基于多谐振电网电压前馈的并网逆变器相位补偿算法研究

A phase compensation algorithm of a grid-connected inverter based on a feedforward multi-resonant grid voltage

在传统比例前馈并网逆变器中,使用多谐振控制能够有效抑制电网背景谐波,提高适应性。但是在弱电网情况下,电网电感会使得系统的相位裕度大幅降低并出现多谐振环节的谐振峰与0 dB线相交的问题。因此提出了一种多谐振控制器与相位补偿器的组合控制策略。首先通过在电网电压前馈回路增加多谐振控制器以抑制电网背景谐波的干扰。其次,为了解决加入多谐振控制器后系统相位裕度不足的局限性,在逆变桥PWM传递函数处增加参数自适应的相位补偿器以提升系统相位裕度。仿真与实验结果证明了提出的控制策略能够有效地提升系统的相位裕度,增强对高次谐波的抑制能力。

In the traditional proportional feedforward grid-connected inverter,the use of multi-resonance control can effectively suppress the background harmonics of the grid and improve adaptability.However,in the case of a weak grid,the grid inductance will greatly reduce the phase margin of the system and cause multiple resonances.The problem is that the resonance peak of the link intersects the 0dB line.Therefore,a combined control strategy of a multi-resonance controller and a phase compensator is proposed.First,a multi-resonant controller is added to the grid voltage feedforward loop to suppress the interference of the grid background harmonics;secondly,in order to solve the problem of adding a multi-resonant controller caused by a limitation in or insufficient system phase margin,a parameter adaptive phase compensator is added to the inverter bridge PWM transfer function to improve that margin.Simulation and experimental results prove that the proposed control strategy can effectively improve the phase margin of the system and enhance the ability to suppress high-order harmonics.