局部阴影条件下基于MMC换流器的光伏并网

提出了局部阴影条件下基于模块化多电平(MMC)的光伏并网系统,并设计了该系统的控制策略。光伏阵列经DC-DC变换电路调节后并入电压源型换流器,构成子模块PSM,子模块PSM和电抗器串联组成MMC。控制系统包括启停控制、最大功率点控制以及并网控制。启停控制,在能量反馈阶段采用直流电压控制策略,在电容放电阶段采用三相同时放电策略;最大功率点跟踪控制采用扰动观测法。利用Matlab/Simulink对光伏并网系统进行仿真,仿真结果表明:该系统能提高太阳能利用率,降低并网输出波形的谐波含量,实现功率独立控制。

Grid-Connected PV System Based on MMC Under Partial Shading

A grid-connected PV system has been proposed based on MMC (modular multilevel converter) under partial shading, followed by a design of the control strategy of the system. Each photovoltaic array is connected with a VSC by a DC-DC converter circuit, thus forming a sub-module PSM, PSM and reactor in series to form MMC. The whole control system includes the start-stop control, the maximum power point control, and the grid connected control system. The start-stop control adopts DC voltage control strategy in the energy feedback phase, three phase simultaneous discharge strategy is used in capacitor discharge phase. By using Matlab/Simulink simulation software, a simulation test of the system has been carried out, with its results to verify the effectiveness and feasibility of the system in that it helps to improve the solar energy utilization, reduce the harmonic content of the grid connected output waveform, and realize the independent control of the output power.