecânicas de baixa freqüência de modo interárea em sistemas de energia elétrica através de duas metodologias: primeiramente, através do método convencional da análise modal linear e, posteriormente, através da aplicação do método da forma normal dos campos vetoriais como ferramenta para viabilizar o acréscimo dos termos não lineares de segunda ordem resultantes da expansão em série de Taylor. Neste caso, o método da forma normal é aplicado a um Modelo de Sensibilidade de Potência com representação de segunda ordem, para investigar os efeitos das interações não lineares entre os modos naturais de oscilação de sistemas de energia elétrica. São consideradas, em ambas as análises, a inclusão de dispositivos FACTS e da modelagem dinâmica das cargas. As simulações são realizadas para um sistema simétrico de duas áreas e para o Sistema Equivalente Sul-Sudeste Brasileiro. A metodologia de análise proposta mostra-se bastante satisfatória como alternativa à simulação não linear no domínio do tempo e à análise modal convencional
Abstract: In this work, the analysis of power systems inter-area mode oscillations is performed by the application of two different methodologies: first, the linear modal analysis, and then the analysis including second order nonlinear terms from a Taylor series expansion, with the application of the method of normal forms of vector fields. In this case, the method of normal forms is applied to a Power Sensitivity Model including second order nonlinear terms, in order to investigate the effects of nonlinear interactions between system modes. Both methodologies consider the inclusion of FACTS devices and dynamic load model. Simulations are performed for a symmetric two-area test power system and for the Equivalent South-Southeast Brazilian system. The results obtained show that the methodology proposed is very effective as an alternative to linear modal analysis and timedomain simulation in the performance of inter-area mode oscillations analysis
Doutorado
Energia Eletrica
Doutor em Engenharia Elétrica
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Zhang, Li. "Study of FACTS/ESS Applications in Bulk Power System." Diss., Virginia Tech, 2006. http://hdl.handle.net/10919/28465.
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The electric power supply industry has evolved into one of the largest industries. Even though secure and reliable operation of the electric power system is fundamental to economy, social security and quality of modern life, the complicated power grid is now facing severe challenges to meet the high-level secure and reliable operation requirements.
New technologies will play a major role in helping today's electric power industry to meet the above challenges. This dissertation has focused on some key technologies among them, including the emerging technologies of energy storage, controlled power electronics and wide area measurement technologies. Those technologies offer an opportunity to develop the appropriate objectives for power system control.
The use of power electronics based devices with energy storage system integrated into them, such as FACTS/ESS, can provide valuable added benefits to improve stability, power quality, and reliability of power systems. The study in this dissertation has provided several guidelines for the implementation of FACTS/ESS in bulk power systems.
The interest of this study lies in a wide range of FACTS/ESS technology applications in bulk power system to solve some special problems that were not solved well without the application of FACTS/ESS. The special problems we select to solve by using FACTS/ESS technology in this study include power quality problem solution by active power compensation, electrical arc furnace (EAF) induced problems solution, inter-area mode low frequency oscillation suppression, coordination of under frequency load shedding (UFLS) and under frequency governor control (UFGC), wide area voltage control.
From this study, the author of this dissertation reveals the unique role that FACTS/ESS technology can play in the bulk power system stability control and power quality enhancement in power system. In this dissertation, almost all the studies are based on the real system problems, which means that the study results are special valuable to certain utilities that have those problems. The study in this dissertation can assist power industry choose the right FACTS/ESS technology for their intended functions, which will improve the survivability, minimize blackouts, and reduce interruption costs through the use of energy storage systems.Ph. D.
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Cetin, Alper. "Design And Implementation Of A Voltage Source Converter Based Statcom For Reactive Power Compensation And Harmonic Filtering." Phd thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608307/index.pdf.
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In this thesis, design and implementation of a distribution-type, voltage source converter (VSC) based static synchronous compensator (D-STATCOM) having the
simplest converter and coupling transformer topologies have been carried out. The VSC STATCOM is composed of a +/- 750 kVAr full-bridge VSC employing selective harmonic elimination technique, a low-pass input filter, and a ∆
/Y connected coupling transformer for connection to medium voltage bus. The power stage of VSC based STATCOM is composed of water-cooled high voltage IGBT modules switched at 850 Hz for the elimination of 5th, 7th, 11th, 13th, 17th, 19th, 23rd,and 25th voltage harmonics. Special care has been taken in the laminated busbar design to minimize stray inductances between power semiconductors and dc link capacitor. Reactive power control is achieved by applying the phase angle control technique. The effect of input filter on total demand distortion has been investigated theoretically by mathematical derivations. The proposed VSC STATCOM has been implemented for reactive power compensation of Coal Preparation System in Kemerkö
y Thermal Power Plant. The field test results have shown the success of the implemented system in view of fast response in reactive power compensation, and minimum input current harmonic content, and compliance with the IEEE Std. 519-1992 even for the weakest power systems. The application of selective harmonic elimination technique and phase angle control to VSC STATCOM has led to optimum switching frequency and device utilization for high voltage IGBTs at the expense of slower response as compared to other PWM techniques.
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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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Lopes, Luiz Antonio Correa. "On the utilization of force-commutated AC controllers in AC power transmission systems." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40387.
