Research On Fault Diagnosis Technology Of Stator Winding Of Permanent Magnet Synchronous Hydroelectric Generator

Permanent Magnet Synchronous Hydroelectric Generator(PMSHG),as a key service equipment in hydroelectric power generation system,is of practical significance to ensure its safe,reliable,stable and efficient operation.In this paper,we mainly focus on stator winding fault diagnosis of permanent magnet synchronous hydroelectric generator.By designing the PMSHG vector control strategy under the variable step climbing search method,a simulation environment of the actual operating conditions of the PMSHG is provided for fault diagnosis.Fault modeling of motors is a prior condition for fault diagnosis,and an accurate and error-free fault model can effectively characterize the fault information.Finite element modeling can better simulate motor faults,but the computational process is complicated and requires long computing time,which is not convenient for the iterative analysis of fault diagnosis algorithms.In this paper,we design a specific modeling method for different fault types of stator winding from the fault mechanism,which greatly reduces the operation consumption and can effectively characterize the fault information,which is beneficial to the research and analysis of PMSHG fault diagnosis algorithm.For stator winding open-circuit fault,a fault topology for permanent magnet synchronous hydroelectric generator has been constructed that allows flexible switching between normal and fault states,making it easy to observe the operational differences of PMSHG before and after the fault.A positive and negative sequence current fault diagnosis method based on rotating coordinates is proposed,which uses the structural asymmetry of the motor caused by open-circuit fault and then sets up a fault indicator containing positive and negative sequence component parameters to achieve fault diagnosis.The algorithm has low dependence on the number of data samples and high diagnostic accuracy,and is suitable for rapid diagnosis.At the same time,no additional sensor equipment is required,further reducing the cost of fault diagnosis.Simulation results verify the advantages of the method.For the interturn short-circuit fault,a mathematical model of the interturn short-circuit fault of the PMSHG in the stationary three-phase coordinate axis system is developed using the multi-loop analysis method.The mathematical model of the motor is extended from the normal state to a fourth-order matrix system to obtain the state equation containing the fault part as well as the normal part components.A fault diagnosis method based on an extended state observer is proposed,in which the faulty part is observed as a fully equivalent disturbance component,the fault characteristics are extracted using a frequency tracking algorithm,and the motor is determined to have an interturn shortcircuit fault when the fault characteristics are greater than a threshold value by setting a suitable threshold value.The algorithm is sensitive to the change of speed as well as interturn short-circuit ratio of PMSHG.Finally,a Modbus communication-based upper computer control program is designed using LabVIEW,and the fault diagnosis algorithm is implanted in the background to complete the state monitoring of the PMSHG.The experimental results verify the effectiveness of the fault motor modeling strategy and the feasibility of the diagnosis algorithm proposed in this paper.