Research on key technologies of transformer free multi-port energy router used in AC / DC distribution network

To deal with that the traditional distribution network cannot meet the new needs, a new distribution network form based on multi-port energy router is proposed. The calculation method of the number of modules of multi-port energy router and the design of grounding mode are given. At the same time, in order to solve the problems of large volume and high noise of traditional transformers, a solution of transformer free multi-port energy router is proposed, and the feasibility of transformer free multi-port energy router is demonstrated from the aspects of steady-state operation, symmetric fault and asymmetric fault. At the same time, a variety of solutions such as zero sequence voltage suppression, DC voltage reduction and temporary blocking are proposed for long-term asymmetric faults, and the relevant simulation verification is carried out.