Accurate track modelling with skin-effect for protection improvement in DC railway system based on RTDS

This paper presents an accurate track modelling for fault current analysis of DC railways based on RTDS (Realtime Digital Simulator). With the introduction of skin effect for rails during the short-circuit transient conditions, an integrated RTDS simulation model of short-circuit fault is proposed. The model includes a novel method based on voltage step series under the equivalent cylindrical conductor of rail to obtain the current series response. By comparing and investigating the waveforms of remote short-circuit current with and without skin effect, the paper pointed out the difference between these two currents. Based on this, the failure analysis can be done more accurately which is beneficial to the accurate setting of DC protection equipment and provides an improvement to the protection system.