Differential current-based identification of permanent faults for three-phase autoreclosure on transmission line with shunt reactors at both ends

Based the principle of segregated current differential, a method to judge permanent fault for three-phase autoreclosure on transmission line with shunt reactors at both ends is proposed. In the proposed method, the currents in shunt-reactors are taken as known quantities, and the capacitance current is compensated by time-domain approach. When circuit breakers at both ends of the faulty line are tripped out, by use of current differential principle the three-phase currents of two shunt reactors at both ends are compared. For instantaneous fault, the current differences of corresponding phases of shunt reactors at both ends are zero; for permanent fault, the current differences of corresponding phases of shunt reactors at both ends are much larger than zero. On this basis, the permanent fault can be identified. A lot of results of EMTP simulation show that the proposed judgment method can effectively distinguish permanent fault from instantaneous fault, thus based on the identification the three-phase adaptive autoreclosure for transmission line with shunt-reactors at both ends can be reliably implemented.