Analyse und aktive Dämpfung von durch Netzeinbruch verursachten Schwingungen am Antriebsstrang einer Windenergieanlage (WEA) mit DFIG

Abstract

Wind turbines with doubly fed induction generators (DFIG) are most popular in the wind branch since years. However, this kind of turbines exhibits a high sensibility to grid faults. Furthermore, oscillations will be induced and transferred to the drive train because of grid faults, which results in large loads to the mechanical components. Due to the coupling with the elastic rotor blades the oscillation frequencies will be changed and extra vibrations will be induced. This feature will be more strengthened with the application of longer and more elas-tic rotor blades. This paper studies the vibrations in the drive train of 5MW DFIG turbine through simulations. Two dominate frequencies of the torsional vibration can be extracted, which is the result of the interaction of flexible rotor b lades and the drive train. According to the frequencies and physical parameters the equivalent model of the drive train can be derived, with which the model-based active vibration damping can be developed. The active damper is designed with the LQG algorithm, which consists of a LQR controller and discrete Kalman Filter. With this concept the oscillations in the drive train, which in our case mainly induced by the grid fault, can be effectively suppressed by the generator control