一种改进的微电网并联逆变器下垂控制策略

An Improved Droop Control Strategy for Parallel Lnverters in Micro Grid

针对虚拟阻抗的引入会导致微电网逆变器输出电压跌落的问题,提出了一种改进的微电网并联逆变器下垂控制策略。首先,通过对基于感性虚拟阻抗的逆变器控制系统闭环传递函数以及感性虚拟阻抗变化对闭环传递函数影响进行频域响应曲线分析,说明了改进下垂控制方法的必要性。其次,通过下垂曲线分析提出基于虚拟阻抗电压反馈的改进下垂控制策略。最后,通过Matlab/Simulink进行仿真验证,结果表明:所提出的改进下垂控制策略不但可以解决逆变器输出电压降落的问题,而且提高了下垂控制的功率分配精度,维持了系统电压和频率的稳定,证明了所提出的改进下垂控制策略的有效性。

Aiming at the problem that the output voltage sag of microgrid inverter can be caused by the introduction of virtual impedance,this paper proposes an improved droop control strategy for parallel inverters in microgrid. Firstly,based on the virtual impedance control system of the closed-loop transfer function of the inverter and the change of inductive virtual impedance on the closed-loop transfer function of frequency response curve analysis,indicating that the improved droop control method is necessity. Secondly,an improved droop control strategy based on virtual impedance voltage feedback is proposed by analyzing the droop curve.Lastly,the Matlab/Simulink simulation results showthat the improved droop control strategy can not only solve the output voltage sag of the inverters,but also improve the accuracy of power allocation of droop control,maintain the system voltage and frequency stability. It is proved that the improved droop control strategy is effective.