一种微电网多逆变器并联运行控制策略

在微电网多逆变器并联系统中,由于逆变器的输出阻抗以及与公共连接点的线路阻抗存在差异,应用传统下垂控制法会导致逆变器间的环流较大及功率均分精度较低。在分析多逆变器并联系统中传统下垂控制法及逆变器输出阻抗对系统性能的影响基础上,通过引入感性虚拟阻抗,提出一种适合微网多逆变器并联的电压电流双环下垂控制策略。虚拟阻抗的引入使输出阻抗仅由滤波电感值决定,减少了逆变器输出电阻的影响;考虑线路阻抗的影响,提出一种新型改进下垂控制算法,通过对下垂系数进行修正,减弱了线路阻抗差异对并联均流的影响,提高了多逆变器并联性能。仿真与实验结果表明了该控制策略的正确性和有效性。

A Control Strategy for Parallel Operation of Multi-inverters in Microgrid

For multi-inverters parallel operation in microgrid,the output impedance of inverters and the line impedance between the inverters and point of common coupling are always different,which can result in big circulating current and lower precision of power sharing among inverters.The traditional droop control strategy and the influence of output impedance of the inverters were analyzed,and a droop control strategy based on voltage and current double-loop for multi-inverters parallel operation in microgrid was proposed by introduction of inductive virtual impedance.The introduced virtual impedance made it possible that the output impedance is only depended on the filtering inductor.The effect of the output resistance of parallel inverters was reduced.Considering the effect of line impedance,an novel improved droop control strategy was proposed.By modifying the droop coefficients,the effect of line impedance on paralleling current sharing was reduced and the system performance of parallel inverters was improved.Both the simulation and experimental results demonstrate that the control strategy is correct and effective.