基于QPR与PI联合控制的改进LCLL型并网电流优化

Optimal Control of Improved LCLL Type Grid-connected Current Based On Joint Control of QPR and PI

针对LCL型并网逆变器存在的谐振问题,提出一种改进的LCLL型滤波器,即在滤波电容两端并联电感,为低次谐波提供通路,不仅可以减少并网电流中的谐波含量,还可以减小谐振峰的峰值。在此基础上采用QPR与PI联合控制的优化控制策略,在保留QPR对并网电流无静差跟踪的前提下,实现了对注入并网电流直流分量的抑制。最后采用Matlab/Simulink进行仿真研究,验证了所提策略的可行性与有效性,结果表明能够实现光伏并网系统具有良好的并网波形质量。

Aiming at the problem of resonance with LCL type grid inverter,it presents an improved LCLL type filter, that is the parallel inductance is applied to both ends of the filter capacitor,to provide access to the low order har- monics and reduce the harmonics in the grid current,but also this method can decrease the peak of the resonant peak. On this basis,the optimized control strategy of combined control of quasi-PR and PI is adopted. This way can achieve static-error-free tracking and PI and quasi-PR control strategy can achieve the suppress the DC component. Results of simulative study with Matlab/Simulink show that,the simulation verifies the correctness of theoretical analysis and the feasibility of control strategy.and the results show that the excellent grid-connected waveform is achieved.