基于H_(∞)滤波器的LCL型并网逆变器有源阻尼方法

Active Damping Method Based on H_∞ Filter of LCL Grid-connected Inverter

LCL型滤波器具有优越的高频谐波抑制性能,但会造成谐振和稳定性问题。对于LCL型并网逆变器,传统的电容电流反馈型有源阻尼方法能有效抑制谐振尖峰,但是需要额外的电流传感器。为此,提出一种基于H_(∞)滤波器的新型有源阻尼控制策略。根据LCL型滤波器状态空间模型及过程噪声模型完成H_(∞)滤波器的求解,可利用入网电流和公共耦合点电压信息估计滤波电容电流并完成反馈,增大系统阻尼,即使LCL型滤波器参数发生摄动也仍能保持估计值的精确度。仿真和实验结果表明,该方法对LCL滤波器参数变化和电网阻抗变化不敏感,验证了该方法的可行性和优势。

Although the LCL filter has a good performance of suppressing high-frequency harmonics,it may cause problems such as resonance oscillation and instability.For an LCL grid-connected inverter,the conventional capacitor-current-feedback type active damping method can suppress the resonant peak effectively,at the cost of additional current sensors.Under this background,a novel active damping control strategy based on an H_∞ filter is proposed.The state space model and process noise model of the LCL filter are derived to solve the H_∞ filter.The filter capacitor current can be estimated according to the information about grid current and the voltage at a point of common coupling,and feedback is further completed.The system damping is improved,and the estimation accuracy can be guaranteed even if parameter perturbations exist in the LCL filter.Simulation and experimental results show that the proposed method was insensitive to changes in the parameters of the LCL filter and the grid impedance,thereby verifying its feasibility and superiority.