Influence Of Damper Winding Number On Reactance And Additon Loss And Temperature Field Of Hydraulic Generator

The damper winding is one of the most important influencing factors of motor start and steady operation in larger hydraulic generator. The damper windings will produce reverse torque to stop the swing of speed in the rotor, when the speed has fluctuated changes in the generator. On the asymmetric operation conditions, the damping windings decrease the electromagnetic torque result from negative sequence rotating magnetic field, the vibration and noise are also reduced accordingly. Therefore, the choice of the number of the damping bars become a important part of research about dynamic-state operation of the generator. In addition, the different numbers of the damping bars, the direct axis synchronous reactance, quadrature axis synchronous reactance, steady state parameters, voltage regulation rate and the regulate of active power and reactive power in the parallel running of the power grid would all have a direct impact. On the steady state of the generator, as the number of the damping bars changes, the additional losses also have some changes. In addition, the influence of damping bar number on generator temperature distribution is studied, which would have a certain significance.In this paper the hydraulic generator in Wuqiangxi power station was taken as an example. According to electromagnetic theory, solved region and mathematical model were given. The Electromagnetic Field of hydraulic generator operating with rated load is analyzed, and the constructions of hydraulic generator with 6 and 8 damping bars in the pole head are comparative studied. Base on the electromagnetic field of hydraulic generator, direct axis synchronous reactance, quadrature axis synchronous reactance and transient reactance of the constructions in steady state is calculated, and the solution is compared to the experimental value. Besides, the additional losses of the structures in load and no-load situation was calculated, in consideration of eddy-current loss in the damping bars the loss distribution is calculated. In the case of loss is calculated, the 3D temperature field is calculated, and some useful conclusions were achieved.