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Recent economic pressures to enhance the transmission capability and controllability of existing power systems have led the new concept of Flexible AC Transmission System (FACTS). The use of power electronics in fast acting power controllers is one of the backbones of the implementation of FACTS.This thesis deals with the use of force-commutated Pulse Width Modulated (PWM) ac controller technology in phase-shifting and var compensation applications. The proposed technology employes as the building block a 4-switch PWM ac controller, which is controlled by means of duty cycle variation. The difficulties of using PWM in high power applications are overcome with a new multi-module PWM ac controller operated with symmetrically phase shifted carriers. This solution results in harmonic cancellation and consequently in high quality (less distortion) waveforms with the power switches (GTO) switching at low frequencies, thus keeping the communication losses low. The resulting power controllers can be considered as intermediate FACTS devices in terms of performance and flexibility.
An application of one phase-shifter and two var compensators in a tie line is also proposed for suppressing inter-area power oscillations. In this scheme the inter-area mode is deactivated if the FACTS devices keep constant the active and reactive power that flow in the tie line. Furthermore, the two interconnected subsystems were virtually decoupled with the proposed approach, in the sense that the small signal disturbances that occur in one side of the tie line do not affect the machines of the other side.
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Eriksson, Robert. "Security-centered Coordinated Control in AC/DC Transmission Systems." Licentiate thesis, Stockholm : Royal Institute of Technology, 2008. http://kth.diva-portal.org/smash/record.jsf?searchId=4&pid=diva2:101.
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Gonzalez-Torres, Juan Carlos. "Transient stability of high voltage AC-DC electric transmission systems." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS041.
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Les nouvelles politiques adoptées par les autorités nationales ont encouragé pendant les dernières années l'intégration à grande échelle des systèmes d'énergie renouvelable (RES). L'intégration à grande échelle des RES aura inévitablement des conséquences sur le réseau de transport d'électricité tel qu'il est conçu aujourd'hui, car le transport de l'électricité massif sur de longues distances pourrait amener les réseaux de transport à fonctionner près de leurs limites, réduisant ainsi leurs marges de sécurité. Des systèmes de transport d’électricité plus complexes seront donc nécessaires.Dans ce scénario, les systèmes de transmission à Courant Continu Haute Tension (HVDC) constituent la solution la plus intéressante pour le renforcement et l'amélioration des réseaux à Courant Alternatif (AC) existants, non seulement en utilisant des configurations point à point, mais aussi dans des configurations multi-terminales. L'introduction des systèmes HVDC aboutira à terme à un réseau électrique hybride haute tension AC/DC, qui doit être analysé comme un système unique afin de mieux comprendre les interactions entre le réseau AC et le réseau DC.Cette thèse porte sur l'analyse de la stabilité transitoire des systèmes de transmission électrique hybrides AC/DC. Plus particulièrement, deux questions ont été abordées: Quel est l'impact d'un défaut du réseau DC sur la stabilité transitoire du réseau AC? Comment est-il possible de se servir des systèmes de transmission DC en tant qu'actionneurs afin d'améliorer la stabilité transitoire AC ?Dans la première partie de ce travail, les modèles mathématiques du réseau hybride AC/DC sont décrits ainsi que les outils nécessaires à l'analyse du système en tenant compte de sa nature non linéaire. Ensuite, une analyse approfondie de la stabilité transitoire du réseau électrique dans le cas particulier d'un court-circuit dans le réseau DC et l'exécution des stratégies de protection correspondantes sont effectuées. En complément, des indicateurs de stabilité et des outils pour dimensionner les futurs réseaux de la MTDC afin de respecter les contraintes des stratégies de protection existantes sont proposés.La deuxième partie de la thèse porte sur les propositions de commande pour la modulation des références de puissance des systèmes de transmission HVDC dans le but d'améliorer la stabilité transitoire du système AC connecté à ce réseau DC. Tout d'abord, nous axons notre étude sur le contrôle non linéaire des liaisons HVDC point à point dans des liaisons hybrides AC/DC. La compensation rapide des perturbations de puissance, l'injection de puissance d'amortissement et l'injection de puissance de synchronisation sont identifiées comme des mécanismes par lesquels les systèmes HVDC peuvent améliorer les marges de stabilité des réseaux AC.Enfin, une stratégie de contrôle pour l'amélioration de la stabilité transitoire par injection de puissance active dans par un réseau MTDC est proposée. Grâce à la communication entre les stations, la commande décentralisée proposée injecte la puissance d'amortissement et de synchronisation entre chaque paire de convertisseurs en utilisant uniquement des mesures au niveau des convertisseurs. L'implémentation proposée permet d'utiliser au maximum la capacité disponible des convertisseurs en gérant les limites de puissance d'une manière décentraliséeThe new policy frameworks adopted by national authorities has encouraged the large scale-integration of Renewable Energy Systems (RES) into bulk power systems. The large-scale integration of RES will have consequences on the electricity transmission system as it is conceived today, since the transmission of bulk power over long distances could lead the existing transmission systems to work close to their limits, thus decreasing their dynamic security margins. Therefore more complex transmissions systems are needed.Under this scenario, HVDC transmission systems raise as the most attractive solution for the reinforcement and improvement of existing AC networks, not only using point-to-point configurations, but also in a Multi-Terminal configuration. The introduction of HVDC transmission systems will eventually result in a hybrid high voltage AC/DC power system, which requires to be analyzed as a unique system in order to understand the interactions between the AC network and the DC grid.This thesis addresses the