A study on frequency adjustment mechanism for wind turbine generation systems

Wind turbine generation systems (WTs) normally do not have mechanisms to control their output, so that the growth in WT penetration has brought difficulty in the frequency control operation of power grids. This paper presents a frequency adjustment mechanism for the WTs consisting of the following controllers: an active power controller, a governor controller, a pseudo synchronization controller and a pitch angle controller. The governor and the synchronization controllers calculate a correction value to make variability of the WT output in response to its share of power generation. Besides, the pitch angle controller is customized from a viewpoint of relaxing restraint in the frequency adjustment mechanism. By these controllers, the proposed mechanism supplies the frequency adjustability to the power grid in consideration of the actual WT output while effectively suppressing the rapid change of rotor angular speed. Through numerical simulations and discussions on their results, validity of the authors’ proposal is verified.