PV Module Modeling and Maximum Power Point Tracking Based on Asymmetric Fuzzy Control

Abstract

In this paper, a parameter estimation method for the single diode model of photovoltaic (PV) module is proposed, and the simulation model of PV module is established. Based on the analysis of the PV module output characteristics under different temperature and irradiance, the monotonic decreasing characteristics of the output power derivative with regard to the output voltage is obtained, and the slope of this function is completely different at both sides of the maximum power point (MPP). Finally, according to those features, the asymmetric fuzzy controller of PV module for maximum power point tracking (MPPT) is designed. The main advantage of the proposed MPPT, compared with MPPT based on symmetric fuzzy control (SFC),is faster, slightly higher efficiency and smaller oscillation. 1 INSTRUCTION The sun radiates an enormous amount of power, out of which approximately is 1.8*10 MW intercepted by Earth. This is several thousand times the present energy consumption of the entire world [Sachin Jain, 2007]. At the same time, the solar energy is clean and renewable. So, the research about the utilization of energy is one of the most popular fields. The main utilization of energy includes light-heat conversion and photoelectric conversion in two ways, of which the photoelectric conversion is more commonly used. PV cell is an energy conversion device that transfers light energy into electrical energy. Single PV cell is the minimum unit which constitute PV module. The Current-Voltage (I -U) characteristics curves of PV module are different and nonlinear under different irradiance and temperature. The MPP of the PV module changes accordingly. PV module has to work at MPP to improve its efficiency, therefore, MPPT is necessary for PV generation system. 2 MODEL OF PV MODULE AND ITS OUTPUT CHARACTERISTICS 2.1 Parameters evaluations of PV Module The model of PV module contains the double-diode model and the single-diode model [Xiao Weidong, 2004]. It is more difficult to determine the 6 parameters in the double-diode model than the 5 parameters in the single-diode model, but the double-diode model does not improve accuracy significantly [Gao Xiankun, 2014]. Figure 1. is the equivalent circuit of single-diode model. The mathematical model is given by