Study Of Ventilation Cooling System Improvement In Hydro-generator Rotor

The cooling methods affect performance and economic indicators of hydro-generator directly. In particular, the loss of large capacity generator also increaseswith the capacity increasing significantly. Therefore, the strengthening of themotor cooling, taking away the heat generated by a variety of loss effectively,and reducing temperature of the generator parts are the main factors to beconsidered in design and manufacture of large-capacity hydro-generator.A250MW air-cooling hydro-generator is taken as an example in this paper.The calculated area of rotor coupling field is determined according to specialventilation and structure, physical model is established under the circumstancesfor the rotating rotor. Given the basic assumptions and boundary conditions tocalculate and analyze the problems of ventilation and heating using the finitevolume element method. Then the temperature of rotor and the distribution of thefluid velocity in the support, yoke ducts, pole gap and air-gap are got. The trendof fluid along axial, radial and circumferential is analyzed, and the surfacethermal coefficients of excitation winding are compared. Comparing thecalculated value of the excitation winding average temperature with the measuredvalue which proves this method is a practicable solution.The further improvements of the ventilation and cooling system structure areresearched according to the distribution of fluid and temperature: the influence offluid flow shape to cooling performance of excitation windings, and the changeregularity of the vortex under different inlet flow situations between two poleswere analyzed. Additionally, a windshield structure was added between twopoles in order to reduce the inhibition effect of vortices to rotor cooling. Aftercalculation, it can be proved that the windshield structure could reduce theinhibition effect. So the high temperature rise of excitation windings could becontrolled effectively, and the operation reliability of the large hydro-generator rotor is improved; the schemes of different sizes are calculated, and the influenceof structure sizes of magnetic pole pallets, insulation and excitation winding isanalyzed for the distributions of fluid and temperature. The conclusions ofreference value for large hydro-generator structure optimization design.