transient stability analysis of hybrid AC/DC electric transmission systems. More in particular, two questions sought to be investigated: What is the impact of a DC contingency on AC transient stability? How can we take advantage of the of DC transmission systems as control inputs in order to enhance AC transient stability?In the first part of this work, the mathematical models of the hybrid AC/DC grid are described as well as the necessary tools for the analysis of the system taking into account its nonlinear nature. Then, a thorough analysis of transient stability of the power system in the particular case of a DC fault and the execution of the corresponding protection strategies is done. As a complement, stability indicators and tools for sizing future MTDC grids in order to respect the constraints of existing protection strategies are proposed.The second part of the thesis addresses the control proposals for the modulation of power references of the HVDC transmission systems with the purpose of transient stability enhancement of the surrounding AC system. Firstly, we focus our study in the nonlinear control of point-to-point HVDC links in hybrid corridors. Fast power compensation, injection of damping power and injection of synchronizing power are identified as the mechanisms through which HVDC systems can improve stability margins.Finally, a control strategy for transient stability enhancement via active power injections of an MTDC grid is proposed. Using communication between the stations, the proposed decentralized control injects damping and synchronizing power between each pair of converters using only measurements at the converters level. The proposed implementation allows to fully use the available headroom of the converters by dealing with power limits in a decentralized way
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Mukhedkar, Radnya A. "Flexible alternating current transmission systems for the prevention of voltage collapse in electrical power systems." Thesis, University of the West of England, Bristol, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.252564.
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Tavakoli-Bina, Mohammad. "The bootstrap variable inductance : a new FACTS controller for AC power systems." Thesis, University of Surrey, 2001. http://epubs.surrey.ac.uk/1043/.
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Yu, Chang. "An investigation of subsynchronous oscillation of AC/DC power systems modeling and analysis /." Click to view the E-thesis via HKUTO, 2006. http://sunzi.lib.hku.hk/hkuto/record/B37151885.
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Xuan, Qing-Yun. "Adaptive protection and control systems for controllable series compensated EHV transmission using neural networks." Thesis, Liverpool John Moores University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337860.
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Yu, Chang, and 余暢. "An investigation of subsynchronous oscillation of AC/DC power systems: modeling and analysis." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B37151885.
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Keeli, Anupama. "Low frequency transmission for remote power generating systems." Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41190.
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The goal of this Masters Thesis research is to evaluate alternative transmission systems from remote wind farms to the main grid using low-frequency AC technology. Low frequency means a frequency lower than nominal frequency (60/50Hz). The low-frequency AC network can be connected to the power grid at major substations via cyclo-converters that provide a low-cost interconnection and synchronization with the main grid. Cyclo-converter technology is utilized to minimize costs which result in systems of 20/16.66 Hz (for 60/50Hz systems respectively). Low frequency transmission has the potential to provide an attractive solution in terms of economics and technical merits.
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Pulazza, Giorgia <1993>. "Planning and flexible operation of storage systems in power grids: from transmission to distribution networks." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2022. http://amsdottorato.unibo.it/10487/1/PHD_Thesis_GiorgiaPulazza.pdf.
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The first part of the thesis has been devoted to the transmission planning with high penetration of renewable energy sources. Both stationary and transportable battery energy storage (BES, BEST) systems have been considered in the planning model, so to obtain the optimal set of BES, BEST and transmission lines that minimizes the total cost in a power network. First, a coordinated expansion planning model with fixed transportation cost for BEST devices has been presented; then, the model has been extended to a planning formulation with a distance-dependent transportation cost for the BEST units, and its tractability has been proved through a case study based on a 190-bus test system.
The second part of this thesis is then devoted to the analysis of planning and management of renewable energy communities (RECs).
Initially, the planning of photovoltaic and BES systems in a REC with an incentive-based remuneration scheme according to the Italian regulatory framework has been analysed, and two planning models, according to a single-stage, or a multi-stage approach, have been proposed in order to provide the optimal set of BES and PV systems allowing to achieve the minimum energy procurement cost in a given REC.
Further, the second part of this thesis is devoted to the study of the day-ahead scheduling of resources in renewable energy communities, by considering two types of REC. The first one, which we will refer to as “cooperative community”, allows direct energy transactions between members of the REC; the second type of REC considered, which we shall refer to as “incentive-based”, does not allow direct transactions between members but includes economic revenues for the community shared energy, according to the Italian regulation framework. Moreover, dispatchable renewable energy generation has been considered by including producers equipped with biogas power plants in the community.
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Castro, Marcelo Silva. "A influencia de controladores FACTS na estabilidade de angulo a pequenas pertubações de sistemas eletricos de potencia." [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/260094.
