Improvement of Transmission Capacity by Thyristor Controlled Reactive Power
TL;DR: In this article, the authors show that if thyristor switched capacitors are used there will also be a positive contribution to transient stability of large-scale power systems and that the use of supplementary control of generators and control of reactive power can be used as an efficient tool to improve damping.
Abstract: This paper shows that thyristor controlled reactive power can be used as an efficient tool to improve damping of large power systems. If thyristor switched capacitors are used there will also be positive contribution to transient stability. Examples of power systems where damping is the critical factor have been investigated. The use of supplementary control of generators and control of reactive power has been studied. Basic configurations of thyristor switched capacitors and thyristor controlled reactors are presented.
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Book•
27 Feb 2002
TL;DR: In this paper, the authors present a comparison of different SVC controllers for power transmission networks with respect to their performance in terms of the number of SVC inputs and outputs, as well as the frequency of the SVC outputs.
Abstract: 1. Introduction. 1.1 Background. 1.2 Electrical Transmission Networks. 1.3 Conventional Control Mechanisms. 1.4 Flexible ac Transmission Systems (FACTS). 1.5 Emerging Transmission Networks. 2. Reactor--Power Control in Electrical Power Transmission Systems. 2.1 Reacrive Power. 2.2 Uncompensated Transmission Lines. 2.3 Passive Compensation. 2.4 Summary. 3. Principles of Conventional Reactive--Power Compensators. 3.1 Introduction. 3.2 Synchronous Condensers. 3.3 The Saturated Reactor (SR). 3.4 The Thyristor--Controlled Reactor (TCR). 3.5 The Thyristor--Controlled Transformer (TCT). 3.6 The Fixed Capacitor--Thyristor--Controlled Reactor (FC--TCR). 3.7 The Mechanically Switched Capacitor--Thristor--Controlled Reactor (MSC--TCR). 3.8 The Thyristor--Switched capacitor and Reactor. 3.9 The Thyristor--Switched capacitor--Thyristor--Controlled Reactor (TSC--TCR). 3.10 A Comparison of Different SVCs. 3.11 Summary. 4. SVC Control Components and Models. 4.1 Introduction 4.2 Measurement Systems. 4.3 The Voltage Regulator. 4.4 Gate--Pulse Generation. 4.5 The Synchronizing System. 4.6 Additional Control and Protection Functions. 4.7 Modeling of SVC for Power--System Studies. 4.8 Summary. 5. Conceepts of SVC Voltage Control. 5.1 Introduction 5.2 Voltage Control. 5.3 Effect of Network Resonances on the Controller Response. 5.4 The 2nd Harmonic Interaction Between the SVC and ac Network. 5.5 Application of the SVC to Series--Compensated ac Systems. 5.6 3rd Harmonic Distortion. 5.7 Voltage--Controlled Design Studies. 5.8 Summary. 6. Applications. 6.1 Introduction. 6.2 Increase in Steady--State Power--Transfer Capacity. 6.3 Enhancement of Transient Stability. 6.4 Augmentation of Power--System Damping. 6.5 SVC Mitigation of Subsychronous Resonance (SSR). 6.6 Prevention of Voltage Instability. 6.7 Improvement of HVDC Link Performance. 6.8 Summary. 7. The Thyristor--Controlled SeriesCapacitor (TCSC). 7.1 Series Compensation. 7.2 The TCSC Controller. 7.3 Operation of the TCSC. 7.4 The TSSC. 7.5 Analysis of the TCSC. 7.6 Capability Characteristics. 7.7 Harmonic Performance. 7.8 Losses. 7.9 Response of the TCSC. 7.10 Modeling of the TCSC. 7.11 Summary. 8. TCSC Applications. 8.1 Introduction. 8.2 Open--Loop Control. 8.3 Closed--Loop Control. 8.4 Improvement of the System--Stability Limit. 8.5 Enhancement of System Damping. 8.6 Subsynchronous Resonanace (SSR) Mitigation. 8.7 Voltage--Collapse Prevention. 8.8 TCSC Installations. 8.9 Summary. 9. Coordination of FACTS Controllers. 9.1 Introduction 9.2 Controller Interactions. 9.3 SVC--SVC Interaction. 9.4 SVC--HVDC Interaction. 9.5 SVC--TCSC Interaction. 9.6 TCSC--TCSC Interaction. 9.7 Performance Criteria for Damping--Controller Design. 9.8 Coordination of Multiple Controllers Using Linear--Control Techniques. 9.9 Coordination of Multiple Controllers using Nonlinear--Control Techniques. 9.10 Summary. 10. Emerging FACTS Controllers. 10.1 Introduction. 10.2 The STATCOM. 10.3 THE SSSC. 10.4 The UPFC. 10.5 Comparative Evaluation of Different FACTS Controllers. 10.6 Future Direction of FACTS Technology. 10.7 Summary. Appendix A. Design of an SVC Voltage Regulator. A.1 Study System. A.2 Method of System Gain. A.3 Elgen Value Analysis. A.4 Simulator Studies. A.5 A Comparison of Physical Simulator results With Analytical and Digital Simulator Results Using Linearized Models. Appendix B. Transient--Stability Enhancement in a Midpoint SVC--Compensated SMIB System. Appendix C. Approximate Multimodal decomposition Method for the Design of FACTS Controllers. C.1 Introduction. C.2 Modal Analysis of the ith Swing Mode, C.3 Implications of Different Transfer Functions. C.4 Design of the Damping Controller. Appendix D. FACTS Terms and Definitions. Index.
