Method of Power-Frequency Interval-Wave for Measurement of Large Grounding Systems

The measurement of grounding impedance has a high requirement for the instrument. In this paper, a method of measuring the power frequency interval wave of large-scale grounding device is proposed, which is studied from three aspects: principle, implementation and field application. The interval wave method outputs the interval voltage signal of power frequency through synchronous high-speed acquisition and power electronic switch, and then removes the influence of field noise by forward and backward difference of adjacent cycle signal. The noise of different types of strong interference is measured in the field, and the denoise performance of the interval wave method is analyzed by simulation. The application of the interval wave method in the measurement of the grounding impedance of a 500kV substation is realized, and the effectiveness of the method is proved by comparing with the different frequency method. The research results of this paper provide a reference for the lightening and intelligence of grounding impedance measurement equipment.