Thyristor and gate controlled series capacitors: comparison of components rating

The TCSC (Thyristor Controlled Series Capacitor) is a commercially available FACTS device developed for controlled compensation of transmission line impedance, what consequently leads to the control of transmission line power flow. The GCSC (Gate Controlled Series Capacitor), a novel 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 the GCSC may replace the TCSC with advantages in almost all situations where transmission line series compensation is needed. A comparison of the sizing of the TCSC and the GCSC components is presented. It is shown that the capacitor in the GCSC can be smaller than in the TCSC. 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.