International timekeeping for power system users

People in our modern society are using navigational systems for position and velocity determination, geodesy, surveying and route determination for aircraft, marine vessels and land vehicles. Accurate and precise timekeeping is finding increasing application by power system engineers and researchers. Precise timekeeping is used in power systems for time synchronizing disturbance recorders, synchronizing measurements across an entire interconnection and locating transmission line faults. With microsecond synchronization, power system phase angles can be measured in real-time. Power system phase angles form the state vector of the power grid. Knowledge of the state vector can increase the performance of state estimators. This paper discusses the present state of international timekeeping from a power systems viewpoint. Recent political and technical achievements are discussed which promise NAVSTAR-Global Positioning System and Global Orbiting Navigation Satellite System availability well into the 21st Century