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.

Thyristor-Based Facts Controllers for Electrical Transmission Systems

Different control aspects related to the use of TCSC for stability improvement of power systems are addressed in this paper. A novel hierarchical control designed for both dynamic and steady state stability enhancement is proposed, and a complete analysis is presented of various locally measurable input signals that can be used for the controller. Control strategies to mitigate adverse interactions among the TCSC hierarchical controls are also presented. A simplified model of the Argentinian high voltage interconnected system is used to illustrate the ideas presented in the paper.

A study of TCSC controller design for power system stability improvement

We have investigated the use of multiple input signals for the design of power system stabilizers and thyristor-controlled series-compensation controllers. These examples show the benefits of combining input signals to move the system zeros to more desirable locations, allowing the controller to be more effective in providing additional damping to the interarea modes. The multiple-input-signal controller can be used as the primary control system or as a backup system when some of the controllers are temporarily unavailable. In some cases, a multiple-input-signal controller structure may be more cost effective than installing a new control device. The choices of the input signals used for the controller designs in the example systems in the article have been based on good knowledge of the systems.

Power system damping controller design-using multiple input signals

This paper develops simple but accurate continuous-time, large-signal dynamic models for a thyristor-controlled series capacitor (TCSC). The models are based on the representation of voltages and currents as time-varying Fourier series, and focus on the dynamics of the short-term Fourier coefficients. Truncating the series to keep only the fundamental components provides a natural dynamic generalization of the familiar quasi-static phasor representation. Systematic simplifications or refinements of their fundamental phasor dynamics model yield a variety of other models. The authors establish that even the simplest of these models predicts the dynamic behavior of the TCSC very accurately. Their phasor models provide a powerful basis for simulation, more than an order of magnitude faster than detailed time-domain circuit simulation. The phasor models present an attractive alternative to sampled-data models, having the advantages of simpler representation, modularity and direct compatibility with the phasor models that are routinely used to represent the dynamics of generators and other power system components.

Phasor dynamics of thyristor-controlled series capacitor systems

This paper deals with the application of the LQG (linear quadratic Gaussian) technique to the design of a robust TCSC (thyristor controlled series compensator) controller for power system oscillation damping enhancement. This paper discusses each process involved in the LQG design technique applied to the TCSC damping controller design. This paper also discusses the pitfalls in applying the LTR (loop transfer recovery) technique to reserve the robustness of the LQG damping controller. The robustness of the designed controller is verified by nonlinear power system simulation, which shows that the controller is effective for damping power system oscillations.

On the robust LQG control of TCSC for damping power system oscillations

Thyristor-controlled series compensation (TCSC) is expected to be applied in transmission systems to achieve a number of benefits. To ensure best use of this new controller, planning engineers require analysis capability tailored to the specific performance characteristics of the TCSC. This paper presents a model for TCSC which is applicable for typical transient and oscillatory stability studies. Also included is a discussion on relevant information to extend the modeling detail of the TCSC for use with long-term stability analysis. >

N.W. Miller

Papers

A thyristor controlled series compensation model for power system stability analysis