Research On Controller For Photovoltaic Power System

Exploitation and utilization of solar energy is an effective way to deal with current energy crisis. As the consumption of coal, oil and nature gas, energy crisis has become a main problem that restricted the development of society. As a kind of new energy, solar energy is wide spread, non-pollution and it doesn't produce any waste. So it is a kind ideal clean energy. Nowadays, solar energy is internationally recognized as a kind of alternative energy.This paper is focused on controller in photovoltaic power system. Mathematical model of photovoltaic cell, maximum power point tracking methods and DC/DC converter are studied in this paper, the hardware and software of controller are designed. The main contents of this paper are as follows:The mathematical model and relevant parameter of photovoltaic cell are introduced. Simulations are performed in MATLAB/Simulink. The effect of illumination intensity and ambient temperature on photovoltaic cell is analyzed and output characteristics of photovoltaic cell under different condition are attained.Several commonly used maximum power point tracking methods are introduced. An improved perturbation and observation method is proposed based on perturbation and observation method. A step-adjusting factor is introduced to perturbation and observation method to make step-length can be adjusted automatically according to environmental change and the operating point will be stable at maximum power point. The algorithm is easy to realize and it has low demand in accuracy of sensor.Several kinds of DC/DC converter that commonly used in photovoltaic power system are introduced and the relationships between parameters are obtained. Simulation models of converter are built in MATLAB. According to the simulation result, Boost converter is used to track the maximum power point and Buck converter is used to charge the storage battery.The hardware and software of controller are designed. Maximum power point tracking and charging and discharging of storage battery are realized. The maximum power point tracking algorithm that could improve the efficiency of photovoltaic power system is realized by Boost converter.