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...

Flexible AC transmission systems (FACTS)

The design of a robust controller for a static VAr compensator (SVC) to improve the damping of a power system is presented. The main contributions of the paper are to formulate and to solve the power system damping control problem using robust optimization techniques, and to synthesize the controller with explicit consideration of the system operating condition variations. Nonlinear simulations using the PSCAD/EMTDC software packages have been conducted to evaluate the performance of the closed-loop system. The results have indicated that the designed controller can provide positive damping to the system under a wide range of operating conditions.

Robust SVC controller design for improving power system damping

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.

Characteristics of Static, Thyristor-Controlled Shunt Compensators for Power Transmission System Applications

This paper concerns the application of static reactive compensators (SVCs) to Power transmission systems. Emphasis is placed on stability, and it is shown that SVCs can provide significant benefits in terms of increased transient stabilty liisand improved damping for synchronizing power flow oscillations. The paper includes descriptions Of static VAR compensators, with technical and economic comparisons of different compensators. An SVC system study model is presented which includes provision for modulating reactive compensation in response to a variety of system functions. Study procedures are illustrated which relate sYstem stability objectives to general specifications of SVCs, indluding their locations, regulating slopes, peak reactive power requirements, and modulation control.

Static Reactive Compensation for Power Transmission Systems

Design of a static voltampere reactive (VAr) controller (SVC) using a novel adaptive scheme is investigated. The proposed controller, which makes use of self-tuning proportional-integral-derivative (PID) control, can provide better damping characteristics than a fixed-gain PID control SVC over a wide range of operating conditions. The system considered is a synchronous generator connected to an infinite bus through a double circuit transmission line. Digital simulations of the system following a three-phase fault under different loading conditions were performed to demonstrate the robustness and effectiveness of the controller. >

Damping of generator oscillations using an adaptive static VAR compensator

Basin Electric Power Cooperative will commission a Static Var System (SVS) in late 1977 to provide automatic, continuous voltage control on a 115 kV network in western Nebraska. This paper describes engineering studies which were conducted to select the SVS rating and site, determine harmonic filtering requirements, synthesize the SVS voltage regulator characteristics and to simulate the steady-state and dynamic performance of the SVS. The studies have shown that the SVS will perform as intended to regulate the steady-state voltage within ±0.5% and reduce post-fault voltage swings which otherwise might cause important motor loads to trip off line.

T. Humann

Papers

Application of a Static VAR System to Regulate System Voltage in Western Nebraska