基于功率状态的分布式电池储能系统协调控制

Coordinated control of distributed battery energy storage system based on state of power

分布式电池储能系统(Battery Energy Storage System,BESS)可有效地应对各种分布式能源(如光伏、风电)接入电网对其产生的电压和频率波动影响。针对分布式储能系统协调控制时负荷分配不均、电压波动等问题,提出基于功率状态(State of Power,SOP)的分布式BESS负荷分配控制策略。该控制策略采用内外双闭环控制方式。在内环中,利用分布式BESS当前的SOP改进传统功率下垂控制,实现负荷有效分配;同时,在外环控制中加入线性电压补偿环节,以解决改进下垂控制中的静态偏差及线路阻抗等因素带来的电网电压下降问题。仿真结果表明,所提出的控制策略可使分布式BESS根据自身SOP有效分配负荷,并在负荷变化时均能维持系统电压和频率稳定在相应给定值附近,其电压和频率波动分别控制在0.1%和0.5%以内,可避免BESS中电池的过充和过放,使得BESS运行稳定,延长寿命。

The Battery Energy Storage System(BESS)can effectively suppress the voltage and frequency fluctuation which caused by the integration of the various distributed energy sources,such as photovoltaic and wind power.To overcome the problems in the distributed BESS control,such as uneven load allocation and voltage fluctuation,a coordinated load allocation control based on state of power(SOP)is developed in this paper.The developed method is based on inner and outer double closed loop control.In the inner loop control,an improved power droop control based on the SOP is presented to effectively allocate the load.In the outer loop control,a linear voltage compensator is addressed to deal with the voltage drop problems caused by the static error of power droop control and line impedance.It is proved that the developed coordinated load control can effectively allocate the loads according to the simulation results.Moreover,the voltage and frequency of the grid can be maintained to the given value using the developed method in various loads.The corresponding voltage and frequency errors are 0.1%and 0.5%respectively.It means the developed coordinated loop control can help the BESS to avoid overcharging and discharging and ensure the stable operation and extended lifespan of the BESS.