Research on topology structure and control strategy of direct-hanging energy storage on the DC side

Abstract

Direct-hanged energy storage of voltage source converters （VSCs） on the DC side can be applied to active or reactive power grids. It has the advantages of peak shaving and valley filling， reducing wind and photovoltaic power curtailment. Given the topology of DC-side direct-hanging energy storage of VSCs， the basic working principle of DC-side energy storage is introduced first. Two control methods are proposed： constant DC voltage control and constant DC control at the pole control level. Moreover， DC voltage open-loop control is proposed since both methods adopt feed-forward control of sub-module quantity. Finally， an RTDS （real-time digital simulation system） is established， and steady-state， dynamic， and control mode switching tests are carried out. The results show that the DC-side energy storage with such topology is characterized by its superior steady-state operation， dynamic voltage， and current response characteristics and has a particular application and promotion value.

Keywords

• dc-side energy storage
• dc voltage control
• dc current control
• step response
• control mode switch