Damping of Ferroresonance in Coupling Capacitor Voltage Transformers with Ferroresonance Suppressing Circuits

In order to restrain ferroresonance in coupling capacitor voltage transformers (CCVT), two kinds of ferroresonance suppression circuits (FSCs): theresonant types, and the fast-saturation reactor type, which are connected to secondary side of CCVTs, are proposed in this paper. Frequency domain analyses, forvoltage ratio magnitude, are carried out for CCVTs to obtain preferable FSC. Furthermore, using surge suppressors such as metal oxide varistors (MOV) toimprove the performance of the FSCs is investigated. Time domain simulations demonstrate that ferroresonance can be cleared in few cycles in presenceof FSCs. The Electromagnetic Transients Program (EMTP) is used for modeling and fine-tuning the FSCs.