Power System Stability Analysis Method Based On Coupled Characteristics And Its Application

With the rapid development of social economy,the increasing scale of power systems,power grid interconnection has become increasingly close and power system stability problems have become increasingly prominent.factors of stability and mutual coupling relations are more complex,which has important academic value and engineering significance to develop and perfect the theory of power system stability rigorous and practical strong analytical method.In this paper,the dynamic equivalence analysis is used to analyze the stability of power system.The main work of this thesis as follows:1.A method of coupling analysis based on dynamic impedance matrix is proposed.Put forward the concept of dynamic impedance matrix and definitions,which can quantify coupling relationship,make up the shortage of the equivalent impedance of the system side;the dynamic impedance matrix is defined based on the coupling characteristics for node self stability characteristics,node stabilization characteristics and system anti impact ability the definition of deduction which can be used for analysis of coupling characteristics of the dominant factor and dominant region,thus forming the coupling characteristics analysis method;the proposed method can not only grasp the different operating conditions of characteristics,can also be used to locate the fault source identification and voltage stability of vulnerable region.The practical system simulation shows the application value of the proposed method.2.An improved static voltage stability analysis method is proposed.On the basis of extracting the diagonal elements of the defined dynamic impedance matrix,the critical conditions and margin indexes of voltage stability are deduced and defined;derive a voltage-reactive power related to change of reactive power compensation,which can rapid assessment reactive power demand in each region;The proposed method only need to use the local node voltage and current information is obtained with the equivalent circuit,which used to evaluate voltage stability level of each node.The above mentioned reactive power demand analysis can optimize the stability characteristics,enhance the power transmission limit,and improve the practicability of the improved analysis method.3.A unified analysis method of static stability characteristics is proposed.On the basis of the power angle stability,the criterion of static power angle stability is derived,and the stability margin index of power angle is obtained;by comparing static power angle stability and static voltage stability deduction,a unified analysis method of static stability characteristics is established,and the implementation steps are described in detail;according to the unified analysis method,explores the transformation of the characteristics of voltage stability and angle stability characteristics and the dominant factors,these are used to derive and define the stability characteristics of dominant index,thus forming a new method to identify the dominant characteristics of stability;4.A voltage stability preventive control strategy based on the analysis of coupling characteristics is proposed.In order to meet the requirement of power system operation,the stability influence degree and stability margin are analyzed,and a two order screening method for contingency selection is obtained;in this method,the stability influence degree is rapidly screened,and the screening set with larger impact on the grid is obtained.Furthermore,a precise collection is made to obtain a smaller margin set;with the impact strength,the events leading factors and constraints,analyzed from the variation of coupling properties and stability,and put forward the corresponding stability preventive control strategy;the strategy applied to the actual system can provide a reference for the power grid,the practical system can produce good engineering benefits.