New method to identify permanent faults for transmission lines with shunt reactors

A novel method of identifying permanent fault for single-phase adaptive reclosure in transmission lines with shunt reactors is proposed. After the tripped phase current from shunt reactor was calculated using the transient fault model as the prototype whether transient or permanent fault, the difference between the calculated current and the measured one of the fault phase from shunt reactor was employed to identify permanent fault. When the single-phase fault is transient, the calculated current is close to the actual measured current. But for permanent fault, the currents are quite different. Therefore, an algorithm using the amplitude ratio of the differential current to the current in neutral reactor was developed to identify permanent fault. ATP simulations show that the proposed algorithm can identify permanent fault correctly and reliably, and promises to be applied to single-phase adaptive reclosure for transmission lines with shunt reactors.