Multi-zone differential protection for transmission networks

This paper proposes a multi-zone differential protection scheme for transmission networks that provides selective backup protection. It uses a current differential algorithm for the detection and location of the faulted item of plant, employs a broadband communication network to transfer/exchange data and uses a GPS time transfer system to time-tag the data. It not only provides a coordinated system of current differential units, but also tackles the problem of data loss by using local data more efficiently.