21-09-2008, 09:49 AM
This is a new technique for the protection of transmission systems by using the global positioning system (GPS) and fault generated transients. In this scheme the relay contains a fault transient detection system together with a communication unit, which is connected to the power line through the high voltage coupling capacitors of the CVT.
Relays are installed at each bus bar in a transmission network. These detect the fault generated high frequency voltage transient signals and record the time instant corresponding to when the initial traveling wave generated by the fault arrives at the busbar.
The decision to trip is based on the components as they propagate through the system. extensive simulation studies of the technique were carried out to examine the response to different power system and fault condition.
The communication unit is used to transmit and receive coded digital signals of the local information to and from the associated relays in the system. At each substation , the relay determine the location of the fault by comparing the GPS time stay measured locally with those received from the adjacent substations, extensive simulation studies presented here demonstrate feasibility of the scheme.
