Wenxia Sima

Corona Ring Design of ±800kV DC Composite Insulator Based on Computer Analysis

This paper presents a 3D electric-field calculation model of the plusmn800 kV DC transmission line composite insulators based on finite element method. With this 3D model, this paper introduces the effect of the tower, transmission lines and the parameters of the corona rings on the potential and e-field distribution along the composite insulators, and optimizes the corona ring design in order to control the maximum e-field along the insulator surface and corona ring surface.

New optimization method on electric field distribution of composite insulator

Due to the geometry configure of composite insulator, the electric field strength near the two ends of composite insulator is always strong. The high electric field strength can cause the partial discharge on the insulation material and the surface of the metal electrodes, and bring premature aging of the insulator. In this paper, a new optimization method on the electric field distribution of composite insulator is put forward, which is the combined use of composite insulators and several units of glass insulator. Based on the finite element method, a three-dimensional electric field calculation model of insulators in the transmission line is established. Then the optimization conditions of surface potential and electric field distribution of composite insulator with glass insulator installed in the high voltage end of composite insulator at different levels of voltage is studied. The results show that by this method, the electric field distribution near the ends of composite insulators is significantly reduced, which can prevent the partial discharge and the aging of the composite material. Finally, this paper recommends the number of glass insulators which should be installed at the high voltage end of composite insulator at different voltage levels.

Electric Field Calculation of 800kV Composite Insulator with Domain-decomposition and Iterative Method

Based on finite element method and the asymptotic boundary condition, the paper presents a new calculation method for unbounded field problem with complex parts by the domain-decomposition and iterative processes. Firstly, the field domain should be decomposed to two parts. One is the concerned domain with finer meshes, the other is the unbounded space domain with coarser meshes. And the two parts have a common domain. Secondly, the concerned domain and the unbounded space domain are calculated separately by the iterative process on the common domain based on the finite element method until the result become stable. This method uses less time to calculation the complex field model and has more accuracy on the concerned domain. It also makes the asymptotic boundary condition to get more accuracy than a further boundary without too much computing time. The paper calculates a 3D model of 800 kV composite insulator with tower conductors and shielding wires. Calculation on the composite insulator of plusmn800 kV UHV DC transmission lines proves the advantage of the method. In the end, the verification tests show good agreement between calculations and measurements.