Estimation of Time drift in Interface energy meters

Time drift in the internal clock of the Special Energy Meters (15-minute interval meter) installed for measuring inter-utility energy exchanges in India is a major concern in energy accounting and deviation settlement. Since the meter clock is accessible only locally, the time drift can only be determined locally by visually comparing the time in the internal clock of the meter with the Indian standard time. Collection of information related to meter time drift every week from the locations where these meters are installed, is a cumbersome process and it is also prone to errors due to manual intervention in data collection. This paper shares the various techniques being applied presently for determination of time drift and proposes a novel application of cross correlation with linear interpolation (used in signal processing) for estimation of meter time drift at the data collection centre. The efficacy of the proposed method has been demonstrated with the help of simulations. The novel application has been successfully used in Western Regional Load Despatch Centre in India and is found to be accurate to +/−1 minute with a reasonable confidence level. The whole process of time drift estimation has been automated to significantly improve the energy meter asset administration.