Multi-objective optimization for simultaneously designing active control of tower vibrations and power control in wind turbines

Abstract

For wind turbines operating in the full load region, stabilizing the generated power at its nominal value is a key objective. Furthermore, the control of tower vibrations is a major constraint in wind turbine structures because diverse loading sources can induce fatigue damage. These goals are often conflicting, and a trade-off solution must be found. To reduce tower vibrations, an additional damping method can be implemented by ensuring coordination between the pitch and torque control scheme. This study proposes a control scheme that balances these two objectives: power generation and tower vibration reduction. The control design is based on a collective pitch combined with two active tower damping controls: one for frontal oscillations to the wind, which generates an extra pitch component, and another for lateral displacements, which produces an additional component of the generator torque. The control parameters are tuned through multi-objective optimization and multi-criteria decision methods with FAST software along with MATLAB/Simulink. The proposed control scheme was simulated according to the extreme wind direction change in the IEC 61400–1 standard. The results show that the proposed procedure achieves a notable reduction in tower vibrations, whereas the generated power is almost unaffected. To support this conclusion, a set of performance indices and the time and frequency responses are analyzed from the simulations Comparisons with other control schemes illustrate the superior performance of the proposed methodology.