Transient analysis of multi-circuit overhead transmission lines with two voltage levels

In this paper a method for a common transient analysis for the multi-circuit overhead transmission line is presented. It takes into account the influences of the mutual couplings between the conductors. It is based on two-port approach, where the phase conductors and earth wires are modelled by inductive and capacitive coupled cascades of two-ports. For a considered network model, a system of ordinary differential equations (ODE) has been formulated and it has been solved in MATLAB using Runge-Kutta method of 4th order. It results in the time distribution of currents and voltages in all conductors. In this paper a system with four three-phase system of two voltage levels (EHV and HV) has been analysed. The calculations were performed for the typical transients that can occur on EHV/HV line - the single phase short circuit together with automatic reclose cycle.