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Orientador: Vivaldo Fernando da CostaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação
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Resumo: Essa dissertação de mestrado apresenta um estudo que avalia o desempenho dos controladores FACTS (Flexible AC Transmission Systems) para a melhoria da estabilidade de ângulo a pequenas perturbações de sistemas elétricos de potência. O potencial do Modelo de Sensibilidade de Potência (MSP), uma alternativa ao clássico modelo Heffron-Phillips (MHP) para o estudo e análise do problema de oscilações eletromecânicas de baixa frequência fracamente amortecidas, é explorado. A análise da estabilidade e o projeto de estabilizadores POD (Power Oscillation Damping) para controladores FACTS são baseados em análise modal, bifurcações de Hopf, gráficos do lugar das raízes, e técnicas de resposta em frequência e no tempo. O desempenho de diferentes sinais de entrada para estabilizadores POD é investigado. Os resultados das simulações revelam que tanto os controladores FACTS série quanto os controladores em derivação possuem um grande potencial para a manutenção da estabilidade angular do sistema
Abstract: This master¿s dissertation presents an assessment of Flexible AC Transmission Systems (FACTS) controllers performance on power system small-signal angle stability improvement. The potential of the Power Sensitivity Model (PSM), an alternative approach to the classical Heffron-Phillips model (HPM) for study and analysis of poorly damped low frequency electromechanical oscillations problem, is explored. The stability analysis and design of FACTS Power Oscillation Damping (POD) controllers are based on modal analysis, Hopf bifurcations, root locus plots, and time and frequency response techniques. The performance of different input signals to the POD controllers is investigated. Simulation results reveal that both shunt FACTS controllers and series ones are very effective on keeping system angle stability
Mestrado
Energia Eletrica
Mestre em Engenharia Elétrica
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Valle, Danilo Basseto do. "A influência do IPFC na estabilidade de pequenas perturbações de sistemas elétricos de potência." [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/261665.
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Orientadores: Vivaldo Fernando da Costa, Igor KopcakDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação
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Resumo: Neste trabalho é avaliada a influência do controlador IPFC (Interline Power Flow Controller ) no desempenho de sistemas elétricos de potência quanto à estabilidade a pequenas perturbações. Foi utilizado um modelo de injeção de potência para inclusão do IPFC em programas de fluxo de carga, considerando a representação das fontes de tensão do dispositivo em coordenadas retangulares e incorporando as equações que representam sua dinâmica. As análises de regime permanente atestam a capacidade do IPFC de gerenciamento e controle dos fluxos de potências ativa e reativa em linhas de transmissão. Entretanto, o ajuste de potência constante do modo de controle pode diminuir a margem de estabilidade de tensão, por não permitir o aumento dos fluxos nas linhas controladas quando o carregamento do sistema cresce. As análises dinâmicas da estabilidade a pequenas perturbações foram realizadas com a inclusão do IPFC e de um POD (Power Oscillation Damping) no Modelo de Sensibilidade de Potência (MSP). Os resultados obtidos revelam que o IPFC possui um grande potencial para a manutenção da estabilidade de ângulo em sistemas de potência quando equipado com controladores POD.
Abstract: This work assess the impact of the IPFC (Interline Power Flow Controller) on the smallsignal stability performance of Power Systems. A power injection model is used to include the IPFC in a power flow routine. The modelling represents the IPFC source voltages in rectangular coordinates and incorporates its differential equations at steady-state. The power flow analysis shows the IPFC effectiveness for the management and control of active and reactive power flows of transmission lines. However, the constant power flow operation mode can decrease the voltage stability margin. The IPFC and a POD (Power Oscillation Damping) were included in the Power Sensitivity Model (PSM) to perform the small-signal stability analysis. Simulation results show that the IPFC with a POD can improve the angle stability of Power Systems.
Mestrado
Energia Eletrica
Mestre em Engenharia Elétrica
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Aqeeli, Mohammed Ali M. "Microwave oscillator with phase noise reduction using nanoscale technology for wireless systems." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/microwave-oscillator-with-phase-noise-reduction-using-nanoscale-technology-for-wireless-systems(46287d2a-bc90-4cee-b893-ccf6a3b0747f).html.
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This thesis introduces, for the first time, a novel 4-bit, metal-oxide-metal (MOM) digital capacitor switching array (MOMDCSA) which has been implemented into a wideband CMOS voltage controlled oscillator (VCO) for 5 GHz WiMAX/WLAN applications. The proposed MOMDCSA is added both in series and parallel to nMOS varactors. For further gain linearity, a wider tuning range and minor phase noise variations, this varactor bank is connected in parallel to four nMOS varactor pairs, each of which is biased at a different voltage. Thus, VCO tuning gain reduces and optimal phase noise variation is obtained across a wide range of frequencies. Based on this premise, a wideband VCO is achieved with low phase noise variation of less than 4.7 dBc/Hz. The proposed VCO has been designed using UMC 130 nm CMOS technology. It operates from 3.45 GHz to 6.23 GHz, with a phase noise of -133.80 dBc/Hz at a 1 MHz offset, a figure of merit (FoM) of -203.5 dBc/Hz. A novel microstrip low-phase noise oscillator is based on a left-handed (LH) metamaterial bandpass filter which is embedded in the feedback loop of the oscillator. The oscillator is designed at a complex quality factor Qsc peak frequency, to achieve excellent phase noise performance. At a centre frequency of 2.05 GHz, the reported oscillator demonstrates, experimentally, a phase noise of -126.7 dBc/Hz at a 100 kHz frequency offset and a FoM of -207.2 dBc/Hz at a 1 MHz frequency offset. The increasing demands have been placed on the electromagnetic compatibility performance of VCO devices is crucial. Therefore, this thesis extends the potential of highly flexible and conductive graphene laminate to the application of electromagnetic interference (EMI) shielding. Graphene nanoflake-based conductive ink is printed on paper, and then it is compressed to form graphene laminate with a conductivity of 0.43×105 S/m. Shielding effectiveness is experimentally measured at above 32 dB as being between 12GHz and 18GHz, even though the thickness of the graphene laminate is only 7.7µm. This result demonstrates that graphene has great potential for offering lightweight, low-cost, flexible and environmentally friendly shielding materials which can be extended to offering required shielding from electromagnetic interference (EMI), not only for VCO phase noise optimisation, but also for sensitive electronic devices.
