Dynamic Characteristic And Interaction Analysis Of Synchronous Generator Based On Phase-amplitude Motion Equation

With the application of renewable generations,long distance power transmissions using HVDC and FACTS,and reactive power compensation device,power converter interfaced devices occupy a high penetration in power systems nowadays.The dynamic stability of the power system depends on the dynamic characteristics of the devices and the network.The premise of the stability analysis is to establish the system model under the corresponding time scale.At present,modeling of devices in power systems is mainly based on the detailed math equation description of the real structure of each device,the physical mechanism of the devices is not well described,and the dynamic characteristics of different devices can't be reflected from a general perspective.Thus,according to phase-amplitude dynamics theory,a physical,functional and universal modeling method based on phase-amplitude motion equation has been proposed.In order to analyze the stability of power electronics dominated power systems under electromechanical time scale,this paper takes the main equipment of conventional grid-synchronous generator as an example,and the dynamic characteristics and dynamic stability of synchronous generator under electromechanical time scale are studied.Specific research content is divided into the following aspects:(1)A SG model based on amplitude-phase motion equation under terminal voltage control is established,which reveals the duality of amplitude motion and phase motion of device.The accuracy of the SG model based on the amplitude-phase motion equation is verified by comparing with the time domain simulation of the electromagnetic transient model.Through the relationship between power and state,the physical meaning of the motion equation is expounded by the concept of virtual capacitor.The relationship between the internal coupling between the amplitude and phase motion and the demagnetization effect of the stator current and the power system stabilizer is explained.This paper summarizes a general idea of device modeling method based on amplitude-phase motion equation.(2)Based on the established amplitude-phase motion model of SG,self-stability and en-stability analysis--a new method of analyzing and quantifying the interaction between devices and amplitude and phase of internal voltage The characteristic of the amplitude of internal voltage of SG responses phase change,and the path of the amplitude motion providing damping to the phase motion are studied.Taking the single machine infinite system as an example,this paper analyzes the reason why the damping of the SG reduces when the excitation magnification K_A increases from the physical meaning of the motion equation and the en-stability of the amplitude motion provided to the phase motion.Then analyzed the stronger the interconnection of the network,the stronger the interaction between the amplitude motion and the phase motion.Finally,the analysis of PSS will affect the internal coupling between the amplitude and phase is proposed,and a new method of configuring PSS through internal coupling to improve the damping of SG is proposed.