Introduction  To better adapt to the development of distribution network, a flexible DC back-to-back interconnection solution based on integrated gate commutated thyristors (IGCT) devices for medium voltage distribution network is proposed for areas with tight land resources, dense and uneven loads. The solution is analyzed, and reasonable wiring, equipment selection and layout plans are provided.

  Method  Key equipment, such as electrical main connections, switches, converters, DC transformers, bridge arm reactors, as well as their layout, were evaluated and compared.

  Result  The results show that the DC transformer solution offers better adaptability, is oil-free, has no fire safety issues, and results in a smaller overall system volume. Semiconductor switches adopts IGCTs. The converter and the DC transformer adopt "full-bridge + half-bridge" topology. The bridge arm reactor adopts dry-type iron-core reactors. The equipment layout is containerized, making installation convenient and facilitating standardized design.

  Conclusion  The proposed solution meets the practical requirements in terms of feasibility, adaptability, land use and cost, and can guide practical engineering applications.