一种抑制电网扰动的单相并网逆变器的控制方法

来自电网的扰动,包括电压跌落、谐波以及电网阻抗的变化等,会影响采用LCL滤波器的光伏并网逆变器的正常并网。提出了一种使用重复控制的双闭环加前馈的单相光伏逆变器控制方法。采用比例控制器的反馈和前馈虽然不能彻底消除谐波影响,却可以抑制LCL滤波器谐振峰,并提供需要的增益和快速的响应,而重复控制则可以保证系统对电网谐波的抑制以及使系统具有良好的鲁棒性,并易于设计和实现。仿真和实验结果表明,控制系统在各种电网扰动发生时,仍然能够保证并网电流指标满足标准的要求。

A Control Method to Suppress Grid Disturbances for LCL-Filter-Based Grid-Connected Inverter

Disturbances from the utility grid including voltage sags,harmonics and the grid impedance will affect the LCL-filter-based grid-connected inverter's connecting to the grid.A repetitive-based controller with dual close-loop and feedforward for single-phase system was proposed.In this method,although could not eliminate the effects of harmonics,the dual close-loop control with feedforward could limit the resonance peak of the LCL filter and bring high gain and rapid response.Meanwhile,the repetitive control could provide the system with the ability to attenuate grid harmonics and good robustness.Additionally,the repetitive controller was also easy to design.Simulation results proved that the grid current quality can satisfy the standard under the condition of different grid disturbances.