Estudio y caracterización de la calidad de suministro eléctrico en los sistemas de alumbrado

Un reciente estudio de la Comisión Europea revela que es posible ahorrar entre un 30% y un 50% en la electricidad empleada en iluminación mediante la inversión en sistemas de iluminación eficientes. En la mayoría de los casos, esas inversiones no solo son rentables y sostenibles, sino que también mejoran la calidad de la iluminación. Según la aplicación, los sistemas de alumbrado para interior y exterior presentan una amplia variedad de tecnologías de lámparas. En el alumbrado de interior se incluyen, entre otras, las incandescentes, halógenas y CFL; mientras que en el de exterior encontramos principalmente lámparas de sodio de alta presión (HPS) conectadas a balastos electrónicos y electromagnéticos. Ambos tipos de alumbrado engloban la cada vez mayor presencia de lámparas de LED. Éstas no se usan actualmente en el alumbrado público, a pesar de presentar continuamente importantes mejoras en la eficiencia y en la calidad del color, lo que permite su aplicación en todos los sistemas de alumbrado. Sin embargo, al usarse el ahorro energético como característica de venta, los usuarios necesitan tener claro su ahorro energético. Por otro lado, la iluminación también afecta a la calidad de suministro del sistema de distribución eléctrico. La calidad de suministro está relacionada con las desviaciones en la tensión y corriente de la forma de onda sinusoidal de amplitud y frecuencia constantes. El deterioro en la calidad de suministro se debe a eventos y perturbaciones en el estado estacionario entre los que se incluye la distorsión armónica entre otras. El tema principal de la tesis es la caracterización armónica de diversas tecnologías de iluminación. Se ha estudiado el cambio a LED en alumbrado de interior y exterior. Para poder evaluar esto ha sido necesaria la realización de diversos experimentos. Se han considerado tanto los armónicos (hasta 150 kHz) como los interarmónicos; así como la agregación de cargas, para lo que se han caracterizado magnitudes, ángulos de fase, y la expresión compleja de las corrientes. Esto servirá de ayuda a la hora de caracterizar el impacto de añadir nuevos dispositivos, y en la caracterización armónica tras dicha agregación. Las conclusiones en el alumbrado de interior revelan que el impacto armónico depende en gran medida de los otros equipos conectados, y que dispositivos como la televisión, el ordenador o el microondas tienen un impacto mucho mayor que las lámparas. El impacto de los LED es menor, para la mayoría de los órdenes armónicos, que en las CFL para la misma cantidad de lúmenes, ya que las primeras absorben menos corriente. Se muestra además un cambio en la emisión hacia las altas frecuencias derivado de la introducción de LED. También parecen aumentar los interarmónicos y los armónicos pares con la introducción de las mismas. Sin embargo, en general, no se espera un gran impacto de lo anterior. Además, en cuanto a los LED en el alumbrado de exterior, su emisión armónica es menor que la de las lámparas HPS para todo el espectro en frecuencia. Por lo que la sustitución de sodio por LED no resultará en un incremento de los niveles armónicos. Algunas otras ventajas como las posibilidades de atenuación incrementarán la eficiencia de nuestro sistema de alumbrado. A pesar de no haberse observado agregación con los balastos electrónicos, se necesitan más medidas para predecir de forma precisa la emisión de mezcla de lámparas iguales y distintas.A recent study carried out for the European Commission has shown that between 30% and 50% of electricity used for lighting could be saved by investing in energyefficient lighting systems. In most cases, such investments are not only profitable and sustainable but they also improve lighting quality. According to the application, indoor and outdoor lighting systems present a wide variety of lamp technologies. The former includes incandescent, halogen and CFL. The latter includes HPS mainly connected to both electronic and electromagnetic ballasts. Both technologies share the incoming presence of LED lamps. At the moment LED lamps are not commonly used as street lighting systems, although recent technology is improving gradually the LEDs efficiency and color quality which allows their application in all lighting systems. However, energy saving is often used as one of their selling features, and customers need to have a clear understanding of LED energy-saving potential. On the other hand, lighting also affects the Power Quality (PQ) of the electrical distribution system. PQ is concerned with deviations of the voltage or current from the ideal single-frequency sine wave of constant amplitude and frequency. Power quality deterioration is due to events and steady state disturbances which include harmonic distortion among others. The main focus of this thesis is the harmonic characterization of several lighting technologies. The change to LED lamps has been considered both in indoor and outdoor. In order to do so, a wide variety of measurements have been needed in both fields of lighting. Harmonics and interharmonics have been considered, and all the frequency range up to 150 kHz has been studied. Aggregation of devices has also been taken into account, in such way; magnitudes, phase angles and complex current from harmonics have been characterized. This will help us to foresee the impact of adding new devices and characterize the expected harmonic content after the addition. Conclusions in indoor lighting reveal that the harmonic impact strongly depends on which other equipment is connected and that devices like TV, computer and microwave have a much bigger impact than the lamps. The impact of LED lamps is smaller, for most harmonics, than for CFLs for the same amount of lumen because LED lamps take less fundamental current. Several of the observations show a shift towards emission at higher frequencies with the introduction of LED lamps. Also interharmonic and evenharmonic levels appear to increase with the introduction of LED lamps. Although no adverse impacts of this are yet to be expected. Moreover, regarding the change to LED in outdoor lighting, the harmonic emission from LED street lamps is less than from HPS lamps, including all frequency bands. Replacing HPS lamps with LED lamps will thus not result in an increase in harmonic levels in the grid. Some other advantages like dimming possibilities and energy savings will increase efficiency within our lighting system. Though no aggregation has been observed with electronic ballasts, more measurements are needed to accurately estimate the emission from uniformed and mixed loads

