Research on Medium-Voltage PCS Voltage Regulator and Its Control Strategy Based on Energy Storage with Hybrid Ultracapacitors

Energy storage systems play an active role in improving the overall power quality of medium-voltage supply power systems and meeting the reliability requirements for sensitive loads in centralized power systems. This paper focuses on the prevailing cascaded topology of Power Conversion Systems (PCS) in grid-connected systems. Firstly, the paper analyzes the working principles of two cascaded PCS topologies and introduces the characters of hybrid ultracapacitors. Then, focusing on the cascaded H-bridge star-connected PCS, with stabilizing grid-connected AC voltage as the control target, it studies a dual-closed-loop vector control strategy in the synchronous rotating reference frame of PCS to actively support the grid-connected point voltage during grid disturbances. Finally, a simulation model is built to verify the feasibility and effectiveness of the proposed voltage control strategy through simulation analysis.