Sensitive ground fault detection system for use in compensated electric power distribution networks

摘要

A system for detecting ground faults in a compensated electric power distribution network includes the determination of zero sequence voltage (V0) and zero sequence current (I0) on a power line and calculating the zero sequence conductance (G0) therefrom. The operation of the conductance calculation circuit occurs only under selected power line conditions involving minimum values of zero sequence voltage, zero sequence current and positive sequence voltage, to ensure the accuracy of a fault direction determination. The conductance values are processed on an adaptive basis in which the difference between the most recent conductance value and a conductance value from a selected previous point in time is determined and then compared against threshold values to make forward and reverse fault declarations.