Research On Unbalanced Electromagnetic Force In Large Nuclear Power Turbine Generator Under Unbalanced Condition

Field current is an important electrical parameter of the generator,and it is also the main information to measure the electrical load and the heating of the rotor.Brushless excitation technology is widely used in the large capacity turbine generator,the field current can't be measured directly.The value of field current is needed in operation analysis and fault diagnosis of the generator need,so the accuracy and speed of the calculation of the field current is very important.In the common faults of turbine generator,rotor eccentricity fault occurs in the generator generally,which affects the safe and stable operation of the rotor.Rotor eccentricity fault causes the distortion of the magnetic field in varying extent in generator,and produces unbalanced electromagnetic force.In this paper,the calculation of field current and the unbalanced electromagnetic force under the rotor eccentricity fault are researched.The main work of this paper are as follows.(1)The finite element calculation method of field current based on virtual working conditions which generator stator side running data remains unchanged is presented.In this paper,a two-dimensional finite element simulation model is established,which is based on a TA-1100-78 type nuclear power quadrupole turbo generator.Based on virtual working conditions,the magnetic field data of the generator under different field current values is obtained by using the ANSYS software,further the electromagnetic torque is figured out.The fitting relation of electromagnetic torque and field current is generated.When the actual electromagnetic torque of the generator is brought into the relations,the field current under corresponding working conditions is acquired.(2)The effect which is caused by rotor eccentricity fault on air gap flux density is analyzed.By setting the rotor eccentricity fault,the air gap flux density distribution is calculated under normal operation and eccentricity fault in the TA-1100-78 type nuclear power quadrupole turbo generator.The characteristics of air gap flux density under different rotor eccentric degree and eccentric direction are analyzed.(3)The variation characteristics of unbalanced electromagnetic force under eccentric fault are analyzed.By using the finite element method,the magnetic field data of different eccentric degree and eccentric direction is calculated,the magnitude and direction of the unbalanced electromagnetic force are obtained based on the discrete formula of the unbalanced electromagnetic force.The effects on unbalanced electromagnetic force under the different eccentric degree,eccentric direction and operating conditions are analyzed.Meanwhile the regulation of the unbalanced electromagnetic force is obtained while the turbine generator with rotor eccentricity fault connects in parallel with system ideally.