The Directional Feature of Current Transients, Application in High-Speed Transmission-Line Protection

This paper presents an orthogonal decomposition method, which is used to extract information from the current transient signals generated after a fault. The orthogonal basis functions are obtained under the condition of maximizing variability (variance) of input signals which, in turn, allows for finding an optimal representation of fault data. The results of the decomposition bring remarkable patterns described by transient signals into sight. Directionality, which appears as one of the foremost features, is highly related to the fault inception angle. This relation is then used to determine the fault direction just by comparing the steady-state prefault voltage angle and the angle of the vector resulting from the representation of the current signal in the space given by the first two orthogonal functions. Time windows shorter than 2 ms are used. Thus, the methodology can be applied in high-speed protection schemes.