A novel non-contact voltage measurement based on distribution lines

Abstract

Currently, for distribution line voltage measurement, there is no effective and convenient dynamic calibration method of coupling capacitance for capacitive coupling-based sensors. Therefore, a differential non-contact voltage measurement method based on harmonic injection is proposed in this paper. Based on the single-probe measurement, a shield is used to reduce the interference of external stray capacitance on the measurement; the probe is improved and a differential circuit structure is introduced, which eliminates the input capacitance of the op-amp; then harmonics are injected into the measurement circuit, and the discrete Fourier transform is used to extract the fundamental frequency and harmonic components in the response signal, and the coupling capacitance parameter is solved by the ratio of the harmonic source to the harmonic response signal and then substituting it into the fundamental equation to achieve the dynamic calibration of the coupling capacitance and fundamental response signal, and the coupling capacitance dynamic calibration and fundamental response signal dynamic calibration, capacitance dynamic calibration and the measurement of fundamental voltage signal; finally, the measurement method proposed in the article can meet the measurement requirements of a 400 V distribution network as shown in the simulation results, and the maximum voltage measurement error is less than 0.4%.