Frequency Tracking Algorithms: A Contribution Considering Phase Unbalance, Step Variations, Noise, Harmonics, and Different Sampling Rates

Frequency estimation has a great importance for protection services, power quality, and in the operation of an electric power system. This paper describes and analyzes six methods used in frequency estimation. The techniques were tested by employing signals generated from mathematical equations, with and without noise and harmonics. Aiming to analyze the algorithms behavior in applications that involve the monitoring of the power quality, a rate of 96 samples per cycle was used. On the other hand, for applications in protection services, 16 samples per cycle were used, since numerical relays work with a lower sample rate. It was also tested the performance of the methods considering a signal obtained from simulations on a test system using the software DIgSILENT ^ . The techniques were compared by performance indicators commonly employed in phasor measurement.