基于级联逆变器的光伏发电系统的新控制方法

摘要

Aiming to the problems of the traditional photovoltaic grid-connected system structure,this paper proposes a new kind of photovoltaic grid-connected cascaded inverter scheme with stepped waveforms and instantaneous current feedback hybrid control.With this method,one part of the cascaded units use stepped waveforms control, the other part of the cascaded units use octave SPWM control with instantaneous current feedback.The output voltage comes from the two parts in series. The output voltage harmonics are analyzed. A simple arithmetic for the trigger angles of the stepped waveforms modulated inverter is proposed, this method is suitable for cascaded inverters with the different voltage steps and the online calculation. Finally, the experimental results verify the theory analysis.%针对传统光伏并网系统结构存在的问题,提出了一种新的阶梯波与电流瞬时值反馈混合控制的光伏并网级联逆变器方案.该方案对一部分级联单元采取梯形波控制,一部分级联单元采取带电流瞬时值反馈的倍频移相SPWM控制,两部分串联叠加形成输出电压,并对逆变器输出电压进行了谐波分析.针对阶梯波调制逆变器的触发角提出了一种简易算法,该算法适用于电压级差不等模式,且可实现触发角在线计算.最后通过实验验证了理论分析.