Research On Electromagnetic Field Of Rotor Winding Inter-turn Short Circuit In Generators

The rotor winding inter-turn short circuit is one of the common faults of generator, which has always been ignored as the influences to the normal running of unit is little and the early fault character is not apparent. If the fault generator is going on longtime running, the exciting current will be increased remarkably, the winding temperature is risen up, the reactive power output is decreased, the waveform distortion of the voltage happens, the abnormal unit vibration appears, and the other kinds of the electrical and mechanical fault happens. So it is necessary to research the fault mechanism, seek the early fault symptom, in order to achieve the early fault diagnosis of the rotor winding inter-turn short circuit fault.In this paper, the finite element method is used for the research of the rotor winding inter turn short circuits fault in generator, the physical model of the generator is established using the large-scale finite element analysis software ANSYS, and the magnetic field distribution is calculated when the inter-turn short circuit occur in the rotor winding in different locations under different degrees. Based on the electromagnetic field calculation results, the magnetic field characteristic and the air-gap flux density characteristic of the generator operated in different conditions is analyzed. Experimentally study on the field winding inter turn fault, the conclusions of the experiments agree with the theoretical calculation. Finally, the harmonic analysis of the air gap flux density of the generator operated in different conditions is carried out, which is based on flourier analysis in higher mathematics, and the harmonic feature of the rotor winding inter-turn short circuit fault has been concluded.