Numerical Calculation Of Electromagnetic Field And Temperature Field For 1000MW Fully Air-cooled Hydro-generators

Owning to high efficiency, simple structure, the convenience of installation, operation and maintenance, the fully air-cooled hydro-generator is applied more and more in the electrical power system. However, the temperature distributions in some assembly of the fully air-cooled hydro-generator are not uniform, and the issues of the thermal stress and thermal deformation are always serious. With the increasing of the unit capacity of the hydro-generator, the electromagnetic load and thermal load are increasing at the same time, the temperature distribution and thermal rise become more serious, and the service life and operation reliability will be directly impacted by them. Therefore, quantitative calculation and deep research on heating and cooling issues for the fully air-cooled hydro-generator are becoming increasingly important.Firstly, a 1000MW fully air-cooled hydro-generator, which unit capacity is the largest in the world now, is taken as an example in this paper, and its 2D FEM model is built. The excitation source in stator and rotor winding under none-load, rated load and leading-phase (full active load, power-factor 0.95) operation conditions is gotten through saturated and end-point condition iteration to 2D magnetic field. Then , the field-circuit-motion coupled time-stepping finite element model of the line-segment of the hydro-generator under one pair of pole is established. The distributions of the hydro-generator stator losses under the three operation conditions are accurately calculated.Secondly, according to the theories of the computational fluid dynamics and computational heat transfer, the 3D model of the stator radial ventilation ducts of the hydro-generator is established, ventilation channel steel and stator windings included. Moreover, the distributions of time-average losses from the electromagnetic field calculation are taken as heat source density, the boundary conditions of 3D fluid-heat transfer coupled field are given, and the fluid-solid interface is dealt with the prism layer meshing method, and then the fluid velocity distributions inside the stator radial ventilation ducts and the temperature distributions in the stator structures are calculated and analyzed in detail by fluid-heat transfer coupled field directly solution method.Finally, the 3D field-circuit-motion time-stepping finite element model of hydro-generator end is built. The distributions of eddy current losses in the end structures under three operation conditions are calculated. On this basis, the effects of the end structure parameters on the eddy current losses are analyzed.The research results provide theory references for design and optimization of the huge fully air-cooled hydro-generator.