弱电网下LCL逆变器阻尼谐振抑制与功率快速调节方法

Damping Resonance Suppression and Fast Power Regulation Method for LCL-Type Inverter under Weak Grid

位于电网末梢或偏远地区的新能源发电弱电网中,大量本地阻感性负荷的接入会引起电网阻抗变化与频率偏移及电压波动,进而影响LCL逆变器自身谐振尖峰抑制及其输出有功与无功动态调节过程。对此,提出了一种LCL逆变器阻尼谐振抑制与功率快速调节方法,包括鲁棒并网电流反馈有源阻尼控制、同步参考系准比例积分控制及功率快速调节。提出的鲁棒并网电流反馈有源阻尼控制增强了系统阻尼特性,抑制了LCL谐振尖峰;光伏能量功率前馈和负载无功快速检测可实现LCL逆变器的有功功率快速调节与电压无功紧急支撑功能;同步参考系准比例积分控制可降低电网基波频率偏移对系统稳定性的影响,增强了系统整体鲁棒性。通过深入分析控制系统动态响应和稳定性,给出了控制参数优化设计方法。最后,仿真及实验结果验证了所提控制策略的可行性。

For weak grids installed at remote areas, the grid-impedance variation and gridfrequency fluctuation affect the resonance peak suppression and active/reactive power distributed accuracy respectively. In this paper, a LCL damping resonance suppression and fast power regulation method is proposed, which includes robust grid-current-feedback active damping control（RGCFAD）, synchronous reference frame quasi-proportional-integral control（SRFQPI） and fast power regulation. The proposed RGCFAD control enhances the system’s damping characteristics and damps well the LCLresonance peak regardless of the grid impedance variation. The active power feed-forward and fast reactive power detection can speed up the system response and compensate load reactive power. The proposed SRFQPI control reduces the influence of the fundamental frequency fluctuation and enhances the overall robustness of the whole system. The stability margin and dynamic response of the overall system are analyzed in detail, and the proper parameters are selected without complicated trial. Finally, Simulation and experimental results have verified the proposed control and design strategies.