Dissertations / Theses on the topic 'Thyristor Controlled Series Compensator (TCSC)'

<p>Series compensation of transmission lines is an effectiveand cheap method of improving the power transmission systemperformance. Series capacitors virtually reduces the length ofthe line making it easier to keep all parts of the power systemrunning in synchronism and to maintain a constant voltage levelthroughout the system. In Sweden this technology has been inuse since almost 50 years.</p><p>The possibility to improve the performance of the ACtransmission system utilizing power electronic equipment hasbeen discussed a lot since about ten years. Some newsemiconductor based concepts have been developed beside thesince long established HVDC and SVC technologies. The ThyristorControlled Series Capacitor (TCSC) is one such concept. Byvarying the inserted reactance an immediate and well-definedimpact on the active power flow in the transmission line isobtained. Several potential applications, specifically poweroscillation damping, benefit from this capability. The conceptimplied the requirement to design a semiconductor valve, whichcan be inserted directly in the high-voltage power circuit.This certainly presented a technical challenge but thestraightforward approach appeared to be a cost-effectivealternative with small losses.</p><p>It was also realized that the TCSC exhibits quite differentbehaviour with respect to subsynchronous frequency componentsin the line current as compared to the fixed series capacitorbank. This was a very interesting aspect as the risk ofsubsynchronous resonance (SSR), which just involves such linecurrent components, has hampered the use of series compensationin power systems using thermal generating plants.</p><p>The thesis deals with the modelling and control aspects ofTCSC. A simplifying concept, the equivalent, instantaneousvoltage reversal, is introduced to represent the action of thethyristor controlled inductive branch, which is connected inparallel with the series capacitor bank in the TCSC. The idealvoltage reversal is used in the thesis in order to describe andexplain the TCSC dynamics, to investigate its apparentimpedance at various frequencies, as a platform forsynthesizing the boost control system and as the base elementin deriving a linear, small-signal dynamical model of thethree-phase TCSC. Quantitative Feedback Theory (QFT) then hasbeen applied to the TCSC model in order to tune its boostregulator taking into account the typical variation ofparameters that exists in a power system. The impact of theboost control system with respect to damping of SSR is finallybeing briefly looked at.</p><p><b>Keywords:</b>Thyristor Controlled Series Capacitor, TCSC,FACTS, reactive power compensation, boost control, phasorestimation, Quantitative Feedback Theory, subsynchronousresonance, SSR.</p>

Submitted by NELSON GIOVANNY ROMERO TAQUIRE (romero.taquire.nelson@gmail.com) on 2016-05-20T21:35:24Z No. of bitstreams: 1 NelsonGiovannyRomeroTaquire2016.pdf: 3534022 bytes, checksum: 59ecb7956af007830fd18b15c10562c2 (MD5)<br>Approved for entry into archive by Felipe Augusto Arakaki (arakaki@reitoria.unesp.br) on 2016-05-24T13:42:19Z (GMT) No. of bitstreams: 1 taquire_ngr_me_ilha.pdf: 3534022 bytes, checksum: 59ecb7956af007830fd18b15c10562c2 (MD5)<br>Made available in DSpace on 2016-05-24T13:42:19Z (GMT). No. of bitstreams: 1 taquire_ngr_me_ilha.pdf: 3534022 bytes, checksum: 59ecb7956af007830fd18b15c10562c2 (MD5) Previous issue date: 2016-03-21<br>Fundação de Ensino, Pesquisa e Extensão de Ilha Solteira (FEPISA)<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)<br>Neste trabalho propõe-se um método para a localização de faltas que, em conjunto com a lógica de um relé diferencial numérico, deve ser usado para proteção de linhas de transmissão com compensação série controlada por tiristores (TCSC). Este método visa solucionar o problema de localização de faltas melhorando a precisão dos algoritmos que utilizam medições de sinais de tensão e corrente numa terminação da linha de transmissão. O cálculo da distância entre a terminação da linha de transmissão e o ponto de incidência da falta é realizado utilizando dois procedimentos: um para faltas produzida no trecho entre a terminação local da linha de transmissão e o TCSC; e o outro para faltas no trecho entre o TCSC e a terminação remota. A detecção do trecho de incidência da falta é obtido usando as medições de escorregamento angular dos sinais de corrente em ambos os extremos da linha de transmissão e a medição da resistência de falta no extremo local, que é variável durante o intervalo de início até um ciclo depois da ocorrência da falta. A aplicação da lógica difusa na comparação destas medições permite detectar com precisão o trecho com falta. O método proposto foi testado usando um sistema teste da literatura onde múltiplos casos de faltas em diferentes pontos da linha de transmissão foram simulados. Os resultados mostram a capacidade do algoritmo em localizar precisamente a posição de ocorrência da falta.<br>This paper proposes a methodology for locating faults in transmission lines with thyristor-controlled series compensation (TCSC) that are protected by numerical differential relays. The proposed methodology aims to overcome problems of fault location improving the accuracy of algorithms that use voltage and current measurement signals from a transmission line termination. The calculation of the distance between the transmission line termination and the fault incidence point employs two procedures: one for faults in the transmission line section limited by the local termination and TCSC; and other for faults in the section limited by the TCSC and remote termination. The detection of the fault incidence section is achieved using measurements of angular deviation for both transmission line terminations and the measurement of fault resistance in the local termination, which varies during the interval from the beginning to one cycle after the fault occurrence. The use of fuzzy logic for comparing these measurements permits the accurate detection of the fault incidence section. The proposed method is tested using a test system from literature system where multiple fault cases in different positions of the transmission line are simulated. The results show the algorithm capability to locate accurately the position of fault occurrence.

