LCL型有源电力滤波器的强鲁棒性控制器优化设计

LCL型有源电力滤波器能有效补偿电网谐波，但LCL型滤波器存在谐振问题，电容电流比例反馈有源阻尼是抑制LCL谐振的主要方式。然而，在数字控制下，谐振频率会随电网阻抗变化，导致反馈系数选取困难。针对该问题，研究了适应电网阻抗宽范围变化的反馈系数选取方法，推导不同反馈系数和谐振频率下的系统稳定条件，优化设计适应电网阻抗变化的反馈系数。此外，随着电网阻抗增加，LCL谐振频率减小，系统带宽变窄，有源电力滤波器采用传统准PR控制补偿高次谐波时，系统相频曲线在控制器谐振点容易穿越-180o线，导致系统不稳定。提出加入相位补偿环节以提升控制器增益处相角，并给出详细设计方法。理论分析表明，所提强鲁棒性控制器优化设计方法，可使有源电力滤波器在保证良好谐波补偿能力的同时具有更宽的稳定运行范围。仿真和实验结果验证了理论分析的正确性。

Optimization design of strong robust controller for an LCL-type active power filter

The LCL-active power filter can effectively compensate for the harmonic of a power grid, but an LCL filter has a resonance problem. Capacitive current proportional feedback active damping is the main way to suppress LCL resonance. However, with digital control, the resonant point will change with the grid impedance, and this makes it difficult to select the feedback coefficient. To solve this problem, this paper researches a selection method of feedback coefficient to adapt to a wide range of grid impedance variation, derives the stability conditions of the system under different feedback coefficients and harmonic frequencies, and optimizes the design of the feedback coefficient to meet the requirements. In addition, with the increase of grid impedance, the LCL resonant frequency becomes smaller and the system bandwidth becomes narrower. When the traditional quasi PR control is used to compensate for the high order harmonics, it is easy for the phase frequency curve of the system to cross the -180o line at the resonance point of the controller. This leads to instability of the system. Phase compensation is proposed to improve the phase angle at the gain of the controller, and the detailed design method is given. Theoretical analysis shows that the proposed robust controller optimization design method can ensure good harmonic compensation ability and a wider stable operation range of active power filter. Simulation and experimental results verify the correctness of the theoretical analysis. This work is supported by the National Natural Science Foundation of China (No. 51407184).