A recursive least-squares digital distance relaying algorithm

Numerical distance relaying algorithm based on Mathematical Morphology and Least-Squares Curve Fitting method

“…The fault distance estimate is carried out using a transmission line model based on differential equations [9][10][11][12][13]. The differential equation model during phase to ground faults is given by: .…”

“…In digital relays, other methods based on transmission line differential equations [8][9][10][11] or on traveling waves approach have been presented. The techniques based on differential equations approaches and impedance estimation methods usually detect the fault in a shorter time than traditional techniques.…”

“…The methodology uses Mathematical Morphology [13] to detect and classify the fault, and Least-Square Curve Fitting to estimate fault location and fault resistance. Distance and fault resistance estimation is realized by a real-time fault location algorithm, which is developed using an instantaneous circuit model [9]. Furthermore, the algorithm has an adaptive window size, which gradually increases its size, until one complete cycle.…”

Transmission Line Distance Relaying Using On-Line Trained Neural Networks

“…A modification for the transmission line model developed in [9] is introduced in this paper. The proposed model does not depend on the storage of the pre-fault load current.…”

“…This error is due to the fact that the actual resistance and inductance seen by the relay are related to each other by the fault distance. An improved version of the distance relay described in [7], [8], that includes the fault resistance and the remote-end infeed, has been proposed in [9]. The fault distance is estimated using the recursive least-squares technique.…”