一种新型多电平逆变器在光伏并网系统的应用

摘要

传统光伏并网逆变器多采用二电平逆变器,多电平逆变器受其复杂电路拓扑的制约在光伏系统中应用较少.在传统五电平逆变器拓扑基础上,提出一种简化的H桥五电平单相光伏逆变器.该逆变器采用特定谐波消除法调制控制方案,系统并网电流采用模糊PI自整定控制方法,输出电压和电流具有较低的谐波和du/dt,改善了系统稳定性,提高了系统动态响应过程.构建仿真实验分析验证了控制策略的有效性和可行性.%Traditional grid-connected photovoltaic (PV) inverters are based on two or three-level inverter. Multilevel inverter topology constrained by its complex circuit system is seldom used in PV system. A modified H-bridge five-level singlephase grid-connected inverter on the base of the traditional five-level inverters topology is proposed.The new inverter uses selective harmonic elimination method,and grid-connected current control using the self-adaptive fuzzy PI control method.The output voltage and current have less harmonics and lower du/dt, the control can improve stability of the system and dynamic response of the process. The simulation results verify that the control strategy is valid and feasible.