Mathematical Models of Short-Circuit and Break Modes in Electric Networks with Multi-Circuitoverhead Lines

A mathematical model of shortcircuit and break (SCB) modes and their combinations in electric networks (EN) with multi-circuit overhead lines (MCOL), the circuits of which have different rated voltages, is proposed. Considering their specifics, the method of calculating the SCB modes in phase coordinates based on superimposing the Actual Emergency Modes with Pre-Emergency Modes (AEM and PEM) is formulated. The article gives a procedure for considering the boundary conditions of fault different types and their combinations in determining the parameters of their modes using additional sources. The technique is focused on multivariate calculations of the totality of faults in ENs with MCOL, i.e. when moving the fault point along their branches and nodes and combinations of these faults with breaks and disconnections of three-phase branches and individual phases.