In this paper a multiple modular mathematical model of a high-voltage short
ring power transmission system fit for digital real-time simulation is pre
sented. Various states on this system have been simulated including regular
operation states, different types of faults at different distances and ope
ration of switches under faults. The results running on a Pentium II 333 sh
ow that the presented model and the given digital integration method are co
rrect and can be realized in real-time.