A Principle of Fault Line Selection Based on Increasing Zero-sequence Current in Non-ground Neutral System

In order to solve the problem of low accuracy of single-phase earth fault selection in non-ground neutral system, in this paper, the method that increasing the zero current of fault line at a short time when the single-phase earth fault occurs is proposed by using injection principle to strengthen the fault steady-state characteristic so as to expand the gap of circuit criterion between the fault line and the non-fault line, meanwhile, improve the selection criterion based on fault steady-state characteristics. According to the single-phase earth fault steady-state characteristics of zero-sequence current, the power capacitor is used to inject the capacitance current to realize the increase. Depending on the principle of not affecting the operation of distribution network, the strength of the increased current is determined. Such equipment has been implemented in power networks, and the result of detecting fault line is accurately.