Pilot protection principle based on current model recognition applicable to transmission line with shunt reactors

A novel pilot protection principle based on current model recognition is proposed for the transmission line with shunt reactors on both sides. The theoretical expression is derived based on the distributed parameter model of transmission line and taken as the benchmark model of out-zone fault, which describes the ratio of the sum of to the difference between the fault currents at both line sides. The model error function of out-zone fault is then constructed to gauge the coincidence degree of the fault data with the benchmark model. The value of model error function is zero for out-zone faults while non-zero for in-zone faults, which can be used to distinguish out-zone fault from in-zone faults. As the shunt reactors are considered, the proposed principle is immune to the distributed capacitance and no capacitive current should be compensated. Since the protection uses fully the fault current information, without the voltage measurement, it functions reliably, quickly and sensitively. Both ATP simulation and dynamic simulation results show the effectiveness of the proposed principle.