Integrated positional protection of transmission systems using Global Positioning System

This paper presents a new technique for the protection of power transmission systems by using the global positioning system (GPS) and fault generated transients, the integrated positional protection technique. The technique is based on the detection and processing of fault generated high frequency transient signals, in which a centralized protection relay provides the protection of multiple transmission lines. A specially designed integrated positional protection relay, which contains a fault transient detection system together with a substation communication network, is connected to the power line through the high voltage coupling capacitors of the CVT. The relay detects the fault generated high frequency voltage transient signals and records the time instant corresponding to when the initial travelling wave generated by the fault arrives at that busbar. The communication unit is used to transmit and receive coded digital signals of the local information to and from the associated relay(s) in the system. At each substation, the relays determine the location of the fault by comparing the GPS time stamps measured locally with those received from the adjacent substations. Extensive simulation studies presented in the paper demonstrate the feasibility of the scheme.