Load mitigation and wind power maximization of a HESG-based wind conversion system

Abstract

This article discusses the control optimization of a hybrid generator-based wind conversion system (WCS). The optimization issues consider the maximization of the extracted wind power for the below-rated wind speeds and the load mitigation for high wind speeds. To do so, a DC/DC converter is used to realize the steady-state control of the generator's velocity through the adjustment of the excitation current, leading to maximization in the wind extracted power. As for the high wind speeds, a H∞ regulator implemented for the pitch control and a filter smoothing for the pitch angle reference are used to mitigate the load. Thanks to the implemented control strategy, the amplitude of the fluctuation of the bending moment was reduced by about 20% and the turbine torque vibration was reduced by 66% in comparison with other existing works from the literature conducted on the same wind turbine. The velocity controller is three times faster than the baseline controller and allows for increasing the wind extracted power by 6%. In this research, an integrated simulation platform, combining the electrical, mechanical, and aerodynamic aspects of a WCS, is set up. The space harmonics of the generator, the commutation effects of the power converters, the flexible coupling between the wind turbine's mechanical elements, and the aerodynamic interactions are taken into account. Finally, the control of the WCS in its full operating range is considered. The mechanical and aerodynamic data from the 1.5 MW WindPACT turbine available in the Fatigue, Aerodynamics, Structures, and Turbulence simulator are used for the simulations.