This paper reports on a new approach for optimal design of corona rings on composite insulator. Finite element method combined with the experimental design methodology and Bat optimization method were used in order to minimize the maximum E-field along the insulator length, with the objective of increasing its long-term performance. Corona ring height (H), radius (R) and tube diameter (Dr) are the most important parameters in the design corona rings. They have been evaluated using different techniques and their optimization was achieved by minimizing the objective function using Bat algorithm which is one of the most recently developed nature-inspired optimization approaches. Simulation studies cover potential and electrical field distributions using COMSOL 4.3, which uses a numerical analysis technique based on Finite Element Method (FEM) were done. Reported results show that the optimized corona ring decreases significantly the electric field near its end fittings. That is, potential distribution will be more uniform with the presence of the optimized corona ring. By installing corona ring, the electric field improves about 58.6% compared with the threshold value. The results show that optimization using Bat algorithm as new methodology is efficient for designing corona rings on transmission line composite insulators and it presents more accurate result in finding the best solutions for corona discharges problems.

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The influences of the pollution layer parameters including; conductivity, position and length on the performance of high-voltage cylindrical insulator were investigated. Parameters effects and their interactions have been assessed and determined using the variance statistical technique and the relation between parameters and the flashover voltage, maximum electric field and the breakdown strength is modeled by the response surface methodology (RMS). The 3D model from Comsol Multiphysics was used for modeling and the FEM method was utilized for simulations. The findings demonstrate that the flashover voltage of the non-uniformly contaminated surface is primarily affected by the pollution layer length. Simulation results show that the intensity of the electric field rises with the increasing in length of pollution layer and its position. It was noted that the experimental tests in laboratory for non-uniform contamination are in strong alignment with simulation studies. The results of this analysis should expand our understanding about the performance of outdoor insulators under specific contaminated conditions. The knowledge gathered can be used to enhance the configuration of insulators used in contaminated regions and it is believed that the current study has resulted methodology to estimate reliably and realistically the pollution performance of cylindrical porcelain insulators.