A new type of differential feeder protection relay using the Global Positioning System for data synchronization

TLDR

The paper proposes a new sampling synchronization technique for a numerical differential feeder protection relay. The relay synchronizes sampling at both feeder ends using a GPS satellite receiver, and its performance was evaluated through EMTP/ATP simulations of a distribution feeder with faults, using current signals and a protection simulator. Simulations show that current transformer saturation degrades sensitivity and stability, but precise GPS‑synchronized differential protection remains fast, selective, accurate, providing high sensitivity on internal faults while staying stable on all external faults.

Abstract

This paper describes a new technique for sampling synchronisation in a numerical differential feeder protection relay. The protection uses a Global Positioning System satellite receiver for sampling synchronization at each end of the protected feeder. The EMTP/ATP power system simulator was used to simulate a typical distribution feeder with faults at various locations. The current signals generated at both ends of feeder were used to evaluate the performance of the protection. These tests were carried out using a protection simulator. The results illustrate the effect of current transformer saturation on the sensitivity and stability of the protection. Finally it is shown that a precisely synchronized differential protection is fast, selective and accurate. On an internal fault it provides a high operating sensitivity, whilst it remains stable on all external faults.