Research On Interal Electrical Faults Of Stator Winding Of Turbogenerator

As the basic equipment of electric energy production, synchronous generator play a very important role in safety and stability of the whole power system. With the rapid development of electric utility industry and the increasing capacity of generator, increasing reliability for safe operation of generator is required. Internal faults in stator windings are the common electrical fault of a generator. Most of these faults are initiated from failure of monitoring the turn-to-turn short circuit in time. If the internal faults are developed without control, there will be disaster to the stator windings. Fault analysis and diagnosis have essential meaning in theory and practical value in engineering.In this thesis, the finite-element method (FEM) was used as the theory basis of electromagnetic field analysis of generator. Ansoft software is used as a tool for analysis and simulation. The finite element method is a powerful method to solve electromagnetic boundary value problems. In the current performance analysis of the motor and other fields on the electromagnetic field calculation, almost without exception, the finite element method or related methods of the numerical calculation were adopted. And the pre-processing of finite element method is a very key step for finite element analysis because it is related to the accuracy, computer efficiency and share resources. Based on Ansoft's Maxwell 2D software environment, the simulation turbogenerator model (The No.3 simulation generator in dynamic simulation laboratory of Hohai University) was established. Then the distributed condition of the electromagnetic field of generator in normal and fault status was calculated. The fault diagnosis for the generator was done by post-processing the simulation results.According to the analysis of the simulation results, in combination with the test data of No.3 simulation generator of dynamic simulation laboratory, the influence of the related electrical parameters of the generator which caused by internal faults of stator winding was analysed systematicly. The change of the electrical parameters such as three-phase stator current and field current in different load levels and different short turn was described, the fault laws was found.The characteristic of pulsation electromagnetic force which act on the stator windings of generator was obtained through the analysis of air-gap magnetic field variation characteristic after the internal fault was occured in the stator winding. Then, the vibration characteristic of stator winding was obtained. The theoretical analysis result was proved through actual measurement of the stator shell and winding vibration signal on the simulated generator when it had internal fault. Meanwhile, the realationship between fault mode and vibration signal was found through the spectrum analytical technology.