高谐波电网工况下光伏逆变器控制策略研究

Contral strategy of PV inverter in high harmnonic power grid

在不同电网工况下,光伏并网逆变器所接负载不同,产生了电流谐波及电网电压畸变等问题。文章提出了全前馈控制与多级比例谐振(Proportion Resonant,PR)相结合的控制策略。该策略对电网电压前馈部分进行改进,加入滤波环节,改善系统实时性并降低了电网电压背景谐波对光伏逆变器的影响;使用多级PR选频补偿控制器,减少交流静态误差,实现对特定次谐波进行补偿,有效减少并网电流谐波含量。最后,在Matlab/Simulink仿真及实验样机上对所提控制策略进行验证,实验结果表明,该控制策略可明显消除电压电流谐波,并改善系统鲁棒性。

Under different grid conditions, the load of PV grid-connected inverter is different,resulting in current harmonics and grid voltage distortion. In this paper,a control strategy combining full feed-forward control with multi-PR is proposed. The feed-forward part of the power grid voltage is improved, the filtering link is added. The real-time performance of the system improves and the influence of the background harmonic on the PV inverter reduces. The multi-PR frequency-selecting controller is used to reduce the static AC error,realize the compensation of specific frequency harmonic and reduce the harmonic content of grid connected current. Finally, the effectiveness of the control strategy is verified by Matlab/Simulink simulation and experimental. The experimental results show that the control strategy can obviously eliminate voltage and current harmonics, improve the system robustness.