含储能双母线直流微电网电压和功率协调控制

Voltage-power coordinated control of a dual-bus DC microgrid with energy storage

双母线直流(direct current,DC)微电网采用传统的下垂控制时,存在电压控制性能与功率分配精度的局限性。为此,提出一种考虑储能荷电状态(state of charge,SOC)均衡的电压和功率协调控制策略。首先,对于高压或低压侧母线电压稳定和功率分配问题,在电压/电流双环控制策略的基础上,采用基于SOC幂指数的自适应系数动态改变功率分配比例,对电压和功率进行精确控制。其次,针对双直流母线由于功率不平衡造成的电压偏移问题,根据双侧直流母线电压差以及高/低侧的工作模式,制定高/低压母线之间DC/DC变换器的控制策略,保证高/低压侧功率平衡和电压稳定。最后,利用Matlab/Simulink软件建立不同工况下双母线直流微电网模型,并进行仿真验证。仿真结果表明,所提出的控制策略可改善功率分配和电压控制精度,使各储能SOC趋于一致,同时实现高/低压直流母线之间功率相互支撑。

For a dual-bus direct current(DC)microgrid adopting the conventional droop control,there are some limitations in voltage control performance and power distribution accuracy.For this reason,a voltage-power coordinated control strategy considering the state-of-charge(SOC)equalization of energy storage is proposed.First,for voltage stability and power distribution at the high-voltage(HV)or low-voltage(LV)side,on the basis of voltage/current dual-loop control strategy,an adaptive coefficient based on the SOC power exponent is used to adjust the power distribution ratio dynamically to realize precise control of voltage and power.Second,for the voltage offset of the two DC buses caused by the power imbalance,the control strategy of the DC/DC converter between the HV/LV buses is formulated according to the voltage difference between the two DC buses and the operating mode at the HV/LV side.In this way,power balance and voltage stability at the HV/LV side are guaranteed.Finally,Matlab/Simulink software is used to establish the dual-bus DC microgrid model for simulation verification.Results show that the proposed control strategy can improve the accuracy of power distribution and voltage control,make the SOC of multiple energy storage units converge to a consensus level,and realize power support between the HV/LV DC buses.