Simulation and Optimization Design of Isolating Switch in the Indoor DC Yard of ±1100kV Converter Station

The ultra-high voltage direct current (UHVDC) transmission technology, which is crucial to balance the reverse distribution pattern of energy and load center in China, has the advantages of large capacity, far distance, low energy consumption and so on. As a key part of DC transmission project, UHV converter station is mainly composed of converter valve unit, bushing, isolating switch and various supporting electrical power fittings. Due to limited space of the indoor DC yard, air clearance between different apparatuses is narrow. When the voltage level raises to ±1100kV, electric field distortion and corona discharge are prone to occur on the surface of the fittings. Therefore, shape design of the shielding electrodes becomes an important issue. In this paper, a finite element model of mushroom-like shielding electrodes for isolating switch has been established by using COMSOL, electric field distribution of the indoor HV corona test hall has been simulated. Then, the advantages of mushroom-like shielding electrodes compared with typical annular shielding electrodes have been illustrated. At last, the laws of distortion effect by apertures on the shielding electrodes with different shapes, sizes and radius of chamfer have been analyzed and compared.