Measurement of the Ground Resistance Using Low-Pass Filter Method in Energized Substations

초록

This paper presents an accurate method for measuring the ground resistance in energized substations and power equipments. Most of substations and electric power equipments are interconnected to an extensive grounding network of overhead ground wires, cables and distribution feeders, neutral conductors, and etc. It is very difficult to measure the accurate ground resistance of high voltage energized substations because of the shunt connections and mutual coupling between interconnected lines and higher order harmonic components caused by switched power supplies and overvoltages. The conventional fall- of-potential method may be subjected to considerable errors if stray ground currents and ground potential rises are present. In this work, the low-pass filter method was proposed to improve the measurement accuracy of the ground resistance by eliminating the effects of harmonic components, stray currents, and unexpected ground potential rise in a model energized system. The accuracy of ground resistance measurement was calculated as a function of the ratio of the test signal to noise (S/N).