Parameters design optimization of 230 kV corona ring based on electric field analysis and response surface methodology

Ageing of composite insulator in field is mainly affected by the corona discharge activity caused by high electric stress near the end fittings. In order to control the electric field stress on the insulator surface below to the accepted limits, new approach to analyze the corona ring effect on the E-field stress is presented in this paper. The effect of geometrical corona ring parameters on the E-field is studied using the finite element and the design of experiment methods. The analysis of variance is used to evaluate the main and the interaction effects of the studied parameters. The relationship between the E-field and the geometrical parameters (ring projection from end, ring radius and ring tube thickness) is modeled and optimized by the response surface methodology. Results show how much the E-field is influenced by the ring tube thickness. Finally, an attempt based on the obtained model is done to estimate the ring parameters to control the E-field lower to the maximum recommended threshold. The proposed methodology gives an efficient fast working tool to examine a complex geometry of corona rings without extra high computational effort, which reduces the time involved during computational analysis.