Mechanism Analysis On Joint Stability Of Internal Voltage Amplitude-Phase Of Synchronous Generator Based On Amplitude-Phase Motion Equation

With the increasing penetration of power electronics in power systems,power system characteristics are changing,and power system stability issues are becoming more complex.Due to changes in the dynamic characteristics of the system,the correlation between the stability defined by the traditional power system analysis is also becoming stronger.The transient characteristics of the power system are determined by the transient characteristics of the equipment and the transient characteristics of the network.Regarding the AC equipment as the AC voltage source with internal voltage consists of two different degree amplitude and phase,is put up by the amplitude-phase motion equation to solve the power system stability problem under the new pattern of electronic power system.It reveals the dynamics of the active/reactive power and phase/amplitude motion in the dynamic process of the system.Based on the idea of amplitude-phase motion equation,this paper studies the transient response and joint stability of internal voltage amplitude-phase of synchronous generator.Specific research contents are divided into the following aspects:(1)The transient model of amplitude-phase motion equation of synchronous generator in electromechanical time scale is established.Based on the physical process of power flow during the operation of synchronous generators and the root cause of the change of internal voltage,it is pointed out that the difference in the power angle stability and voltage stability is fundamentally derived from the difference in the understanding of kinetic energy and potential energy.Based on this,amplitude and phase motion equation of synchronous,whose internal voltage is driving by active/reactive power,is established.The accuracy of the amplitude-phase motion equation model of synchronous machine and the advantage of the model in explaining internal voltage amplitude motion mechanism are verified by comparing with the short-circuit fault simulation of the third-order transient model of synchronous machine.(2)Based on the amplitude-phase motion transient model of synchronous generator,the idea of studying equipment transient characteristics from the perspective of time-domain response characteristics is proposed,and the open-loop transient response characteristics of synchronous generator are analyzed.Then,in the closed-loop system,the loop of activephase motion and reactive-amplitude motion interaction is obtained.Based on the transient model of amplitude-phase motion equation of synchronous machine,the mechanism of joint stability of internal voltage amplitude and phase under power grid fault is analyzed.The transient behavior of internal voltage state in synchronous machine under fault is described by active-phase and reactive-internal voltage amplitude curves.Based on the principle of equal area,the mechanism of joint stability of internal voltage amplitude and phase under fault is analyzed.Proposing an optimal control method based on the influence of internal potential amplitude on the phase swing process of synchronous machine.