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

Abstract

Assessing high frequency (HF) distortion in power systems is a new challenge in the framework of in-situ power quality monitoring. The 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 in its digital form into the signal processing 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 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 signal processing stage to the whole measurement chain uncertainty and identify achievable accuracy levels for different frequency ranges and magnitudes of HF distortion. The results highlight the strengths of the DPT compared to other techniques and demonstrates its potential to include HF in a comprehensive waveform distortion assessment in power systems.

Problema Emergente das Distorções entre 2 e 150 kHz em Redes Elétricas: Levantamento Bibliográfico

“…Apesar da adição de faixas de supraharmônicas nas Emendas 1 e 2 da IEC-61000-2-2, informa-se na Emenda 2 que "os métodos de medição dos níveis de perturbação estão fora do escopo deste documento". Atualmente sugere-se que a medição de supraharmônicas seja feita no contexto dos métodos de medições já existentes nos anexos das IEC-61000-4-7 e IEC-61000-4-30 (Collin et al, 2019), os quais são comparados por Klatt et al (2014). O anexo B da norma IEC 61000-4-7 estabelece procedimentos de medidas para faixas apenas entre 2 e 9 kHz.…”

“…Entende-se, de forma geral, que as normas atuais da IEC para testes de supraharmônicas são incompletas. Métodos alternativos aos da IEC e da CISPR também têm sido apresentados, tanto na questão do tratamento das medidas (software) quanto na questão dos equipamentos necessários para as medidas (hardware) (Rodrigues et al, 2018;Mendes et al, 2018;Collin et al, 2019).…”

Comparison of Measurement Methods for 2–150-kHz Conducted Emissions in Power Networks

“…However, in recent years many efforts have been put into developing alternative measurement methods. New advanced techniques have been published aiming to increase accuracy or reduce computational effort, therefore increasing the range of possibilities [13], [14], [15], [16], [17]. Thus, there is the need to extend the previous comparisons to include these novel, specifically designed measurement methods for emissions in the 2 kHz to 150 kHz range.…”

Measurement of 2–150 kHz Conducted Emissions in Power Networks

“…However, in recent years, many efforts have been put into developing alternative measurement methods. New advanced techniques have been published aiming to increase accuracy or reduce computational effort, therefore increasing the range of possibilities [13]- [17]. Thus, there is the need to extend the previous comparisons to include these novel, specifically designed measurement methods for emissions in the 2-150-kHz range.…”