Hydropower generation is clean, pollution-free, and renewable, and has good social and economic benefits, so it is given priority for development throughout the world. The capacity of hydropower stations is increasing to 1000 MW from 700 MW. As the p value on the bearing reaches a new height, coupled with the original risk of easy damage, the thrust bearing faces new technical challenges. Maglev technology is studied and applied to a large vertical-shaft hydro-generator set to solve the bearing problem. The maglev device is designed, and the working principle is expounded, using active-control repulsive-suspension technology. The levitation-force addition and the torque cancellation are realized by controlling the frequency of the excitation power supply. The dynamic mathematical models of levitation force and torque are derived. Combined with the design and theoretical analysis, the vector-control strategy is developed and the simulation analysis is completed. According to the results, the controller is improved to enhance the response performance. Finally, a control experiment is carried out on the prototype, and the results verify the effectiveness of the design and control strategy.
An asymmetric-primary axial-flux hybrid-excitation generator (APAFHG) has already been proposed to improve the starting performance of vertical axis wind turbines. However, the double-stator single-rotor structure causes a problem: different torque proportions create different rotor maglev forces, which will cause fluctuation and negatively impact the rotor bearing and even the operation of the wind power generation system. Therefore, a mathematical model considering the double-stator single-rotor structure and a proportional integral-based torque control strategy considering double-stator distribution are proposed in this paper to help APAFHG offer a good starting performance in vertical-axis wind power generation system and to stabilize maglev force generated by double-stator quadrature axis current simultaneously. Finally, the cooperation control of the maglev force and torque distribution is realized in MATLAB/Simulink, and the rotor maglev force will be relatively stable despite mechanical torque changes, which is a basis for the wind turbine to stably operate as the wind constantly fluctuates in vertical axis wind power system.
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