Multi-point time-synchronized waveform recording for the analysis of wide-area harmonic propagation

This paper focuses on studying the phenomenon of harmonic distortion propagation through distribution networks. This phenomenon is governed by a combination of factors involving the nature of harmonic loads and their dynamic interaction, the influence of background voltage distortion, and harmonic impedance values. The objective of the proposed research includes evaluation of the network response at different nodes to harmonic current injections via utilizing a time-synchronized distributed measurement system. The study is performed in a fully controlled and flexible test network with three medium voltage/low voltage (MV/LV) distribution substations and several managed LV harmonic sources, namely PV inverter, single-phase EV charger and emulated harmonic load with reference current injections. A selection of the results is analyzed and interpretation of the observed phenomena is given with implications that synchronized harmonic measurements can be considered as potential powerful instruments for analyzing power quality disturbances

Supraharmonics in low voltage networks

This document presents a methodology for the identification of supraharmonic emissions (current and voltage conducted emissions between 2-150 kHz) at the end-user side of the distribution grid, using low power LED lamps as Equipment Under Test (EUT). First chapter presents a brief classification of power quality disturbances and describes those related to waveform distortion. Second chapter describes the measurement and experimental setups used to assess the supraharmonic emissions from selected EUT. Third chapter explains the methodology for the identification of supraharmonic emissions when EUT perform in single operation, and fourth chapter shows the interaction of such emissions for EUT in simultaneous operation. Along with a set of experimental combinations, supraharmonic emissions and their more relevant metrology aspects are discussed through the text. Results show how voltage and current supraharmonic emissions are (or not) affected by different variations in voltage source, equivalent network impedance, measurement setup and circuit topology of selected EUT. This research is aimed to contribute to the understanding and systematic assessment of supraharmonic emissions, with a special emphasis on metrological aspects and statistical methods for their identification.Este documento presenta una metodología para la identificación de emisiones supraarmónicas (emisiones conducidas de tensión y corriente entre 2-150 kHz) en el lado del usuario final de la red de distribución, utilizando lámparas LED de baja potencia como Equipo Bajo Prueba (EBP). El primer capítulo presenta una breve clasificación de las perturbaciones de la calidad de potencia y describe aquellas relacionadas con la distorsión de la forma de onda. El segundo capítulo describe la configuración experimental y de medición utilizada para evaluar las emisiones supraarmónicas de los EBP seleccionados. El tercer capítulo explica la metodología usada para la identificación de las emisiones supraarmónicas cuando los EBP funcionan de manera individual, y el cuarto capítulo muestra la interacción de dichas emisiones en la operación simultánea de los EBP. Junto con un conjunto de combinaciones experimentales, las emisiones supraarmónicas y sus aspectos metrológicos más relevantes se analizan a través del texto. Los resultados muestran cómo las emisiones supraarmónicas de tensión y corriente se ven (o no) afectadas por diferentes variaciones en la fuente de tensión, la impedancia de red equivalente, el sistema de medición y la topología del circuito del EBP seleccionado. El objetivo de esta investigación es contribuir a la comprensión y el estudio sistemático de las emisiones supraarmónicas, con especial énfasis en los aspectos metrológicos y los métodos estadísticos para su identificación.Maestrí

Technical design and commissioning of the KATRIN large-volume air coil system

The KATRIN experiment is a next-generation direct neutrino mass experiment with a sensitivity of 0.2 eV (90% C.L.) to the effective mass of the electron neutrino. It measures the tritium $\beta$-decay spectrum close to its endpoint with a spectrometer based on the MAC-E filter technique. The $\beta$-decay electrons are guided by a magnetic field that operates in the mT range in the central spectrometer volume; it is fine-tuned by a large-volume air coil system surrounding the spectrometer vessel. The purpose of the system is to provide optimal transmission properties for signal electrons and to achieve efficient magnetic shielding against background. In this paper we describe the technical design of the air coil system, including its mechanical and electrical properties. We outline the importance of its versatile operation modes in background investigation and suppression techniques. We compare magnetic field measurements in the inner spectrometer volume during system commissioning with corresponding simulations, which allows to verify the system's functionality in fine-tuning the magnetic field configuration. This is of major importance for a successful neutrino mass measurement at KATRIN.Comment: 32 pages, 16 figure

Data-Driven Modelling for Harmonic Current Emission in Low-Voltage Grid Using MCReSANet with Interpretability Analysis

Even though the use of power electronics PE loads offers enhanced electrical energy conversion efficiency and control, they remain the primary sources of harmonics in grids. When diverse loads are connected in the distribution system, their interactions complicate establishing analytical models for the relationship between harmonic voltages and currents. To solve this, our paper presents a data-driven model using MCReSANet to construct the highly nonlinear between harmonic voltage and current. Two datasets from PCCs in Finland and Germany are utilized, which demonstrates that MCReSANet is capable of establishing accurate nonlinear mappings, even in the presence of various network characteristics for selected Finland and Germany datasets. The model built by MCReSANet can improve the MAE by 10% and 14% compared to the CNN, and by 8% and 17% compared to the MLP for both Finnish and German datasets, also showing much lower model uncertainty than others. This is a crucial prerequisite for more precise SHAP value-based feature importance analysis, which is a method for the model interpretability analysis in this paper. The results by feature importance analysis show the detailed relationships between each order of harmonic voltage and current in the distribution system. There is an interactive impact on each order of harmonic current, but some orders of harmonic voltages have a dominant influence on harmonic current emissions: positive sequence and zero sequence harmonics have the dominant importance in the Finnish and German networks, respectively, which conforms to the pattern of connected load types in two selected Finnish and German datasets. This paper enhances the potential for understanding and predicting harmonic current emissions by diverse PE loads in distribution systems, which is beneficial to more effective management for optimizing power quality in diverse grid environments

