基于电网电压前馈的VSG平衡电流控制策略

在电网电压不平衡条件下基于虚拟同步发电机(VSG)控制策略的逆变器输出三相电流不平衡并且电流幅值过大。针对此问题,提出一种基于电网电压前馈的VSG平衡电流控制策略。利用VSG电流内环的控制框图推导出前馈控制器的传递函数,再将电网电压经前馈控制器前馈至电流内环,减轻故障电压对电流波形的干扰,降低电流畸变率。将瞬时有功、无功功率的平均值反馈到VSG算法得到抑制负序电流的电压参考指令,在电网电压故障期间使并网电流依然保持三相平衡而且幅值稳定。最后通过MATLAB/Simulink仿真证明了所提控制策略的有效性。

VSG Balanced Current Control Strategy Based onGrid Voltage Feedforward

The output three-phase current of the inverter based on the control strategy of virtual synchronous generator (VSG) is unbalanced and the current amplitude is too large. To solve this problem, a VSG balanced current control strategy based on voltage feedforward is proposed. The transfer function of the feedforward controller is derived by using the control block diagram of the VSG current inner loop, and then the grid voltage is fed forward to the current inner loop through the feedforward controller. The interference of the fault voltage to the current waveform and the current distortion rate are reduced. The average values of instantaneous active power and reactive power are fed back to VSG algorithm to get the voltage reference instruction of restraining negative sequence current, which can make the grid connected current keep three-phase balance and stable amplitude during the voltage fault period. Finally, the effectiveness of the proposed control strategy is proved by MATLAB/Simulink simulation.