Energy Management Expert Assistant, a New Concept

In recent years, interest in home energy management systems (HEMS) has grown significantly, as well as the development of Voice Assistants that substantially increase home comfort. This paper presents a novel merging of HEMS with the Assistant paradigm. The combination of both concepts has allowed the creation of a high-performance and easy-to-manage expert system (ES). It has been developed in a framework that includes, on the one hand, the efficient energy management functionality boosted with an Internet of Things (IoT) platform, where artificial intelligence (AI) and big data treatment are blended, and on the other hand, an assistant that interacts both with the user and with the HEMS itself. The creation of this ES has made it possible to optimize consumption levels, improve security, efficiency, comfort, and user experience, as well as home security (presence simulation or security against intruders), automate processes, optimize resources, and provide relevant information to the user facilitating decision making, all based on a multi-objective optimization (MOP) problem model. This paper presents both the scheme and the results obtained, the synergies generated, and the conclusions that can be drawn after 24 months of operation

Future work on harmonics : some expert opinions part I : wind and solar power

A workshop on power system harmonics was organized in Stockholm in January 2014. On the agenda was among others a discussion on what are the main issues on harmonics at the moment and in the near future. The results of this discussion are summarized in this paper and some of the issues are discussed in more detail in this paper and in its companion paper. This paper discusses emission from wind and solar power as well as advantages and disadvantages of active and passive filters

Novel Segmentation Technique for Measured Three-Phase Voltage Dips

This paper focuses on issues arising from the need to automatically analyze disturbances in the future (smart) grid. Accurate time allocation of events and the sequences of events is an important part of such an analysis. The performance of a joint causal and anti-causal (CaC) segmentation method has been analyzed with a set of real measurement signals, using an alternative detection technique based on a cumulative sum (CUSUM) algorithm. The results show that the location in time of underlying transitions in the power system can be more accurately estimated by combining CaC segmentation methods

