Transient analysis of 150 kV shunt reactor at Bulukumba Substation

This paper presents the study of the transient phenomena originating from the shunt reactor energizing and de-energizing at the Bulukumba Substation. The unsymmetrical phase inrush current during a shunt reactor energizing and overvoltages provoked by current chopping are analyzed. Unsymmetrical phase inrush current that occur at shunt reactor energizing depend on the time in the time instant of circuit breaker pole operation with respect to the reference signal At shunt reactor with solidly grounded neutral, unsymmetrical currents cause zero sequence current to flow which may activate ground fault relay (mal-operation). In the interruption of reactor current (de-energizing), excessive overvoltages across the circuit breaker due to current chopping can occur and the magnitude of the overvoltages will also depend on the time of circuit breaker pole operation. In order to avoid mal-operation of relay ground fault, good setting of relay can be applied for shunt reactor protection especially ground fault relay. As for the case of current chopping over voltages, the surge arrester will protect adequately the reactor and the circuit breaker against the maximum phase-to-ground peak voltage. This study has been carried out by simulation using software ATP/EMTP.