Orientador: Jose Sanches Mantovani<br>Resumo: Neste trabalho propõe-se um método para a localização de faltas que, em conjunto com a lógica de um relé diferencial numérico, deve ser usado para proteção de linhas de transmissão com compensação série controlada por tiristores (TCSC). Este método visa solucionar o problema de localização de faltas melhorando a precisão dos algoritmos que utilizam medições de sinais de tensão e corrente numa terminação da linha de transmissão. O cálculo da distância entre a terminação da linha de transmissão e o ponto de incidência da falta é realizado utilizando dois procedimentos: um para faltas produzida no trecho entre a terminação local da linha de transmissão e o TCSC; e o outro para faltas no trecho entre o TCSC e a terminação remota. A detecção do trecho de incidência da falta é obtido usando as medições de escorregamento angular dos sinais de corrente em ambos os extremos da linha de transmissão e a medição da resistência de falta no extremo local, que é variável durante o intervalo de início até um ciclo depois da ocorrência da falta. A aplicação da lógica difusa na comparação destas medições permite detectar com precisão o trecho com falta. O método proposto foi testado usando um sistema teste da literatura onde múltiplos casos de faltas em diferentes pontos da linha de transmissão foram simulados. Os resultados mostram a capacidade do algoritmo em localizar precisamente a posição de ocorrência da falta.<br>Abstract: This paper proposes a methodology for locating faults in transmission lines with thyristor-controlled series compensation (TCSC) that are protected by numerical differential relays. The proposed methodology aims to overcome problems of fault location improving the accuracy of algorithms that use voltage and current measurement signals from a transmission line termination. The calculation of the distance between the transmission line termination and the fault incidence point employs two procedures: one for faults in the transmission line section limited by the local termination and TCSC; and other for faults in the section limited by the TCSC and remote termination. The detection of the fault incidence section is achieved using measurements of angular deviation for both transmission line terminations and the measurement of fault resistance in the local termination, which varies during the interval from the beginning to one cycle after the fault occurrence. The use of fuzzy logic for comparing these measurements permits the accurate detection of the fault incidence section. The proposed method is tested using a test system from literature system where multiple fault cases in different positions of the transmission line are simulated. The results show the algorithm capability to locate accurately the position of fault occurrence.<br>Mestre

Modern interconnected power systems are becoming highly complex and sophisticated, while increasing energy penetrations through congested inter-tie lines causing the operating point approaching stability margins. This as a result, exposes the overall system to potential low frequency power oscillation phenomena following disturbances. This in turn can lead to cascading events and blackouts. Recent approaches to counteract this phenomenon are based on utilization of wide area monitoring systems (WAMS) and power electronics based devices, such as flexible AC transmission systems (FACTS) and HVDC links for advanced power oscillation damping provision. The rise of hybrid AC-DC power systems is therefore sought as a viable solution in overcoming this challenge and securing wide-area stability. If multiple FACTS devices and HVDC links are integrated in a scheme with no supervising control actions considered amongst them, the overall system response might not be optimal. Each device might attempt to individually damp power oscillations ignoring the control status of the rest. This introduces an increasing chance of destabilizing interactions taking place between them, leading to under-utilized performance, increased costs and system wide-area stability deterioration. This research investigates the development of a novel supervisory control scheme that optimally coordinates a parallel operation of multiple FACTS devices and an HVDC link distributed across a power system. The control system is based on Linear Quadratic Gaussian (LQG) modern optimal control theory. The proposed new control scheme provides coordinating control signals to WAMS based FACTS devices and HVDC link, to optimally and coherently counteract inter-area modes of low frequency power oscillations inherent in the system. The thesis makes a thorough review of the existing and well-established improved stability practises a power system benefits from through the implementation of a single FACTS device or HVDC link, and compares the case –and hence raises the issue–when all active components are integrated simultaneously and uncoordinatedly. System identification approaches are also in the core of this research, serving as means of reaching a linear state space model representative of the non-linear power system, which is a pre-requisite for LQG control design methodology.

