Research On Transmission Section Identification Considering Power Grid Partition And Line Overload Control Strategy

The cascading trips caused by power system line overload often cause large-scale blackouts,which seriously affects national security and production activities.Because of the complex structure of the system and numerous lines,it is not economical and desirable to closely monitor each component.Therefore,identifying the transmission section of one of the weak links in the power grid,determining the key lines and studying the effective control strategy of line overload are of great fundamental significance for preventing cascading trips.Combining the idea of community division in complex network theory,this paper gives the integrated weighted edge median of line active power and line voltage,proposes a grid partition method based on improved GN splitting,amends the condition of partition termination,and evaluates the partition results by using flow direction consistency index and modular evaluation index.Then,based on the grid partition topology and the graph theory cut set search principle,a method of power transmission section identification combined with graph theory square matrix operation is studied.Secondly,the key lines in each transmission section arc determined by synthesizing the safety margin of transmission lines and the influence factors of branch breaking.To solve the overload problem of other lines caused by power flow transfer of key lines after fault removal,a bi-objective optimization model including minimum active power adjustment and minimum voltage offset of units and loads is constructed.According to the characteristics of the model,a basic harmony search algorithm is introduced,and the uniformly distributed initial harmony database and variable dimension and sound memory database are used to improve the model.The control strategy of line overload is obtained.Finally,the method of partition,section identification,key line determination and line overload control strategy are tested by using the IEEE 39-bus system and a provincial power grid as examples.The results verify the feasibility and effectiveness of the proposed method and control strategy.