Coordination Strategy of Multi-Port Solid-State Transformer in Medium-Voltage Distribution Networks Based on Hierarchical Voltage Control

This paper proposes a coordination strategy of multi-port solid-state transformer (MPSST) in medium-voltage distribution networks (MVDNs) based on hierarchical voltage control. Firstly, the island operation characteristics of the MPSST are analyzed briefly, and each source-load-storage unit's influence mechanism on the power balance and the MPSST's DC bus voltage is clarified. Then, the coordinated strategy of the MPSST under the island operation is suggested, and the hierarchical voltage control is used to adjust the PV unit, energy storage unit (ESU), and adjustable loads. Finally, a detailed simulation model of the MPSST in the MVDNs is constructed, and the proposed coordinated strategy is verified. The findings show the method can effectively ensure the DC bus voltage stability of the MPSST under different conditions.