Research On Transient Stability Analysis Of Power System Based On Response Information

As an established trend in the development of power systems,regional grid interconnection brings significant economic benefits,but also challenges the operation and safety control of the power system due to transient stability issues.The traditional power grid security and stability control strategy is based on the analysis of the existing fault strategy table.Because the strategy table cannot be exhaustive,the power grid appears passive and conservative in the face of small probability events.The rapid development of phasor measuring devices and high-speed communication technology have made it possible to obtain and transmit response information in real time.The power system transient stability analysis technology based on response information weakens the role of system models and parameters,does not need to anticipate the operation mode and fault combination,and can provide a basis for the emergency control of the system.The main work of this thesis is as follows:(1)In the identification of critical clusters based on response information,a method for identifying critical clusters of power systems based on dynamic frequency deviation is proposed.When transient instability occurs in a power system,the most common situation is to first appear as two clusters,and the identification of critical clusters is the difficulty and key to the analysis of transient power angle stability after dual-machine equivalence in a multi-machine power system.The traditional method of identifying the power angle gap is not efficient,while the method of compound power angle is restricted by the setting value.Therefore,this thesis proposes to use the maximum gap of the dynamic frequency deviation of each generator to divide the generators into the critical group and the remaining group.Simulation examples verify the effectiveness and rapidity of the proposed method.(2)In the power system transient power angle stability judgment based on response information,the power angle instability judgment method based on the change trend of angular velocity difference and power angle difference is improved.In this thesis,the two clusters of critical clusters are identified based on the dynamic frequency deviation method.After the two clusters are equalized,the characteristics of the phase plane motion trajectory after the failure are used for analysis.The least square method is used to fit the first derivative curve of the motion trajectory into the second and third polynomial functions to solve the problem of uneven curve.In this thesis,the concavity and convexity of the quadratic function is used to analyze the transient stability of the system,and the third-order polynomial function is used to replace the quadratic parabola to determine the instability moment earlier,and the rapidity is added on the basis of accurately determining the transient power angle stability of the system.,In order to meet the requirements of real-time analysis.Finally,the feasibility and rapidity of the method are verified by simulation examples.(3)In the judgment of power system transient voltage stability based on response information,based on the characteristic relationship between power and current during voltage instability,it is proposed to use the derivative of power variation to predict power,and then quickly analyze the transient stability of the system;Voltage stability analysis is also included in the comprehensive transient stability analysis program,which completes the transient stability analysis program.The curve fitting of the first derivative by the least square method can not only avoid the influence of measurement error,noise,etc.,but also predict the power change and the moment of instability in the future.Finally,an example is used to verify the effectiveness of the method in this thesis.