This project is a continuation of a previously funded project on the application of Kalman filtering to power system protective relaying. The renewal addresses several different areas including the use of the extended Kalman filtering (to accommodate nonlinear models), the inclusion of fault security analysis, digital protection of power system components with a minimum time methodology, identification of the severity of system wide disturbances, and the computation (identification) of the fault location. Included in the study are series compensated lines, multi-terminal lines, high impedance faults, transformer location, dynamic security assessment and evaluation, and the use of vector signal processors in the implementation of the Kalman filter.