Measuring active power of synchronously sampled AC signals in presence of interharmonics and subharmonics

The problem of estimating the value of the active power of the AC signal in the presence of subharmonics and interharmonics is considered. Recently suggested methods are analysed, especially those that are based on the application of the undersampling method; their limitations and the errors that occur with their application have also been included in the analysis. The analysis makes use of the most general model of the voltage and current signal, i.e. the most complex spectral content that can be expected to appear in practice. A simulation of the suggested procedure has been carried out, as a final confirmation of the possibility of having accurate processing by using the synchronised sampling technique, even in the presence of subharmonics and interharmonics.