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Santos, Milana Lima dos. "Avaliação do desempenho de linhas de transmissão de energia elétrica de meia onda." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/3/3143/tde-12112010-175512/.
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A transmissão de grandes blocos de energia elétrica por longas distâncias é uma tecnologia cujo domínio é de bastante interesse para o Brasil, devido às suas características de grande dimensão territorial, com uma distância considerável entre geração e centros de carga, e com um grande potencial energético ainda não explorado. A solução mais utilizada na transmissão em corrente alternada convencional, que é a compensação, ao longo da linha, da reatância série e paralela, se torna dispendiosa quando aplicada em distâncias muito longas. Sabe-se que a transmissão em corrente continua é uma solução viável para este tipo de transmissão. Outra opção, que é objeto deste trabalho, é a transmissão em linhas de \"pouco mais de meio comprimento de onda\", cujo principal atrativo é o fato de as distâncias entre as gerações na Amazônia e os centros de carga no Sudeste brasileiro serem bastante próximas do meio comprimento de onda das tensões e correntes alternadas em 60 Hz. Neste trabalho, serão descritas etapas de definição de condutor economicamente mais adequado e projeto da geometria da torre. Com base nesses dados, serão avaliados algumas propriedades das linhas de meia onda, durante operação normal, curtos-circuitos e energização. Serão também analisadas as perdas resistivas.Bulk power transmission over long distances is a technology of much interest to Brazil, due mainly to the large territory owned with considerable distances between generation and the load centers; to which, it can be added the large amount of energetic potential still unexplored. When conventional AC power transmission is used, usually it is necessary to provide series and shunt compensation, solution that becomes expensive when applied to very long distances. It is known, though, that DC power transmission is still a viable solution to this type of transmission. In this work, differently of the above alternatives, it will be addressed another type of transmission, the so-called half-wavelength transmission lines (HWLL). One interesting requirement of this technology is the fact that these lines should be about 2500 km long, which is approximately the same distance between the generation area (Amazon region) and the load centers located in the Southeast region of the country. In this work, it will be suggested some steps to define the most suitable conductor cross section resulting from the compromise between line components acquisition and installation costs as well as power loss costs. Subsequently, a suitable geometry for the tower that could be used will be selected. Some of the properties of HWLL will be assessed for normal operation, short circuits and line energization. Finally, Joule losses will also be examined.
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Lessa, Avanir Carlos. "Estudo e modelagem de um DSTATCOM para aplicação em sistemas de distribuição com problemas de desequilíbrio de tensão." reponame:Repositório Institucional da UFABC, 2014.
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Orientador: Prof. Dr. Claudionor Francisco do NascimentoDissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Engenharia Elétrica, 2014.
Os sistemas de distribuição de energia elétrica, de um modo geral, são radiais. Estes sistemas podem possuir problemas de qualidade da energia elétrica em suas barras, tais como os desequilíbrios de tensão e de corrente. Ademais, as redes de distribuição podem conter uma grande quantidade de cargas monofásicas e trifásicas desequilibradas, indutivas e não lineares, o que pode resultar nos seguintes problemas: baixo fator de potência, desequilíbrio de tensão e distorção harmônica. Nesse sentido, devido à dinâmica destas cargas e a ocorrência de fenômenos, como afundamento de tensão por partidas de grandes motores e curtos-circuitos, há a necessidade de solução destas anormalidades, com respostas rápidas de estabilização. De maneira a atender a esta necessidade, os resultados das recentes pesquisas baseadas na eletrônica de potência têm proporcionado a utilização de equipamentos capazes de trabalhar em sistemas de potência de alta tensão. Esse avanço permite aplicações de dispositivos FACTS (Flexible Alternating Current Transmission Systems) nas operações de flexibilidade e mitigação de problemas comuns às redes de energia elétrica de transmissão e de distribuição, melhorando, assim, a qualidade da energia elétrica, o que aumenta a confiabilidade destes sistemas. Com este propósito, o presente trabalho tem como objetivo principal o estudo e a modelagem de um DSTATCOM (Distribution Static Compensator) em um sistema de distribuição de energia elétrica com variações de tensão, avaliando os possíveis benefícios proporcionados a este sistema. Os resultados de simulação foram obtidos com o auxílio do software MatLab/Simuling.
