The gate pulse unit for SVC produces firing pulses for TCR and TSC. The logic determines whether a TSC is to be switched in or out. Bref TCR is calculated from Bref SV C and if Bref TCR ≤ 0, then a TSC is switched in. If Bref TCR ≥ BL, then a TSC is switched out. In computing Bref TCR from Bref SV C the effect of leakage reactance of the step down transformer is to be considered as BSV C is given by