多路并网光伏发电系统的仿真与分析

Simulations and Analysis on a Multi-branch Grid-connected Photovoltaic System

对一种多路并网光伏发电系统进行了细化研究,该系统中所有光伏阵列各自通过一个Boost DC/DC电路和同一个逆变器并联,然后实现并网。先讨论了各主要元件的参数选取方法,并确定了控制策略。前级Boost斩波电路通过调节占空比改变光伏阵列的输出电压,实现最大功率点跟踪;后级逆变电路采用电压外环,电流内环的双环控制方法,电压外环控制逆变器直流侧电容电压的稳定并给出内环电流参考值的幅值,电流内环控制逆变器输出电流为参考值以实现并网,各路光伏阵列的最大功率点跟踪相互独立,互不干扰,提高了效率。最后用Matlab/Simulink进行了仿真,验证其有效性。

This paper gives a detailed research on a multi-branch grid-connected photovoltaic PV system. In the system, the connection of all PV arrays in paralled with a unique inverter through respective Boost DC/DC choppers to connect to the grid. The components parameters design and the control strategy is presented in this paper. The forestage Boost chopper changes the output voltage of the PV array by adjusting the duty cycle to realize the maximum power point tracking（MPPT）. The controller for the inverter contains inner current loop and external voltage loop. The external loop stabilizes the voltage of the dc-link capacitor for the inverter and provides the magnitude of the reference current for the inner loop, while the inner loop controls the output current of the inverter to track reference current and meet the requirements for grid connected. The MPPT of each PV array is independent one another, which leads to higher efficiency. Simulations by Matlab/Simulink and the corresponding analysis are carried out . The results confirm the effectiveness of the photovoltaic system.