Protection algorithm based on spectrum characteristic of transient component

When a fault occurs on a transmission line, fault generated high frequency transient components are a series of natural frequencies in frequency domain. This paper proposes a protection algorithm for EHV (Extra High Voltage) transmission line based on spectrum characteristic of natural frequency. Spectrum correlation coefficient is used to determine whether a fault is internal or external fault. It can reduce trip time and not affected by swing, load current and power system operation mode etc. The scheme performance was proven using PSCAD/EMTDC simulations in 500-kV power system considering critical fault cases.