An Improved Current Differential Protective Principle of UHV Transmission Line

This paper presents an improved current differential protective principle. Marti model of the transmission line is applied in this principle, which place emphasis on solving frequency-dependent line parameters. The operating current expressions for an internal fault are also deduced in frequency domain. Finally, simulating comparison have been carried out between the proposed protective principle and Bergeron model based protection for Chinese 1000kV UHV AC test demonstration project. Simulation results show that this improved principle has high reliability for both internal and external faults.