Evaluation of an Asynchronous Sampling Correction Technique Suitable for Power Quality Measurements

− The accurate measurement of many power quality parameters using digital sampling techniques relies on synchronisation between the sampling system and the signal under analysis. If synchronisation is not available measurement errors result due to the difference in frequency of the digitised signal and that expected and based on the sampling clock of the measurement system. A method is presented of correcting for this lack of synchronisation. This method relies on a time domain interpolation technique to modify the sampling rate of the captured signal in software. In order to find the correct sampling rate a scanning technique is used which requires some method of assessing the lack of synchronisation and associated error in the analysis of the signal. A number of methods of achieving this are presented and compared. The suitability of the algorithm for power quality measurements under noisy conditions is assessed.