Research On Protection Of Electric Propulsion System Based On Fault Diagnosis Of Rectifier Generator

The rectifier generator plays a major role in the electric power source in the ship’s electric propulsion system.The safe and stable operation of the ship is directly affected by the reliability during the normal operation,the rapid diagnosis and the impact after the fault,and the protection after the fault.Therefore,the protection of the electric propulsion system based on the fault diagnosis of the rectifier generator has attracted the attention of scholars at home and abroad and has become the focus of research,which has certain practical engineering significance.This article has conducted in-depth research on the following aspects.First and foremost,the simulation models of the prime mover and its speed governing system,the 12-phase synchronous rectification generator and its excitation system,and the propulsion system are constructed by basing on the ring network structure of the ship electric propulsion system.Under different working conditions,the simulation operation of the single rectification power generation system and marine electric propulsion system are realized.The simulation results are correct and lay the foundation for the follow-up research.Next,the fault mechanism and characteristics of the rectifier short-circuit fault on the output side of the generator and the open-circuit fault of the rectifier component are deep studied.Aiming at the short-circuit fault on the output side of the generator,the expression of the short-circuit current on the output side under no-load operation is derived.Based on this,the simulation is verified.The open-circuit fault of the rectifier component is divided into five sub-class faults.The voltage of DC side and the phase current of AC side are simulated and compared.Through simulation analysis,the effects of the above two types of faults on the propulsion system are summarized.Then,for the rectifier short-circuit fault on the output side of the generator and the open-circuit fault of the rectifier component,wavelet analysis and BP neural network,as well as wavelet analysis and RBF network method are used to diagnose which category the fault belongs to.After that,the faulty diodes are effectively positioned using the 12-phase current of the AC side of the generator.In addition,a novel DC current-limiting circuit breaker is designed.The topology,working principle,control principle and parameter design are analyzed.The simulation models are built to verify the performance of the novel DC current-limiting circuit breaker.The marine electric propulsion system protection schemes are designed with the purpose of ensuring sustainable power supply to the load.The simulation verification protection schemes have certain feasibility.In the final analysis,with the requirements of real-time,fault diagnosis and protection,the real-time simulation platform for fault diagnosis and protection of marine electric propulsion system is completed by using SQL Server,LabVIEW,MATLAB and Veristand.The practicality of the real-time simulation platform is verified by examples.