Proposal of a Desynchronized Processing Technique for Assessing High-Frequency Distortion in Power Systems

Assessing high-frequency (HF) distortion (HFD) in power systems is a new challenge in the framework of in situ power quality monitoring. The International Electrotechnical Commission (IEC) suggests the use of a high-pass filter in the measurement chain, which can be analog (with a dedicated channel for HF assessment) or integrated into its digital form into the signal processing (SP) stage, in order to reduce the measurement uncertainty. This paper proposes a desynchronized processing technique (DPT) as an effective alternative to the other digital filtering techniques presented in the literature, which also allows for a potential simplification of the measurement hardware. The DPT performance is analyzed by means of numerical experiments and laboratory measurements performed using two different test beds and both 16- and 24-bit analog-to-digital converters (ADCs). The test beds are used to evaluate the combined contribution of the ADC and the SP stage to the whole measurement chain uncertainty and identify achievable accuracy levels for different frequency ranges and magnitudes of HFD. The results highlight the strengths of the DPT compared to other techniques and demonstrate its potential to include HF in a comprehensive waveform distortion assessment in power systems.