Performance Analysis Of Large Induction Motor In Power Supply Fault Based On Field-circuit Coupling Method

In recent years,the economy is developing rapidly.Because of its advantages of large-scale production,long distance transmission and convenient use,electric energy has become the main energy for human production and life.As the main power production plant,the safe and economic operation of the thermal power plant is the fundamental to ensure the development of the national economy.As the main power equipment in the power plant,the failure of the motor will directly affect the normal operation of the power plant,and then affect the normal production of the power.Power plant electric low voltage bus suddenly short-circuit or open circuit fault,the bus voltage will change,access to the bus is not only in the motor running state of asymmetric and in transient process,the process is complex,not only affect the motor running,which will damage the motor and its driving device.Therefore,it is of great significance to simulate and analyze the operation of asynchronous motor with abnormal power supply.In this paper,a high voltage motor used in a power plant is taken as an example,First,the voltage of various short circuit faults in the low voltage busbar of the plant with the motor is calculated,It is concluded that the power supply voltage of the motor is asymmetrical three phase voltage when the fault occurs.Then,the mathematical model of the three-phase asynchronous motor is established,and based on the actual parameters of the high voltage and large capacity motor,the field circuit coupling model is established.In the no-load and load conditions,when the low voltage bus of large asynchronous motor connected transformer the occurrence of various short-circuit faults,respectively before and after each phase winding current,electromagnetic torque and motor fault of the motor running at steady state radial air gap magnetic flux density and the harmonic content are analyzed and simulated.The results of the comprehensive comparative analysis.Then the operation of the large asynchronous motor under the rated voltage of single-phase and two-phase break suddenly broken,with the simulation analysis of constant power loads respectively in the no-load and the motor windings of each phase current,electromagnetic torque and motor fault before and after the operation when the single-phase break curve of radial magnetic gap at steady state is the dense and harmonics,the simulation results are compared and analyzed.At last,the iron consumption and copper consumption in the case of power supply failure in asynchronous motor with load are analyzed and calculated.The results show that after a variety of failures,the maximum torque produced by single-phase ground short circuit and the maximum loss after failure is the most serious damage to the motor and the driven equipment.