A Constant-bandwidth MPPT Strategy for Variable-speed WECS

The implementation of maximum power point tracking(MPPT) control to variable-speed wind turbines below the rated wind velocity helps the turbines to improve its efficiency,thereby to increase its annual power generation.Nowadays,the most commonly used MPPT strategy is the so called power-signal-feedback(PSF) MPPT method.However,the study of this paper shows that the conventional PSF method has the drawbacks of low tracking bandwidth,which indicates low MPPT speed.And what’s worse,the tracking bandwidth will get narrow when the turbine is operating in low wind velocities.Thus,to overcome this drawback,a new MPPT method was proposed,where a power error feed forward branch was added to the conventional PSF method.The design details on how to realize the constant MPPT bandwidth was also given.The proposed MPPT method was verified by simulation and experimental results performed by a 1.2 kW variable-speed wind turbine.