Distribution systems of electric power, in general, are radial. These systems have power quality problems in their power bars, such as the voltage variations. Moreover, the distribution networks contain a large amount of single-phase and three-phase unbalanced loads, inductive and non-linear, which may result in the following problems: low power factor, voltage unbalance, and harmonic distortion. Accordingly, due to the dynamic loads and the occurrence of these phenomena, such as voltage sag matches by large motors and short circuits, there is a need for solution of these abnormalities, with responsive stabilization. In order to meet this need, the results of recent research based on power electronics have provided the use of equipment to work on systems of high voltage power. This advancement allows applications FACTS devices (Flexible Alternating Current Transmission Systems) flexibility in operations and mitigation of problems common to the networks of electricity transmission and distribution, thus improving the quality of electric power, which increases the reliability of these systems. For this purpose, the present work has as main objective the study and modeling of a DSTATCOM (Distribution Static Compensator) in a system of electricity distribution, evaluating the possible benefits provided to the electric power system. The simulation results were obtained with the aid of software Matlab/Simuling. The effectiveness of the work has been proven since the DSTATCOM installed, the distribution network operated within established standards.
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Oldeen, Joakim, and Vishnu Sharma. "Reinforcement Learning for Grid Voltage Stability with FACTS." Thesis, Uppsala universitet, Institutionen för informationsteknologi, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-414418.
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With increased penetration of renewable energy sources, maintaining equilibrium between production and consumption in the world’s electrical power systems (EPS) becomes more and more challenging. One way to increase stability and efficiency in an EPS is to use flexible alternating current transmission systems (FACTS). However, an EPS containing multiple FACTS-devices with overlapping areas of influence can lead to negative effects if the reference values they operate around are not updated with sufficient temporal resolution. The reference values are usually set manually by a system operator. The work in this master thesis has investigated how three different reinforcement learning (RL) algorithms can be used to set reference values automatically with higher temporal resolution than a system operator with the aim of increased voltage stability. The three RL algorithms – Q-learning, Deep Q-learning (DQN), and Twindelayed deep deterministic policy gradient (TD3) – were implemented in Python together with a 2-bus EPS test network acting as environment. The 2-bus EPS test network contain two FACTS devices: one for shunt compensation and one for series compensation. The results show that – with respect to reward – DQN was able to perform equally or better than non-RL cases 98.3 % of the time on the simulation test set, while corresponding values for TD3 and Q-learning were 87.3 % and 78.5 % respectively. DQN was able to achieve increased voltage stability on the test network while TD3 showed similar results except during lower loading levels. Q-learning decreased voltage stability on a substantial portion of the test set, even compared to a case without FACTS devices. To help with continued research and possible future real life implementation, a list of suggestions for future work has been established.
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Korejčík, Michal. "Návrh transformátoru s regulací fáze pro laboratorní výuku." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2012. http://www.nusl.cz/ntk/nusl-219412.
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This thesis deals with a power flow control in the electric power system. An overview of FACTS devices is introduced; their basic characteristics as well as examples of their application are discussed. A significant part of this thesis investigates phase shifting transformers (PST´s), which seem to be suitable for implementation in the transmission system of the Czech Republic. The PST´s are useful devices that control active power flows on cross-border lines and regulate unwanted and unexpected power flows. Basic types and characteristics of the PST´s are discussed. In chapter 7 is designed laboratory task that should validate the regulatory capabilities of the transformer PST. Designs of models of individual parts of this laboratory task are presented. In the last part of this thesis the regulation effect of the PST is validated in the GLF/AES program.
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Tambey, Neelima. "Flexible AC transmission systems (FACT) controllers for damping power system oscillations." Thesis, 2003. http://localhost:8080/xmlui/handle/12345678/5553.
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Yuma, Galu. "Stability analysis of Tshwane municipality electric power network." Thesis, 2009. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1000497.
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M. Tech. Electrical Engineering.The main focus of this dissertation is to present the modelling and simulation of the Centurion suburb of the Tshwane Municipality electric power system using MATLAB/SIMULINK package. The basic system is tested under large and small disturbances to study the dynamic behaviour of the system and the stability margins associated with the different configurations of the system.
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Jovcic, Dragan. "Control of high voltage DC and flexible AC transmission systems." 1999. http://hdl.handle.net/2292/272.
