Optimization of Electric Field Grading Systems in Non-Ceramic Insulators

In this work two electrical stress grading techniques for non-ceramic insulators are analyzed. In both techniques some parameters were optimized for a 115 kV non-ceramic insulator. Electric field simulations were performed with finite element method while, for the optimization process, different functions of the MATLAB (R) optimization toolbox were used. In the first case the optimized parameters were the relative permittivity of the material and the geometry of insulator on the energized side. The simulations were made under power frequency and under normalized lightning impulse. Modification of the shape next to the energized side consists of changing the inclination angle of the housing material. Furthermore, the corona ring position is optimized on the energized side of the non-ceramic insulator for comparison with the aforementioned method. According to the results, it was found that there are geometric parameters and material properties that minimize the value for the maximum electric field along the insulator surface.