Power flow (PF) control can increase the utilization of the transmission system and connect lower cost generation with load. While PF controllers have demonstrated the ability to realize dynamic PF control for more than 25 years, PF control has been sparsely implemented. This research re-examines PF control in light of the recent development of fractionally-rated PF controllers and the incremental power flow (IPF) control concept. IPF control is the transfer of an incremental quantity of power from a specified source bus to specified destination bus along a specified path without influencing power flows on circuits outside of the path. The objectives of the research are to develop power system operation and planning methods compatible with IPF control, test the technical viability of IPF control, develop transmission planning frameworks leveraging PF and IPF control, develop power system operation and planning tools compatible with PF control, and quantify the impacts of PF and IPF control on multi-decade transmission planning. The results suggest that planning and operation of the power system are feasible with PF controllers and may lead to cost savings. The proposed planning frameworks may incent transmission investment and be compatible with the existing transmission planning process. If the results of the planning tool demonstration scale to the national level, the annual savings in electricity expenditures would be $13 billion per year (2010$). The proposed incremental packetized energy concept may facilitate a reduction in the environmental impact of energy consumption and lead to additional cost savings.

This thesis studies different aspects of Flexible AC Transmission System (FACTS) devices which are used to improve the power transfer capability and increase the controllability in electric power systems. In the thesis, different aspects on the usage and control of Dynamic Power Flow Controllers (DPFC) and related FACTS devices are studied. The DPFC is a combination of a Phase Shifting Transformer (PST) and a Thyristor Switched Series Capacitor (TSSC)/Thyristor Switched Series Reactor (TSSR). The thesis proposes and studies a new method, the Ideal Phase-Shifter (IPS) method, for selection and rating of Power Flow Controllers (PFC) in a power grid. The IPS method, which is based on steady-state calculations, is proposed as a first step in the design process for a PFC. The method uses the Power controller plane, introduced by Brochu et al in 1999. The IPS method extends the usage of decoupling methods in the Power controller plane to a power system of arbitrary size. The IPS method was in the thesis used to compare the ratings of different PFC:s required to improve the power transfer capability in two test systems. The studied devices were here the PST, the TSSC/TSSR and the DPFC. The thesis treats control of ideal Controlled Series Capacitors (CSC), TCSC, TSSC/TSSR, and DPFC. The goals of the FACTS controllers which are developed are Power Oscillation Damping (POD), fast power flow control, and transient stability improvement in the power system. New adaptive control strategies for POD and power flow control are proposed and studied in different models of power systems by time-domain simulations. A strategy for transient stability improvement is also proposed and studied. Additionally, different methods for study of Subsynchronous Resonance (SSR), which is associated with series compensation in power systems, are investigated. Here, four of the most common methods for frequency scanning to determine the electrical damping of subsynchronous oscillations in a power grid are studied. The study reveals significant differences of the electrical damping estimates of the studied standard methods when applied to a four-machine test system.<br>QC 20110819

