Improved High-Precision Extraction Algorithm for Resistive Current of Three Phase Arresters

The on-line monitoring of arrester resistive leakage current can effectively judge the operation of arresters. The fundamental current and the third harmonic current are the key indicators to judge the aging and damp of arrester, which are particularly important for the on-line monitoring of Metal oxide surge arrester (MOA). However, due to the influence of interphase interference and harmonic voltage of power grid, the accuracy of on-line monitoring results is not high and there are large errors. In this paper, the self capacitance and stray capacitance of three-phase arrester are calculated to separate the capacitive current from the total leakage current, so as to effectively reduce the influence of interphase interference. At the same time, the influence of grid harmonics on resistive third harmonic current is compensated to improve the accuracy of resistive leakage current. The algorithm builds a simulation model on the MATLAB / Simulink platform, obtains the capacitance values by using the algorithm, and verifies the correctness of the algorithm by evaluating the error between the extracted resistive current value and the ideal resistive current value. In addition, by analyzing the influence of interphase interference under different voltage fluctuations and different total harmonic distortion rate of power grid, it is proved that the algorithm can effectively reduce the influence of interphase interference.