Rozprawy doktorskie: „IMPACTS OF POWER QUALITY”

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Mngxuma, Khayakazi. "The power quality of wind turbines in Sout Africa and their impacts on distribution networks". Master's thesis, University of Cape Town, 2005. http://hdl.handle.net/11427/5157.

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Includes bibliographical references (leaves 75-78).
This thesis describes an investigation into the power quality of wind turbines and the impacts this could have on distribution networks. The main focus is on voltage fluctuations and flicker as grid connected wind turbines could have a huge impact on these, especially when connected to weak distribution networks.

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Choudhry, Mohammad A. "A methodology for evaluating energy efficient lighting technologies for their performance, power quality and environmental impacts". Diss., Virginia Tech, 1995. http://hdl.handle.net/10919/40213.

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Orebrand, Idah, Max Rosvall i Melissa Eklund. "Microgeneration of PV power and its impact on power quality in the distribution grid". Thesis, Uppsala universitet, Institutionen för teknikvetenskaper, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-324313.

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This bachelor thesis examines the impacts of installed microgeneration of PV power in the distribution grid. The thesis examines the selected distribution grids power quality and how it is affected in terms of exceeding currents, voltages and reverse power flows and how the future trend of microgeneration of PV power will develop. A case study is made on Gotland with the support of the distribution grid owner, GEAB. Three of GEAB's distribution grids with different customer configurations and grid structures are being used to create different case scenarios. The production from the PV plants is calculated with production data from a project that GEAB performed with PV plants but dismantled in 2016. The Newton-Raphson power flow method is used to run the simulations of the grids with different amount of installed PV power. The results show that exceeding maximum current is the first parameter to limit and affect the power quality for all grids. After this the three grids can handle different amounts of installed PV power with respect of the remaining parameters. The simulations also show that losses in the grid are reduced due to installations of PV plants, although their small magnitude do not make them a significant aspect to consider when evaluating microgeneration in the distribution grid. When comparing to future scenarios it is concluded that the grids are dimensioned to handle a various amount of installed microgeneration without the power quality being affected. To analyse the sensitivity of the results a sensitivity analysis is performed on the slack node voltage by alternating the voltage level. The result indicates that a higher slack node voltage gives more exceeding voltages for the city power grid and the two rural grids.

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Taylor, Ryan. "The economic impact of poor power quality to New Zealand". Thesis, University of Canterbury. Engineering, 2011. http://hdl.handle.net/10092/8973.

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This project entitled 'The Economic Impact of Poor Power Quality to New Zealand' aims to identify the most problematic and costly power quality issues for industry and residential customers in New Zealand. The economic cost or poor power quality will be used by the EPECentre in their future power quality work. Some recommendations are included from the researcher where appropriate. Society is becoming more dependent on computers and digital circuitry. Industry, commercial and residential users are now dependent on a reliable, high-quality electrical power source to ensure these devices are operational. Electricity supply, however, is not perfect and when electronic equipment encounters electricity that is not of a regular sinusoidal waveform, loss of performance or failure may occur. These issues are termed power quality issues and include: • Voltage sags • Surges • Transients • Harmonics • Momentary power interruptions

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Morales, Ana. "Impact of decentralized power on power systems". Doctoral thesis, Universite Libre de Bruxelles, 2006. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210841.

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Wind generation is one of the most successful sources of renewable energy for the production of electrical energy. Wind power offers relatively high capacities, with generation costs that are becoming competitive with conventional energy sources. However, a major problem to its effective use as a power source is the fact that it is both intermittent and diffuse as wind speed is highly variable and site-specific. This is translated in large voltage and frequency excursions and dynamically unstable situations when fast wind power changes. Very high wind speeds will result in sudden loss of wind generator production. The requirement to ensure that sufficient spinning reserve capacity exists within the system to compensate for sudden loss of generation becomes crucial. From the utilities operators’point of view, the primary objective is the security of the system, followed by the quality of the supplied power.

In order to guard the system security and quality of supply and retain acceptable levels, a maximum allowed wind power penetration (wind margin) is normally assumed by the operators. Very conservative methods are used to assess the impact of wind power and the consequences turn to under-exploitation of the wind power potential in a given region. This thesis presents the study of actual methods of wind power assessment, divided into three parts:

1. Part I: Impact on the Security of Power Systems

2. Part II: Impact on the Power Quality

3. Part III: Impact on the Dynamic Security of Power Systems
Doctorat en sciences appliquées
info:eu-repo/semantics/nonPublished

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Neto, Aimé Fleury de Carvalho Pinto. "Avaliação do impacto de sistemas fotovoltaicos conectados à rede de distribuição de baixa tensão". Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/86/86131/tde-09112016-201805/.

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Este trabalho apresenta a avaliação dos impactos elétricos da inserção da geração distribuída de sistemas fotovoltaicos conectados à rede de distribuição em baixa tensão, com a finalidade de identificar os impactos e demonstrar que estes podem ser controlados. O estudo consistiu de uma avaliação teórica e de um estudo de caso da inserção da geração fotovoltaica considerando aspectos da qualidade de energia da rede, curva de carga resultante, vida útil de transformadores e gestão ativa da demanda. Os resultados mostraram que a inserção da geração fotovoltaica na rede de baixa tensão altera a curva de carga da unidade consumidora, mas que essas alterações podem ser controladas pela gestão ativa da demanda utilizando armazenamento de energia. Os resultados também mostraram que a geração fotovoltaica também afeta a tensão e o fator de potência da unidade consumidora, mas que essas alterações podem ser controladas pela produção de potência reativa pelo inversor. Além disso, verificou- se que a geração fotovoltaica não afetou a distorção harmônica de tensão da rede e que aumentou a vida útil do transformador.
This work presents the evaluation of grid connected photovoltaic systems\' impact on low voltage electrical grid, in order to identify the impacts and demonstrate that it can be controlled. The study consisted of a theoretical evaluation and of a case study of photovoltaic generation inclusion considering aspects of grid power quality, resulting load curve, lifespan of transformers and demand side management. The results showed that the inclusion of photovoltaic generation in low voltage network changes the load curve of the consumer unit, but these changes can be controlled by demand side management using energy storage. The results also showed that the photovoltaic generation also affects the voltage and the power factor of the consumer unit, but these changes can be controlled by the production of reactive power by the inverter. Furthermore, it was found that the photovoltaic generation does not affect the voltage harmonic distortion of the mains and it increases the lifespan of the transformer.

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Villegas, Ruiz Eloy Ángel. "Wave aberrations in ophthalmic progressive power lenses and impact on visual quality". Doctoral thesis, Universidad de Murcia, 2009. http://hdl.handle.net/10803/10843.

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Las lentes progresivas (LP) para gafas es una solución muy extendida para la presbicia, ya que proporcionan una visión continua a todas las distancias debido a un cambio progresivo de potencia. En este trabajo se han medido las aberraciones de frente de onda espacialmente resueltas y la calidad visual en estas lentes. Además del astigmatismo que aumenta periféricamente, también se han encontrado pequeños valores de aberraciones de tercer orden, coma y trefoil, que producen un bajo deterioro de la calidad óptica y visual. El logaritmo de métricas sobre la PSF del sistema lente con ojo son las que mejor predicen la agudeza visual. Durante la primera semana de adaptación, no se aprecia una mejora significativa de la agudeza visual a través de distintas zonas de las LPs. Al comparar diferentes LPs, las aberraciones, principalmente el astigmatismo, se comporta como un colchón de agua, que se puede mover pero no eliminar.
Progressive lenses (PL) are designed to provide continuous vision at all distances by means a progressive change in spherical power from upper to lower zones. In this thesis, we measure the spatially resolved aberrations and the visual quality of PLs. In addition to astigmatism, third order aberrations, coma and trefoil, are also found in the PLs, but the impact of these aberrations on visual performance is limited. The logarithm of metrics on the PSF of the entire system eye plus PL are the parameters that best predict the visual acuity. There is not a significant improvement of visual acuity through the different zones of the PLs during the first week of adaptation. The current designs of PLs are somehow similar to a waterbed, with the aberrations, mainly astigmatism, being the water: they can be moved but they cannot be eliminated.

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Van, der Westhuizen Bernard Cornelius. "Impact of coal quality on equipment lifetime at coal-fired power stations". Diss., University of Pretoria, 2019. http://hdl.handle.net/2263/79670.

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With the export of coal being more lucrative than selling coal to South African power producers, power station operators might consider accepting lower-quality coal. While the impact lower quality coal has on cycle efficiency is understood, the influence it has on equipment reliability and lifetime is often not understood. This study focusses on addressing the question of how different characteristics of coal influences different damage mechanisms of common power station equipment. The results are translated into a reference framework that can be used when coal quality variation is expected. The influence of coal calorific value and ash content has on air-heater element erosion was evaluated. This was accomplished by establishing a correlation between calorific value and ash content of coal from a specific colliery; this was then used to calculate the mass of fly ash and flue gas produced when burning enough coal to satisfy the boiler load. An erosion model was then used along with historical coal quality and air heater erosion history to develop and fit a model for full boiler load. The model was verified against data not used during the development of the model, and a seemingly good prediction was made when compared to the measured result. The calorific value of the coal in the model was varied for a hypothetical situation; this indicated that as calorific value decreases the erosion of air heater elements increases. The influence abrasiveness index has on mill liners was also investigated as part of this study. Historical liner ultrasonic thickness and coal abrasiveness index results were used to fit a mathematical formula. The results indicate that for the ball mills at the power station used in the case study, the abrasiveness index did not have a significant influence on the wear rate of mill liners. The relationship was established to be directly proportional to increased abrasiveness index resulting in an increased wear rate. The final two case studies that form part of this overall study were focussed on boiler temperature variations as a result of variation in coal calorific value and establishing the impact coal “hang-ups” have on the lifetime of a drum reclaimer. The first of these two case studies was completed by creating a mathematical thermo-hydraulic model of a hypothetical boiler and calculating the effect calorific value would have on the boiler temperature distribution. The results were then compared to temperature-related damage mechanisms; the comparison indicated that a variation in calorific value, whether up or down from the designed value would be negative for overall boiler health. The final case study was not completed due to the unavailability of related equipment. A full description of the envisaged study is provided.
Dissertation (MEng)--University of Pretoria, 2019.
Mechanical and Aeronautical Engineering
MEng
Unrestricted

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Thapar, Alok. "Investigation of power quality catagorisation and simulating its impact on sensitive electronic equipment /". [St. Lucia, Qld.], 2004. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe18160.pdf.

