This paper presents advanced digital simulation studies on a comprehensive EHV transmission line system with an aim to validate high performance numeric distance relays. A 500 kV analogue transmission line system specially designed for evaluation of power system protection and control systems and devices is first introduced. A real time digital simulator (RTDS) system used to model and simulate the analogue system is then introduced, which is the main part of the paper. Special emphasis is placed on the utilisation of the newly developed advanced feature of the RTDS to suit the purposes of this application. Extensive simulation studies proved that the digital modelling and simulation is in close agreement with its analogue counterpart.