Considering that the low voltage and small capacity ratings of traditional distributed energy storage system cannot meet the increasing capacity of renewable energy
the battery energy storage system(BESS)based on cascaded H-bridge topology is presented to achieve high-voltage and large-capacity. Moreover
in order to make BESS connected to grid friendly
the virtual synchronous generator(VSG)is investigated. Firstly
the second-order equivalent model of synchronous generator(SG)is analyzed and the VSG control strategy for BESS is given combined with primary frequency and voltage regulation of SG. Besides
the small signal dynamic model in wideband of VSG is established to analyze the inherent power coupling problem and the effect of AC side impedance on VSG control
also
the relationship between control parameters of VSG and performance of BESS is analyzed by frequency domain model
which provide the basis of stability analysis and the design and optimization of key parameters of VSG. Simultaneously
aiming to the problem of state of charge(SOC)balancing for sub-module batteries
a method based on improved nearest level modulation(I-NLM)is proposed and the modulation principle and implementation process are given. Finally
the effectiveness of VSG control on BESS and equalization method for SOC are verified through computer simulation.