基于H_∞控制的并网逆变器输出端扰动抑制

Disturbance Rejection at the Output of Grid-connected Inverter based on H-infinity Control

针对光伏系统并网时负载变化、电网电压波动和外部噪声等输出端扰动问题,应用H_∞理论构建抑制并网逆变器输出端干扰的控制系统模型,该模型中电网电压、参考电流和外部噪声作为输入信号,逆变器的输出电流作为输出反馈信号,实现并网电流的间接稳定控制;同时采用带阻尼谐振的谐波补偿器作为性能加权函数,优化并网电流的谐波输出。仿真表明设计的H_∞控制器在上述3种输出端扰动的情况下均能保障并网电流总谐波畸变率小于5%,与电网电压同频同相的并网要求,且优于PI控制和准PR控制,增强了光伏并网系统的鲁棒性能。

To reject disturbances at the output of grid-connected photovoltaic system such as load changes,grid voltage fluctuations and external noise,a control system model of the grid-connected inverter is constructed based on H-infinity theory.In this model,grid voltage,reference current and external noises are used as input signals,and the output current of the inverter is used as the output feedback signal to indirectly control the grid current.Meanwhile,a harmonic compensator with damping resonance is used to realize the grid current harmonics suppression.The simulation results show the grid current controlled by the designed H_∞controller can meet requirements of total harmonic distortion rate less than 5%,same frequency and phase with grid voltage when the load varies,grid voltage waves and noise occurs at the output.The comparison of PI control,Quasi-PR control and H_∞control simulation results shows that the grid connected current controlled by H_∞control has better harmonic performance,and the robust performance of the PV system is improved.