High-accuracy, wide-range frequency estimation methods for power system signals under nonsinusoidal conditions

A numerical differentiation-based algorithm for high-accuracy, wide-range frequency estimation of power systems is proposed in this paper. The signal includes up to 31st-order harmonic components. Using the central numerical differentiation of multipoints on the basis of Lagrange interpolation, the estimated frequency of nonsinusoidal signals of power systems can be measured at an accuracy of 99.999% over a wide range of from 10 to 100 Hz with fundamental amplitude varying from 100 to 300 V and with a fundamental phase angle varying from 0 to 360. The proposed algorithm needs at most two cycles or 40 ms for estimation of frequency over 40 to 60 Hz, and needs at most three cycles or 60 ms over 10 to 40 Hz or 60 to 100 Hz. Using Matlab software, the simulation results of the test example are satisfactory.