Analysis and calculation of electromagnetic force on damper windings for 1000MW hydro-generator

In the actual operation of the hydro-generator, the damper system is one of the key points on which the fault mostly happened. The problems such as damper winding vibration and fracture caused by electromagnetic force often occur. Due to the relative movement between magnetic field produced by harmonic and negative sequence currents and damper windings, the electromagnetic force acting on damper windings is more obvious, therefore, it is very necessary to quantitatively calculate the electromagnetic force on damper windings with harmonic and native sequence currents considered. In this paper, the 1000 MW hydro-generator was taken as an example, and the 2D electromagnetic field-circuit-motion coupled time-stepping element method mathematical model of the hydro-generator was established, using the independent coordinate system subdivision method, which can fully consider the slot effect, saturation effect, etc. The calculation results indicate that the value and distribution of electromagnetic force on damper windings are much different between rated load operating and negative sequence operating condition, the connection feature of the damper windings and magnetic slot wedge both have influence on electromagnetic force on damper windings. So these factors had been taken into account in this hydro-generator model. The conclusions in this paper can provide theory reference for large capacity hydro-generator design.