Digital protection of electrified railways network systems

This paper presents advanced digital protection technique for typical dc system of cairo underground metro.the dc electric railway system is simulated by atp program. this typical system is composed of the ac source,transformer,rectifier,running rails,feeder's wires,main and the auxiliary wires etc. extensive simulation results for normal and abnormal conditions are carried out. the results acquire the digital protection for dc system of cairo underground metro. the proposed model would be a powerful tool for good understanding,designing and planning of the performance for dc system of cairo underground metro. the obtained results present the performance of suggested technique for typical dc system of cairo underground metro that indicates an accepted degree of accuracy.