Double stage harmonic and interharmonic processing technique

Measurement and analysis experiences have shown great difficulties in interharmonic detection and measurement due to their small amplitudes and their consequent vulnerability from harmonics spectral leakage. A new approach that has a general validity and results fully compatible with the IEC standard is presented. This approach is based on a double stage signal processing technique; in the first stage, the harmonic components are estimated and filtered away from the original signal, so that the second stage analysis can be performed for interharmonics estimation without harmonic tone spectral leakage. The procedure is successfully applied to both numerical and experimental tests