Judgment Of System Transient Condition Stability And Disturbance Type Screening Method Based On Trajectory Eigenvalues

Whether the safe and stable operation of the power system directly affects the socio-economic development,the actual power system inevitably suffer from various disturbances.If can’t judge the transient stability of the system after disturbance and identify the type of disturbance,measures to deal with the normal power supply,the scope of failure may expand,and then lead to the occurrence of major accidents in the power system.More serious condition will cause the system oscillation even disconnection and produce incalculable economic losses and unpredictable social impact.In order to accurately determine the transient stability of the system after the disturbance and filter the types of disturbances,on the basis of studying the existing methods and aiming at the shortcomings of the existing methods,this paper attempts to use the fluctuation characteristics of the trajectory eigenvalues of the System after disturbances to transient stability judgment and disturbance type screening,and the key issues are analyzed and discussed.Firstly,the linearization model of high order system is established,and the influence of main components such as governor and excitation system on the system linearization model is fully considered.In the linearization of the governor and the excitation system model,considering the complexity of the model,a linearized processing method of the complex module model at the non-equilibrium point is realized by using the Laplace inverse transformation.Secondly,the fluctuation of the trajectory characteristic of the trajectory eigenvalues of the system after disturbance is compared with the result of the system transient stability determined by the relative power curve of the generator under the disturbance,and the trajectory characteristic is attenuated,eventually converge to a small range of fluctuations system disturbance if the transient instability,the trajectory eigenvalues of the root without regular oscillation,there is no convergence trend.According to this law,this paper attempts to propose a method to determine the transient stability of the system based on the trajectory eigenvalues after disturbances.This method determines that the transient stability of the system under the expected accident is longer,but because the trajectory eigenvalues root curve is the results of all the variables,including the generator power angle,the machine terminal voltage and other variables,so the accuracy of the traditional single variable to determine the system transient stability has greatly improved for power planning and operation of the off-line operation Stability analysis.Finally,the influence of the size and type of the disturbance on the trajectory eigenvalues root is different.Especially the fluctuation range of the trajectory eigenvalues root is obvious.The difference between the root fluctuation characteristics of the system trajectory eigenvalues under the action of harmful disturbance and harmless disturbance is very significant.The variance is used to analyze the oscillation and the dispersion degree of the trajectory eigenvalues’ curve after the disturbance.Based on the quantization index,in this paper,we propose a method to identify the disturbance variance based on the variance of the trajectory eigenvalues after disturbances.To solve the fastness problem,this method uses the first swing period after the disturbance as the time section to calculate the fluctuation variance of the characteristic root of the time section trajectory.The results show that the type of the expected disturbance is consistent with the result of the recognition of the disturbance recognition area,which proves that this method can effectively meet the requirement of fast and accurate filtering of the disturbance type in the system transient analysis.