SOC Balance Control Strategy Based on High Voltage Cascaded Power Conversion System

High-voltage cascade battery energy storage system is one of the effective means to solve the problem of large-scale grid connection of renewable energy power generation such as photovoltaic power generation. In view of the proposed battery SOC imbalance in the star-shaped combined cascade large-capacity battery energy storage system, the three-phase SOC balance control is realized by injecting zero sequence voltage, and the equilibrium control of SOC between different cascade units in each phase is realized by stacking the base wave component with SOC as the feedback amount. In simulink, the SOC balance control of 35kV high voltage energy storage converter formed by 33 subunits is simulated. The simulation results show that the proposed SOC balance control strategy can effectively realize the battery SOC balance, which verifies the correctness and feasibility of the control strategy.