考虑到控制延时,LCL型光伏并网逆变器传统电容电流反馈有源阻尼（CCFAD）仅能保证采样频率fs的1/6以内系统稳定。弱电网中,电网阻抗的变化会导致实际谐振频率fr偏移,若fr大于fs/6,系统鲁棒性将会变差。为解决传统CCFAD有效阻尼区间不足的问题,提出一种基于延时补偿的改进CCFAD控制策略,通过在电容电流反馈通道串入级联超前相位补偿器,补偿控制延时引起的相位滞后,将有效正阻尼区扩展至（0,fs/3）频段,扩大系统稳定域。此外,电流控制环采用比例复数积分（PCI）控制策略,提高了并网电流跟踪性能,仿真和实验验证了所提策略的可行性。与传统CCFAD方法相比,所提延时补偿策略扩大了有效阻尼区,增强了系统鲁棒性。
Abstract
Considering the digital control delay, the boundary frequency of the equivalent positive and negative damping zone of the traditional capacitor current feedback active damping （CCFAD） of LCL-type photovoltaic grid-connected inverter is fs/6 （fs, is the sampling frequency）. Under weak grid, the variation of grid impedance will cause the actual resonance frequency fr shift, and if fr>fs/6, the robustness of the system will be threatened. In order to solve the above problem, an improved compensation strategy is proposed, the phase lag caused by digital control delay was compensated by adding a cascade lead phase compensator into the capacitor-current-feedback path, so the effective positive damping region was broadened to （0,fs/3）. In addition, the grid connected current tracking performance was improved due to the proportional complex integral （PCI） controller in the current control loop. Simulation and experiment verify the feasibility of the proposed strategy. Compared with the traditional CCFAD, the proposed delay compensation strategy expands the effective damping region and enhances the robustness of the system.
关键词
光伏发电 /
并网逆变器 /
延时补偿 /
有效阻尼 /
鲁棒性 /
弱电网
Key words
PV power /
grid-connected inverter /
delay compensation /
active damping /
robustness /
weak grid
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基金
国家自然科学基金（51567004）; 广西自然科学基金（2021GXNSFAA220136）; 广西高等学校高水平创新团队及卓越学者计划（桂教人才〔2020〕6号）
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