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MATOS, JANARA de C. "Aspectos hidrobiologicos do complexo de represas Paraibuna-Piratininga, Sao Paulo, com enfase na comunidade fitoplanctonica". reponame:Repositório Institucional do IPEN, 2010. http://repositorio.ipen.br:8080/xmlui/handle/123456789/9513.

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Made available in DSpace on 2014-10-09T12:27:30Z (GMT). No. of bitstreams: 0
Made available in DSpace on 2014-10-09T14:08:22Z (GMT). No. of bitstreams: 0
Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

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Galetta, Wilhelmina Magdalene. "Factors that impact project quality at a nuclear power plant in South Africa". Thesis, Cape Peninsula University of Technology, 2013. http://hdl.handle.net/20.500.11838/955.

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Thesis submitted in fulfilment of the requirements for the degree Master of Technology: Business Administration in Project Management in the Faculty of Business at the Cape Peninsula University of Technology 2013
The nuclear industry has established stringent controls to ensure that electricity is produced in a safe and reliable manner. It is expected that a nuclear power plant should be operated safely, adheres to processes and procedures that govern those safe operations, and implements projects or modifications that are of a high quality; and this would be considered as ‘business as usual’. This is crucial for an industry that is under constant scrutiny, since every project or modification, which is implemented, is critically judged. One important contributing factor to the successful operation of any nuclear power plant is the implementation of projects and modifications in accordance with respective nuclear codes and standards, specifications, processes and procedures. The industry demands that this should be a norm, as quality is synonymous with safety and reliability; factors that cannot be compromised or divorced from each other on a nuclear power plant. Recently, however, there has been great concern relating to non-conformances experienced throughout the project lifecycle, which ultimately affects the quality of modifications and projects, which are implemented at the plant. The research project investigates factors that affect project quality at a nuclear power plant in South Africa. Against the above backdrop, the research problem was “the delivery of poor quality projects have an adverse effect on modifications and projects, which are implemented at the nuclear power plant in South Africa”. The primary research objectives of this study are the following: · To investigate the root cause and impact of inconsistent project quality practices on the project lifecycle; and · To recommend measures that should be established to improve the way in which project quality is conducted throughout the project lifecycle.

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Gumede, Nomfusi Leticia. "An investigation on the impact of procurement quality management in a nuclear power station". Thesis, Cape Peninsula University of Technology, 2011. http://hdl.handle.net/20.500.11838/2221.

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Thesis (MTech (Quality))--Cape Peninsula University of Technology, 2011.
This research project in Procurement Quality Engineering was conducted at a Nuclear Power Generation Company in the Western Cape, South Africa. During the past decade, quality management has become increasingly recognised as highly desirable for all organisations at all levels. All organisations, to varied degrees, can benefit from the application of quality management skills in some parts of their daily operations. The research project will investigate the impact or effect of late deliveries of spares on the operational cost of the organisation. The organisation is not aware what impact the delivery of spares has on operating costs. Against the above background, the problem to be researched within the ambit of this dissertation reads as follows: "Poor product and / or service delivery from Vendors and / or Suppliers have an adverse impact on the output of the Procurement Quality Department" .The primary research objectives of this study are the following: ~ To emphasise the importance of quality within the supply chain. ~ To investigate the impact of non-conforming items delivered to a Nuclear Power Plant. ~ To determine measures which can be put in place to improve communication between suppliers, vendors, buyers and procurement quality engineering. ~ To determine or investigate the cost of poor quality in the organisation. ~ To improve the quality of goods and services through the application of a quality management system within the supply chain. The research method used in this research project involved both qualitative and quantitative research processes. Questionnaires and statistical techniques were used to analyse the data, and to draw conclusions and recommend possible areas for improvement. The research methodology falls within the ambit of a case study.

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Ntsadu, Ntlahla. "Impact assessment of large-scale penetration of permanent magnet synchronous generators on power quality". Master's thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/26891.

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Wind power generation has gained a large share in the renewable energy market over the past few years. This study investigates the impact of large scale penetration of permanent magnet synchronous generator (PMSG) based wind turbines on power quality of the grid. PMSGs are attractive due to the absence of a gearbox in the drive-train, which results in lower maintenance costs and higher reliability. Moreover, the advancements in power electronics have facilitated PMSGs to generate optimal power at varying wind speed conditions. This is achieved through the use of maximum power point tracking algorithms. The drawbacks of PMSG-based wind energy systems are that they inject harmonics into the network and cause flicker as well as other power quality issues. Despite these disadvantages, the grid code requires that PMSGs stay connected to the grid even under grid disturbances. This is because the reactive power control capability of PMSG-based wind energy systems can actually assist with voltage support. It will be shown in this study that disconnecting large scale PMSGs based wind turbines during grid disturbances has a detrimental effect on transient stability of the grid. This study will show that PMSG-based wind energy systems improve transient stability and assist in voltage support through reactive power control. Moreover, the impacts of large scale PMSG based wind turbines on power quality of the grid can be reduced by various means, which are also addressed in the study.

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Carlsson, Fredrik. "On impacts and ride-through of voltage sags exposing line-operated AC-machines and metal processes". Doctoral thesis, KTH, Electrical Systems, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3681.

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During the last decade, power quality has been recognised asa global problem. Among different types of power qualityproblems, voltage sags have been identified to be one of themost severe problems for different process industries. The mostcommon reason to voltage sags is lightning strikes in powerlines. Protection equipment, usually located at switchyards,disconnect faulted power lines as soon as possible, which isapproximately 100 ms. Thus, the duration of voltage sags areapproximately 100 ms. The sensitivity to voltage sags ofelectrical equipment in process industries can be observed asfor instance malfunction, automatic turnoff or damages.

This thesis gives an overview of three metals processes withfocus on the sensitivity to voltage sags and interruptions. Theinherent energy in the process is used to find the sensitivity.This energy may also be used to obtain "ride-through" for theprocesses. The three metals processes are a blast furnaceprocess, a hot rolling mill process and a cold rolling millprocess. The main attention in this thesis is paid to the blastfurnace process, which is powered by a line-operatedsynchronous machine.

The thesis shows that the protection equipment forelectrical machines can be adjusted to avoid unnecessaryshutdowns. It is also explained why there are high torque andcurrents during voltage sags as well as after voltage sags. Itis shown that the first peak torque and current during thevoltage sags is almost proportional to the voltage change, thatis the voltage magnitude before the voltage sag minus thevoltage magnitude during the voltage sag. The first peak torqueand current after the voltage sag depends sinusoidal-like onthe duration of the voltage sag and almost proportional to thevoltage change during the voltage sag. There is no fluxsaturation during voltage sags, however after voltage sagssaturation is very likely to occur. The thesis explains why andalso how the flux is changed during and after voltage sags.

The duration of voltage sags is in many cases set by theprotection equipment located in switchyards. It is shown thatthe durations of voltage sags can be changed to durations thatwill cause less peak torque and current after voltage sags forline-operated AC-machines. It is also shown how this istheoretically achieved.

Keywords:Rolling mill, Blast furnace, Power Quality,Synchronous machine, Asynchronous machine, Voltage sag, Voltageinterruption, Ride-through, Process disturbances, Simulation,Modelling

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Akinyemi, Ayodeji Stephen. "Assesment of renewable energy resources and the impact of DG on power quality in distribution network". Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/13563.

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Includes bibliography.
For many years, power systems were vertically operated; large power generation plants produced all of the electrical power. This kind of generation is often related to adequate geographical placement such as water sources, coal sources etc. The power is then transmitted towards large consumption centres over long distances using different high-voltage transmission levels. This operating structure was built on the basis of economy, security, and quality of supply. This very centralized structure is operated by hierarchical control centres and allows the system to be monitored and controlled continuously. The generation is instantly adjusted to match consumption by monitoring the frequency, on the basis of very elaborate load forecasting models. The voltage is also controlled to be within specific limits by means of appropriate coordination of devices such as, generators, online taps changers, and reactive compensation devices. The power system operation is changing due to the restructuring and continuous growth in the demand however, due to major changes in the legislative framework for the power sector and the fast movement towards liberalization of the electricity markets, renewable energy sources were introduced to distribution systems. These units are of limited size (2MVA or less) and can be connected directly to the distribution network or on the customer side of the meter. Efforts to reduce CO2 emissions related to electricity generation, and to reduce fuel imports, have led to a significant increase in the deployment of renewable energy generation technology. Renewable energy sources (RES) are predicted to play a key role in the power distribution systems; they are the key to a sustainable energy supply infrastructure because of their inexhaustible and none polluting nature. However, the integration of renewable energy resources create special technical and economical challenges that have to be comprehensively investigated in order to facilitate the deployment of these renewable energy sources units in the distribution system. This dissertation investigates the renewable energy resources, types, advantages and disadvantages of renewable energy resources, the prospects of renewable energy resources in South Africa and Nigeria, challenges facing the integration of renewable energy resources into the distribution network.

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Björn, Robert, i Anders Westlinder. "Energy savings by using low energy light bulbs and automation,and the impact on the power quality". Thesis, Linköpings universitet, Institutionen för teknik och naturvetenskap, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-80518.

