Analysis of interpolar air motion coherence and heat transfer under different asymmetric rotor yoke ventilation duct structures of the pumped storage power machine

Abstract

Large-capacity per pole and high current density in the rotor lead to the high heat load per unit volume of the excitation winding. In order to improve cooling efficiency on the heat exchange surface and the axial uniformity of the rotor excitation winding temperature, the asymmetric yoke ventilation duct structures with four different widths are proposed along both sides of the pole axis. However, the structure of yoke ventilation duct with different width not only affect motion coherence of interpolar air at different axial positions, but also produce two adjacent interpolar air motion difference. Consequently, it is essential to study the flow rate distribution, motion law and motion difference of interpolar air for the accurate temperature field analysis of the rotor excitation winding. Taking a Xiangshuijian pumped storage machine with rated capacity of 277.8MVA (generator condition)/ 286.4MVA (motor condition) and rated speed of 250 rpm as an example, based on the multiple frames of reference model, the fluid-structure coupling analysis is performed in the solution domain by the finite volume method. The obtained numerical results of excitation winding average temperature are validated using the temperature measured data under the operation conditions of rated power generation, 80% power generation and rated pumping.