Maximum power point tracking method and device, and photovoltaic power generation system

摘要

A maximum power point tracking method, device and a photovoltaic power generation system. The maximum power point tracking method involves sampling a present voltage and a present current of a photovoltaic array and obtaining a present power based on the present voltage and the present current. The maximum power point tracking using a difference between the present power and a power for a previous sampling time as a present perturbation power, and based on a ratio of the present perturbation power to a perturbation power for a previous sampling time obtain a gradient perturbation voltage step ratio. Further, the maximum power point tracking obtains a perturbation voltage step based on the gradient perturbation voltage step ratio and the voltage difference between the present voltage and the voltage for the previous sampling time, and control an output voltage based on the perturbation voltage step.

主权项

1. A maximum power point tracking method, for enabling a photovoltaic array to operate at maximum power point, comprising:
step a: sampling a present voltage and a present current of the photovoltaic array; step b: obtaining a present power based on the present voltage and the present current sampled at a present sampling time; step c: using a difference between the present power and a power for a previous sampling time as a present perturbation power, and obtaining a present gradient perturbation voltage step ratio based on a ratio of the present perturbation power to a perturbation power for a previous sampling time, wherein the power for the previous sampling time is obtained based on a voltage for the previous sampling time and a current for the previous sampling time which are sampled at the previous sampling time, and the perturbation power for the previous sampling time is a difference between the power for the previous sampling time and a power for a sampling time immediately before the previous sampling time; step d: obtaining a perturbation voltage step based on the present gradient perturbation voltage step ratio and a voltage difference between the present voltage and the voltage for the previous sampling time; and step e: controlling an output voltage of the photovoltaic array based on the perturbation voltage step.