考虑SOC均衡的直流微网储能系统控制策略研究

Research on control strategy of DC microgrid energy storage system considering SOC equilibrium

在直流微电网中分布式储能系统起着稳定母线电压、维持系统功率平衡的关键作用。针对多个储能单元中荷电状态(SOC)不同会造成过充或者过放,从而影响系统稳定性的问题,提出一种改进SOC均衡下垂控制策略。首先,将储能装置的下垂系数与SOC嵌套反正切函数联系,充分利用反正切函数和幂函数的优点。其次引入变加速因子,在SOC差异较小时进一步加快均衡速度。同时,为了解决均衡过程中引起的母线电压偏差问题,在上述改进控制策略基础上增加二次电压补偿环节,使用一致性电压均衡器减少母线电压的波动。最后搭建了直流微网储能系统的仿真模型。仿真结果验证了所提控制策略可以动态实现SOC快速均衡,并有效维持了微网内功率平衡和母线电压稳定。

Distributed energy storage system plays a key role in stabilizing bus voltage and maintaining power balance in DC microgrid.Aiming at the problem that different state of charge(SOC)in multiple energy storage units will cause overcharge or overdischarge,which will affect the stability of the system,an improved SOC balanced droop control strategy was proposed.Firstly,the droop coefficient of the energy storage device was connected with the SOC nested arctangent function to make full use of the advantages of the arctangent function and the power function.Secondly,a variable acceleration factor was introduced to further accelerate the equalization speed when the SOC difference is small.At the same time,in order to solve the problem of bus voltage deviation caused by the equalization process,the secondary voltage compensation link was added on the basis of the above improved control strategy,and the consistency voltage equalizer was used to reduce the fluctuation of the bus voltage.Finally,the simulation model of DC microgrid energy storage system was built.The simulation results verify that the proposed control strategy can dynamically achieve fast SOC balance and effectively maintain power balance and bus voltage stability in the microgrid.