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Detta examensarbete har utförts i samarbete med Kjell & Company som är en rikstäckande butikskedja som tillhandahåller hemelektronikprodukter via internet och 55 butiker fördelade över 30 orter. Syftet med detta examensarbete är att jämföra elförbrukning och kostnader för olika lågenergilampor med glödlampan som referens samt att studera elkvalitén med avseende på eventuella nätstörningar lamporna kan ge upphov till och även undersöka om det går att minska elförbrukningen genom att automatisera exempelvis belysning och annan elutrustning. Undersökningen har gjorts genom att mäta på lampor och utrustning med hjälp av en Norma D1150 wattmeter och en Fluke 43 Power Quality Analyzer samt att utföra beräkningar på utförda mätningar och på tillverkarens angivna data. Alla mätningar har utförts med universitetets utrustning och i universitets lokaler förutom mätningen på delar av automationstesterna som mättes med en elmätare PM 300 i ett hushåll. Allt material som testerna utförts på har kommit från Kjell & Co förutom glödlamporna som är inköpta i en annan butik på grund av att Kjell & Co inte har några i sitt sortiment. Slutsatsen som kan dras av undersökningarna blir att genom att byta ut gamla glödlampor mot halogen- eller lågenergilampor går det att göra en betydande energi- och kostnadsbesparing. Vad gäller de övertoner som alstras av de enskilda lågenergilamporna är övertonshalten i strömdelen hög men strömmen i sig väldigt låg, i milliamperenivå. Därför är det svårt att se att dess inverkan ska vara av någon betydelse för elkvalitén idag. I fråga om automatiseringen av mediautrustningen går det att göra en energivinst så länge som utrustning ansluten i slaveuttagen förbrukar mer än grenkontaktens 2,2 W. När det gäller automatiseringen av en lampa med rörelsevakt så gav det i detta fall en energibesparing men om andra mätmetoder används eller är lyset alltid släcks manuellt när det inte behövs kan det ge andra utfall.

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Al-Azmi, Bader N. A. "Impact of emissions results from power generation on the air quality of selected urban areas in Kuwait". Thesis, Loughborough University, 2009. https://dspace.lboro.ac.uk/2134/36134.

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Air pollution in urban areas is a problem affecting many countries in the world and has important implications for health and environmental management. However, air quality prediction plays an important role in the controlling air pollution problem. Air-quality models are also extensively used in all aspects of air pollution control and to predict spatial and temporal dispersion of pollutants in the atmosphere. The main objectives of this work are to provide an overview of the pollutant levels and their trends in the study area (Rabia) and to predict the ground level concentrations of sulphur dioxide (SO2) and nitrogen oxide (NOx) mainly emitted from power generation stations by using Source Complex model for Short-term Dispersion (ISCST 4.5) for years 2001 and 2004. The hourly air pollutants concentrations were measured continuously by fixed ambient air stations located over the polyclinics in Rabia area in Capital Governorate in the State of Kuwait.

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Iessa, Hassan. "Concentrating food materials using electrokinetically enhanced filtration (EKEF) : impact on filtration efficiency, quality compounds and power consumption". Thesis, University of Newcastle upon Tyne, 2016. http://hdl.handle.net/10443/3483.

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Countries around the world are suffering from many problems caused by the misuse of their resources either by using non-renewable ones or destroying the valuable features of the resources that are available. Some of the most important challenges facing humanity are related to food and energy security. Food security includes many aspects besides providing people with an adequate amount of safe and healthy food; it also includes improving food processing to produce acceptable, high quality food products with reduced losses of nutrients, carbon footprint and using fewer resources in the production/packaging processes. Dried and concentrated foods have become an important category in the food products marketplace. Many of the usual traditional methods require very high energy inputs. These methods may also have significant negative impacts on the foodstuffs, especially their chemical properties, such as loss of essential nutrients, as well as their appearance, aromas and flavour. This project aimed to combine the electrokinetic phenomenon of electro-osmosis with the traditional functions of filtration to form a process of electrokinetically enhanced filtration (EKEF). This process is based on using electrokinetic effects to enhance conventional filtration technologies to concentrate foodstuffs at low temperature which saves energy, time, and product constituents associated with product quality, especially the temperature-sensitive components such as Vitamin C, fruit/vegetable colours and key aromas. This study is concerned with factors affecting the efficiency of the EKEF process after its application to concentrate orange juice (14% dry matter content, pH=3.6) and malt extract (20% dry matter content, pH=4.55), and monitoring the changes that occur in indicators of food quality, such as the change in pH value, vitamin C content, colour, dry matter as well as the energy inputs to facilitate the EKEF. The process of electrokinetics was combined with micro-filtration (MF) to speed up the process and save time and energy. This is carried out in an EKEF-rig which was designed to meet the project needs with an ability to change all the dependent parameters to find the optimum conditions to run this application. Applying EKEF improved the filtration process and achieved net dewatering efficiencies up to 7.43% and 4.86% for orange juice and 10.68% and 6.26% for malt extract after 5.5hrs of processing under 30V and 15V respectively; and increased dry matter content from 14% to ii 33.09% and 29.52% for orange juice and from 20% to 34.2% and 32.14% for malt extract after 5.5hrs under 30V and 15V respectively. The maximum dry matter content was 28.75% and 29.63% under the control condition after the same time for orange juice and malt extract respectively. Results showed that the performance of the EKEF process was dependent upon several parameters such as the sample’s conductivity, applied voltage used, applied pressure, initial sample’s thickness (the distance between electrodes) and filters pore size; all of these factors had a positive impact on improving the process efficiency except of the initial sample’s thickness which had a negative impact. Regarding the impact on the heat-sensitive food compounds, here represented by vitamin C; applying EKEF for 5.5hours reduced vitamin C retention in the concentrated juice to 41% under 15V and 7% under 30V. The retention of the total filtrate was also influenced by the EKEF process, where it fell to 48% under 15V and 35% under 30V. Vitamin C retention was better under the EKEF process compared with its value under conventional thermal methods, where it needed about 10-15min at 50-75ºC and (3min) at 90ºC to drop to 50% or less (Vikram et al., 2005). EKEF also had a negative impact on the juice colour and pH value. The direction of water flow and the profile of fluid flow between the two electrodes were thoroughly investigated to identify the main filtration outlet and its position; the power consumption of the application was also calculated and compared with power consumption of conventional thermal methods. The EKEF process resulted in a large power consumption addition compared with applying the pressure only; however, the required additional energy needed to achieve the same increase in dewatering efficiency by increasing the pressure only without EK was relatively small. On the other hand, EKEF showed a good efficiency in energy saving compared with the power consumption required in more conventional thermal methods used to evaporate an equal amount of water. This saving was up to 18.35 times and 47.34 times in OJ and ME dewatering respectively.

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Reed, Donna K. "Impact zone delineation for biological assessment of power plant effluent effects on snail populations in the Clinch River". Diss., Virginia Tech, 1993. http://hdl.handle.net/10919/38639.

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Carter, Shaun A. "Geochemical analysis of the Powder River, Wyoming/Montana and an assessment of the impacts of coalbed natural gas co-produced water". Laramie, Wyo. : University of Wyoming, 2008. http://proquest.umi.com/pqdweb?did=1663116711&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.

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Chen, Cheng. "The Impact of Voltage Dip Characteristics on Low Voltage Ride Through of DFIG-based Wind Turbines". Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-254388.

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In last decade, there is a large increase in installed capacity of wind power. Asmore wind power is integrated into utility networks, related technologychallenges draw much attention. The doubly fed induction generator (DFIG) isthe mainstream choice for wind turbine generator (WTG) in current market andthe object of this thesis. It is very sensitive to voltage dips. The enhancement oflow voltage ride through (LVRT) is one of the most important issues for DFIG,and many works have already been done to provide solutions.In current works, the voltage dip waveforms that are applied in LVRTrelated works are largely different from waveforms in reality, because they failto consider the the effect of realistic wind farm configurations on waveforms ofvoltage dips and significant influences of additional characteristics of voltagedips. The true impact of the voltage dip needs to be assessed in performanceevaluation and development of LVRT methods. To support the development ofpractical LVRT capacity enhancement solutions, the application of voltage dipknowledge is definitely demanded.In this thesis, the characteristics of realistic waveform voltage dips in windfarm are analyized based on voltage dip knowldege from power quality field,measured voltage dip from industry and realistic wind farm configurations.Classical analysis theory is applied to explain the principles of the impact ofvoltage dip characteristics on dynamic behavior of DFIG. The impacts of manywidely neglected characteristics such as phase angle jump (PAJ), point on wave(POW) of initiation and recovery, voltage recovery process, transformerconfigurations, load effect are revealed and verified by simulations. The impactof many voltage dip characteristics on DFIG are studied for the first time.
De senaste tio åren har sett en stor ökning av installerad effekt av vindkraft.Mer vindkraft i elnäten har lett till större uppmärksamhet om dess tekniskautmaningar. Den dubbelmatad asynkrongenerator (DFIG) är idag denvanligaste förekommande typen i vindkraftverk. Den är mycket känslig förspänningssänkningar. Förbättring av tålighet för spänningssänkningar (LVRT)är en av de viktigaste frågorna för DFIG, och många studier har redan söktlösningar.I befintliga studier om LVRT har spänningssänkningarna skiljt sig väsentligtfrån verkliga vågformer, då de inte har tagit hänsyn till realistiskavindparkkonfigurationer och betydande påverkan av ytterligare egenskaper hosspänningssänkningar. För att stödja utvecklingen av praktiska LVRT lösningarbehövs mer kunskap om spänningssänkningar för att bedöma dess verkligainverkan.Detta examensarbete förbättrar LVRT analysen av DFIG genom att tillämpakunskap om spänningssänkningar från elkvalitetsområdet, tillsammans medrealistiska vindparkskonfigurationer. Inflytandet av ändringar i fasvinkel(PAJ), fasvinkeln vid sänkning och återhämtning (POW), spänningsåterhämtning, transformatorkonfigurationer, last och många andra egenskaperav spänningssänkningar ingår också. Inflytandet av många egenskaper avspänningssänkningar studeras här akademiskt för första gången. Denkaraktäristik av realistiska spänningssänkningar som inträffar vid generatornspoler, och de effekter dessa har, studeras och förklaras genom teoretisk analysoch intensiva simuleringar.

