Enhanced Active Power Control With Adjustable Range of Non-Pitch Regulation for Desired Reference Power Tracking in PMVG-Based WTS

Abstract

This study presents an enhanced active power control (APC) strategy to track the desired reference power in a permanent magnet vernier generator (PMVG)-based wind turbine system (WTS). In order to mitigate the frequent pitch actuation requirement in the traditional APC, a rotor speed variation control (RSVC)-integrated with non-pitch regulation is conventionally employed. However, the fixed perturbation range of non-pitch regulation during downward pitch adjustments in existing approaches reduces power extraction because of the sluggish speed tracking response caused by higher rotor inertia. Additionally, the speed variation range for RSVC is considerably reduced. To deal with this, this study firstly proposes a novel method to achieve an adjustable range of non-pitch regulation to enlarge the speed variation range and improve the power extraction through generator-stator electric power dependent pitch compensation signal. In addition, the conventional method for RSVC is replaced by a conditional generator current reference setting according to the WTS operating regime. Next, a modified control strategy is proposed considering generator and turbine losses to improve the reference power tracking response. Finally, the superiority of the proposed control method is verified through the simulation of a 15-MW NREL WTS, its practical applicability is demonstrated through 5-kW experimental prototype with PMVGs.