Wavelet packet decomposition for IEC compliant assessment of harmonics under stationary and fluctuating conditions

This paper presents the validation and characterization of a wavelet based decomposition method for the assessment of harmonic distortion in power systems, under stationary and non-stationary conditions. It uses Wavelet Packet Decomposition with Butterworth Infinite Impulse Response filters and a decomposition structure, which allows the measurement of both odd and even harmonics, up to the 63rd order, fully compliant with the requirements of the IEC 61000-4-7 standard. The method is shown to fulfil the IEC accuracy requirements for stationary harmonics, obtaining the same accuracy even under fluctuating conditions. Then, it is validated using simulated signals with real harmonic content. The proposed method is proven to be fully equivalent to Fourier analysis under stationary conditions, being often more accurate. Under non-stationary conditions, instead, it provides significantly higher accuracy, while the IEC strategy produces large errors. Lastly, the method is tested with real current and voltage signals, measured in conditions of high harmonic distortion. The proposed strategy provides a method with superior performance for fluctuating harmonics, but at the same time IEC compliant under stationary conditions

A robust wavelet-based hybrid method for the simultaneous measurement of harmonic and supraharmonic distortion

This paper introduces a new method for the simultaneous measurement of harmonic and supraharmonic distortion with improved robustness against amplitude and power frequency deviations. The proposed algorithm is based on wavelet analysis and it is designed to analyze a detect-all=true10 cycles measurement interval, something crucial when implementing methods to measure harmonic and supraharmonic content according to the IEC 61000-4-7 standard. Discrete Fourier Transform (DFT)-based methods, instead, must analyze a fixed detect-all=true200 interval in order to avoid apparent shifts of the supraharmonic frequency components. The results of the experimental measurements presented in the paper show that the DFT-based methodology suggested in the IEC 61000-4-7 standard produces results affected by the value of the power frequency and amplitude while the proposed method, instead, is insensitive to them. This feature also removes the need of a previous high pass filtering stage, required for the IEC method. Moreover, the proposed method has the additional advantage of working on the same measurement interval to calculate both harmonics and supraharmonics, which reduces the complexity of data handling by avoiding multithreaded Data Acquisition (DAQ) operations

On the suitability of the CISPR 16 method for measuring conducted emissions in the 2–150kHz range in low voltage grids

The IEC 61000–2–2 standard defines the compatibility levels to evaluate the conducted disturbances in the low voltage grid for the 2-150 kHz range. For frequencies 9–150 kHz, they are defined in terms of quasi peak values measured according to CISPR 16–1–1 standard, but no clear guidance is given on how to apply this standard to grid measurements. The definition of the method in CISPR 16–1–1 accepts a wide range of different implementations, all of them fulfilling the compliance requirements. The reasons are that the standard does not propose a fixed implementation but a ‘black-box’ approach, and some of the proposed configuration values are non-normative and/or wide tolerances are allowed. In this context, some parameters have a pivotal role in the results provided by the method. The impact of variation of these parameters on the measurement results is addressed in this work. In particular, the accuracy requirements and the reproducibility issues of the standard are studied. For that purpose, a high number of different compliant implementations have been developed and the influence of different features of the CISPR 16–1–1 method on the results of these implementations is identified and analyzed. The results show that the wide tolerances allowed by the CISPR 16 specification impede the comparison of results provided by measuring receivers based on different implementations of the standard. Results of the study also show that reproducibility issues for the same input signal may be relevant and generate inconsistences. Moreover, a fixed specific configuration does not ensure that uncertainty issues are solved, as the technical approach used in the implementation of the damped meter has a strong influence on the outputs. An unambiguous guidance of digital implementation of the standard could fix these issues

Statistical relationship between RMS and QP spectra of voltage measurements in the 9–150 kHz range

The main objective of this work is to obtain an empirical relationship between the root-mean-square and the quasi-peak spectra of voltage recordings in the electrical grid, based on a statistical analysis of a set of on-field measurements for the CISPR Band A (9–150 kHz). The lack of a relationship between the weighting root-mean-square and quasi-peak detectors implies the impossibility of calculating quasi-peak (QP) spectra from root-mean-square (RMS) measurements. It is of great interest that quasi-peak values can be estimated by simple calculations from RMS values, so that comparison to compatibility levels could be applied. This work defines an empirical relationship between the statistical variation of instantaneous RMS values over time, the maximum RMS value of these instantaneous values and the QP output. This relationship is described in the form of a simple equation that can be applied to RMS provided by the RM-A method, specifically developed for the CISPR Band A. A method for the fast assessment of QP values from simple RMS receivers is proposed as a potential application of the numerical RMS-QP relationship. Both the numerical RMS-QP relationship and its application as a simple and fast assessment method are evaluated with disturbances recorded in the low voltage grid.This project (18NRM05) has received funding from the EMPIR program co-financed by the Participating States and from the European Union's Horizon 2020 research and innovation program. This work was funded in part by the Basque Government under the grants IT1436–22 and PRE_2022_2_0074. This work was supported in part through grant PID2021–124706OB-I00 funded by MCIN/AEI/10.13039/501100011033 and by ERDF A way of making Europe

Flicker of Modern Lighting Technologies Due to Rapid Voltage Changes

The purpose of the present paper is to evaluate the sensitivity of modern lighting technologies to different types of RVCs. In order to do that, 27 modern lampsmainly LEDhave been subjected to real RVCs and their response has been assessed. The detection of RVCs on the grid has been performed according to the IEC 61000-4-30 detection method, while the response of the lamps has been measured with a light flickermeter and characterized using the instantaneous flicker perception, as defined in IEC 61000-4-15. The obtained results show a high dispersion in the response of the modern lighting technologies and high values of flicker perception, although with a lower sensitivity than the incandescent lamp. The results led the authors to propose the definition of a new immunity test to be added to the lamp immunity protocol IEC TR-61547-1, to ensure that newly produced lamps cause limited irritation to grid users.This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 676042. This work also received financial support from the Spanish MINECO through the project DPI2014-53317-R (cofinanced with the European Regional Development Fund) and from the Basque Government (Basque Country, Spain) through the project IT1087-16