Capacitor Voltage Balance and Energy Balance Control Strategy for Hybrid DC Energy Consuming Device

In offshore flexible DC transmission systems, fault crossing and surplus power dissipation can be achieved by configuring DC energy dissipation devices on the onshore DC side. Based on the analysis of the topology and operating mode of hybrid energy dissipation devices, this paper proposes capacitor voltage balance strategies and energy balance strategies for sub-modules under different operating modes. Compare and analyze different energy balance strategies in terms of energy balance effectiveness, computational complexity, and resource costs. Select energy balance strategies that meet engineering requirements. Based on the engineering design of the German Borwin6 hybrid DC energy consumption device, the effectiveness and feasibility of the proposed sub module capacitor voltage balance strategy and energy balance strategy in actual working conditions are verified through system simulation.