Research Of Eccentricity And Short Circuit Faults On Magnetic Field And Electromagnetic Vibration Characteristics Of Synchronous Generator

Synchronous generator plays an important role in the industrial production.In recent years,along with the increase of the unit capacity of generator and the complexity of structure design,more stringent requirements are put forward.Serious economic losses will happen in the event of failure.In this paper,in order to improve the fault diagnosis technology of synchronous,magnetic field,radial electromagnetic force and electromagnetic vibration under eccentric and winding short-circuit fault are researched.And the corresponding characteristics under different faults are also be studied.In order to study the rotor eccentricity fault,the short circuit fault and the composite fault,magnetic field,electromagnetic force and vibration of a 6MW synchronous generator are calculated.The traditional calculation method based on the equivalent networks is invalid in the case of the inner asymmetric magnetic field which caused by eccentricity fault and short circuit fault.For this purpose,the finite element model of the generator is established and the transient calculation for magnetic field of different faults are finished.The variation characteristics of air-gap magnetic field in different fault types are analyzed based on the results of transient magnetic fields.According to the changes of magnetic field before and after faults,a method of detect exciting winding short circuit position has been proposed.The exciting currents of stator winding short-circuit fault and asymmetric load operation also be calculated,and through comparing the excitation current of each frequency component,the two kinds of different situations have been distinguished.Based on the results of magnetic field,the radial electromagnetic force of generator are calculated by the Maxwell equations.Meanwhile,the change of electromagnetic force affected by corresponding fault parameters is studied in different operating conditions,and the results of electromagnetic force between analytic computation method and finite element method were compared.Electromagnetic forces close to the inner diameter of the stator are taken as loadcondition,curves of vibration displacement of the generator are obtained according to the three-dimensional model of the generator.The influences of different faults are analyzed qualitatively by comparing the curves of rated condition with that of faults.And the radial vibration signal of generators can be used to detected air-gap eccentricity and winding faults.