LCL滤波器并网逆变器控制策略研究与仿真

Research and simulation on grid-connected inverter control strategy with LCL filter

LCL滤波器比单电感L滤波器在光伏并网电流高次谐波的抑制上更具优势,但其输出电流控制存在不稳定现象。本文提出比例谐振补偿与分裂电容电流反馈结合的并网电流控制方法,通过分裂电容电流反馈直接控制法将受控系统降为一阶稳定系统,消除谐振尖峰,使电流控制增益设计不受谐振尖峰的限制,减小由电网阻抗变化产生的不利影响,增强控制系统鲁棒性。最后通过仿真进行验证,结果表明所提控制策略可有效抑制光伏并网电流谐波,且具有良好动态性能。

LCL filter has more advantages than L filter in the high harmonics inhibition of PV grid current, but its output current control shows instability phenomenon. A novel control strategy that combined proportion resonance （PR） compensating and splitting capacitor current feed-back was proposed. The controlled system was reduced to a first-order stability system through splitting capacitor current feed-back method, and the resonant peak of LCL filter was effectively eliminated, so that the design of current control gain will not restricted by resonant peak, reducing disadvantage effects which caused by impedance changes of power grid, and the control system robustness was enhanced. Finally, the simulation results show that the proposed control strategy can effectively suppress the PV grid current harmonics, and has good dynamic performance.