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Pignatti, Alex Almeida. "O impacto da topologia de conexão de transdutores na obtenção de indicadores de qualidade de energia". Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/3/3143/tde-15072013-154428/.

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A Agência Nacional de Energia Elétrica (ANEEL) deverá estabelecer a regulamentação para distúrbios de qualidade de energia em um futuro próximo. Há ainda questões em aberto sobre os procedimentos de medição e limites máximos para os indicadores de qualidade de energia. Este trabalho aborda uma dessas questões, que é a conexão de transdutores e os impactos nos índices de qualidade de energia associados. Simulações em ATPDraw e campanhas de medição foram realizadas de modo a identificar o comportamento dos indicadores de distorção harmónica sob as duas configurações possíveis de conexão de transdutores: dois equipamentos com ligação entre fases ou três com ligação fase-neutro. Os resultados das simulações e os valores medidos mostram grandes discrepâncias entre ambas as configurações, e as diferenças tornam-se ainda mais significativas com o incremento do desequilíbrio do sistema elétrico. As causas subjacentes deste fenômeno são investigadas e discutidas
The Brazilian electricity regulatory agency (ANEEL) is expected to establish a legal framework for quality disturbances in the near future. There are still some open questions regarding metering procedures and maximum limits for Power Quality indicators. This work addresses one of such issues, namely the connection of the associated transducers and its impact on PQ indexes. Simulations in ATPDraw and on-field measurement campaigns were carried out so as to identify the behavior of harmonic distortion indicators under the two possible transducer configurations: two phase-to-phase or three phase-to-neutral transducers. Simulation results and measured values show large discrepancies between both configurations, and the differences become more significant as the electrical systems unbalance increases. The underlying causes of this phenomenon are investigated and discussed.

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Romero, Mauro. "The impact of marketing actions on the perception of quality and satisfaction of consumers of electricity in the state of Ceara". Universidade Federal do CearÃ, 2007. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=3539.

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As mudanÃas no mercado regulado pelo Estado exigiram uma adequaÃÃo do foco produtivo das concessionÃrias de energia elÃtrica em atingir as metas dos indicadores de desempenho tÃcnico e operacional, para o foco na satisfaÃÃo do consumidor dentro de suas expectativas. Desta forma, este trabalho desenvolve um estudo exploratÃrio junto a uma empresa do ramo de energia elÃtrica localizada no Estado do CearÃ, com o propÃsito de verificar as relaÃÃes entre suas aÃÃes de marketing e o nÃvel de satisfaÃÃo de seus clientes. Por meio da teoria que aborda a estrutura das caracterÃsticas intrÃnsecas Ã produÃÃo dos serviÃos, percepÃÃo de qualidade e satisfaÃÃo do cliente, a pesquisa dispÃe-se a responder Ã seguinte questÃo: qual a relaÃÃo entre as aÃÃes de marketing em uma empresa monopolista e os resultados de pesquisas de satisfaÃÃo de clientes? Para este fim, foram utilizados relatÃrios gerenciais, pesquisas de opiniÃo realizadas pela AssociaÃÃo Brasileira de Distribuidoras de Energia ElÃtrica e entrevistas aos gestores da organizaÃÃo. Conduziu-se um estudo de caso comparando a performance da empresa entre os perÃodos de 2004 e 2006, segundo a avaliaÃÃo do cliente e mediante os indicadores operacionais de desempenho. De acordo com esta abordagem, verificaram-se quais os atributos de qualidade que mais evidenciaram a influÃncia das aÃÃes mercadolÃgicas.

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Namkoong, Gon. "Molecular beam epitaxy grown III-nitride materials for high-power and high-temperture applications : impact of nucleation kinetics on material and device structure quality". Diss., Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/16426.

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Bouhadda, Hanen. "Impacts des non-linéarités dans les systèmes multi-porteuses de type FBMC-OQAM". Thesis, Paris, CNAM, 2016. http://www.theses.fr/2016CNAM1115/document.

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Dans cette thèse une étude des performances des systèmes OFDM et FBMC/OQAM en présence d'amplificateur de puissance sans mémoire en terme de TEB est présentée. Ensuite, nous avons proposé une technique de linéarisation d'AP par pré-distorsion adaptative neuronale. Aussi, nous avons proposé deux techniques de correction des non-linéarités au niveau du récepteur
In our work, we have studied the impact of in-band non linear distortions caused by PA on both OFDM and FBMC/OQAM systems. A theoretical approach was proposed to evaluate the BER performance for the two systems. This approach is based on modeling the in-band non-linear distortion with a complex gain and an uncorrelated additive white Gaussian noise, given by the Bussgang theorem. Then, we have proposed different techniques to compensate this NLD either on the transmitter or the receiver sides

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Paludo, Juliana Aramizu. "Avaliação dos impactos de elevados níveis de penetração da geração fotovoltaica no desempenho de sistemas de distribuição de energia elétrica em regime permanente". Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/18/18154/tde-23042014-153815/.

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O emprego de geradores fotovoltaicos (FV) conectados ao sistema de distribuição de energia elétrica tem apresentado um crescimento significativo na última década. No Brasil, sua existência ainda é reduzida, entretanto a previsão é que esta aumente nos próximos anos em função das novas regulamentações estabelecidas pelas concessionárias de energia, com apoio da Agência Nacional de Energia Elétrica. O estudo das consequências trazidas pela conexão massiva de geradores FV possibilita o planejamento correto de operação do sistema de distribuição, evitando assim, a degradação da qualidade da energia elétrica fornecida aos consumidores. Dentro desse contexto, este trabalho possui como objetivo a análise da influência que um elevado nível de penetração de sistemas FV possui em um sistema de distribuição de energia elétrica. Durante as análises, foram considerados diversos geradores FV distribuídos aleatoriamente em dois sistemas de distribuição teste bastante distintos. O programa de simulação computacional empregado foi o OpenDSS. Os estudos consideraram situações de regime permanente e foram feitas abordagens empregando variações temporais, com o propósito de avaliar o comportamento e a interação entre os perfis de carga e geração FV. Os resultados mostraram a importância de considerar as variações temporais de demanda e de geração, e apontaram que o perfil de tensão em regime permanente, nível de desbalanço de tensão, perdas técnicas, regulação da tensão e desconexão dos geradores são fatores importantes que devem ser avaliados em estudos deste tipo. Além disso, mostrou-se que possíveis impactos negativos decorrentes da introdução massiva de geradores fotovoltaicos podem ser mitigados utilizando as soluções propostas ao final deste trabalho.
The employment of photovoltaic (PV) generators connected to the grid has increased significantly in the past decade. In Brazil, there are a few PV systems nowadays, but this scenario tends to change since new regulations have been established by the utilities with support of the Brazilian Electrical Energy Agency. The study of the effects caused by high penetration levels of PV generators enables the correct operation of the distribution networks and prevents the degradation of power quality provided to the consumers. In this context, the purpose of this research is to analyze the consequences caused by high-penetration levels of PV systems in distribution networks. Several distributed PV generators are considered and located randomly in two distinct distribution test feeders. The studies were carried out by using the software OpenDSS. The analysis focused on steady state studies and typical daily load and PV generation curves have been considered to evaluate the behavior and the interaction between loads and PV generation. The results have shown the importance of considering such load and power variation, and pointed out that voltage profile, voltage unbalance level, technical losses, voltage regulation and generators disconnection are important issues to be studied in situations like the ones analyzed in this work. Furthermore, possible negative impacts caused by high PV penetration levels can be mitigated by employing the potential solutions proposed in this dissertation.

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Oliveira, Roger Alves de. "Afundamentos de tensão em consumidores industriais : uma análise baseada no fator de impacto e na severidade dos eventos considerando os efeitos de faltas elétricas em sistemas de potência". reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2018. http://hdl.handle.net/10183/185257.

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The present work deals with a comparative analysis of IEEE 1564 standardization and Module 8 of Distribution Procedures of the Brazilian Agency of Electrical Regulation, within the scope of voltage sags. For such comparison, a case study of monitoring is performed on an industrial consumer sensitive to the disturbance during 24 months. Additionally, since the main causes of the voltage sags are the electrical faults of the system to which the industry is inserted, the relations between both events are analyzed. From the simultaneity of these contingencies, a unique set of data was obtained through MATLAB R , which allowed the clustering of variables with K-means algorithm through WEKA software. Simultaneous events were also convenient for the validation of a simulation model in ANAFAS software. The results obtained with the application of such methodology allowed to know the impact of the events, to analyze the vulnerability area, to propose mitigations in the power system under study, as well as to validate a simulation model of sags with relative error less than 10 % to more than 70 % of cases.

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Motoki, Edison Massao. "Procedimentos para mitigação do impacto de qualidade de energia na indústria têxtil". Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/3/3143/tde-27072007-164807/.

