Output power smoothing of variable speed wind farms using rotor-inertia

•In this paper, the conventional vector control of the generator is replaced with a fuzzy PID controller.•The optimal power point of the wind turbine is tracked in such a way that the output power is smoothed.•The scheme enables the wind farm to produce a constant power.•In this paper, the rotor-inertia of turbines is used as an energy storage systems.

Due to variations of wind speed, the output power of small-scaled or mid-scaled wind farms is fluctuating and this may negatively impact the power system. This paper proposes a new fuzzy PID controller scheme for a variable speed wind farm. In this scheme, by using the rotor-inertia as an energy storage system, two purposes are satisfied. Firstly, the optimal power point of each turbine is tracked in such a way that the total output power of the wind farm is also smoothed. Secondly, the proposed scheme enables the wind farm to produce a predetermined output power. To show the performance of the proposed scheme, a doubly fed induction generator (DFIG) based wind farm is simulated and the results are compared with conventional scheme. Also, the tracking capability of the pre-scheduled output power is verified.