Research On Stator Electrical Quantity And Electromagnetic Torque Of Nuclear Power Turbo-generator Under External Asymmetry

When the giant nuclear power half-speed turbo-generator comes along external asymmetry,the harmonic electromagnetic torque and the harmonic tangential electromagnetic force of the rotor field winding in the giant nuclear power half-speed turbo-generator tends to be more substantial and can not be neglected.Moreover,it could severely threaten the safe operation of the giant nuclear power half-speed turbo-generator.Besides,the calculation of the stator electrical quantity of the giant nuclear power half-speed turbo-generator,such as the stator fundamental negative sequence current,the stator fundamental positive sequence current,the current asymmetrical degree,and so on,have provided radical data for the discussion of the electromagnetic torque?power factor?power angle and voltage regulation rate.Accordingly,the investigation on the stator electrical quantity,the electromagnetic torque and the tangential electromagnetic force of the rotor field winding in the giant nuclear power half-speed turbo-generator is so important that it possesses much theoretical meanings and engineering value.Taking a 1400MVA nuclear power half-speed turbo-generator as an example,the two-dimensional finite element model of nuclear power half-speed turbo-generator is set up.Meanwhile,with the alteration of the current asymmetrical degree,the stator three-phase fundamental voltage amplitude characteristics,the stator three-phase fundamental current amplitude characteristics,the stator fundamental positive sequence current amplitude characteristics,the stator fundamental positive sequence voltage amplitude characteristics,the stator fundamental negative sequence current amplitude and the stator fundamental negative sequence voltage amplitude are studied respectively under stable condition.Moreover,doing experiment on a experimental generator,it also verifies the effectiveness of the changing law of the stator three-phase fundamental voltage amplitude characteristics and the stator fundamental positive sequence voltage of the nuclear power half-speed turbo-generator effectively.Based on the improvement of the traditional complex field symmetrical component method,a novel method for the calculation of the second harmonic electromagnetic torque based on the network parameter method is proposed in this dissertation.At the same time,the correctness of the new network parameter analytical method is verified by the data from the simulation of the nuclear power half-speed turbo-generator.This new network parameter analytical method adopts the stator fundamental positive sequence current,the stator fundamental positive sequence voltage,the current asymmetrical degree and the other parameters to accurately calculate the second harmonic electromagnetic torque amplitude of the three-phase synchronous non-salient generator under the stable external asymmetry.Based on this,respectively in this dissertation the network parameter analytical method and the finite element method are both harnessed to discuss the impact of the existence of the damper winding and the wedge winding,the alteration of the damper winding material and the alteration of the wedge winding material on the second harmonic electromagnetic torque amplitude of the nuclear power half-speed turbo-generator.The mathematical model based on a new vector analysis for electromagnetic torque is built up in this dissertation.Based on that,this dissertation thoroughly analyzes and studies the influence of the stator negative sequence vector on the electromagnetic torque of the three-phase synchronous non-salient generator by the new vector analysis mathematical model.Compared with the network parameter method,it has great improvement that it could effectively analyze the effect of the negative sequence current on the electromagnetic torque.Then using the simulation model of the nuclear power half-speed turbo-generator,the constant electromagnetic torque,the second harmonic electromagnetic torque,the high harmonic electromagnetic torque and the harmonic contents of the electromagnetic torque are respectively investigated by the finite element method.Meanwhile the correctiveness of the analysis of the mathematical model based on a new vector analysis for electromagnetic torque is proven by the finite element simulation result.The symmetrical component method,the generator positive sequence equivalent circuit and the generator negative sequence equivalent circuit are employed.Then based on that,under the stable external asymmetrical condition,on the case of not existing the damper winding and the wedge winding,existing the damper winding but not existing the wedge winding and existing both the damper winding and the wedge winding,as the current asymmetrical degree changes,the constant component of the total tangential electromagnetic force of all field winding in the three-phase synchronous non-salient generator in the complex magnetic field are investigated by the new analytical method proposed in this dissertation.Further,under the stable external asymmetrical condition,on the case of not existing the damper winding and the wedge winding,existing the damper winding but not existing the wedge winding and existing both the damper winding and the wedge winding,as the current asymmetrical degree alters,the finite element method is employed to analyze the law of the constant component and the second harmonic component amplitude of the total tangential electromagnetic force of all rotor field winding in the complex magnetic field.The effectiveness of the new analytical method is tested by the finite element simulation result.At the same time,the distribution law of the constant component and the second harmonic component amplitude of the tangential electromagnetic force in each slot of the rotor field winding is studied in the complex magnetic field.Additionally,the effect of the damper winding and the wedge winding on the constant component of the tangential electromagnetic force of the nuclear power half-speed turbo-generator in each slot of the field winding in the complex magnetic field is discussed.Finally,the effect of the damper winding on the second harmonic component amplitude of the tangential electromagnetic force of the nuclear power half-speed turbo-generator in each slot of the field winding in the complex magnetic field is analyzed.