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O avanço crescente da tecnologia nos processos industriais atuais, bem como o elevado grau de interação de equipamentos e processos, provocou o aumento da sua sensibilidade a variações de energia, ou o aumento do grau de sensibilidade de algumas cargas industriais, o que gera interrupções de produção industrial. Essas, ocasionadas por problemas de qualidade de energia, levam a diversos fatores indesejáveis às indústrias, tais como: perdas de produção, perdas de faturamento, perda de matéria-prima, uso irracional de energia, dentre outros. Um processo têxtil apresenta grandes perdas de produção quando ocorrem esses eventos. Esta dissertação apresenta uma série seqüencial de procedimentos técnicos adotados experimentalmente em duas plantas de fiação sintética, para mitigar o impacto da qualidade de energia numa indústria química-têxtil. O problema de qualidade de energia estudado foi a variação de tensão de curta duração (VTCD), especificamente os afundamentos de tensão, sobre uma carga crítica. Quando esses eventos ocorriam, havia um grande volume de perdas no processo, em função da descontinuidade operacional provocada por esses afundamentos de tensão. Por meio de procedimentos foi possível identificar a carga crítica, no caso, os conversores estáticos de freqüência utilizados amplamente nesse processo. Uma vez identificada essa carga, foi possível a realização de intervenções objetivando reduzir a sua sensibilidade. Dois experimentos realizados através de um painel que simulou a situação do processo, com testes de afundamentos de tensão em conversores estáticos de freqüência, além de outros trabalhos experimentais utilizados como referências nessa dissertação, serviram como complemento para a conclusão. As intervenções realizadas tiveram como conseqüência a melhoria de qualidade do produto, aumento da produtividade, além de grande retorno financeiro.
The increasing evolution of technology in the current industrial processes, as well as the high interaction degree of equipment items and processes, have caused the increase in their sensitivity to voltage variations. The increase of sensitivity in some industrial loads generates interruptions in the industrial production. That happens due to power quality problems, which causes many undesired effects to the industries, such as losses in production, invoicing and raw material, unreasonable use of energy, among others. A textile process presents large production losses whenever these events in the process occur. This dissertation presents a sequence of technical procedures adopted experimentally in two yarn plants, to mitigate and reduce the impact of power quality problems in the chemical textile plant. The problem of power quality studied was short duration voltage variations, specifically the voltage sags. These events lead to a big volume of loss in the process, by operational disruption of sensitivity loads provoked by the voltage sags. By means of the proposed procedures it was possible to identify the critical load, in this case the ASD (Adjustable Speed Drive), a kind of load used extensively in the textile process; once identified this load, it was possible to carry out interventions aiming at the reduction of loads sensitivities. Two experiences were realized through a panel that simulated the process, by applying voltage sags to the drivers - ASD (Adjustable Speed Drive). Besides that other research works surveyed to complement and conclude this dissertation. The interventions realized have had as consequence the improvement in the product quality, increasing productivity, as well as an excellent payback.

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Ramos, Mário César Giacco. "Uma contribuição para a área de saúde por meio da verificação do impacto da qualidade de energia e das instalações elétricas nos equipamentos eletromédicos". Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/3/3143/tde-01072009-120057/.

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Em todos os segmentos da sociedade, a utilização de equipamentos eletrônicos projetados e construídos com avançadas tecnologias eletrônicas e controlados por microprocessadores aumenta a cada dia. Na área de saúde, denominados de equipamentos eletromédicos, dão suporte aos setores de diagnóstico, tratamento ou, procedimento cirúrgico, melhorando a qualidade dos serviços e o atendimento aos pacientes. No entanto, o sucesso global do processo deverá considerar a qualidade das instalações elétricas nesses ambientes, bem como a qualidade da energia elétrica fornecida a esses equipamentos. Este trabalho tem como objetivo comprovar, por meio de pesquisa em laboratório, o risco de diagnósticos médicos baseados em informações fornecidas por equipamentos eletromédicos, alimentados em redes elétricas que não atendem às normas vigentes ou, totalmente perturbadas por outros equipamentos típicos dos ambientes médico-hospitalares. A metodologia aplicada consistiu em medições dos parâmetros referentes à qualidade de energia elétrica nos estabelecimentos assistenciais de saúde. Atenção especial foi dada ao conteúdo harmônico de tensão e aos afundamentos de tensão de curta duração produzidos por equipamentos de raios X, mamografia, tomografia computadorizada, ressonância magnética nuclear e motores elétricos de indução. Em seguida, essas perturbações foram reproduzidas em fontes de tensão específicas para essa finalidade, instaladas no Laboratório do Centro Tecnológico de Qualidade de Energia da Escola Politécnica da Universidade de São Paulo, conhecido como Enerq-ct. Equipamentos eletromédicos portáteis, gentilmente cedidos por diversos fabricantes nacionais, foram submetidos a esses sinais para verificação do seu desempenho. Os resultados obtidos demonstram a importância da qualidade de energia elétrica bem como, a qualidade dos serviços de manutenção nas instalações elétricas desses ambientes.
Through all segments of our society, there is a daily increase in the use of electronic equipment designed and built with advanced electronic technology and computerized control. In the health-medical area, designated electromedical equipment, they provide support to sectors in charge of diagnosis, treatment or surgical procedures, improving the quality of services and the manner patients are cared for. However, the global success of this process must take into consideration the quality of electrical installations at these facilities, as well as the electrical power supplied to the equipment. The aim of this work is to attest through laboratory research the risk of medical diagnoses based on information provided by electromedical equipment powered through electrical networks which do not meet the standards in effect, or which are completely disturbed by other equipment typical of electromedical environments. The methodology applied consisted of measurements of the parameters referring to the quality of electrical power in health care facilities. Especial attention was given to the voltage harmonic content and to short duration voltage sags caused by X-ray, mammography, computerized tomography and nuclear magnetic resonance equipment or by induction motors. Later, these disturbances were reproduced in power supplies which are specific to this objective, installed at Laboratório do Centro Tecnológico de Qualidade de Energia da Escola Politécnica da Universidade de São Paulo- Energy Quality Technological Center of the Technical School of the University of Sao Paulo , known as Enerq-ct. Portable electromedical equipment, kindly supplied by national manufacturers, were subjected to these signals for assessment of their performance. The results obtained demonstrate the importance of the quality of electrical power as well as the quality of maintenance of electrical installations within these environments.

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Gadelha, Thayannã Yury Furtado. "Impacto dos sistemas de geração distribuída fotovoltaica sobre a tensão em regime permanente das redes de distribuição /". Ilha Solteira, 2019. http://hdl.handle.net/11449/190754.

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Orientador: Júlio Borges de Souza
Resumo: Devido a um conjunto de questões econômicas e ambientais, a geração distribuída baseada em fontes renováveis tem sido incentivada por vários países. No Brasil, a conexão de unidades de geração distribuída fotovoltaica (GDFV) às redes de distribuição de baixa tensão, por meio de unidades residenciais e comerciais, tem apresentado uma rápida expansão. Diante deste cenário, é necessário investigar os possíveis impactos negativos que tal expansão pode resultar sobre os sistemas de distribuição. Neste trabalho, busca-se avaliar o impacto sobre a tensão em regime permanente. Para se alcançar tal objetivo, utiliza-se como modelo do sistema de distribuição a rede de teste IEEE 13 barras. Através do software de acesso livre OpenDss, o qual é devidamente apresentado, o comportamento da tensão ao longo desta rede, antes e depois da inserção da GDFV, é estudado por meio de simulações pontuais e diárias. Também é analisado neste trabalho de que forma o sistema de geração distribuída fotovoltaica, através do uso do controle voltvar, pode atenuar tal impacto.
Abstract: Due to a set of economic and environmental issues, distributed generation based on renewable sources has been encouraged by several countries. In Brazil, the connection of photovoltaic distributed generation units (PVDG) to low voltage distribution networks through residential and commercial units has shown a rapid expansion. Given this scenario, it is necessary to investigate the possible negative impacts that such expansion may result on distribution systems. This work aims to evaluate the impact on the steady state voltage. To achieve this goal, the IEEE 13 bus test network is used as a model of the distribution system. Through the open access software OpenDss, which is properly presented, the behavior of the voltage along this network, before and after the insertion of the PVDG, is studied through punctual and daily simulations. It is also analyzed in this work how the photovoltaic distributed generation system, by voltvar control, can mitigate such impact.
Mestre

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Arango, Tania Paola Ledesma. "Avaliação do impacto de motores de indução trifásicos em redes de distribuição de energia elétrica e uma proposta de regulamentação para seu acesso às redes de baixa tensão". Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/3/3143/tde-28102009-094244/.

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Este trabalho tem por objetivo apresentar e discutir alguns modelos desenvolvidos para a avaliação do impacto de motores de indução trifásicos nas redes de distribuição de energia elétrica partindo de seus dados de placa e utilizando algoritmos evolutivos para o cálculo dos parâmetros elétricos do circuito equivalente do motor. A discussão é de fundamental importância, na medida em que as distorções na onda de tensão impactam diretamente na qualidade do suprimento promovida por uma concessionária de energia elétrica, a qual deve fornecer aos seus consumidores uma tensão puramente senoidal, com amplitude e frequência constantes. Destaca-se a importância da representação de alguns aspectos específicos na avaliação do impacto de motores trifásicos na rede de distribuição. Por exemplo, a representação correta dos motores de indução na sua partida permitirá a identificação de afundamentos momentâneos de tensão tanto em pontos da rede secundária quanto da rede primária. Este trabalho apresenta o modelo de representação do motor de indução e dos elementos constituintes das redes de baixa e média tensão, incluindo os transformadores de distribuição, que possibilitam a análise do impacto desta carga perturbadora em toda a cadeia da rede, partindo-se do ponto de ligação do equipamento e analisando-se, dependendo do caso, a rede secundária, transformador de distribuição, rede primária e subestação de distribuição. Com o módulo computacional desenvolvido a partir da metodologia proposta neste trabalho, foi possível propor critérios bem definidos para avaliar se a partida de motores causa algum prejuízo para a rede de baixa tensão e/ou aos demais consumidores. Foi apresentado um método detalhado e um método expedito que permitem avaliar a viabilidade da instalação de um motor em uma determinada barra dependendo de sua potência, da potência nominal do transformador de distribuição e da sua distância até o transformador. Os critérios e os métodos estabelecidos neste trabalho constituem-se em uma proposta de regulamentação para o acesso de motores de indução à rede de baixa tensão e representam a segunda grande contribuição deste trabalho.
Much research is currently being conducted on the subject of Power Quality in electrical systems. This stems from the widespread use of polluting devices that introduce distortions on voltage waveforms so these become increasingly different form pure sinusoidal. At the same time, there has also been an increase on the use of sensitive equipment that cannot operate properly when fed by a non-sinusoidal source. This work focuses on the development of a few models aimed at evaluating the impact of electrical motors on electricity distribution networks. Motors have a direct impact on the quality of electrical energy provided to the networks customers, mainly owing to voltage sags during the motors startup. A detailed representation of all components (motors, primary circuits, distribution transformers and secondary circuits) has been developed. This allows a precise identification of critical points of the distribution system as to voltage sags. The first important contribution of this work refers to the computation of the motors equivalent circuit from its rated data using evolutionary algorithms. With these models, two different methods for evaluating the impact of the connection of a motor at a given load point were developed. These methods take into account the motors rated power, the distance between the distribution transformer and the load point, and the transformers rated power. The methods constitute a proposal for a regulatory framework within this subject, and they represent the second major contribution of this work.

