Assessing Distortion Within the IEC Framework in the Presence of High Frequency Components: Some Considerations on Signal Processing

Assessing distortion within the lEC framework in the presence of high frequency (HF) components is considered in this paper from the perspective of signal processing. To reduce uncertainty when assessing HF distortion, the lEC suggests the use of a high-pass filter, which can be analogue (with a dedicated channel for HF assessment) or integrated in its digital form into the signal processing stage. This paper extends the proven desynchronized processing technique (DPT), previously introduced for harmonic and interharmonic analysis, as an alternative filtering technique and compares its performance against three digital filtering techniques presented in literature. Particular attention is paid to the error introduced by the desynchronization of the fundamental frequency, which naturally deviates from its rated value, with the fixed 200ms window recommended by the lEC for HF distortion assessment. Two case studies highlight the strengths and weaknesses of the techniques and demonstrate the potential of the DPT to analyse HF distortion.