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

Development and metrological characterization of measuring instruments for low-voltage networks monitoring

This thesis collects the main results about my research and the work related to the designing of monitoring systems of LV distribution networks. The first three chapters are introductive; the first one describes the main concepts contained in the guide for the evaluation of measurement uncertainty (also called GUM), since some of them are recalled in the next sections. Chapter 2 provides the main notions on the smart grid concept, the new generation of distribution networks characterized by a high degree of automation, and on the main power quality problems affecting the grids. Therefore, the following standard, connected to the above topics, are presented: (i) EN 50160. (ii) IEEE 519. (iii) IEC 61000-4-7. Finally, chapter 3 presents a general description of the main sensors suitable for the LV monitoring systems for the acquisition of voltage and current waveforms, providing information on the working principles, the metrological performances and recalling the related standards (as the IEC 61869). Chapter 4 gets to the heart of the work done in my PhD course; in fact, the two monitoring devices specifically developed to meet the needs of the future smart grids are presented: the Guardian Meter and the Network Monitoring Unit. Hence, information is provided on the purposes of each device, on their technical characteristics, on the tests conducted for the metrological characterization and on the results related to measurement performance. It is noteworthy that the testing activity has led to the development of procedures, some of which innovative, for the metrological evaluation of monitoring devices. In fact, the last chapter collects the scientific outcomes deriving from the R&D activity, which can be the starting points for the updating of current standards related to monitoring systems and for the development of new procedures to evaluate the metrological performance of the energy meters

Discussion on Electric Power Supply Systems for All Electric Aircraft

The electric power supply system is one of the most important research areas within sustainable and energy-efcient aviation for more- and especially all electric aircraft. This paper discusses the history in electrication, current trends with a broad overview of research activities, state of the art of electrication and an initial proposal for a short-range aircraft. It gives an overviewof the mission prole, electrical sources, approaches for the electrical distribution system and the required electrical loads. Current research aspects and questions are discussed, including voltage levels, semiconductor technology, topologies and reliability. Because of the importance for safety possible circuit breakers for the proposed concept are also presented and compared, leading to a initial proposal. Additionally, a very broad review of literature and a state of the art discussion of the wiring harness is given, showing that this topic comes with a high number of aspects and requirements. Finally, the conclusion sums up the most important results and gives an outlook on important future research topics

Wind Power

This book is the result of inspirations and contributions from many researchers of different fields. A wide verity of research results are merged together to make this book useful for students and researchers who will take contribution for further development of the existing technology. I hope you will enjoy the book, so that my effort to bringing it together for you will be successful. In my capacity, as the Editor of this book, I would like to thanks and appreciate the chapter authors, who ensured the quality of the material as well as submitting their best works. Most of the results presented in to the book have already been published on international journals and appreciated in many international conferences

Development and Experimentation of Traceable Characterization Methods for Medium Voltage Instrument Transformers for PQ and PMU Applications

L'abstract è presente nell'allegato / the abstract is in the attachmen

PMSG-based wind power integration-modelling and analysis of impacts on the dynamic performances of a power system and mitigation under stochastic wind disturbances.

Doctor of Philosophy in Electrical Engineering. University of KwaZulu-Natal, Durban 2017.Because of the ever-growing demand for electrical energy and environmental challenges of fossil fuel consumption, a priority has been given to the development of wind energy systems, among which, currently, permanent magnet synchronous generator (PMSG)-based wind power is receiving much attention from researchers, engineers, and turbine manufacturers. However, high PMSG-based wind power integration into a power system brings several challenges to transmission system operators. One of the challenges is its impacts on the dynamic performances of a power system due to the presence of stochastic wind disturbances. Thus, for a thorough investigation of the influences of stochastic wind speed disturbances, a proper wind speed model should be adopted. Therefore, this thesis proposes the use of Markov chain model for modelling wind speed series in dynamic simulations of wind turbines. In this regard, comparison of statistical quantities of measured wind speed data from Durban and Markov model generated ones confirms the accuracy of the model adopted. The results have shown that the dynamic performances of a power system deteriorate with the presence of stochastic wind speed disturbances, and thus the need for improving poor dynamic performances. Wind gusts cause stress, over currents, over voltages and instability in a power system. This thesis, therefore, introduces novel mitigation techniques based on virtual controls stemming from real resistors, compensators, and damper windings, and supplementary controllers to enhance the dynamic performances of a wind turbine directdriven PMSG, the main component of a PMSG-based wind farm. In the proposed schemes, the virtual controllers adjust the terminal d- and q-axis reference voltages in the generator side converter controller and their influences on the dynamic performances of the wind turbine are investigated. MATLAB/Simulink simulations on a wind turbine connected to an infinite bus show that virtual controls are effective in enhancing the dynamic performances of the PMSG. Local oscillations caused by wind disturbances are efficiently suppressed. Overall, the proposed mitigation techniques smooth the rotor speed and power of a PMSG, and hence reducing the influences of the stochastic wind speed disturbances. Furthermore, the results have demonstrated that stochastic wind speed disturbances affect the dynamic performances of a power system containing a PMSG-based wind farm as the dynamics of synchronous machines within the system depend on power balance, which is influenced by the power response of the wind farm. Finally, investigations in this thesis have confirmed that virtual controls and FACTS devices such as STATCOM and SVC are efficient in improving the dynamic performances of a power system containing PMSG-based wind farms under stochastic wind disturbances

Measurements, Models, Systems and Design

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Grid-Connected Renewable Energy Sources

The use of renewable energy sources (RESs) is a need of global society. This editorial, and its associated Special Issue “Grid-Connected Renewable Energy Sources”, offers a compilation of some of the recent advances in the analysis of current power systems that are composed after the high penetration of distributed generation (DG) with different RESs. The focus is on both new control configurations and on novel methodologies for the optimal placement and sizing of DG. The eleven accepted papers certainly provide a good contribution to control deployments and methodologies for the allocation and sizing of DG