The Analysis Of Voltage Stability Correlation And Its Application In Power System Based On Dynamic Mutual Impedance

In recent years,with the rapid development of world economy,the time has come for a large power grid interconnection.So many large power system voltage collapse accidents have taken place around the world,which has brought great influence to the stability of society and people's live and production.Voltage stability has become the main issue affecting the safety and stability of the power system operation.The nonlinear dynamic analysis method is used in this research to define nonlinear dynamic impedance matrix with the basis of the comprehensive dynamic equivalence principle.Diagonal elements are called dynamic self-impedance,while off-diagonal elements are called dynamic mutual impedance in dynamic impedance matrix.Dynamic mutual impedance can reflex the effects that current changes between load buses have on voltage changes.The module value of dynamic mutual impedance between any two load buses can show the strength of electric connection between them.Based on that feature,electrical distance between load buses can be defined.The voltage dynamic mutual impedance refers to the superposition of effects that the current changes of all nodes in the system have on the voltage of a certain node,whose mean value can be used to identify the voltage weak nodes of the system and locate the corresponding reactive power compensation.The effectiveness of the method that dynamic mutual impedance analyzes electric connection and voltage stability is examined by means of the stimulation of IEEE-14 buses system.Voltage reactive partition control can effectively improve the power transmission capacity and voltage stability of power system,but whether the partition results are reasonable or not has direct influence on the realization of the optimal control strategy.Therefore,the research on partition problem is of great significance.In this research,the dynamic mutual impedance module and the mean values of voltage dynamic mutual impedance are applied to the reactive voltage partition,which put forward the partitioning method based on the electrical distance of dynamic mutual impedance.Upon the physical significance of dynamic mutual impedance,the electrical distance is determined and the load subgraph model is established as the equivalence of load space.What is more,the spectrum clustering algorithm is utilized to partition load buses and then indicate the reasonable partition for a group of load buses recursively.Subsequently,the PV node is merged to each given partition,and then the whole partitioning work of reactive control zone is done.The result of the partition is supposed to be synthesized with the mean value of voltage dynamic mutual impedance of each load bus,so that the crucial load buses in each partition can be identified.The given method is applied to the stimulation of IEEE-14 and IEEE-30 node system,and the results help validate the feasibility and effectiveness of the proposed partitioning method.