阶调式模块化多电平变换器的研究及应用

Research on gradationally controlled modular multilevel converter and its application

随着模块化多电平变换器(Modular Multilevel Converter,MMC)桥臂中串联的子模块个数增多,硬件成本升高,制约了其在光伏并网发电系统的发展。针对这一问题,通过分析阶调式多电平逆变器的工作原理和控制策略,提出了阶调式模块化多电平变换器(Gradationally Controlled Modular Multilevel Converter,GC-MMC),并将其应用于光伏并网发电系统中。此外,为了解决电容电压平衡控制问题,提出了一种适用于GC-MMC的电容电压平衡控制算法。最后在Matlab/Simulink环境下搭建了基于GC-MMC的光伏并网发电仿真系统,并分别与基于VSC和MMC的光伏并网发电系统进行比较。仿真结果表明,在相同条件下,GC-MMC输出电平数比MMC更多,并且基于GC-MMC的光伏并网发电系统无需滤波环节,有效降低了系统硬件成本。

As the number of sub-modules(SM)connected in series in one arm increases,the hardware cost of Modular Multilevel Converter(MMC)rises.It limits the development of MMC applied in the grid-connected PV system.To solve this problem,a Gradationally Controlled Modular Multilevel Converter(GC-MMC)is proposed and applied to the grid-connected PV system through analyzing the working principle and control strategy of gradationally controlled multi-level inverters.Aiming at the problem about controlling the voltage of capacitors,a capacitor voltage balancing controlled algorithm for GC-MMC is proposed.A grid-connected PV system based on GC-MMC is built with Matlab/Simulink.Compared with systems based on VSC and MMC,the simulation results show that the number of levels output by GC-MMC is higher than that of MMC.The filter is not needed by the grid-connected PV system based on GC-MMC,which reduces the hardware cost effectively.