Finite Element Aanalysis And Optimization Design Of750kV Transmission Line Grading Rings On High Altitude Area

In rencent years,the silicone rubber insulator is widely used in high voltagetransmission lines especially in the750KV voltage class for its good nature ofantifouling,insulation,portable and easy installation.The brittle fracture,interfacebreakdown,aging,pockety eletric field and other problems coming with compositeinsulator closely connect with its special construction.The higher altitude has ahigher requirements to insulation performance,so we need to study the distributionof electric field along the composite insulator string,to control the electric fieldvoltage distribution of composite insulator by optimizing the structure parametres ofequalizing ring,preventing the discharge and ensure its safety.This paper make a study on the equalizing ring used in Xining-Golmudpower transmission line.There is not a uniform rule for external insulationperformance in high altitude among nations,so this paper raise a calculation apply toelevation correction calculating coefficient in Qinghai-Tibet plateau.Using finiteelement method,comparing two simulation software through simulating theequalizing ring cooperate with AC750KV composite insulator.And studied how thesurface electric field distribution,voltage distribution, the ring radius and tube radiusof equalizing ring,and raised distance compact on electric field of insulator.Inaddition,the reasonable structure parametres of equalizing ring were achieved in thispaper at the point of electric field controling.The results showed that the use of equalizing ring has significantlyimproved the surface electric field distribution of insulator,the surface maximumvalue of electric field on composite insulator’s high voltage side,equalizing ring andconnection hardware controled under the maximum value of external insulationelectric field in high altitude region.The optimized equalizing ring can satisfy the high altitude750kV transmission line on the use of composite insulator. The resultsprovides the beneficial reference for the design of external insulation for750KV ACtransmission lines.