Numerical differentiation and digital FIR filter based algorithm for power system measurement

A numerical differentiation and digital FIR filter based algorithm for parameter measurement of non-sinusoidal signals of power systems is presented in this paper. Numerical differentiation is used for parameter computation, and digital FIR filter is used for decomposing the non-sinusoidal signals into individual sinusoidal component of each harmonic. A low-pass FIR filter is used for decomposition of fundamental component, and a set of band-pass FIR filter is used for decomposition of harmonic components. Using numerical differentiation, the frequency, amplitude and phase angle of fundamental and other harmonic components can be estimated at a high accuracy in at most 2 cycles, 40 ms. Moreover, estimation of one parameter is not influenced by change of other parameters. The simulation results of a study example carried out in Matlab show good dynamics of the proposed algorithm.