Application of VSC Based DC Distribution Network and Key Technology

Due to the continuous development of distributed energy and energy storage systems, the VSC based DC and AC-DC hybrid distribution networks have been developed rapidly in recent years. Compared with the traditional AC distribution network, DC distribution network can remove the power conversion links in power supply, storage, and end loads, reducing the complexity and cost of the access system, improving the network efficiency and power quality. This paper introduces several VSC based DC distribution network projects to be implemented in China. The key technologies proposed, including AC/DC conversion, control and protection, fault isolation and restore, and DC transformer, are analyzed together with their technical challenges. This paper also explains the development trends of several DC distribution network related subjects such as DC voltage level, key equipment development, rapid protection & isolating fault, and regional coordinated control etc.