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Barrett, S. R. H. "The air quality impacts of aviation". Thesis, University of Cambridge, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.596408.

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This thesis takes a multi-scale approach to addressing the issue of air quality and human health impacts attributable to aviation. In particular, processes at the exhaust plume (~ 1 km), local (~ 10 km), regional (~ 1000 km) and global (~ 10 000 km) scale are addressed. At the plume scale, a three-dimensional integral plume model is developed and applied to elucidate aspects of near-field dispersion processes. A new method for approximating dispersion at the local scale is developed, which allows the air quality in the vicinity of large numbers of airports to be rapidly estimated. At the regional and global scales, an atmospheric chemistry-transport model is adapted to understand the intercontinental transport of aircraft pollution. This thesis includes the first estimate of the number of premature mortalities attributable to aviation worldwide. A key finding is that aircraft cruise emissions are more important in terms of their total public health impacts than landing and takeoff (LTO) emissions. On this basis, it may be appropriate to change aircraft emissions regulations, which currently only cover LTO emissions on the assumption that cruise emissions do not degrade air quality.

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Navarrete, Pablo-Romero Javier. "Power Quality for Distributed Wind Power Generation". Thesis, KTH, Elektroteknisk teori och konstruktion, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-105221.

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Wind power often is a source of voltage fluctuations and possible voltage issues are raised when considering interconnecting wind turbines to an electric grid. Also, the power electronics introduced in the wind turbines might insert more fluctuations and different PQ problems. Distributed generation seems to be a good option in order to try to mitigate these problems. The first goal of the work is to create a model of a small electric grid, using MATLAB/Simulink. The models aims to simulate various DFIG wind turbines coupled to the grid in different conditions of location and wind. Then, the main objective is to analyze the PQ in the grid with this type of turbine. For this, once the simulations have been done, the results obtained have allowed calculating different indices to study PQ in the model. Afterwards, a comparison of those indices in the different conditions is made.
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Suwanapingkarl, Pasist. "Power quality analysis of future power networks". Thesis, Northumbria University, 2012. http://nrl.northumbria.ac.uk/12625/.

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SILVA, Tiago Alencar. "AVALIAÇÃO PROBABILÍSTICA DO IMPACTO DA GERAÇÃO DISTRIBUÍDA EÓLICA NOS AFUNDAMENTOS DE TENSÃO DE CURTA DURAÇÃO". Universidade Federal do Maranhão, 2012. http://tedebc.ufma.br:8080/jspui/handle/tede/1875.

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Submitted by Maria Aparecida (cidazen@gmail.com) on 2017-08-29T13:12:16Z No. of bitstreams: 1 Tiago Silva.pdf: 3175763 bytes, checksum: 8eba0f17a1a1f6fa2606a5235969987e (MD5)
Made available in DSpace on 2017-08-29T13:12:16Z (GMT). No. of bitstreams: 1 Tiago Silva.pdf: 3175763 bytes, checksum: 8eba0f17a1a1f6fa2606a5235969987e (MD5) Previous issue date: 2012-11-09
CNPQ
The Distributed Generation (DG) can improve the power quality indices associated with Short Duration Voltage Variations (SDVV) due to the reduction in the electric network loading, which in turn causes an improvement in the pre-fault voltage profile. On the other hand, the DG can also deteriorates the power quality indices related to SDVV due to the increasing in the fault currents, which in turns reduce the post-fault voltages. Furthermore, the assessment of the DG impact on SDVV is more difficult with the presence of renewable energy resources. This complexity is due to fluctuations in output power caused by stochastic variations in the primary energy source (sun, wind, tide levels, etc.). Additionally, the bibliographical review on Predictive Assessment of Short Duration Voltage Variations (PAVV) revealed that none of the existing methodology considered the impact of fluctuations in the output power of a wind DG on power quality indices related to SDVV. It was also noticed that the load variations during the study period are ignored in the papers on SDVV. The existence of these deficiencies and the governmental incentives for the use of wind generation motivated this research. The main aim of this dissertation is the development of a methodology for the PAVV capable of recognizing uncertainties associated with wind DG and load fluctuations. The modeling of these uncertainties was carried out using NonSequential Monte Carlo Simulation (MCS). The nodal voltages in the fault scenarios generated by MCS were evaluated using the Admittance Summation Method (ASM) in phase coordinates. The combination of the MCS with the ASM allowed estimating the following indices related to SDVV: the expected value of the SARFI (“System Average RMS – Variation – Frequency Index”) and expected nodal frequency of SDVV. Furthermore, the probability distributions and box plots of the SARFI index have been obtained. The proposed method for the PAVV was tested and validated in a test system with 32 buses. The tests results demonstrated that the DG insertion causes an improvement in the power quality indices associated with SDVV. Additionally, the substitution of conventional DG by wind DG cause a small deterioration in the power quality indices related to SDVV due to fluctuations in the output power of the wind DG. Finally, it was observed that the load fluctuations during the study period cause significant variations in the SARFI index.
A Geração Distribuída (GD) pode melhorar os índices de qualidade de energia associados com as Variações de Tensão de Curta Duração (VTCD) devido a redução no carregamento da rede elétrica, que por sua vez causa uma melhoria no perfil de tensão pré- falta. Por outro lado, a GD também pode degradar os índices de qualidade de energia associados com VTCD devido ao aumento nas correntes de falta, que por sua vez reduzem as tensões pós-falta. Além disso, a avaliação do impacto da DG sobre VTCD é mais difícil com a presença de fontes de energia renováveis. Esta complexidade se deve as flutuações na potência de saída causadas pelas variações estocásticas na fonte de energia primária (sol, vento, níveis de maré, etc.). Adicionalmente, a revisão bibliográfica realizada sobre Avaliação Preditiva de VTCD (APVT) revelou que nenhuma metodologia existente considerou o impacto de flutuações na potência de saída de geradores eólicos nos índices de qualidade referentes às VTCD. Também foi observado que flutuações de carga ao longo do período de estudo são desconsideradas nos artigos sobre APVT. A existência destas deficiências nos métodos de APVT e os incentivos governamentais para o uso de geração eólica motivaram esta pesquisa. O principal objetivo desta dissertação é o desenvolvimento de uma metodologia para a APVT capaz de reconhecer as incertezas associadas com a GD eólica e flutuações de carga. A modelagem destas incertezas na APVT foi realizada através do uso da Simulação Monte Carlo (SMC) não-sequencial. As tensões nodais nos cenários de falta gerados pela Simulação Monte Carlo (SMC) foram calculadas usando-se o Método de Soma de Admitância (MSA) em coordenadas de fase. A combinação da SMC com o MSA permitiu estimar os seguintes índices probabilísticos relacionados com as VTCD: valor esperado do SARFI (“System Average RMS – Variation – Frequency Index”) e frequência nodal esperada de VTCD. Além disso, foram obtidas distribuições de probabilidade e diagramas de caixa associados com o SARFI. O método proposto nesta dissertação para a APVT foi testado em uma rede de distribuição de 32 barras. Os resultados dos testes mostram que a inserção de GD causa uma melhoria nos índices de qualidade associados com as VTCD. Adicionalmente, a substituição de GD convencional por GD eólica causa uma pequena deterioração nos índices de qualidade referentes às VTCD devido as flutuações na potência de saída da GD eólica. Finalmente, também foi observado que as flutuações na carga ao longo do período de estudo causam variações significativas no índice SARFI.

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Farzanehrafat, Ali. "Power Quality State Estimation". Thesis, University of Canterbury. Electrical and Computer Engineering, 2014. http://hdl.handle.net/10092/9830.

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Traditional state estimation whereby the state of the system is assessed based on a limited number of measurements is a well established tool for steady-state situations where the frequency of the system is 50 Hz. Previous contributions have looked at extending this concept to the power quality area. This area of research is called Power Quality State Estimation (PQSE) and represents a class of techniques. Under the umbrella of PQSE, the main contribution of this work is taking Transient State Estimation (TSE) on step further. A new three-phase formulation for TSE using the Numerical Integrator Substitution (NIS) will be detailed. NIS approach, also known as Dommel's method, gives a numerical solution to describe the transient behaviour of a dynamic system at discrete time points. The new transient state estimator is implemented and verified by applying the proposed algorithm to a real distribution test system. It's performance and accuracy are investigated in presence of measurement noise, background harmonics, multiple faults, etc. The conducted study has shown this technique has a great potential.

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Hornik, Tomas. "Power quality in microgrids". Thesis, University of Liverpool, 2010. http://livrepository.liverpool.ac.uk/1456/.

