Harmonic estimation in power systems basing on numerical differentiation

An algorithm for harmonic estimation based on numerical differentiation and central Lagrange interpolation of multipoint is presented in this paper. The proposed algorithm is adaptive for the cases, in which the fundamental frequency vary from 30 Hz to 100 Hz, the fundamental amplitude vary from 120 V to 300 V, and the fundamental phase angle vary from 0 to 360. The maximal errors for the amplitude and phase angle of each harmonics are all 0.001%. Simulation analysis is carried out in Matlab software with a testing example with the results satisfactory.