Multi-Field Coupling Simulation Optimization of High-Speed Mechanical Switch Unit

Abstract

A pilot project of ±500 kV flexible DC power grid is built in China, with hybrid HV circuit-breaker as its key control and protection equipment. Fast mechanical switch unit is the key component for hybrid DC circuit breaker, adopting electromagnetic actuator. Electromagnetic fields, thermal fields and mechanical fields are involved in mechanical action process, so it is needed to carry on multi-field coupling simulation optimization design. Firstly, structure of high speed mechanical switch unit was designed, based on double coil for pushing metal disk and bitable spring holding mechanism. Then, multi-field coupling method was proposed to fully reflect mechanism motion, contact collision and coil temperature rise for the high-speed mechanical switch unit. Finally, multi-field coupling simulation optimization design was carried out for the switch unit. Key factors for performance improvement were preliminarily determined. Influence of different repulsion coil turns on opening time, coil temperature rise and opening bounce was analyzed. Optimal technical parameters were determined. Simulation results show that the high-speed mechanical switch unit can reach rated opening insulation clearance within 1.8 ms. In this paper, the optimal design provides theoretical guidance for fast mechanical switch and important reference for fast mechanical switch design with other structures.