Frequency Tracking In Power Networks Of Harmonics

Three new techniques for frequency measurement are prw posed in the paper. The first is a modified zero aoshing method using curve fitting of voltage samplar. The second method is based on polynomial fitting of the DFT quasistationary phasor data for calculation of the rate of change of the positive sequence phase angle. The third method o p erateh on a complex signal obtained by the standard kchnique of quadrature demodulation. All three methods AX characterized by immunity to reasonable unounts of noise m d harmonics in power systems. The performance of the proposed techniques is illustrated on several scenarios by computer simulation.