Adaptive Kalman Filtering in Computer Relaying: Fault Classification Using Voltage Models

This paper describes a new probabilistic technique for fault classification to be used in digital distance protection of power systems. The new technique is based on an adaptive Kalman filter using voltage measurements. The voltage data of each phase is processed in two Kalman filter models simultaneously. One Kalman filter assumes the features of a faulted phase while the other has the features of an unfaulted phase. The condition of the phase, faulted or non-faulted, is then decided from the computed a posteriori probabilities.