多模块三电平逆变器并联系统环流谐振抑制

Circulation Resonance Suppression of Multi-module Three-level Inverter Parallel System

基于LCL型滤波器的并网逆变器并联是提高模块化三电平并网逆变器系统功率等级的一种有效方法,但同时会带来环流、谐振以及电流分配不均等诸多问题,影响并网系统的安全可靠运行。针对并联模块间可能产生的环流谐振问题,分析其产生的机理,采用脉宽调制(PWM)载波同步以及环流谐振控制器来抑制系统环流谐振。最后,以两个模块化三电平逆变器并联系统为例,通过建立模块化三电平并联逆变器的仿真和实验,验证其环流谐振抑制方法的有效性。

The parallel connection of grid-connected inverter based on LCL filter is an effective method to improve the power level of the modular three-level grid-connected inverter system,but it also brings many problems such as circulation current,resonance,and uneven current distribution which affects the safe and reliable operation of the gridconnected system.Aiming at the problem of circulation current resonance that may occur between parallel modules,the mechanism of its generation is analyzed,and the pulse width modulation(PWM)carrier synchronization and circulation current controller are used to suppress the circulating current resonance of the system.Finally,a two-parallel three-level inverter parallel system is used as an example.The simulation and experiment of the modular three-level parallel inverter are established to verify the effectiveness of the circulating resonance suppression method.