A new digital algorithm for power system frequency measurements

In this paper, a simple method for measuring the frequency of a power system is presented. The method is based on the curve fitting technique and uses digitized samples of voltage at a relaying point. Mathematical developments of the new method are described. The main parameters that affect the accuracy of the algorithm are discussed. Inclusion of decaying DC and harmonic frequency components is also described. An algorithm based on the method is implemented on an IBM PC AT and it was tested using simulated and field recorded data. From simulation, it shows that if a 12-bit A/D converter is used, the absolute error of measuring frequency is within ±5 Hz when the frequency swings between ±10 Hz about a normal frequency. Finally, comparison between other techniques is also presented