Ground Fault Detection and Feeder Protection of 2x25kV Railway Traction System

In a new 2X25 kV System, Scott transformer is used as a traction transformer and to supply the power to the railway traction system. It is protected using the percentage differential relay. However, region from the low voltage side of the Scott transformer to the first autotransformer is unprotected at the field and to protect the system during fault on this region is very important. Thus, development of protection scheme is required. Herein, we modeled 2X25kV traction system in EMTP, simulate faults and developed a specific relationship to provide the protection for this scheme. We have taken the current input from feeder current transformers and observed its current during the faults. This performance of this scheme is verified using EMTP. Further, impedance to distance ratio is non-linear due to the autotransformer between catenary, rail and feeders in 2x25kV railway traction system. To observe this behavior as per field details and provide the accurate relay setting, we simulate the faults over the length of protected line in EMTP and field test are carried out. In the event of a fault on unprotected region and on the protected line, trip occurs and relay recorded fault details at the field.