Research On The Twelve Phase Rectifier Power Generation System And Its Fault Diagnosis

Twelve phase rectifier generator system is used in ship and other fields because of its high quality power output,high efficiency and reliability.As the power source of the whole ship electric power system,the reliability of the normal operation and the timely processing of the fault have a direct impact on the operation state of the whole ship and the safety of life and property.In this paper,the topology structure of the power generation system is determined,that is,the twelve phase AC synchronous generator is connected to four groups of three-phase uncontrolled rectifier,and the four sets of rectifiers are connected in series with two sets of parallel forms,different from the traditional system of four groups of parallel rectifier.Under normal operating conditions,the mathematical model of the system was studied and the system simulation model was established.The model of synchronous generator is built based on dq0 coordinates with the method of decomposition of the stator and rotor.For the whole power system,the simulation analysis is carried out to simulate the no-load,sudden load and unload load,and the correctness of the model is verified.Secondly,for the power system based on the generator rotor dq0 coordinate system,by modifying the system simulation model,the fault simulation models of twelve phase AC synchronous generator under different external fault types are got,and the fault features are deeply studied.For the fault of rectifier side short circuit,the relationship expressions of AC and DC short circuit current in new topological structure is deduced and the correctness is verified by simulation.For the fault of the rectifying element,the characteristics of the rectifying element voltage and current in the normal,open circuit and short circuit three states are given,and the simulation analysis is carried out to obtain the fault characteristics.In the case of loss of magnetic fault for the generator,the simulation analysis is given.Furthermore,by decomposing stator and rotor,a simplified multi-loop mathematical model and simulation model in the twelve phase rectifier generator independently are established,meanwhile the twelve phase AC synchronous generator damping winding is equivalent to the DQ axis to achieve a simplified multi-loop model.The simulation and analysis of three kinds of generator stator inter-turn short circuit and stator branch open welding are carried out to obtain the waveform of the voltage and current under different faults,and the corresponding fault characteristics based on the Fourier analysis method is studied.Finally,two fault diagnosis methods,BP neural network and the loose wavelet neural network,are used to diagnose the fault of stator winding short circuit in generator.The sample input data of BP neural network is twelve phase current,and the sample input data of the loose type wavelet neural network is the DC side voltage signal.Diagnosis results show that both two methods can achieve correct fault recognition,but the applicability of the second methods is stronger.