低压微网并联逆变器系统功率均分策略

Power equalization strategy for low-voltage microgrid shunt inverter system

针对低压微网中各线路参数不同导致并联逆变器有功功率的分配不均,提出了自适应虚拟阻抗的控制策略。首先以两台并联逆变器为研究对象,分析阻感比大的情形下有功分配不均以及环流产生的原因;其次通过引入自适应虚拟阻抗对传统下垂控制进行改进,并加入电压和频率补偿环节;最后在电压电流环中采用二阶广义积分和准比例谐振控制器提高系统的跟踪能力。通过Matlab搭建仿真实验,结果表明:自适应虚拟阻抗的引入,能够确保有功功率的均分,能够应对负荷变化的情形,在电压和频率补偿环节也能够有效改善母线电压的跌落以及提高系统的稳定性。

In low-voltage microgrids,the difference of each line parameter will lead to the uneven distribution of active power in shunt inverters,for which the control strategy of adaptive virtual impedance is proposed.Firstly,two shunt inverters are taken as the research object,and the reasons for the uneven active power distribution and the generation of circulating current in the case of large resistance-inductance ratio are analyzed;secondly,the traditional sag control is improved by introducing the adaptive virtual impedance,and the voltage and frequency compensation links are added in it;finally,the second-order generalized integral and quasi-proportional resonance controllers are used in voltage-current loops to improve the tracking capability of the system.The simulation experiments are constructed by Matlab,and the simulation results show that the introduction of adaptive virtual impedance can ensure the equalization of active power and cope with the load variation,and the voltage and frequency compensation links can effectively improve the bus voltage drop and improve the stability of the system.