WIND TURBINE MASS AND AERODYNAMIC IMBALANCES DETERMINATION

This paper evaluates the use of simulations to investigate wind turbine mass and aerodynamic imbalances. Faults caused by mass and aerodynamic imbalances constitute a significant portion of all faults in wind turbine. The aerodynamic imbalances effects such as deviations between the three blades pitch angle are often underrated and misunderstood. In practice, for many wind energy converters the blade adjustment is found to be sub-optimal. The dynamics of a model wind turbine was simulated in three different scenarios that are normal operating conditions, blade imbalance, and aerodynamic imbalance. Blade element momentum method was used to determine the effects of blade deviations. The blade imbalance was simulated by scaling the mass density of one blade, which creates an uneven distribution of mass with respect to the rotor. The results showed that an aerodynamic imbalance fault varies with rotor speed and wind velocity. They also reveal the extent of energy loss and additional loads. These conclude that, unlike mass imbalance, aerodynamic imbalance can’t be eliminated by counterweights. The balancing of the rotor requires a method to determine its imbalances. This paper proposes also a methodical system for the reconstruction of two types of imbalances that are, mass and aerodynamic imbalances from pitch angle deviation. The methodical system with simple finite element will be based on the inversion of the (nonlinear) operator equation that links the imbalance distribution of the rotor to its vibrations during operation of the wind turbine. This methodical system will enable to eliminating aerodynamic imbalances which leads to a maximized life time of blades, drive train, main frame and tower.