孤岛直流微电网的多储能SOC稳定均衡控制策略

Multi-storage SOC stabilization and equalization control strategy for islanded DC microgrids

孤岛直流微电网一般需要配置多组储能单元保证系统稳定性。为实现多储能单元在充放电过程中荷电状态(state-of-charge,SOC)均衡,防止过充过放加速老化,提出了一种改进SOC稳定均衡控制策略。首先,利用幂指函数嵌套反正切函数构建下垂系数与SOC的关系,合理设计下垂系数中加速因子与收敛因子参数使SOC快速达到均衡状态,实现自适应控制。其次,引入母线电压与虚拟压降二次补偿,减少母线电压波动同时忽略线路阻抗影响,提高电流分配精度。然后,通过频域根轨迹分布,讨论该策略控制参数对系统稳定的影响。最后,仿真结果验证了所提控制策略在正常充放电、负载或光伏功率波动、储能单元额定容量不同等工况下均能更好地实现SOC快速稳定均衡,电流精确分配,母线电压偏差较小且稳定性更强。

Islanded DC microgrids generally need to be configured with multiple energy storage units to ensure the stability of the system.To realize state-of-charge(SOC)equalization of multiple energy storage units during charging and discharging,and to prevent overcharging and over-discharging from accelerating the aging,an improved SOC stabilization and equalization control strategy is proposed.First,the power finger function nested inverse tangent function is used to construct the relationship between droop coefficient and SOC,and the parameters of acceleration factor and convergence factor in the droop coefficient are reasonably designed to make the SOC reach the equilibrium state quickly and realize adaptive control.After that,the influence of the control parameters of this strategy on system stability is discussed.Finally,simulation results verify that the proposed control strategy can better achieve fast and stable equalization of SOC,accurate current distribution and smaller bus voltage deviation with better stability under normal charging and discharging,load or PV power fluctuation,and with different rated capacities of energy storage units.This work is supported by the National Key Research and Development Program of China(No.2021YFB2601403).