Influence of power system´s harmonic voltage on on-line leakage current monitoring of MOA

The surge arrester is an important piece of overvoltage protection equipment in substations, and the latent faults of MOA can be found by on-line resistive leakage current monitoring. It is reasonable to adopt the resistive leakage current´s first component i_r and third component i_3r as the metal oxide surge arrester´s indicators. These indicators can find the aging phenomenon of the metal oxide surge arrester in time. But the existence of harmonic voltages in the power system will influence the indicators´ accuracy. In this work, this influence is analyzed and an improved compensation method to separate the resistive leakage current under the existence of harmonic voltage is described. Finally, according to these methods, an on-line resistive current MOA monitoring system based on a bus-module is developed.