Hybrid FFT and HAQSE Based Method for Fast and Accurate Online Harmonic/Interharmonic Estimation in Modern Power System

The paper focuses on accurately estimating harmonics/interharmonics in the power system. Traditionally, these components are estimated using fast Fourier transform (FFT) but the problem arises when interharmonic components are present in the signal. This paper uses the idea to estimate the integer part of frequency component using FFT and then fractional part is calculated using Hybrid A&M (Aboutanios and Mulgrew) q-shift estimator (HAQSE) algorithm. A periodicity filter is used to detect whether interharmonics are present in the signal or not. To show the effectiveness of the proposed method a comparison has also been made in terms of estimation time required by the algorithm with respect to parametric method. The method is tested using synthetic signals. Relative rms reconstruction error is also calculated which shows that the estimation performed is accurate. Since the proposed method is computationally less burdened it can be run with low-cost hardware for online monitoring of harmonics/interharmonics in emerging electric power systems.