弱电网条件下提升LCL型逆变器稳定性的控制策略

弱电网条件下,由于逆变器并网阻抗与电网阻抗之间不匹配程度增加,导致并网逆变器可能失稳.为提高逆变器的稳定性,提出一种可提高系统相角裕度的新型控制方式.根据逆变器的分层控制结构,分别在控制层的电流内环引入带有延时补偿的有限集模型预测控制,在电压外环引入逆模型前馈控制,通过这2种控制的引入降低了系统控制环路的阶数,提高逆变...

Control Strategy for Improving the Stability of LCL-type Inverter under Weak Grid Conditions

Under weak grid conditions,the mismatch between grid-connected impedance and grid impedance increas?es,which leads to the instability of a grid-connected inverter.To improve the inverter’s stability,a novel control meth?od is proposed,which can improve the phase angle margin(PM)of the system.According to the inverter’s hierarchical control structure,the finite control set model predictive control(FCS-MPC)with delay compensation is introduced into the current inner loop in the control layer,and the inverse model feedforward control is introduced into the voltage outer loop,so as to reduce the order of the control loop in the system and improve the PM of inverter output impedance and the stability of the grid-connected inverter.Finally,a simulation model of LCL-type inverter is built on a Matlab/Simu?link platform,and the output waveforms of grid-connected inverter under different control strategies are compared,which verifies the effectiveness of the proposed control strategy.