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Rapidly increasing energy demand from the industrial and commercial sector, especially in the current climate of high oil prices, steadily reducing energy sources and at the same time increased concerns about environmental changes, have caused fast development of Distributed Power Generation Systems (DPGS) based on renewable energy. A recent concept is to group DPGS and the associated loads to a common local area forming a small power system called a microgrid. This small autonomous system formed by DPGS can offer increased reliability and effciency of future power system networks. Furthermore, the improvement of the control capabilities and operational features of microgrids brings environmental and economic benefits. The introduction of microgrids improves power quality, reduces transmission line congestion, decreases emission and energy losses, and effectively facilitates the utilisation of renewable energy resources. As a consequence of the fast expanding DPGS based on renewable energy sources, Transmission System Operators (TSO) have issued strict interconnection requirements (grid code compliance), e.g., on power quality control, reactive power control, fault ride-through etc. Among these different requirements issued by the grid operators, power quality have recently gained a lot of attention due to excessive non-linear and unbalanced loads over-stressing the power systems and causing system failure. As nonlinear and/or unbalanced loads can represent a high proportion of the total load in small-scale systems, the problem with power quality is a particular concern in microgrids. In this work, different control strategies are proposed and implemented for the grid and microgrid connected voltage-source inverters (VSI), based on H^inf and repetitive control techniques. The repetitive control, which is regarded as a simple learning control method, offers very good performance for voltage and current tracking as it can deal with a very large number of harmonics simultaneously. This leads to a very low Total Harmonic Distortion (THD) of the output voltage and/or the current even in the presence of nonlinear loads and/or grid distortions. Initially, a voltage controller proposed in the literature for microgrid applications is further developed and experimentally tested. The aim is to improve power quality and tracking performance, while considerably reducing the complexity of the controller design. The model of the plant is reduced for single-input-single-output (SISO) repetitive control design. As a consequence, the design becomes much simpler and the stability evaluation easier. Moreover, a frequency adaptive mechanism is proposed so that the controller can cope with grid frequency variations in the grid-connected mode. This mechanism allows the controller to maintain very good tracking performance over a wide range of grid frequencies. Then, a H^inf repetitive control strategy for the inverter current is proposed and validated with experiments. As a result, the power quality and tracking performance are considerably improved. In order to demonstrate the improvements, the proposed controller is compared with the traditional proportional-resonant (PR), proportional- integral (PI) and predictive deadbeat (DB) controllers. Finally, the advantages of the proposed voltage and current controllers based on H^inf and repetitive control techniques are put together for consideration in microgrid applications and experimentally tested. The proposed cascaded current-voltage control strategy is not a simple combination of the two control strategies, but a complete re-design after realising that the inverter LCL filter can be split into two separate partsfor the design of the controllers. As a consequence, the cascaded controller is able to maintain low THD in both the microgrid voltage and the current following into/from the grid at the same time. It also enables seamless transfer of the operation mode from standalone to grid-connected or vice versa. It turns out that the voltage controller can be reduced to a proportional gain cascaded with the internal model (in a re-arranged form), which can be easily implemented in real applications. Experiments under different scenarios (e.g. in the standalone mode or in the grid-connected mode, with linear, nonlinear or unbalanced loads etc.) are presented to demonstrate the excellent performance of the controllers.

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Gomez, Alvita Maria. "Manufacturing equipment changeover impacts on component quality". Online version, 2008. http://www.uwstout.edu/lib/thesis/2008/2008gomeza.pdf.

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Khadkikar, Vinod. "Power quality enhancement at distribution level utilizing the unified power quality conditioner (UPQC)". Mémoire, École de technologie supérieure, 2008. http://espace.etsmtl.ca/164/1/KHADKIKAR_Vinod.pdf.

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Les equipements bases sur de Felectronique de puissance emergent rapidement telle une composante essentielle aux systemes de distribution a haute puissance modernes. Les equipements de conversion de la puissance qui beneficient de cette technologic offrent un eventail de possibilites et permettent entre autre une flexibilite de controle, une reduction des coiats, une optimisation des Fespace et des performances, etc. D'un autre cote, Foperation de ces equipements peut entrainer certains des plus serieux problemes de la qualite de I'onde tels une consommation de puissance reactive et la generation d"harmoniques qui polluent le reseau de distribution. De plus, les equipements modernes sont de plus en plus sensibles a la tension d'alimentation qui leur est imposee. Augmenter la capacite des postes de generation d'electricite existants est difficile et tres couteux. surtout lorsque Fon considere les contraintes environnementales. Desormais, Famelioration de la qualite de Fonde peut non seulement rendre les reseaux de distribution plus propres et performants mais entraine aussi une reduction importante des pertes lors du transport et par consequent, des economies significatives. Les filtres actifs de la puissance sont largement utilises afin de remedier a quelques uns des plus importants problemes de la qualite de Fonde. La tendance actuelle vise la conception d'equipements multitache qui permettent de remedier a plusieurs problemes de la qualite de I'onde simultanement. Le conditionneur universel de puissance, mieux connu sous Fappellation anglophone Unified Power Quality Conditioner (UPQC). est Fun des filtres actifs des plus polyvalents permettant de compenser significativement les problemes de la qualite de Fonde tels les harmoniques de tensions, hauts et creux de tension, desequilibre de tension et papillotements, harmoniques de courant, puissance reactive de charge, desequilibre du courant et courant de neutre. Le UPQC consiste en un dispositif divise en deux onduleurs de tension connectes dos-a-dos a travers un bus de tension continue commun autosupporte. Le premier onduleur est controle telle une source de tension variable de la meme maniere que Fon fait regulierement avec un filtre actif serie, alors que le second est controle en courant d'une maniere similaire a un filtre actif parallele. La litterature existante sur le sujet suggere que le filtre actif parallele soit assigne a la compensation de la puissance reactive consommee par la charge. D'autre part, le filtre actif serie est toujours utilise afin de mitiger les problemes relies a la tension. Les hauts, creux et papillotements de la tension sont des deteriorations de la qualite de Fonde de courtes durees. L'approche traditionnelle de controle du UPQC afin d'ameliorer les problemes de la qualite de I'onde presentent le desavantage de la sous-utilisation de Fonduleur du filtre actif serie. Par consequent, le facteur d'utilisation du filtre actif serie est beaucoup plus bas que celui du filtre parallele. Le present travail de doctorat est base sur la philosophic d'utilisation optimale des ressources disponibles, c'est-a-dire de la maniere la plus efficace possible et avec le meilleur rendement afin d'ameliorer Fefficacite du systeme et de reduire le cout de fabrication et d'operation. Ce travail propose un concept de controle innovateur appele Power Angle Control (PAC). ce qui signifie, controle de Fangle de puissance. Le concept stipule que les con\'ertisseurs serie et parallele se partagent la puissance reactive de la charge, en parfaite coordination, sans affecter le fonctionnement fondamental de la compensation du UPQC. Cette situation resulte en une meilleure utilisation de Fonduleur serie. en une reduction de la capacite de Fonduleur parallele et ultimement, en une reduction du cout de Fensemble du UPQC. De plus, cette these introduit une nouvelle fonctionnalite au UPQC dans laquelle il est possible d'etendre le concept du UPQC triphase a trois fils vers celui triphase a quatre fils. Le concept PAC developpe dans ce travail a ete valide avec succes par simulation numerique et extensivement par de multiples manipulations en laboratoire. Les resultats experimentaux montrent que, dans les conditions presentes au laboratoire avec une charge tres inducti\ e. un redressement de Fangle de puissance 6=28° entre la tension de source et celle resultante a la charge peut reduire la capacite du convertisseur parallele de 50%. L"e\aluation de la performance du concept PAC en presence de hauts. de creux et de distorsion de la tension de source et d'une charge non-lineaire est aussi effectuee. Sous Feffet de la distorsion de la tension de source (THD de la tension de source = 6.6%) ainsi que d'une charge non-lineaire (THD du courant de charge = 23.4%), le UPQC controle avec le concept PAC compense efficacement les harmoniques de la tension de source (THD de la tension de charge = 3.2%) et la distorsion du courant (THD du courant de source 2.94%) et permet le partage simultane de la puissance reactive entre le convertisseur parallele et serie. Ce travail a ete partiellement execute en collaboration avec Hydro-Quebec, Montreal, Canada et ITnstitut de recherche d"Hydro-Quebec IREQ, Varennes, Canada.

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Patocka, Filip. "Environmental Impacts of Pumped Storage Hydro Power Plants". Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for vann- og miljøteknikk, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-26677.

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Massive development of new renewable energy sources is taking place all over the world in 21st century and Europe is not an exception. Wind turbine parks are being planned and built on shore, in coastal zones and in the seas of European countries.With such a development of renewable sources comes a challenge of stable and continuous supply of electrical power which meets the demand. Renewable energy sources often have power output which cannot be easily regulated according to demand, but are rather fully dependent on forces in nature, such as a wind speed for wind power turbines, or solar radiation for photovoltaic solar modules. This problem has to be handled in order to ensure the safe and reliable operation of electricity grid in the future, which is capable of connecting the renewable energy input.This thesis is a continuation of suitability exploration of a current Norwegian hydropower system as so called the Green battery of Europe. This balancing system could secure the planned European wind power projects during situations when the production is larger than the demand by storing energy in upper reservoirs using pumping storage hydropower. During conditions when the demand is larger than generated energy the extra input can be produced by Norwegian hydropower system as well.The specific focus of this thesis is on evaluating the potential environmental impacts on Totak reservoir in Telemark county in Norway, caused by development of pumping storage hydropower. This hydropower plant is considered as a part of the system balancing the power output from TradeWind project, which is a wind power capacity scenario project for year 2030 consisting of 94,6GW of installed capacity in the North Sea in Belgium, Denmark, Germany, UK, Netherlands and Norway.During the work in this thesis, model of pumping storage hydropower plant between Totak and Songavatnet reservoirs was used to calculate characteristics of operation as water level fluctuation characteristics, transferred water volumes and other characteristics for two variants of installed power output within period of 2000-2006.Results of the pumping model were used to model the changes in temperature regime and ice formation of Totak reservoir. This was done by MyLake model developed by Norwegian Institute for Water Research in Oslo and further modified at NTNU for usage in reservoirs. With this so called MyLakeR model I modelled the temperature regime and ice cover in period of 2000-2006 for both current situation and situation after developing the pumping storage hydropower.This thesis provides the required complete hydrological forcing from pumping storage hydropower plant to the environment. Actual evaluation of impacts is often dependent on particular data which has to be collected on site, therefore only evaluation of potential impacts was done when the relevant data were available.Pumping model has proven to be a powerful and reliable tool. MyLakeR model showed that the modification done on a lake model allows successful modelling on more complex sites such as Totak reservoir. It also showed that for an ice routine of the model there is a need for further adjustments in order to model the ice cover regime affected by pumping storage hydropower.

