Effect of Damper Winding and Stator Slot Skewing Structure on No-Load Voltage Waveform Distortion and Damper Bar Heat in Large Tubular Hydro Generator

We study the influence of the damper bar pitch, the stator slot skewing degree, and the damper bar number per pole on the no-load voltage waveform harmonic distortion factor (HDF) and the damper winding heat of a tubular hydro generator. We implemented 288 different design schemes using a 36-MW fractional-slot tubular hydro generator. The following influence factors were investigated: continuous variation, variation range, variation step, and higher-order harmonics of no-load voltage. Thus, the relation among these structure parameters and the HDF, the losses, and the highest temperature of the damper bars is revealed. In addition, the calculated models and results are validated directly by test data, and measures are proposed for their improvement. The present research not only corrected the errors in the related papers we published before, but also provides guidelines for optimizing the no-load voltage waveform and decreases the damper bar losses and heat, as well as a more comprehensive, accurate, and effective reference for improving tubular hydro generator design and manufacture.