The Research Of The Unbalanced Electromagnetic Force Of Generator Under The Typical Faults

Despite the vigorous development of new energy, coal-fired power plants play an important role in power production in China. The research of the unbalanced electromagnetic force of typical faults in multiple loading conditions is of great significance to generator manufacturing and operation or maintenance of equipment. In addition, it is meaningful to research the forewarning device.Rotor eccentricity and stator winding inter-turn short circuit fault are the typical forms of generator faults. Both types can lead to magnetic field distortion in generator, and result in unbalanced electromagnetic force acting on the rotor. The type of SDF-9 generator is the research object of this paper. The structure model of the generator was established by means of the finite-element simulation tools Ansoft. The accuracy of the simulation model is verified by analyzing the spectrum of the stator winding inter-turn short circuit fault.In the paper, on the basis of the simulation model, the position and degree of the rotor eccentricity and winding inter turn short-circuit were set respectively. In order to pave the way for studying the unbalanced electromagnetic force under different loading conditions, the static magnetic field distribution was simulated. The formula of quantity and degree of unbalanced electromagnetic force was deduced in the paper, the article summarizes the change rules with rotor eccentricity and winding inter turn short-circuit. On the basis of this, this paper discusses the relationship of unbalanced electromagnetic force generated by the composite fault and the two kinds of single fault.Considering the fact that the operating conditions of the generator will be changed with the load and operation of the system, the paper studies the generator in grid-connected operation under different loading conditions. In order to simulate all kinds of operating conditions, no-load characteristic curve, which will provide basis for excitation current and armature current, was fitted by means of measured data. The paper calculates the unbalanced electromagnetic force and epitomizes the changing regularity with the fluctuation of active power and reactive power. At last, the paper proposed effective measures to restrain the unbalanced electromagnetic force.