Effects of POD control on a DFIG wind turbine structural system

This paper investigates the effects power oscillation damping (POD) controller could have on a wind turbine structural system. Most of the published work in this area has been done using relatively simple aerodynamic and structural models of a wind turbine which cannot be used to investigate the detailed interactions between electrical and mechanical components of the wind turbine. Therefore, a detailed model that combines electrical, structural and aerodynamic characteristics of a grid-connected Doubly Fed Induction Generator (DFIG) based wind turbine has been developed by adapting the NREL (National Renewable Energy Laboratory) 5MW wind turbine model within FAST (Fatigue, Aerodynamics, Structures, and Turbulence) code. This detailed model is used to evaluate the effects of POD controller on the wind turbine system. The results appear to indicate that the effects of POD control on the WT structural system are comparable or less significant as those caused by wind speed variations. Furthermore, the results also reveal that the effects of a transient three-phase short circuit fault on the WT structural system are much larger than those caused by the POD controller

Electromechanical interactions of full scale converter wind turbine with power oscillation damping and inertia control

In this paper, the impacts of power oscillation damping (POD) and inertia controller on the structural system of wind turbine (WT) are evaluated. Synchronous generators (SGs) fitted with well-established power system stabilisers (PSS) are declining leading to reduced power system inertia and damping capability which are critical to system stability performance. The WTs will become more dominant and should therefore be capable of providing inertia response and POD to maintain system performance. However, there has been some concern amongst the industry regarding effects of inertia and POD controls on WT performance when the active power modulation is utilised by both controllers particularly during frequency event that leads to low-frequency power oscillations. A detailed grid-connected full-scale converter (FSC)-WT system which combines aerodynamic, electrical, and mechanical characteristics was developed to assess its interactions with the POD and inertia controllers and also the resulting impact on the WT structural system. The obtained results show that the implementation of the POD/inertia controllers on the FSC-WT can improve the inertia response and oscillation damping but will affect the dynamics of its drivetrain, blades, and tower. However, these effects are shown to be smaller than the effects caused by the credible electricity system faults