Design of Grading Structures in Insulators Having Octa Bundle Conductor

Insulators in transmission system provides isolation for the conductors, thus preventing electrical leakage and ensuring safety. Comprehending the electric field behaviour is essential for the effective functioning of insulating materials. Increasing the number of bundles in the conductor is an effective way to reduce electric field in the insulator and the end fitting regions. In addition, grading structures are used at the end of the insulator to avoid concentration of high electric field. This paper aims in designing the grading structures: Ring 1 and Ring 2, used in octa bundle 765kV insulator and octa bundle 1200kV insulator. Three geometrical parameter of Ring 1 and five parameters of Ring 2 are identified for optimization. The Three dimensional modelling of the insulators and electric field analysis is performed using Finite Element Method based software. Optimum parameters of the Ring 1 and Ring 2 are achieved by using stochastic algorithms. Multi-objective Grasshopper optimization algorithm (MOGOA) is used in this paper to suggest the optimum parameters of grading structures. The suggested optimum geometries produced electric fields which are in compliance with the threshold limits. Moreover, the algorithm has reduced the high electric field to 46% in Insulator 1 and 16% in Insulator after optimization.