Research On Fault Diagnosis Of Loss Of Excitation In Asynchronized High-voltage Generator

The tendency of generators in power system operations to lose one part or all of the excitation suddenly will have a huge impact on the stability of the generator and power grid.An asynchronized high-voltage generator is a new type of generator that combines the traits of the asynchronized synchronous with extra-high-voltage generator.Because its operating characteristics are different from those of conventional synchronous generators,it is extremely necessary to investigate the influence of loss of excitation and fault diagnosis.A finite element model of the asynchronized high-voltage generator considering the field-circuit-movement coupling is established in this paper.This model is used to analyze the operation state of asynchronized high-voltage generator after loss of excitation and the process of loss of excitation fault of asynchronized high-voltage generator under different slip rates and loads.The relationship between slip rate and active load before loss of excitation and the relationship between the maximum increase multiple of the stator current after short-circuit loss of excitation and the slip rate before loss of excitation fault are explored.It is concluded that the proportion of the active load of the generator before loss of excitation is closely related to the slip rate in the stable asynchronous operation state after loss of excitation,the greater the absolute value of slip rate before loss of excitation,the greater maximum maximum increase multiple of the stator current.The stator current of the generator also increases after short-circuit fault on the stator side.In order to accurately diagnose the loss of excitaion fault and exclude other faults,the open-circuit loss of excitaion fault and short-circuit fault on the stator side are simulated.The loss of excitaion fault diagnosis system based on wavelet packet analysis and BP neural network is established and the logical unit is introduced.It is proved that this system can eliminate the interference of short-circuit fault on the stator side and determine the type of loss of excitaion fault accurately.This fault diagnosis system provides a powerful basis for the operation and loss of excitaion protection in asynchronized high-voltage generator.