Real-time accurate power system frequency meter and its quality evaluation based on simulations and large area system observations

The solution of accurate power system frequency meter/registrator is presented. The meter is equipped with a standard PC DAQ-card which is able to perform the background data acquisition process. The method is based on system voltage signal zero-crossings observations, and zero positions processing targeted to instant system frequency estimation. Different observations of the real power system signals are presented-local and distanced, where two parallel observations were made in 25 km distanced subsystems. The results were verified with the standard signals from AFG of the known frequency and it was confirmed that the accuracy is a few hundred /spl mu/Hz.