Search

The thyristor-controlled series capacitor (TCSC) is a commercially available flexible ac transmission system (FACTS) device developed for controlled compensation of transmission-line impedance, which consequently leads to the control of transmission-line power flow. The gate-controlled series capacitor (GCSC), a FACTS device based on a pair of gate-commutated switches in parallel with a capacitor, can also control impedance and power flow of transmission lines. Here, it is shown that in many situations where a controllable series compensator must be installed, the GCSC may be used instead of the TCSC, possibly with some advantages. A comparison of the sizing of the TCSC and the GCSC components is presented. It is shown that the capacitor in the GCSC can have lower megavolt-amperes than in the TCSC, especially for power-flow control applications. Also, it is shown that the thyristor valve in the TCSC needs to have a higher current rating than the gate-commutated switch valve in the GCSC. [ABSTRACT FROM AUTHOR]

The subsynchronous resonance (SSR) phenomenon may occur when a steam turbine-generator is connected to a long transmission line with series compensation. The main purpose of this work is to verify the capability of the gate-controlled series capacitor (GCSC) to mitigate SSR. For this study the GCSC was tested in conjunction with the IEEE First Benchmark Model. The actual possibility of controlling SSR was verified by digital simulation using the Alternative Transients Program/Electromagnetic Transients Program. As a result it was shown that GCSC can damp SSR even without a specific control. It was also shown that, using a simple controller, SSR as well as electromechanical oscillation can be damped. [ABSTRACT FROM AUTHOR]

An effective method of eliminating numerical oscillations in switching functions due to Gibbs phenomenon in mathematical representations is introduced in this letter. Switching functions for the gate-controlled series capacitor (GCSC) are presented to illustrate the propoced technique. [ABSTRACT FROM AUTHOR]