No-Load Voltage Waveform Optimization and Rotor Heat Reduction of Tubular Hydro-Generator

Improvement of no-load voltage waveforms and reduce the temperature of rotor are important problems for optimizing quality requirement of electric power and ensuring the operation safety of generator and power system. A 15 MW tubular hydro-generator is proposed, the no-load voltage waveform of which is poor, heat of rotor is severe. The multi-slice moving electromagnetic field-circuit coupling model of the hydro-generator and 3D temperature field FE model of the rotor are built up, the no-load voltage waveform and rotor heat are analyzed. The original design and 2 different optimized design schemes are compared. The results show that, slot skew of stator can optimize the no-load voltage, however the temperature of rotor is reduced rarely. Besides the above measure, increase the damper bar pitch, airgap, diameter of damper bar, and decrease the damper bar assembling airgap, the no-load voltage waveform can be optimized, and minimize the loss and temperature of rotor parts, such as damper bars, iron core, and exciting windings. The research is helpful for improve the design standard and enhance the operation reliability of the large hydro-generator and electric network.