LED street lighting: A power quality comparison among street light technologies

High-pressure sodium lamps are currently the main lamps used in public lighting. However, the possibility of using high-power light emitting diode (LEDs) for street lighting is growing continuously due to their greater energy efficiency, robustness, long life and light control. The aim of this paper is to study the power quality of high-power lighting networks based on LED and high-pressure sodium lamps. Both electromagnetic and dimmable electronic ballasts, which can dim the lamp output smoothly and uniformly, have been used connected to high-pressure sodium lamps. High-pressure sodium lamps connected to electronic equipment have been tested with different arc power levels using dimming on a 230V power supply. The study presented in this paper is completely based on measurements, including harmonic currents in the frequency range up to 150 kHz for all the technologies. The main results show a broadband spectrum in LED lamps which confirms other research in Fuorescent lamps powered by high-frequency ballasts. Results also indicate a decrease in the harmonic value with increasing harmonic order, and a decrease in the harmonic value at half load (60%) compared with full load (100%). Although total harmonic distortion of the current is lower with highpressure sodium lamps connected to electronic rather than electromagnetic ballasts, LED lamps achieved the lowest total harmonic distortion of curren

Microgrids Power Quality Enhancement Using Model Predictive Control

In electric power systems, any deviation with respect to the theoretical sinusoidal waveform is considered to be a disturbance in the power quality of the electrical grid. The deviation can alter any of the parameters of the waveform: frequency, amplitude, and symmetry among phases. Microgrid, as a part of the electric power system, has to contribute providing an adequate current waveform in grid connected-mode, as well as to guarantee similar voltage features than the standard requirement given for public distribution grids under normal exploitation conditions in islanded mode. Adequate power quality supply is necessary for the correct compatibility between all the devices connected to the same grid. In this paper, the power quality of microgrids is managed using a Model Predictive Control (MPC) methodology which regulates the power converters of the microgrids in order to achieve the requirements. The control algorithm is developed for the following microgrids working modes: grid-connected, islanded, and interconnected. The simulation results demonstrate that the proposed methodology improves the transient response in comparison with classical methods in all the working modes, minimizing the harmonic content in the current and the voltage even with the presence of non-balanced and non-harmonic-free three-phase voltage and current systems

A Novel Direct Load Control Testbed for Smart Appliances

The effort to continuously improve and innovate smart appliances (SA) energy management requires an experimental research and development environment which integrates widely differing tools and resources seamlessly. To this end, this paper proposes a novel Direct Load Control (DLC) testbed, aiming to conveniently support the research community, as well as analyzing and comparing their designs in a laboratory environment. Based on the LabVIEW computing platform, this original testbed enables access to knowledge of major components such as online weather forecasting information, distributed energy resources (e.g., energy storage, solar photovoltaic), dynamic electricity tariff from utilities and demand response (DR) providers together with different mathematical optimization features given by General Algebraic Modelling System (GAMS). This intercommunication is possible thanks to the different applications programming interfaces (API) incorporated into the system and to intermediate agents specially developed for this case. Different basic case studies have been presented to envision the possibilities of this system in the future and more complex scenarios, to actively support the DLC strategies. These measures will offer enough flexibility to minimize the impact on user comfort combined with support for multiple DR programs. Thus, given the successful results, this platform can lead to a solution towards more efficient use of energy in the residential environment

