On-line Detection Algorithm for Interharmonics Based on Spectrum Domain Filtering

Magnitude and phase on-line monitoring of harmonics and interharmonics are the foundation of power quality improvement while speed and precision of the algorithm are the keys of on-line monitoring techniques. This paper studies the spectrum leakage of harmonic and interharmonic and then proposes a rapid on-line detection algorithm based on spectrum domain filtering. The algorithm divides the original signals into three parts those are fundamental signals, harmonic signals and interharmonic signals, and then filters the harmonic signals in frequency domain so as to eliminate the spectrum interference to the interharmonic signals. Thus, only one time of FFT(Fast Fourie Transform) calculation is needed, which reduces calculation burden of the algorithm remarkably with a good precision and makes the algorithm easy to be implemented in on-line monitoring device. A comparative simulation of four different interharmonic detection algorithms was conducted in Matlab to verify the feasibility and superiority of the proposed algorithm.