Fault Detection Analysis in Ball Bearings using Machine Learning Techniques

The Bearing element is very essential component of any rotating equipment. Any defect in the bearings lead to instable performance of the machinery. To avoid such malfunction and breakdown of the machinery equipment due to misalignment is review critically in this research paper and various machine learning techniques to tackle the issue is highlighted. This review article finds the basis for developing an effective system in order to reduce the breakdown of machinery or equipment. Conventional Machine Learning methods, like Artificial neural network, Decision Tree, Random Forest, Support Vector Machines(SVM) have been applied to detecting categorizing fault, while the application of Deep Learning methods has ignited great interest in the industry

Characterizing Light Output Variations from Solid State Lighting Due to High Frequency Electromagnetic Interference

Consumer electronic devices employing active power electronic switching have been increasingly used in the last decade. With the rise in number of these devices, the emission of harmonic currents by these devices has changed both in magnitude and character. The effects of harmonic frequencies up to 2000 Hz on various electrical and electronic devices has been the subject of considerable scrutiny over the past decade. However, newer consumer devices employ switched mode power electronic circuits that switch in the multiple kilohertz range. The emission from these devices, along with power line communication, are sources of high frequency currents in the range of 2 to 150 kHz. As a result, there has been an appreciable rise in the amount of conducted emission in the frequency range 2 to 150 kHz. One of the important outcomes of rising emission in this frequency range is that there have been reported cases of interference with various consumer electronic devices. Among the devices in which interference has been reported are the new generation of solid state LED lamps which have become popular in the last 3-5 years. Considerable research has been done in the past about the effects of light flicker and the modulation of light output from incandescent lamps, on human beings. However, the utilization of power electronic converters changes this paradigm considerably. Unlike incandescent bulbs, where low frequency modulation of input voltage resulted in visible flicker, observations and reports have shown that LED lamps may be susceptible to flicker from frequencies above the 2 kHz mark. As a result, old methods of predicting flicker and studying it may no longer be applicable. This thesis attempts to shorten this gap in knowledge by exploring the topic of LED flicker due to high frequency distortion, and the factors that affect it. This was achieved by exposing LED lamps of various sizes and from various manufacturers, to realistic voltage distortion signals, recorded in the power system. Signals with high-frequency distortion superimposed on to the fundamental, were used. The test set-up used, allowed for the testing of light equipment with various types and levels of distortion at different points on wave. For the first time, experimental results showed that not only does high frequency voltage distortion cause changes in average value of light output and the modulation of light output, but that this change depends upon the point-on-wave at which the high frequency distortion appears. The mathematical tool of cross-correlation was proposed to quantify the effect of point-on-wave of high frequency distortion on light output. The utilization of this tool showed that LED lamps are susceptible to distortion appearing near the peak or near the zero crossing of the input voltage. In order to understand the dependence of LED flicker on the topology of the LED driver, five LED driver development boards available commercially were also subjected to the above mentioned high frequency voltage distortion. The results showed that light flicker from LED lamps is not necessarily a by-product of LED driver topology. The utilization of discontinuous conduction mode of operation and an isolation transformer in the LED driver is not sufficient to disconnect the LED load from input voltage variations. LED drivers of the same topology can behave completely different, likely due to the control methodology employed by each manufacturer. Finally, a simulation model of a popular LED driver solution: a flyback DC-DC converter with primary side regulation was developed to verify the experimental results and perform root cause analysis for the observed phenomena. Changes in control methodology and circuit design were suggested to overcome this flicker problem and evidence of the degradation of circuit components due to excess heat generated by high frequency distortion was shown

Prediction of EMI Filter Attenuation in Power-Electronic Converters via Circuit Simulation

This article investigates the conducted-emission (CE) suppression characteristics of electromagnetic interference (EMI) filters used in power-electronic equipment by time-domain circuit simulation. An operational definition of insertion attenuation is introduced by comparing the CE in the absence and in the presence of the EMI filter. For the sake of exemplification, the analysis focuses on switched-mode dc-dc converters. It is shown that the EMI-filter attenuation behaves differently from the standard insertion loss (IL) and exhibits peculiar properties in these circuits. Namely, its response is known at discrete frequencies where the converter generates CE and may strongly depend on the harmonic index so to jump between quite different levels from a harmonic component to the next one, with a pseudoperiodic behavior, which can be related to the duty cycle. This effect is caused by circuit nonlinearity and is partially mitigated if the simulation accounts for two practically relevant aspects: random instability of the duty cycle and resolution bandwidth of the EMI receiver. The dependence of the common-mode (CM) and differential-mode attenuations on the loading conditions and duty cycle is analyzed, and it is shown that linear IL models provide reasonable predictions of CM attenuation only. Finally, experimental evidence of the unveiled phenomena is presented