Analysis Of Asynchronous Motor Combined Voltage-Angle Stability Problem Based On Phase-Amplitude Motion Equation

Asynchronous motor is the main load in the power system,so its dynamic characteristics will have a great impact on the stability of the system.Therefore,the research on the dynamic characteristics of the asynchronous motor connected to the grid is very important for analyzing and solving the problem.A suitable asynchronous motor model not only simplifies the problem,but also allows a more intuitive physical understanding of the characteristics of the asynchronous motor and its interaction with the system.However,the traditional asynchronous motor modeling methods are mostly based on mathematical descriptions.Due to the high dimensionality,nonlinearity and strong coupling characteristics of the asynchronous motor itself,it brings difficulties to the intuitive analysis problem.Therefore,based on the concept of internal potential rotation vector of asynchronous motor,this paper proposes the amplitude and phase motion model of asynchronous motor,which takes active and reactive power as excitation,internal potential amplitude and rotation frequency as response.This modeling method utilizes dynamics to analyze the dynamics of the asynchronous motor by abstract physical motion.The focus of this paper is divided into four parts:1.Based on the balance of the active and reactive power of the network supply and power required by the asynchronous motor and the balance between the air gap power and the mechanical power,with the active and reactive power as the excitation,the amplitude and rotation frequency of the internal potential of the asynchronous motor in response,the amplitude-phase motion model of the asynchronous motor is established,and then the correctness of the model is verified by time domain simulation.2.Based on the established amplitude and phase motion model of asynchronous motor,a large disturbance stability criterion for asynchronous motor based on power factor balance and air gap power and mechanical power balance is proposed.The asynchronous motor is used under different types of mechanical loads and different fault types.The form of instability is analyzed,and the physical process is analyzed by the idea of dynamics.Then the results of theoretical analysis are verified by time domain simulation.3.Based on the role of the asynchronous motor air gap magnetic field in its normal working operation,according to the active and reactive power supplied by the network and the active and reactive power required by the asynchronous motor,the rotor flux and rotor speed of the asynchronous motor in response,the asynchronous motor model is established.Then the influence of the rotor flux linkage on the interaction between the network and the asynchronous motor is analyzed.The influence of the rotor flux linkage on the stability of the asynchronous motor is analyzed.4.In view of the large-scale use of reactive power compensation devices in the system for reactive power compensation of asynchronous motors,it is especially important to analyze the interaction mode of reactive power compensation devices and the asynchronous motors.Therefore,based on the power transmission and balance,the working principle of the reactive power compensation device is analyzed from the physical point of view.Then,according to the active and reactive power model of the asynchronous motor,the reactive power compensation device is analyzed for the active and reactive power to analyze its effect on the amplitude and frequency dynamics of the internal potential of the asynchronous motor.