954Â citations
TL;DR: In this article, the authors reviewed literature on using high speed thyristor based control of HVAC power system elements to enhance the power carrying capacity of existing transmission circuits without compromising reliability.
Abstract: The paper reviews literature which addresses the application of Flexible AC Transmission System (FACTS) concepts to the improvement of Power System utilisation and performance. It summarises literature on using high speed thyristor based control of HVAC power system elements to enhance the power carrying capacity of existing transmission circuits without compromising reliability. It describes a study system representative of existing power systems that has been developed to evaluate the economic and technical issues of loading transmission lines to their thermal limits. Considered are two scenarios, a multi-line corridor and a long radial interconnection, where the issues addressed are transient and dynamic stability, power flow control, reactive support and voltage stability. A benchmark system is developed to validate performance of die more simple devices. It is concluded that FACTS devices have the potential to significantly increase system stability margins thereby increasing loading capabil...
544Â citations
TL;DR: In this paper, a new controller for the generator excitation system is described that uses a combination of feedback linearizing and the observation decoupled state space, which can be realistically implemented using only local measurements, and whose performance is consistent with respect to changes in network configuration, loading and power transfer conditions.
Abstract: A new controller for the generator excitation system is described that uses a combination of feedback linearizing and the observation decoupled state space. This creates a controller that can be realistically implemented using only local measurements, and whose performance is consistent with respect to changes in network configuration, loading and power transfer conditions. The control differs in this respect from linear constant-gain controllers such as power system stabilizers, whose characteristics can vary significantly with changes in operating conditions. The design is well-suited to a multimachine setting, in that it is not based on an infinite-bus approximation. Simulations were performed on a 38-bus reduced modelof the Northeast Power Coordinating Council system and benchmarked against simulations in which automatic voltage regulators with power system stabilizers were substituted in place of the nonlinear controls. >
363Â citations
TL;DR: In this paper, a control strategy for the damping of electromechanical power oscillations using an energy function method is derived, which is shown to be effective both for damping large signal and small signal disturbances and are robust with respect to loading condition, fault location and network structure.
Abstract: This paper examines improvement of power system dynamics by use of unified power flow controllers, thyristor controlled phase shifting transformers and thyristor controlled series capacitors. Models suitable for incorporation in dynamic simulation programs for studying angle stability are analysed. A control strategy for the damping of electromechanical power oscillations using an energy function method is derived. The achieved control laws are shown to be effective both for the damping of large signal and small signal disturbances and are robust with respect to loading condition, fault location and network structure. Furthermore, the control inputs are easily attainable from locally measurable variables. The effectiveness of the controls are demonstrated for model power systems.
279Â citations
Book•
01 Jan 2001
TL;DR: This book discusses the design Principles of Single-Input Single-Output Nonlinear Control Systems and their applications in Electric Power Systems and Nonlinear Excitation Control of Large Synchronous Generators.
