A Semi-DC Substation in Urban Distribution System: System Design and Inter-feeder Power Translation

With the continuous integration of a large number of distributed energy resources and the widespread access of power electronic devices, traditional distribution networks are gradually evolving into a new form of active distribution networks. The substantial integration of distributed resources and the uncertainty demand of nonlinear loads make current distribution networks prone to issues, such as voltage beyond limits and feeder power imbalances. To address these problems and enhance the flexibility of power flow regulation in urban distribution networks, this paper proposes a topology design for a "semi-DC" AC substation, which includes two AC feeders and one DC bus. The DC bus is connected to the AC feeders in both series and parallel configurations, which are used to achieve regulation of voltage beyond limits and power flow transfer between the dual feeders, respectively. To verify the effectiveness of this substation in power flow regulation and voltage limit management, simulation results are provided. The simulation results demonstrate that the "semi-DC" AC substation successfully compensates for voltage sags and enables power mutual assistance between the dual feeders.