For an LCL-type inverter connected to weak grid,the appearance of grid impedance often results in a decrease in the phase margin,serious distortion of grid-connected current and even system instability.To solve this problem,an improved grid-connected current control strategy is proposed,in which a multi-resonance controller is introduced in the voltage feedforward loop to suppress the voltage background harmonics and a phase compensator is added to the current feedforward loop to improve the system's phase margin,so as to avoid the risk that the resonance peak of the multi-resonance link intersects with the-180° line.Theoretical analysis and simulation results show that the proposed strategy can effectively suppress the harmonics of LCL-type grid-connected current,improve the current quality and enhance the stability of the grid-connected system.
关键词
弱电网/LCL型并网逆变器/多谐振控制器/并网电流前馈/相位补偿器
Key words
Weak grid/LCL-type grid-connected inverter/multi-resonance controller/grid-connected current feedforward/phase compensator
维普
万方数据