Analysis about Potential Distribution of the Ur 780kV Metal-oxide Surge Arrester for 1000kV Substation

Decrease the rated voltage of the arrester can optimize insulation coordination, and reduce 1000kV substation over-voltage level or lower insulation level of equipments, which can improve the economy of project. But lower rated voltage on behalf of the higher chargeability on internal resistance of the arrester, which will affect the MOA potential distribution. In order to study the potential distribution characteristics of the lower rated voltage MOA on 1000kV substation, using the software Ansys with finite element method to build 3-D model of Y20W - 780/1526 type arrester. Analysis and calculated the potential distribution of the arrester on five different kinds of grading shunt capacitors configuration scheme, selecting the optimal configuration scheme to test. The curve of potential distribution shows that the simulation results and the test results are basic consistent, the maximum relative deviation is 7.32%. This paper verified the potential distribution non-uniform coefficient of the rated voltage decreased surge arrester which used at 1000kV substation can match the engineering specification requirement, less than 1.15, by rational allocation of the grading shunt capacitors under the equalizing ring, flange and coat condition such as size structure unchanged. The research results can provide reference for the design of rated voltage decrease for UHV surge arresters.