Power system insulation deterioration detection method, insulation deterioration detection device, insulation deterioration detection system, and insulation deterioration determination device

摘要

PURPOSE:To reduce the influence of a residual component, noise, etc., so as to detect the insulation deterioration of a three-phase power system with high sensitivity by detecting zero-phase voltages in bands except the resonance frequency of the power system. CONSTITUTION:A sensor device 20 is constituted of a V0 sensor using a grounding transformer composed of a star-connected primary winding 22 connected to a three-phase bus 3 and delta- connected secondary winding 23 and a slave station 21 is connected to a host station through a communication line 33. The voltage V0 detected across both ends of a current-limiting resistance 24 is inputted to an amplifier 25 by which the voltage is converted into a voltage signal which is suitable for signal processing. A V0 signal generated when deterioration occurs contains many frequency components other than a power supply frequency and frequencies of the natural-number multiple of the frequency and, the frequency components become larger as their frequencies become lower. Therefore, when the power supply frequency component which contains the largest amount of a residual component is eliminated from the output signal of the amplifier 24 by means of a 5-Hz notch filter 26 and system noise is removed by means of a 1kHz low-pass filter 27, only the small V0 signal which becomes relatively large when deterioration occurs can be extracted with high accuracy.