提高光伏并网逆变器在弱电网下稳定性的阻抗相角补偿控制

针对LCL型并网逆变器自身存在的谐振现象,提出一种电容电压惯性反馈控制策略来抑制其谐振尖峰。在弱电网情况下,由于电网阻抗和并网逆变器输出阻抗的相互作用,使得并网逆变器的稳定性急剧恶化。于是提出输出阻抗相角补偿加滤波器的方法,提高逆变器输出阻抗相角使其满足稳定裕度,从而提高并网逆变器在弱电网下的稳定性。在MATLAB/Simulink仿真平台上搭建并网逆变器系统仿真模型,对所提方法进行仿真验证。仿真结果表明,所提方法不仅能提高并网逆变器的稳定性,而且还能改善并网电流的质量,降低谐波总畸变率。

Impedance phase angle compensation control for improving stability of photovoltaic grid connected inverter in weak grid

Aiming at the resonance phenomenon of grid-connected inverter with LCL, an inertial feedback control strategy based on capacitor voltage is proposed to suppress the resonance peak. However, in the case of weak grid, the stability of grid-connected inverter deteriorates sharply due to the interaction between the grid impedance and the output impedance of grid-connected inverter. Therefore, a phase angle compensation method with filter is proposed to improve the output impedance phase angle of the inverter to meet the stability margin, thus improve the stability of grid connected inverter in weak grid. The simulation model of grid connected inverter system is built on MATLAB/Simulink platform and the proposed method is verified by simulation. The results show that the proposed method can not improve the stability of grid connected inverter, but also improve the quality of grid connected current and reduce the total harmonic distortion rate (THD).