改进下垂控制的逆变器并联运行研究

Research on Parallel Operation of Inverters Based on Improved Droop Control

在微电网逆变器并联运行系统中,传统的下垂控制因输电线路阻抗存有差异导致无功功率不能合理分配;同时在负荷突变时固定的下垂系数会造成系统电压出现跌落。对此,提出一种改进的下垂控制策略。在传统无功-电压下垂方程的基础上添加积分环节,并将下垂系数修正为包含功率的一次函数项,同时引入PI控制的电压误差反馈环节,从而实现了无功功率的均分,改善了系统电压的跌落,提升了电压的质量和动态稳定性能。最后在MATLAB/Simulink软件中搭建仿真模型,仿真验证了该改进策略的有效性。

In microgrid systems with parallel operating inverters,traditional droop control cannot properly allocate reactive power due to the difference of transmission lines impedance.Besides,when load mutates the fixed droop coefficient will cause voltage drop.In this regard,an improved droop control strategy is proposed.An integral factor is added on the basis of traditional reactive power-voltage droop equation,and the droop coefficient is modified into a power-containing linear function term.Moreover,a PI controlled voltage error feedback step is introduced,so as to realize equal allocation of reactive power,improve the system′s voltage drop,and enhance quality and dynamic stability of voltage.The simulation through MATLAB/Simulink modeling confirms the effectiveness of the improved strategy.