Study On Electromagnetic Field And Losses In The End Of AC Excitation Variable Speed Pumped Storage Generator Motor

China has put forward the strategic goal of “carbon neutral” by 2060 and “carbon rich” by 2030,so it should vigorously develop clean energy.As the large variable speed pumped storage generator motor has the advantages of good speed adaptability,expanding the operating range of pump turbine,fast regulation of active and reactive power and good stability,it is responsible for energy saving and emission reduction.At present,some progress has been made in the research of variable speed pumped storage motor at home and abroad,but there is a lack of systematic research on the electromagnetic field and loss in the end region of variable speed pumped storage generator motor,which may lay a hidden danger to the long-term stable operation of variable speed pumped storage generator motor.The increased capacity of variable speed pumped storage generator motors leads to increased end leakage,which can cause local overheating of the motor and even burn the insulation,affecting the safe and stable operation of the motor.In this paper,the electromagnetic field and the loss of each structural component of a 10 MW AC excitation variable speed pumped storage generator motor are studied in detail as an example.First,the electromagnetic field of the variable speed pumped storage generator motor is analyzed and calculated.A 2-D transient electromagnetic field mathematical and physical models of the variable speed pumped storage generator motor is established.The loss variation law in the linear section area under different speeds of the generator operating conditions is studied.The accuracy of the calculation results is also verified through tests.The mathematical and physical models of the 3-D transient electromagnetic field in the end region of the variable speed pumped storage generator is established.Double convergence iteration is used to determine the excitation current and power angle.The flux density,eddy current density and loss variation patterns of each component in the end region under different speeds of generator operating conditions are analyzed.Secondly,the excitation current and power angle of a variable speed pumped storage generator motor at sub-synchronous speed of 460 rpm under the generator condition are determined.The 3-D electromagnetic field at the end of the variable speed pumped storage generator motor at different leading phase depths is calculated.The magnetic density of stator press finger,rotor finger plate,stator clamping plate and rotor retaining ring and the eddy current density of stator press finger and rotor finger plate at the end region of different phase depth are studied.The loss variation of each component in the end region are explored at different leading phase depths.Finally,the influence of the tilt angle of the step core at the end of the stator,the tilt angle of the step core at the end of the rotor and the thickness of the first rotor core on the magnetic density and losses of the generator of the variable speed pumped storage generator motor is studied.The variation rule of flux density of stator end core and end elements with different end core structures are studied at sub-synchronous speed of 460 rpm under generator conditions.The effects of different structures on the losses of end elements are studied.The coupling model of fluid and heat transfer at the3-D end of the variable speed pumped storage electric motor is established.The temperature rise of each component at the end is calculated by taking the loss value calculated from the 3-D transient field as the heat source under the temperature rise test condition.The results are compared with the measured values.The accuracy of the calculation method in this paper is verified.