Abstract: Preface. 1. Introduction. 2. Basic Concepts of Nonlinear Control Theory. 3. Design Principles of Single-Input Single-Output Nonlinear Control Systems. 4. Design Principles of Multi-Input Multi-Output Nonlinear Control Systems. 5. Basic Mathematical Descriptions for Electric Power Systems. 6. Nonlinear Excitation Control of Large Synchronous Generators. 7. Nonlinear Steam Valving Control. 8. Nonlinear Control of HVDC Systems. 9. Nonlinear Control of Static Var Systems. 10. Nonlinear Robust Control of Power Systems. Index.
258Â citations
References
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TL;DR: In recent years, there has been a rapid increase in the number of thyristor-controlled shunt compensators used in industrial and utility systems for dynamic power factor correction and terminal voltage stabilization as mentioned in this paper.
Abstract: In recent years, there has been a rapid increase in the number of thyristor-controlled shunt compensators used in industrial and utility systems for dynamic power factor correction and terminal voltage stabilization. These thyristor-controlled shunt compensators function as variable reactances operated in both the inductive and capacitive domains.
293Â citations
TL;DR: In this paper, an analytical basis for the St. Clair line loadability curve is presented and the extension of its use into the EHV and UHV transmission area is discussed.
Abstract: This paper contains the development of an analytical basis for the St. Clair line loadability curve and presents the extension of its use into the EHV and UHV transmission area. A brief historical background describes the origin and pertinent aspects of the St. Clair curve including the fact that the old curve, originally intended for transmission voltages up to 330-kV, is derived empirically based upon practical considerations and experience. In order to extend the usefulness of such line loadability characteristics into the EHV and UHV range, a simplified representation of the system, which incorporates flexibility to include both line and system parameters, is utilized to compute maximum line loadability subject to assumed system performance criteria. It is shown that, for a reasonable and consistent set of assumptions, with regard to system parameters and performance criteria, EHV and UHV transmission line loadability characteristics are nearly identical to the original St. Clair curve. The paper further illustrates the relative influence of these assumptions on the derived characteristics, In particular, the electrical strength of the sending- and receiving-end systems is found to have an increasingly important influence on the loadability of transmission lines as the voltage class increases. The analytical approach to determination of transmission line loadability curves enables the user to examine specific situations and assumptions and to avoid possible misinterpretation of generalized conceptual guides-particularly in the EHV/UHV range where system parameters can have a significant impact on loadability.
201Â citations
TL;DR: In this paper, the authors analyzed the effect of switched series capacitors on the transient stability of a 2-circuit ac transmission link by using equal-area diagrams for two kinds of disturbances: 1) a permanent fault on one ac circuit, cleared by opening a section of that circuit, without reclosure and 2) a dc line operating in parallel with the ac line.
Abstract: Improvement of transient stability of a 2-circuit ac transmission link by use of switched series capacitors is analyzed by equal-area diagrams for two kinds of disturbances: 1) a permanent fault on one ac circuit, cleared by opening a section of that circuit, without reclosure and 2) a permanent fault on a dc line operating in parallel with the ac line. In both cases, the aggregate megavar rating of series capacitors required for a given transient stability limit is shown to be smaller if some capacitors are switched than if all are unswitched. Moreover, the scheme with switched capacitors reduces the angular swing of the machines and the fluctuation of load voltages during the swing.
153Â citations
TL;DR: In this article, the operating and performance characteristics of two basic types of static, thyristor-controlled shunt compensators, one with a fixed capacitor bank and the other with synchronously switchable capacitor banks, are presented with regard to power transmission system applications.
Abstract: The operating and performance characteristics of two basic types of static, thyristor-controlled shunt compensators, one with a fixed capacitor bank and the other with synchronously switchable capacitor banks, are presented with regard to power transmission system applications. The operating principles, and the similarities and differences between the performance of the two schemes are discussed in the areas of steady-state voltage versus VAR characteristic, behavior under small and large system disturbances, harmonic generation, and loss versus output VAR characteristic.
96Â citations
19Â citations