微电网储能系统SOC平衡和电压频率恢复研究

RESEARCH OF SOC BALANCE AND VOLTAGE FREQUENCE RECOVERY OF MICROGRID ENERGY STORAGE SYSTEM

为避免微电网中分布式储能系统（distributed energy storage systems,DESS）损坏,延长DESS的使用寿命,需要DESS之间的荷电状态（state-of-charge,SOC）保持平衡。但由于线路阻抗和初始SOC的不一致,DESS的SOC存在不平衡的现象。提出一种适于交流孤岛微电网的SOC平衡控制方案,通过引入虚拟阻抗来改善算法切换过程中暂态有功均分特性,利用加入SOC因子补偿的下垂控制实现各DESS单元的SOC控制,同时保证原下垂控制即插即用的特性。SOC平衡以后,通过将算法切换到传统的下垂控制的双模式控制实现频率的恢复,并在无功-电压（Q-E）下垂算法中加入SOC因子实现电压补偿,保证电压频率工作在限定的范围。不同工况下的仿真结果和实验结果验证该方案的有效性和可行性。

In order to avoid the damage of distributed energy storage system（DESS）in microgrid and prolong theservice life of DESS,the State-of-Charge（SOC）of DESS must keep balance. However,the SOCs of DESS are notbalance due to inconsistent line impedances and initial SOC. A SOC balance control scheme suitable for AC islandingmicrogrid is presented,the transient active power sharing performance in the algorithm switching process is improvedthrough introducing virtual impedance. The SOC control of each DESS unit is realized by adding SOC factor tocompensate droop control,at the same time the original plug and play characteristics of droop control is ensured. Oncethe SOC is balanced,the frequency recovery is realized by switching algorithms to dual-mode control of traditional droopcontrol. And SOC factor is added in the reactive-voltage（Q-E）droop algorithm to achieve voltage compensation andensure that the voltage frequency works in a limitative range. The simulation and experimental results under differentconditions verify the validity and feasibility of the scheme.