Control of Stand-Alone Hybrid Wind-Photovoltaic Energy System Using Fuzzy Logic ☆

Standalone hybrid wind-photovoltaic system performance is strongly dependent on the DC bus voltage and the ability to reach the point of maximum power under the variation of weather condition and load consumption. In the paper, the proportional-integral controller and bidirectional DC/DC converter are used to keep DC bus voltage in constant value. To obtain the maximum power from wind turbine and solar panel, a proposed method to find the point of maximum power combining fuzzy logic and perturb and observe method is introduced, in which a maximum power point tracking fuzzy logic controller with only one input is designed to obtain the maximum power from solar panel. The advantages of the MPPT fuzzy logic controller with one input are its simple structure, reducing the complexity in the steps of fuzzification, building fuzzy rules, and defuzzification compared to the maximum power point tracking fuzzy logic with two inputs. In order to avoid the over-charge and over-discharge of lithium-ion battery, a fuzzy logic supervisor is used. The simulation results in Matlab/Simulink software are presented to show the good performances of the proposed controllers in the standalone hybrid wind-photovoltaic system.