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Analytical modeling of HVDC systems has been a difficult task without a to-date reported model convenient for serious analysis of practically reported HVDC stability problems. In order to cover the frequency range f<100Hz, and to cater for different model requirements, three different HVDC-HVAC models are developed in this Thesis: Detailed linear-continuous model, simplified linear continuous model and linear discrete model. Detailed HVDC-HVAC system model is intended for small signal analysis of HVDC-HVAC interactions and resulting stability problems. It demonstrates good response matching against PSCAD/EMTDC simulation, where the CIGRE HVDC Benchmark model is used as the test system. All model variables (states) and parameters have physical meaning, and the model consists of modules, which reflect actual physical subsystems. Simplified HVDC-HVAC system dynamic model is developed as a fourth order dynamic model, which is less accurate but more convenient for the analysis, than the detailed model. The model proves to be reliable for controller design for mitigation of composite resonance and for the study of non-linear effects in HVDC systems. The developed linear discrete model is primarily intended for the system analysis at frequencies close to 100Hz on DC side of HVDC system. A new approach in modeling of TCR/TCSC, based on the same principles for HVDC modeling, is presented in this Thesis. The model development is far less difficult than the similar models presented in literature. PSCAD/EMTDC simulation confirms the model validity. The simplified, linear-continuous model is used for the analysis of dominant non-linear effects in HVDC systems. The analysis of non-linear mode transformation between constant beta and constant gamma operation, shows that limit-cycle oscillations are not expected to develop, for normal operating conditions. The analysis of converter firing angle modulation shows that converter behaves as a non-linear element only for some unlikely operating conditions. In this Thesis, it is attempted to counteract the composite resonance phenomenon by modifying the resonant condition on DC system impedance profile. This is accomplished by designing a supplementary HVDC controller that acts on HVDC firing angle on both line ends. PSCAD/EMTDC simulation results show that significant reduction in DC side first harmonic component (in some cases to 1/4 of the original value) is possible with the newly designed controller. Chapter 5 studies 100Hz oscillations on DC side of HVDC system. A methodology for designing a new controller to counteract negative affects of these oscillations is presented. Linear simulation of the detailed controller design confirms noticeable reduction in second harmonic on DC side. The eigenvalue decomposition and singular value decomposition is used for small-signal analysis of HVDC-HVAC interactions. The analysis of sensitivity of the dominant system eigenvalues with respect to the AC system parameters, shows the frequency range for the possible oscillatory instabilities at rectifier and at inverter side. The rectifier side of the system is most likely to experience instability at higher frequencies, whereas at inverter side the instabilities can be expected at lower frequencies. Further analysis shows that reduction in the AC system strength i will predominantly affect the eigenvalues at lower frequencies, where the SCR reduction at inverter side much more affects the system stability. The analysis of interactions between AC and DC systems through the influence of inherent feedback loops gives recommendations for the possible control of interaction variables with the aim of system stability improvement. The root locus technique is used for the stability analysis of HVDC control loops, where all conventional and some alternative control methods suggested in the literature are investigated. It is found that DC feedback, at rectifier side, significantly improves the system stability at lower frequencies, however, at frequencies close to the first harmonic this feedback control degrades the system stability, actually accelerating the development of composite resonance. At inverter side, most of the feedback loops improve the system stability in a certain frequency range, whereas at other frequencies they noticeably deteriorate stability. Among all reported inverter control methods, reactive current feedback is found to be the best option. The last Chapter develops a new controller for HVDC system operation with very weak inverter AC systems. The selection of feedback signal for this controller, is based on the analysis of positioning of zeros for candidate feedback signals. It is found that AC current angle is the best inverter feedback signal. This feedback signal can move the unstable complex eigenvalues left, into the stable region, without significantly affecting remaining eigenvalues. For the additional improvement in the system performance, a second order filter, designed using control theory, is placed into the feedback loop. The main design objective is the system robustness with respect to the AC system parameters changes. The controller designed in this Thesis, tolerates very wide changes in system strength, 1.7
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"Aplicação do dispositivo FACTS (Flexible AC Transmission Systems) em sistema de distribuição -simulação de desempenho." Tese, Biblioteca Digital de Teses e Dissertações da USP, 2006. http://www.teses.usp.br/teses/disponiveis/3/3143/tde-08122006-161400/.
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Chen, Ying-Ren, and 陳膺仁. "Use of Fuzzy Control Theory and Flexible AC Transmission System Devices to Enhance Power System Stability." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/74631371907710425783.
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碩士國立聯合大學
電機工程學系碩士班
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The trend of power deregulation and distributed generation is going to increase the degree of complexity and difficulty in power system operation and control. Due to the slow response characteristics and the lack of flexibility in changing control functions, the traditional power system control methods can not fulfill the control and operational requirements of a new power system. In recent years, the fast development of high-capacity power electronic devices and digital control techniques has resulted in the possibility of implementing high-power, fast-response power flow controllers. An ac transmission system with above mentioned power electronic based power flow controllers is normally named the flexible ac transmission systems, FACTS. The main objective of this research is to investigate various control schemes, in which FACTS devices and fuzzy controllers based on intelligent control algorithms are used to improve the power system overall performance both in steady-state and transient state. In this study, only three typical FACTS controllers, i.e., Thyristor controlled series capacitor, TCSC, static var compensator, STATCOM, and the unified power flow controller, UPFC are investigated in terms of the possibility to increase the power system control performance both in steady state power flow regulations and in transient state dynamic stability enhancement. To solve the problems in choosing optimal parameters for the internal parameters of fuzzy controllers, a genetic algorithm, GA, based method has been successful applied. Comprehensive computer simulation studies based on two typical test power systems have been carried out. Results have been presented and discussed to verify the effectiveness of the proposed fuzzy controller based FACTS control schemes which have higher application flexibility and overall control performance.
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Maturu, Suresh. "Performance Evaluation Of Distance Relays For FACTS Compensated Transmission Lines." Thesis, 2011. https://etd.iisc.ac.in/handle/2005/2084.
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With limited enhancement or expansion of the transmission infrastructure, the contemporary power systems are operating under more stressed conditions. It becomes important to fully utilize the existing transmission system to supply load demand as much as possible, thus eliminating or reducing the need for new transmission investment.
Flexible AC Transmission System (FACTS) technology provides an alternative to fully utilize the existing transmission lines as well as new and upgraded lines, by controlling power and also enhancing the power transfer capability of transmission lines. However, the implementation of FACTS controllers in the transmission system has introduced new power system dynamics that must be addressed in the area of power system protection, such as rapid changes in line impedance, power angle, line currents, transients introduced by the occurrence of fault and associated control action of the FACTS controller. Therefore, the performance of the protection system must be carefully analyzed in the presence of FACTS controllers.
