Ultra fast pilot protection of a looped distribution system

The distribution system considered in this work is the FREEDM* loop. The loop is divided into different zones for protection. A fast pilot protection scheme is proposed for this looped system. The scheme makes time synchronized measurements of line currents, converts them to digital word. Time synchronization is added using a GPS. This time-synchronized digital word is transmitted to a computer, which executes a protection strategy for differential protection as primary and overcurrent protection as backup based on the requirements of the FREEDM system. A trip signal generated by this strategy is sent to the breaker to trip the line to complete the experimental setup. Since the protection algorithm is based on digital signals, this scheme is much faster than a conventional differential pilot protection algorithm.