No-Load Voltage Waveform Optimization and Damper Bars Heat Reduction of Tubular Hydrogenerator by Different Degree of Adjusting Damper Bar Pitch and Skewing Stator Slot

To analyze the influence of no-load voltage waveforms and damper bar losses and heat by the damper bar pitch and stator slot skew, finite-element model (FEM) computations are conducted. The calculation models are multislice moving electromagnetic field-circuit coupling model for the hydrogenerator and three-dimensional temperature field FEM for the rotor. This analysis considers the factors such as the rotor motion and the nonlinearity of time-varying electromagnetic field, the anisotropic heat conduction of the rotor core lamination, and the different heat dissipation conditions on the windward and the leeward sides of the poles. Then, the no-load voltage waveforms of a 36 MW tubular hydrogenerator are optimized and the damper bar heat at the rated load is reduced with the design scheme by adjusting the damper bar pitch and the stator slot skew. The results show that the waveforms of the no-load voltage are improved and the temperature of damper bars are reduced when reasonably increasing damper bar pitch and skewing stator slots. The calculated results are well coincident with the test data. The research is helpful for improving the design standard and enhancing the operation reliability of the large tubular hydrogenerator and electric network.