The Rotor Speed Control Of Wind Energy Conversion System Based On PMSG

In the rapid development of the energy industry, wind energy has received significantattention for the characteristic of large reserves and pollution-free. Direct-driven configurationwith permanent-magnet synchronous generator (PMSG) is an attractive choice for windenergy conversion systems (WECS) because of the gearbox elimination, no additionalexcitation equipment and low maintenance requirements. With the mature development of fullpower converter technology, the control strategies of WECS has changed from the traditionalmechanical control of wind turbine to the electric control of the generator, and the vectorcontrol strategy has been widely used in the direct-drive WECS based on PMSG.In the studies of the dynamic performance of the direct-drive WECS based on PMSG, atwo-mass model of the drive train is used in this paper. The stability of the system can beanalyzed through the eigenvalue based on the power signal feedback (PSF) control strategy.And it is implied that the drive train can cause oscillations which can make a pulsation to therotor speed when the wind speed varies. For the purpose of the stability of the system, amethod of adding the stiffness of the system is usually used to damp the oscillation. And it isusually realized by designing a digital notch filter which is hard to design. In this paper, thedynamic of the system is analyzed based on the math model of WECS based on PMSG and thevector control theory. A control strategy based on MPTA is proposed to reduce the pulsationof the generator speed when the wind speed varies. The speed of the generator can becontrolled by controlling the electromagnetic torque. Besides, it makes the system stable andeliminates the pulsation of the generator speed. At last, a simulation is made based onMatlab/Simulink. Firstly, the system can be controlled when the wind speed is constant.Secondly, the control strategy is effective when the wind speed is varying and it is implied inthe simulation diagrams that the pulsation of the generator speed can be eliminated effectively,which reduces the mechanical fatigue and increases the lifetime of the system.