Modelling and control of variable‐speed multi‐pole permanent magnet synchronous generator wind turbine

TLDR

Variable‑speed pitch‑controlled wind turbines with multi‑pole permanent magnet synchronous generators and extremely soft drive‑train shafts are the focus, but such generators lack inherent damping and can become unstable without external damping. The study designs a frequency converter to actively damp drive‑train oscillations and to independently control active and reactive power, thereby assisting the power system and ensuring stable turbine operation. A full back‑to‑back converter wind turbine model is presented, comprising aerodynamic rotor, two‑mass drive‑train, permanent magnet generator, and converter system submodels, and a control strategy is developed to manage turbine and converter functions. Simulations in DIgSILENT demonstrate that the proposed model and control strategy achieve stable operation under normal conditions. © 2008 John Wiley & Sons, Ltd.

Abstract

Abstract Emphasis of this article is on variable‐speed pitch‐controlled wind turbines with multi‐pole permanent magnet synchronous generator (PMSG) and on their extremely soft drive‐train shafts. A model and a control strategy for a full back‐to‐back converter wind turbine with multi‐pole PMSG are described. The model comprises submodels of the aerodynamic rotor, the drive‐train by a two‐mass model, the permanent magnet generator and the full‐scale converter system. The control strategy, which embraces both the wind turbine control itself and the control of the full‐scale converter, has tasks to control independently the active and reactive powers, to assist the power system and to ensure a stable normal operation of the wind turbine itself. A multi‐pole PMSG connected to the grid through a full‐scale converter has no inherent damping, and therefore, such configuration can become practically unstable, if no damping by means of external measures is applied. In this work, the frequency converter is designed to damp actively the drive‐train oscillations, thus ensuring stable operation. The dynamic performance of the presented model and control strategy is assessed and emphasized in normal operation conditions by means of simulations in the power system simulation tool DIgSILENT. Copyright © 2008 John Wiley & Sons, Ltd.