Research On Extract Method For Resistive Current Of Zinc Oxide Arrester

Zinc oxide lightning arrester works as an important protection power equipment in the power system to protect the other power equipments from suffering lightning overvoltage and operating over-voltage. However, under a long time working condition, zinc oxide lightning arrester are influenced by the overvoltage and environmental factors, leading to the degradation or aging in the electrical properties of the zinc oxide lightning arrester and seriously threatening the safe operation the zinc oxide lightning arrester and the protected power equipments. Detecting the resistance current component of the zinc oxide lightning arrester can be used to evaluate the degradation or aging of the zinc oxide lightning arrester. This article mainly aims at the extraction method for the resistive current component of the zinc oxide lightning arrester.By analyzing the working principle of zinc oxide lighting arrester and common fault causes, the principle and characteristics of several extraction methods for the resistive current of zinc oxide lightning arrester resistance are summarized. Based on the above analysis, a kind of resistance current extraction method is proposed in this paper. According to the orthogonality of the resistive current component and the capacitive current component of zinc oxide lightning arrester under the ac excitation voltage, as well as the excitation voltage and the total leakage current, the equivalent capacitance of zinc oxide arrester can be obtained. The capacitive current component is then calculated according to the calculated equivalent capacitance and the excitation voltage derivative. The resistive current component of the zinc oxide lightning arrester is successfully extracted by subtracting the capacitive current component from the total leakage current. The resistive current extraction method proposed in this paper is analyzed by contrast with the capacitive current compensation method frequently used in engineering application. The validity of the method proposed in this paper is verified by the simulation analysis. At the same time, the effect of the harmonic voltage, the equivalent circuit parameters of the zinc oxide lightning arrester and the current noise on the resistive current extraction method proposed in this paper and the capacitive current compensation method are also studied.The simulation results show that both the capacitive current compensation method and the resistive current extraction method proposed in this paper can accurately obtain the resistive current component under ideal condition. The harmonic voltage has a greater impact on the capacitive current compensation method, but has almost no effect on the resistive current extraction method proposed in this paper, it shows that the proposed method has a certain ability to adapt the harmonic voltage. The resistive current component and the capacitive current component of zinc oxide lightning arrester are closely related to the equivalent circuit parameters of the zinc oxide lightning arrester, but the equivalent circuit parameters of zinc oxide lightning arrester hardly affect the accuracy of the capacitive current compensation method and the presented resistive current extraction method. In addition, the resistive current extraction method is almost not affected by noise, illustrating that the resistive current extraction method has a certain ability of resisting noise.