Orientador: Prof. Dr. Edmarcio Antonio Belati<br>Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Engenharia Elétrica, 2017.<br>Neste trabalho analisou-se o desempenho de um Sistema Elétrico de Potência, quando alocados TCSC (do inglês, Thyristor Controlled Serie Compensator), e determinaram-se seus parâmetros ótimos de controle buscando maximizar a capacidade de transmissão total do sistema e melhorar o seu perfil de tensão, operando com suas variáveis dentro de limites pré-estabelecidos. Para tanto, foram modeladas variações do problema de Fluxo de Potência Ótimo Reativo (FPOR) e executadas em duas fases, identificadas como fase de alocação e fase de análise. Na fase de alocação foram realizadas simulações para analisar a alocação de diferentes quantidades de TCSC no sistema, com o objetivo de maximizar a capacidade de transmissão total e, por conseguinte, com base em um carregamento previsto na rede, foi determinada a quantidade mínima de dispositivos necessários para atender tal demanda. Em seguida, com o número de TCSC definido, os mesmos foram realocados com o objetivo de minimizar o desvio de tensão. Na fase de análise, os TCSC alocados na fase anterior foram mantidos com objetivo de otimizar o perfil de tensão, simulando variações nas cargas do sistema. Na fase de alocação, foi utilizada uma modelagem de Programação Não Linear Inteira Mista (PNLIM). Na fase de análise, o perfil de tensão foi otimizado por meio de uma modelagem de Programação Não Linear (PNL). Os resultados obtidos para os sistemas testes IEEE-14 e -118 barras demonstram os benefícios da utilização de TCSC na rede, pois possibilitou o aumento da carga total do sistema, e proporcionou uma melhora no perfil de tensão por meio do seu ajuste ótimo.<br>This work analyzed the electric power system performance when allocated TCSC (Thysristor Controlled Series Compensator) and determined their optimal control parameters in order to maximize the total transmission capability of the system and improve the voltage profile, operating within their pre-stablished limits. For this purpose, variations of Reactive Optimal Power Flow (FPOR) problems were modeled and executed in two phases, identified as phase of allocation and phase of analysis: In the allocation phase, simulations were performed to analyze the allocation of different amounts of TCSC in the system in order to maximize the total transmission capacity and, therefore, based on a predicted loading in the network, the minimum amount of devices was determined to attain such demand. Then, as the number of TCSC was defined, they were reallocated with the objective of minimizing the voltage deviation. In the analysis phase, the TCSC were maintained by considering the objective of optimizing the voltage profile and simulating loads variations of the system. In the allocation phase, a Mixed Integer Nonlinear Programming (MINLP) model was used. In the analysis phase, the voltage profile was optimized through a Nonlinear Programming (NLP) modeling. The results for the IEEE-14 and -118 test systems demonstrated the benefits of using the TCSC in the network because it allowed the increase of the total load of the system and provided an improvement in the voltage profile through its optimum adjustment.

Economic, environmental and legislative problems limit the scope of electric utilities in regards to construction of generation facilities and new transmission lines. In this respect, power electronics based FACTS technology was initiated by the EPRI in the late 1980s which aimed to enhance power transmission capabilities of existing transmission corridors. The FACTS Controllers achieve this objective by controlling the power system parameters like series impedance, shunt admittance, current, voltage and phase angles. A variety of FACTS Controllers have been envisaged, designed and installed in transmission utilities worldwide. The emergence of FACTS Controllers has followed two different technical approaches to develop two different groups of controllers – thyristor based and self-commutated converter based. The former include the Static VAr Compensator (SVC), the thyristor controlled series capacitor (TCSC) and phase shifter. STATCOM, SSSC and UPFC comprise the later. Among the thyristor based FACTS Controllers, the thyristor controlled series capacitor (TCSC) is one which is predominantly used for power flow control. It is a series FACTS device which can be used for rapid and continuous control of the effective series impedance of a line. Since the active power flow in a line is inversely proportional to its reactance, the TCSC can be used to control the active power flow in the line to any specified value, within operating limits. For power system planning, design, operation and control, power flow solution of the network installing TCSC is an essential requirement. This necessitates a TCSC power flow model. The earliest algorithms for power flow were based on the Gauss-Siedel iterative scheme. However, Gauss-Siedel method was found to be system dependent. For large system size, it sometimes failed to converge. Later, the Newton-Raphson algorithm came into being. It possessed quadratic convergence characteristics. Subsequently, the Newton-Raphson algorithm emerged as the de-facto standard for power flow in industry. In light of this, a Newton-Raphson model of the TCSC has been an essential requirement for power flow solutions of networks installing TCSCs. In this work, two separate Newton power flow models of the TCSC have been developed. The first one is a susceptance model, which subsequently employs a separate Newton Raphson loop for solving the TCSC firing angle. The second one is a more comprehensive Newton-Raphson model, which treats the firing angle itself as one of the state variables along with the bus voltages and angles. Both the proposed models demonstrate very good convergence characteristics when tested on a small six bus system and the IEEE 30 bus test system.<br>Dr. Suman Bhowmick Department of Electrical Engineering Delhi Technological University (Formerly Delhi College of Engineering) Delhi -110042

碩士<br>國立成功大學<br>電機工程學系碩博士班<br>90<br>Abstract This thesis investigates the application of variable-impedance characteristics of thyristor-controlled series capacitor (TCSC) of flexible AC transmission systems (FACTS) on control performance of three-phase induction machines. Both qd0-axis and three-phase abc frame induction-machine models are respectively employed to study steady-state and dynamic characteristics of the studied machine under different operating conditions. Regarding to speed control performance of an induction motor and active-power control of a grid-connected induction generator (GCIG), the steady-state performance of TCSC under different values of transmission line impedance, the dynamic control characteristics of TCSC, and the performance of a designed speed controller are investigated.