The Research Of DC Insulator Based On Leakage Current

With the rapid economic development, energy demand in our country grows deeply. Government proposed and implemented the "West to East" project. At the same time, ultra high voltage (UHV) and extra high voltage (EHV) transmission lines have developed sharply. Flashover often occurred in these transmission lines which has been put into operation and caused long-time, large-scale power outage and huge economic losses. At present, there is no ideal quality testing equipment for insulators which largely hinders the rapid development of insulator manufacturing and greatly affects service life prediction and evaluation of insulators in power system.In recent years, our predecessors have done many flashover mechanism studies and found that the leakage current is easy to measure and closely related to the development process of flashover discharge. The leakage current can generally reflect the impacts by the degree of contamination, the level of moisture, the withstand voltage, the insulator shape and other factors. Therefore, the research to insulator contamination and leakage current under humid conditions is very important.Firstly, based on the medium equivalent circuit theory, this paper constructs a leakage current distribution model for insulator which is put in the DC electric field, and selects the relevant boundary conditions to make simulation studies and experiments. And then according to the characteristics of DC insulator leakage current and the measurement requirements, this paper designs a set of insulation resistance measurement system based on leakage current. This system consists of a portable high-voltage power supply, a data acquisition box and an operation control box. At last, set up an artificial high-pressure laboratory; simulate the operating conditions in natural environment by controlling effect factors of flashover, such as the humidity, the ash and salt density, etc. And make artificial contamination experiments with these insulators used in EHV transmission lines and analysis these test results with mathematical statistics method. After experimental comparison, we get the relationship formula to reflect the characteristics of insulator flashover. These data have important reference value for the anti-fouling design and the operation maintenance of actual transmission lines.