engleski

Fault-tolerant Control of a Wind Turbine subject to Generator Electromechanical Faults

A fault-tolerant control methodology that adapts the wind turbine generator operation to reallocate the stress from damaged rotor or stator parts to healthy generator area while achieving the safe operation and extracting the maximum available power in the faulty state is proposed in the thesis. To this aim, generator stator flux or torque building current are modulated based on the instantaneous rotor flux position to suppress the rapid development of some of the most common generator electromechanical faults. The methodology is suitable for all of the wind turbine generator types: squirrel-cage and doubly-fed induction generators, as well as permanent magnet and wound-rotor synchronous generator. Wide range of operation and fault conditions are covered with the methodology: from early stage of fault development to broken rotor cage or inter-turn short circuit. The methods are conceived as modular extensions to the conventional wind turbine control system and can be applied to new or already installed wind turbines. Both empirical machine understanding and optimal control methods are used to contribute to the simplicity and theoretical profoundness of the methodology. Common machine control approaches are improved with more sophisticated and robust estimation algorithms. Parameter identification and compensation of non-fundamental wave anisotropic machine characteristics are utilised for more accurate rotor flux position assessment and controller adaptation to gain smoother generator torque in normal or faulty operation. Extensive simulations are performed for validation of the proposed methodology with detailed verifications of its known possible negative side effects using proven and certified tools. In addition, scaled experimental set up is used to back theoretical considerations and validate the methodology robustness.

wind turbine generator control; generator electromechanical faults; faulttolerant control; model predictive generator control; Kalman filter; generator anisotropy compensation; squirrel-cage induction generator; doubly-fed induction generator; permanent magnet synchronous generator; wound-rotor synchronous generator

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