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In this paper, a new control method is proposed for a multi-input inverter to track the maximum power point of hybrid photovoltaic (PV) and wind turbine generator (WTG) systems connected to a 380 V grid. This new control scheme has two main functions, namely, shifting the voltage of PV and WTG to the optimum condition and maintaining stability of the grid system. The proposed maximum power point method shifts the voltage of PV and WTG step-by-step until the delta voltage is close to zero, which indicates that the grid power is adequate. The delta voltage is the point at which the controller must stop shifting the voltage to maintain grid stability. From the simulation results, the power of a hybrid PV/WTG system using the proposed maximum power point tracking controller is the maximum, while the voltage and frequency of the grid system are kept constant, compared to that possible with the perturbation & observation method. [ABSTRACT FROM AUTHOR]

This paper described a hybrid system that combines micro hydro, wind turbines and fuel cells for remote and isolated areas. The system uses Fuzzy Logic Controllers for tracking the maximum power of wind generator and balancing the power demand using fuel cell. The proposed system provides voltage and frequency as satisfactory as grid quality. The maximum power tracker applied Fuzzy Logic with 3 inputs, e.g. the rotor speed, error and Δ error of rotor speed. The outputs of Fuzzy Logic are the id and iq for adjusting the generator speed control. The balancing of power is met by the electrolysis, which is controlled by dc-to-dc converter. The dc converter is driven by Fuzzy Logic. The simulation results indicate the proposed control system stabilizes the voltage at constantly 220 volt and frequency 49.8 to 50.5 Hz. under various load changes. The best maximum power tracked is 96.2 % when the wind speed is 10 m/s. [ABSTRACT FROM AUTHOR]