Method for the identification of weak and/or strong branches of an electric power transmission system

A method for the identification of weak and/or strong branches of an electric power transmission system which employs known analytical methods appropriate to power flow in nodes and branches of the power transmission system and which analyses functional relations between active and reactive load for this system, characterised in that the electric parameters characterising the nodes and branches of the power transmission system are subjected to computational treatment in order to obtain equations of power flow in all nodes of the system at assumed 100 percent base system load, which is used to calculate complex voltage values in those nodes, and thereafter an electrical model of a system branch situated between two receiver nodes is assumed and a limiting curve /P-Q/ is constructed, which shows the functional relation between reactive load /Q/ and active load /P/ for the assumed electrical model of the branch, and a base load point for that branch is assumed, and then a branch voltage stability coefficient for the analysed system branch is determined, after which the total system load is increased to oveload the system to 120% base load and all operations relating to the determination of the voltage stability coefficient for the analysed system branch at the predetermined system oveload are repeated, and then the numerical value of the branch voltage stability coefficient is compared with a threshold value considered to be a safe margin for maintaining voltage stability for the analysed branch, and the value of the difference between the values of the branch voltage stability coefficients determined for both types of system load is checked whether it is more than, equal to or less than zero, and on the basis of those comparisons the analysed branch is identified as weak or strong.