A New Study of Direct-Driven Wind Energy Conversion System under Variable Wind Speed

The direct drive wind turbine systems (without gearboxes) paid attention in recent studies for wind energy field, because several independent researchers have found that malfunctioning of the multiplier is the principal cause of downtime, and without gearboxes, the noise levels are reduced. Actually, solely the permanent magnet synchronous generators and the electrically excited synchronous generator are used in the direct drive wind turbine technology to produce electrical energy. This paper presents a novel study of a direct drive vertical axis wind turbine based on doubly fed induction generator (DFIG), where, the topology stator is connected directly to the grid while the rotor is connected to grid with back to back converters. The study includes the sizing, modeling, and control of the proposed system. The vectorial control of active/reactive power injected to the grid is selected. A variable wind speed is used to test the complete system; simulations are effectuated in Matlab/ Simulink. The results illustrate the operating efficiency of a DFIG in dire ct drive vertical axis wind turbine systems, and the better performance of the vectorial control in stator powers tracking.