改进最优梯度法在光伏发电系统MPPT中的应用

Application of improved optimum gradient method in MPPT of PV system

在外部环境变化时,很难快速有效地对光伏发电系统最大功率点进行跟踪。传统最优梯度法在跟踪光伏发电系统最大功率点时响应速度慢且存在振荡问题,本文提出了一种结合模糊控制(Fuzzy logical control,FLC)和最优梯度法(Optimum gradient method,OGM)的光伏发电系统最大功率点跟踪(Maximum power point tracking,MPPT)方法。当系统功率距离最大功率点较远时,利用最优梯度法进行跟踪,当达到最大功率点附近时,利用模糊控制算法进行跟踪。仿真结果表明,所提出的改进方法可以有效地进行最大功率点跟踪,解决了最优梯度法在最大功率点处振荡的问题,跟踪速度提升了64%,在外界环境快速变化时也可有效地进行最大功率跟踪。

The maximum power point （MPP） of a photovoltaic system is difficult to track when the external environment changes. The response of the traditional optimum gradient method （OGM） is slow and there is vibration near the maximum power point. To solve such problem, an MPPT method is proposed based on the combination of fuzzy logical control and optimum gradient method, in which the optimum gradient method is adopted when the system power is away from the MPP, and the fuzzy logical control method is used for the condition that the system power is near the MPP. Simulation results show that the proposed MPPT can achieve better maximum power point tracking and solve the vibration problem of traditional optimum gradient method. The tracking speed of the proposed algorithm will increase 64%. Moreover, the tracking will be effectively when the external environment changes rapidly.