Analysis of transmission line current differential protection scheme based on synchronized phasor measurement

Distance relaying principle is a widely used protective scheme for the protection of all types of transmission lines. GPS and fiber optic communication channels has made accurate current differential protection scheme possible for transmission line protection. Time signal accuracy can be provided with GPS. Current differential relays are used for the protection of electrical equipment such as transformers and generators against internal faults because of their simplicity and sensitivity. Current differential relays are now being used for protection of transmission lines with the development in communication technology. A new technique for protection of transmission lines using current differential scheme which uses GPS for time tagged measurement of the line current and bus voltage and fibre optic for communication has been developed. This paper analyzes the sensitivity of the current differential protection scheme for different values of fault resistance, fault locations, fault inception angles, series compensation and delay in synchronization.