基于多PR控制的并网逆变器设计与参数整定

摘要

在LCL型三相并网逆变器的应用中，电流控制器的结构和参数对系统的性能和输出电流质量非常重要。采用电容电流内环、并网电流外环的双闭环控制策略，在并网电流外环中应用并联多谐振的PR控制器，达到无稳态误差跟踪并网电流基波，减小输出电流中谐波的目的。针对控制系统阶次高，参数设计复杂的问题，采用根轨迹理论分析了双闭环控制器参数对极点的影响，并在此基础上设计控制器参数，从而保证系统有较好的稳定性和动态性能。通过仿真验证了该控制策略和参数整定方法的有效性。%In the application of the three-phase LCL-type grid-connected inverter,the structure and parameters of the current-controller are very important for the system performance and output current quality. In this paper a dual-loop control scheme with the capacitor current inner loop and grid connected current outer loop is used for the grid-connected inverter,and a multi-resonance proportional resonant(PR)regulator is adopted in the grid current loop to track the given fundamental sinusoidal current as well as eliminate certain harmonics to improve the quality of the grid current. Furthermore,because the system is of high order and complicated,the theory of root locus is applied to analyze the dual-loop controller parameters,based on which the controller parameters can be properly selected to guarantee the stability of the system and the dynamic performance. Finally,the simulation results demonstrate the effectiveness of the control strategy and tuning method.