A new method to extract the resistive current of MOA based on least square

The prominent feature of the degradation of metal oxide surge arrester is an obvious increase of the resistive current, especially its fundamental and third harmonic, so it is very important to measure the resistive current. In this paper, a new method for the measurement of the resistive current is presented. At first, the time-domain equations of the resistive current, the capacitive current and the total leakage current on the applied voltage are deduced based on the equivalent model of MOA. According to the observed data and the fitted data of the total leakage current, the least square is then used to obtain the circuit parameters of the equivalent model. By substituting these circuit parameters into the relevant time-domain equations, both the resistive current and the capacitive current are obtained. In addition, the influence of the circuit parameters, harmonic voltage and current noise on the proposed method is also studied. The simulation results show that the proposed method can extract the resistive current exactly when the applied voltage and the total leakage current are ideal. The circuit parameters, harmonic voltage and current noise have little effect on the proposed method. Moreover, the proposed method can not only obtain the resistive current and the capacitive current at the same time, but give the circuit parameters of MOA as well.