均压环改善绝缘子串电压分布研究

绝缘子电场强度分布不均和绝缘子串电压分布不均是绝缘子污闪电压低的重要因素。为此,提出了在绝缘子铁帽上增加均匀环的办法以提高绝缘子串闪络电压。均压环可使单个绝缘子瓷表面电场方向更垂直于绝缘子表面,改善其电位分布,抑制带电粒子迁移与发展,降低泄漏电流,从而提高闪络电压;均压环也可改善长串绝缘子极不均匀的“U”型电压分布,提高绝缘子串防污性能。仿真与实验室试验数据表明:均压环可提高单个绝缘子的污闪电压达40%,可降低串中绝缘子最大电压差比例和平滑绝缘子串电压曲线;均压环最佳改善效果受其安装位置、数量和绝缘子串长度影响。

Research on Improving the Voltage Distribution of the Insulator String by Voltage Balance Slices

It is an important reason for the bad anti-pollution performance of the insulator string that the electric field strength and the voltage distribution are all not uniform.A method of adding a voltage balance slice(VBS) on the cap of ceramic insulator can enhance the flashover voltage of ceramic insulator.The VBS can make the electric field direction on the upper surface of insulator be more perpendicular to the surface of insulator than parallel to the surface,which improve the electric field distribution of insulator,restrain the electriferous particle moving and developing,reduce the leak current and improve the flashover voltage.The voltage distribution of long insulator string is not even and take on the U shape and the partial discharge and breakdown will happen on the insulator whose voltage is highest,the flashover happens on the whole insulator string.The VBS can also improve the voltage distribution of insulator string and decrease the voltage on the terminal insulators and enhance its anti-pollution performance.The simulation and testing data show that the VBS can enhance the pollution flashover voltage about 40% in the condition of laboratory and can decrease the maximal withstand voltage rate of the insulator and flat the voltage curve of the insulator string.The optimal improving effect of the VBS is influenced by its installation location and amount,which must be devised by the length of the insulator string.Some VBSs are installed on the insulator string,which will be propitious to increase the flashover voltage and the anti-pollution flashover performance,and its operation reliability is enhanced.