The thesis aims at evaluating the performance of distance relays when different types of FACTS controllers, in particular Voltage Source Converter (VSC) based FACTS controllers, are incorporated at the midpoint of the transmission system to achieve voltage profile improvement and power transfer capability. The detailed models of these controllers and their control strategies are described. The presence of FACTS controllers in the loop affects both steady state and transient components of voltage and current signals. The rapid response of FACTS controllers to different power system configurations significantly affects the apparent impedance seen by distance relays. The apparent impedance seen by distance relays would be different from that of the system without FACTS controller. Due to this, the distance relay may malfunction, resulting in unreliable operation of the power system during faults. Furthermore, the effect of FACTS controllers on distance relay operation depends on the type of FACTS controller used, the application for which it has been installed and its location in the power system. The distance relay is evaluated for different loading conditions and for various fault conditions. Simulation studies are carried out using PSCAD/EMTDC based transient simulation package.
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Maturu, Suresh. "Performance Evaluation Of Distance Relays For FACTS Compensated Transmission Lines." Thesis, 2011. http://etd.iisc.ernet.in/handle/2005/2084.
Full textAbstract:
With limited enhancement or expansion of the transmission infrastructure, the contemporary power systems are operating under more stressed conditions. It becomes important to fully utilize the existing transmission system to supply load demand as much as possible, thus eliminating or reducing the need for new transmission investment.
Flexible AC Transmission System (FACTS) technology provides an alternative to fully utilize the existing transmission lines as well as new and upgraded lines, by controlling power and also enhancing the power transfer capability of transmission lines. However, the implementation of FACTS controllers in the transmission system has introduced new power system dynamics that must be addressed in the area of power system protection, such as rapid changes in line impedance, power angle, line currents, transients introduced by the occurrence of fault and associated control action of the FACTS controller. Therefore, the performance of the protection system must be carefully analyzed in the presence of FACTS controllers.
The thesis aims at evaluating the performance of distance relays when different types of FACTS controllers, in particular Voltage Source Converter (VSC) based FACTS controllers, are incorporated at the midpoint of the transmission system to achieve voltage profile improvement and power transfer capability. The detailed models of these controllers and their control strategies are described. The presence of FACTS controllers in the loop affects both steady state and transient components of voltage and current signals. The rapid response of FACTS controllers to different power system configurations significantly affects the apparent impedance seen by distance relays. The apparent impedance seen by distance relays would be different from that of the system without FACTS controller. Due to this, the distance relay may malfunction, resulting in unreliable operation of the power system during faults. Furthermore, the effect of FACTS controllers on distance relay operation depends on the type of FACTS controller used, the application for which it has been installed and its location in the power system. The distance relay is evaluated for different loading conditions and for various fault conditions. Simulation studies are carried out using PSCAD/EMTDC based transient simulation package.
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Yan, Ping. "Congestion Management, Total Transfer Capability Improvement and Short-Term Adequacy Evaluation in Deregulated Power Systems – Prospering and Surviving in the Competitive World." Thesis, 2011. http://hdl.handle.net/1969.1/ETD-TAMU-2011-08-10086.
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While two objectives of deregulation are to reduce service interruptions and achieve lower energy costs, deregulation has actually introduced new problems in both areas.
Since the transmission network was built in the last century, mainly for the regulated power systems, with mostly local power transfers, the increased long distance power transfer introduced by free energy trading has made congestion happen more frequently. When congestion happens, service interruptions occur and higher energy costs arise.
We approach the issue from the viewpoints of both planning and online operations. Accordingly, we develop a reactive online remedying method that uses Flexible AC Transmission (FACTS) devices to eliminate congestion with minimum transaction curtailment to maintain market force. We also develop a proactive preventive method for offline planning, such as in the day-ahead market, which uses FACTS devices to maximize the Total Transfer Capability so that more transactions can be scheduled without causing congestion in the system. Optimal Power Flow is used for both methods with FACTS devices treated as control variables so that they can be adjusted to the best FACTS parameters to minimize the transaction curtailment or maximize the Total Transfer Capability. We demonstrate that FACTS devices are very effective for both situations.
Since the installation of FACTS devices involves heavy infrastructure investment, an effective pricing method needs to be in place to encourage this investment by guaranteeing sufficient return. This research uses a novel pricing scheme to charge for both utilizing the FACTS devices and having the FACTS devices operating at their limits. The owners of the FACTS devices will then be able to recover their investment.
With the above control method and the pricing method, we can make better use of the existing transmission network and relieve congestion. However, deregulation may also degrade system reliability since the generation companies are not obligated to sell into the market and market participation is driven by market forces instead.
We use the market share based short-term adequacy analysis method to address generation resource adequacy issues. The market share based method uses the market share time series for the generation companies to reflect their market behavior in the new environment. Multiple regression modeling, a tool of time series analysis, is used to model involved factors. We demonstrate how the market share based short-term adequacy analysis method can capture the adequacy problems that the traditional method cannot. In addition, it can also help to remedy the adequacy problems, which can in turn reduce service interruption and thus the energy price.