Research on Medium Voltage DC Self-powered Topology and Control Strategy Adapted to DC Distribution Network

Compared to AC distribution networks, DC distribution networks could effectively reduce the conversion process, and improve energy utilization efficiency of distributed renewable energy. To replace the power supply circuit by AC in DC distribution networks, a novel DC Self-powered circuit and control strategy is proposed, which contains a primary part and secondary part. Firstly, the modular multilevel technology is applied for the DC Self-powered primary circuit, which works in resonant mode. In the primary circuit, the half bridge submodule is used for the upper bridge, while the chopper submodule is designed for the lower bridge. Secondly, a voltage closed-loop control strategy with the voltage balancing for submodule capacitors was designed. Finally, to verify the feasibility and effectiveness of the topology and control strategy, a simulation model was established on the MATLAB/Simulink platform. The results show that the circuit can achieve a smooth voltage reduction effect.