Enhanced FFT-based parametric algorithm for simultaneous multiple harmonics analysis

An enhanced FFT-based parametric (E-FFT) algorithm suitable for on-line harmonic analysis of electrical power systems is presented. This E-FFT algorithm exploits its iteration loops in combination with the characteristic of steep-descent gradient search strategy, to limit the sensitiveness of the total harmonic distortion caused by changes in the number of parameters involved in distorted signal models. The E-FFT algorithm performs reasonably well with short data record length. Unlike most gradient-descent search algorithms for a global minimum point, the proposed E-FFT algorithm averts the risk of being trapped at any local minimum point in the search path. The E-FFT algorithm differs from other FFT and Kalman filter based tracking algorithms, in that it is able to provide simultaneous tracking of co-variations between integer and non-integer (sub) harmonics in a small number of iteration steps. Numerical illustrative examples demonstrating the operation of this E-FFT algorithm and its simulated performance results are also presented.