SOC Balance Control Method for Cascaded Energy Storage System Based on Nearest Level Modulation

Abstract To address the issue of in-phase state charge(SOC) unbalancing in a cascaded H-bridge battery energy storage system, this paper proposes novel control strategy based on nearest level modulation(NLM). Through NLM, first calculates number sub-modules needed, then adjusts priority different SOC by charging state, so that with larger deviation converge to average value. Considering large participating or discharging may bring distortion PCS output, limiting deviations during is and close cooperate charging/discharging process reduce output. The simulation result verified correctness strategy.