Bilingual multimedia resources to improve learning in engineering subjects

Estudios demuestran que la tasa de éxito de las asignaturas se fomenta si los alumnos aprecian la interdisciplinariedad entre asignaturas. Por otro lado, el uso de las nuevas tecnologías como el aprendizaje multimedia resulta esencial hoy día, más aún si se realiza en un segundo idioma. En el artículo se describen una serie de recursos multimedia bilingües que pretenden servir para mejorar el aprendizaje en asignaturas de ingeniería, permitiendo desarrollar competencias transversales y específicas de las titulaciones de grado de Ingeniería Industrial. El uso de esta experiencia puede suponer importantes mejoras a nivel de título, ya que poner de manifiesto el nexo de unión entre varias asignaturas ayuda al aprendizaje, además de ofrecer una prospección de futuro en las diversas asignaturas del grado, lo que motivará y alentará al alumnado en promocionar a los siguientes cursos. Ver una aplicación práctica concreta en 1º curso (o incluso ver en los vídeos) y saber que serán capaces de realizar el dispositivo con el que se ha realizado dicho ensayo en asignaturas posteriores, animará al alumnado y les pondrá imagen a prácticas concretas de cursos siguientes, hecho que siempre es demandado por los alumnos durante los primeros cursos.Studies show that the success rate of the subjects is encouraged if students appreciate the interdisciplinarity between subjects. On the other hand, the use of new technologies such as multimedia learning is essential today, even more if it is done in a second language. The article describes a series of bilingual multimedia resources that aim to serve to improve learning in engineering subjects, allowing to develop transversal and specific competences of Industrial Engineering degree programs. Important improvements can also be achieved at degree’s level, since highlighting the link between various subjects helps learning, as well as offering future prospects within the subjects of the degree, which will motivate and encourage students to be promoted. Seeing a specific practical application in 1st year course and know (or even watch videos) that they will be able to make the device that will be used in later subjects, will therefore encourage the students and will put image to concrete practical lessons of following courses, which is always demanded by the students during the first courses

Effectiveness of a strategy that uses educational games to implement clinical practice guidelines among Spanish residents of family and community medicine (e-EDUCAGUIA project):A clinical trial by clusters

This study was funded by the Fondo de Investigaciones Sanitarias FIS Grant Number PI11/0477 ISCIII.-REDISSEC Proyecto RD12/0001/0012 AND FEDER Funding.Background: Clinical practice guidelines (CPGs) have been developed with the aim of helping health professionals, patients, and caregivers make decisions about their health care, using the best available evidence. In many cases, incorporation of these recommendations into clinical practice also implies a need for changes in routine clinical practice. Using educational games as a strategy for implementing recommendations among health professionals has been demonstrated to be effective in some studies; however, evidence is still scarce. The primary objective of this study is to assess the effectiveness of a teaching strategy for the implementation of CPGs using educational games (e-learning EDUCAGUIA) to improve knowledge and skills related to clinical decision-making by residents in family medicine. The primary objective will be evaluated at 1 and 6months after the intervention. The secondary objectives are to identify barriers and facilitators for the use of guidelines by residents of family medicine and to describe the educational strategies used by Spanish teaching units of family and community medicine to encourage implementation of CPGs. Methods/design: We propose a multicenter clinical trial with randomized allocation by clusters of family and community medicine teaching units in Spain. The sample size will be 394 residents (197 in each group), with the teaching units as the randomization unit and the residents comprising the analysis unit. For the intervention, both groups will receive an initial 1-h session on clinical practice guideline use and the usual dissemination strategy by e-mail. The intervention group (e-learning EDUCAGUIA) strategy will consist of educational games with hypothetical clinical scenarios in a virtual environment. The primary outcome will be the score obtained by the residents on evaluation questionnaires for each clinical practice guideline. Other included variables will be the sociodemographic and training variables of the residents and the teaching unit characteristics. The statistical analysis will consist of a descriptive analysis of variables and a baseline comparison of both groups. For the primary outcome analysis, an average score comparison of hypothetical scenario questionnaires between the EDUCAGUIA intervention group and the control group will be performed at 1 and 6months post-intervention, using 95% confidence intervals. A linear multilevel regression will be used to adjust the model. Discussion: The identification of effective teaching strategies will facilitate the incorporation of available knowledge into clinical practice that could eventually improve patient outcomes. The inclusion of information technologies as teaching tools permits greater learning autonomy and allows deeper instructor participation in the monitoring and supervision of residents. The long-term impact of this strategy is unknown; however, because it is aimed at professionals undergoing training and it addresses prevalent health problems, a small effect can be of great relevance. Trial registration: ClinicalTrials.gov: NCT02210442.Publisher PDFPeer reviewe