Simulation Research on Coordination of Electrical and Structural Parameters in Composite Insulator with Field Grading Materials

Local overstress in composite insulators is a critical problem that affects insulation performance of high voltage transmission system. In addition to traditional methods, applying field grading materials (FGMs) with nonlinear electrical properties is also a promising method. To self-adaptively optimize the electric field strength distribution, electrical and structural parameters of FGMs need to be coordinated. Using finite element modeling, we examine the influence of FGMs with different electrical and structural parameters on field strength distribution of a 220kV AC transmission line epoxy composite insulator. The results indicate that the increase of non-linear coefficient has saturation effect on the reduction of local concentrated electric field strength. Non-linear coefficient of 10-20 is efficient for field grading. The coordination of threshold field strength and length of FGM layers is essential for the improvement of field strength distribution. And the increase of thickness of FGM layers also benefits field grading.