Positional protection of transmission systems using Global Positioning System

This paper presents a new technique for the protection of power transmissio n systems by using the Global Positioning System (GPS) and fault generated transients. In the scheme, the relay contains a fault transient detection s ystem together with a communication unit, which is connected to the power l ine through the high voltage coupling capacitors of the CVT. Relays are ins talled at each busbar in a transmission network, These detect the fault gen erated high frequency voltage transient signals and record the time instant corresponding to when the initial travelling wave generated by the fault a rrives at that busbar, The communication unit is used to transmit and recei ve coded digital signals of the Local information to and from the associate d relay(s) in the system. At each substation, the relays determine the loca tion of the fault by comparing the GPS time stamps measured Locally with th ose received from the adjacent substations. Extensive simulation studies pr esented in the paper demonstrate the feasibility of the scheme.