Design and development of high performance integrated protective scheme for A.C. traction

This work mainly focus the simulation of a protection scheme for railway traction system and its implementation with the help of a high speed DSP micro controller. In order to simulate current and voltage wave-forms during traction loading, fault and associated harmonics in overhead lines of traction, a complete model of traction system has been designed and simulated in MATLAB environment. The DSP processor performs the digital filtering on the acquired samples, executes the relaying software and perform different relay operations. The proposed digital relaying scheme includes single phase distance protection, detection of wrong phase coupling and accurate fault detection during high resistance faults. Fault detection during high resistance faults in overhead lines can be achieved with the aid of Delta-I (ΔI) relay characteristics, to discriminate the fault current and load current and provides the protection even when the fault current is less than the maximum load current.