METHODS AND USES OF PRECISE TIME IN POWER-SYSTEMS

As evidenced by recent papers on disturbance recorder synchronization, protective and adaptive relaying and state vector measurement, utility interest in using accurate and standardized time over wide geographical areas has increased. The accuracies and availabilities of sources of precise time have increased while the costs of the necessary equipment have decreased. Microsecond timekeeping is now available to the utility user. Power system applications include maintaining the general public's timekeeping, event recorder synchronization, relay testing, synchronous digital sampling, voltage phase angle (and hence system state vector) measurement, and fault location. This paper briefly describes worldwide standard times, practical methods of transferring time from government standards agencies to the utility user, applications and utility experience. New material is presented on the performance of standard timekeeping services and utility experience with equipment in substations and control centers.