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Tai, Sio Un. "Power quality study in Macau and virtual power analyzer". Thesis, University of Macau, 2012. http://umaclib3.umac.mo/record=b2586277.

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Pan, Haibo 1973. "SMES for power quality improvement and uninterruptible power supply". Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33342.

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The history of applied superconductor-based equipment in industry, especially in power system, is briefly reviewed. The thesis presents a development of a superconducting magnetic energy storage system for power quality improvement and uninterruptible power supply (PQ/UPS SMES). The configuration of such a system and its control concept are analyzed in full details. Evaluation tests of an SMES system operating on a simple power system are presented and analyzed. They validate the applicability of such a system, as an attractive alternative for power quality improvement and uninterruptable power supply.
The PQ/UPS SMES system as well as the power network has been modeled using Matlab/Simulink simulation environment for convenience. The Simulink models of all relevant components are also presented. Finally, all the evaluation tests are also done in Simulink simulation environment.

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Davis, Christina Clarkson. "Understanding and Predicting Water Quality Impacts on Coagulation". Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/70883.

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Effective coagulation is critical to the production of safe, potable drinking water, but variations in the chemical composition of source water can present challenges in achieving targeted contaminant removal and predicting coagulation outcomes. A critical literature review describes factors affecting the hydrolysis reactions of metal salt coagulants and the resulting precipitates. Properties of two key contaminants, turbidity and natural organic matter (NOM), are explored in the context of removal during coagulation, and the influence of co-occurring ions is described. While it is apparent that NOM character determines the minimum achievable organic carbon residual, the effects of water quality—including pH, NOM character and concentration, and concentrations of synergistic and competitive ions—on overall coagulation efficacy and NOM removal may be underestimated. An experimental research plan was devised to investigate the influence of water quality in coagulation and provide data to support the development of a predictive coagulation model. NOM is capable of interfering with ferric iron hydrolysis and influencing the size, morphology, and identity of precipitates. Conversely, calcium is known to increase the size and aggregation of Fe3+ precipitates and increase surface potential, leading to more effective coagulation and widening the pH range of treatment. Experiments and modeling were conducted to investigate the significance of the Fe/NOM ratio and the presence of calcium in coagulation. At the high Fe/NOM ratio, sufficient or excess ferric hydroxide was available for NOM removal, and coagulation proceeded according to expectations based upon the literature. At the low Fe/NOM ratio, however, NOM inhibited Fe3+ hydrolysis, reduced zeta potential, and suppressed the formation of filterable Fe flocs, leading to interference with effective NOM removal. In these dose-limited systems, equilibrating NOM with 1 mM Ca2+ prior to dosing with ferric chloride coagulant increased the extent of Fe3+ hydrolysis, increased zeta potential, decreased the fraction of colloidal Fe, and improved NOM removal. In dose-limited systems without calcium, complexation of Fe species by NOM appears to be the mechanism by which coagulation is disrupted. In systems with calcium, data and modeling indicate that calcium complexation by NOM neutralizes some of the negative organic charge and minimizes Fe complexation, making Fe hydrolysis species available for growth and effective coagulation. Experiments were conducted to investigate the influence of aqueous silica and pH on the removal of natural organic matter (NOM) by coagulation with ferric chloride. Samples with preformed ferric hydroxide were also compared to samples coagulated in situ to assess the role of coprecipitation. The moderate (10 mg/L) and high (50 mg/L) SiO2 concentrations both demonstrated interference with NOM removal at pH 6.5-7.5. In turn, NOM at 2 mg/L as DOC interfered with silica sorption at the moderate silica level and in samples with preformed ferric hydroxide at the high silica level. The combination of NOM and high silica led to decreases in DOC sorption and unexpected increases in silica sorption in the coprecipitated samples. The fraction of colloidal Fe passing a 0.45-μm filter also increased in the coprecipitated samples with both NOM and high silica. It is hypothesized that the combination of NOM and high silica synergistically interfered with Fe precipitation and particle growth processes, with NOM having the greater effect at lower pH and shorter reaction times, and silica exerting greater influence at higher pH and longer reaction time. Direct competition for surface sites and electrostatic repulsion were also influential. An overall goal for this research was the development of a quantitative coagulation model. Previous attempts to model coagulation have been limited by the inherent complexities of simultaneously predicting ligand sorption, metal complexation, floc surface charge, and particle removal. A diffuse layer (DLM) surface complexation model was formulated to simultaneously predict sorption of NOM and other key species, including silica, calcium, and carbonate alkalinity. Predictions of surface potential were used to estimate zeta potential and resulting regimes of effective aggregation and turbidity removal. The model provided good predictive ability for data from bench-scale experiments with synthetic water and jar tests of nine U.S. source waters. Under most conditions, the model provides excellent capability for predicting NOM sorption, calcium sorption, and particle destabilization and adequate capability for predicting silica sorption. Model simulations of hypothetical scenarios and experimental results help to explain practical observations from the literature. The DLM can be optimized to site-specific conditions and expanded to include sorption of additional species, such as arsenic.
Ph. D.

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Abou-Senna, Hatem. "Microscopic Assessment of Transportation Emissions on Limited Access Highways". Doctoral diss., University of Central Florida, 2012. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5090.

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On-road vehicles are a major source of transportation carbon dioxide (CO2) greenhouse gas emissions in all the developed countries, and in many of the developing countries in the world. Similarly, several criteria air pollutants are associated with transportation, e.g., carbon monoxide (CO), nitrogen oxides (NOx), and particulate matter (PM). The need to accurately quantify transportation-related emissions from vehicles is essential. Transportation agencies and researchers in the past have estimated emissions using one average speed and volume on a long stretch of roadway. With MOVES, there is an opportunity for higher precision and accuracy. Integrating a microscopic traffic simulation model (such as VISSIM) with MOVES allows one to obtain precise and accurate emissions estimates. The new United States Environmental Protection Agency (USEPA) mobile source emissions model, MOVES2010a (MOVES) can estimate vehicle emissions on a second-by-second basis creating the opportunity to develop new software “VIMIS 1.0” (VISSIM/MOVES Integration Software) to facilitate the integration process. This research presents a microscopic examination of five key transportation parameters (traffic volume, speed, truck percentage, road grade and temperature) on a 10-mile stretch of Interstate 4 (I-4) test bed prototype; an urban limited access highway corridor in Orlando, Florida. The analysis was conducted utilizing VIMIS 1.0 and using an advanced custom design technique; D-Optimality and I-Optimality criteria, to identify active factors and to ensure precision in estimating the regression coefficients as well as the response variable. The analysis of the experiment identified the optimal settings of the key factors and resulted in the development of Micro-TEM (Microscopic Transportation Emissions Meta-Model). The main purpose of Micro-TEM is to serve as a substitute model for predicting transportation emissions on limited access highways to an acceptable degree of accuracy in lieu of running simulations using a traffic model and integrating the results in an emissions model. Furthermore, significant emission rate reductions were observed from the experiment on the modeled corridor especially for speeds between 55 and 60 mph while maintaining up to 80% and 90% of the freeway's capacity. However, vehicle activity characterization in terms of speed was shown to have a significant impact on the emission estimation approach. Four different approaches were further examined to capture the environmental impacts of vehicular operations on the modeled test bed prototype. First, (at the most basic level), emissions were estimated for the entire 10-mile section “by hand” using one average traffic volume and average speed. Then, three advanced levels of detail were studied using VISSIM/MOVES to analyze smaller links: average speeds and volumes (AVG), second-by-second link driving schedules (LDS), and second-by-second operating mode distributions (OPMODE). This research analyzed how the various approaches affect predicted emissions of CO, NOx, PM and CO2. The results demonstrated that obtaining accurate and comprehensive operating mode distributions on a second-by-second basis improves emission estimates. Specifically, emission rates were found to be highly sensitive to stop-and-go traffic and the associated driving cycles of acceleration, deceleration, frequent braking/coasting and idling. Using the AVG or LDS approach may overestimate or underestimate emissions, respectively, compared to an operating mode distribution approach. Additionally, model applications and mitigation scenarios were examined on the modeled corridor to evaluate the environmental impacts in terms of vehicular emissions and at the same time validate the developed model “Micro-TEM”. Mitigation scenarios included the future implementation of managed lanes (ML) along with the general use lanes (GUL) on the I-4 corridor, the currently implemented variable speed limits (VSL) scenario as well as a hypothetical restricted truck lane (RTL) scenario. Results of the mitigation scenarios showed an overall speed improvement on the corridor which resulted in overall reduction in emissions and emission rates when compared to the existing condition (EX) scenario and specifically on link by link basis for the RTL scenario. The proposed emission rate estimation process also can be extended to gridded emissions for ozone modeling, or to localized air quality dispersion modeling, where temporal and spatial resolution of emissions is essential to predict the concentration of pollutants near roadways.
ID: 031988296; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (Ph.D.)--University of Central Florida, 2012.; Includes bibliographical references.
Ph.D.
Doctorate
Civil, Environmental and Construction Engineering
Engineering and Computer Science
Civil Engineering

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Bryans, A. G. "Impacts of tidal stream devices on electrical power systems". Thesis, Queen's University Belfast, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.438131.

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KANT, VINAY. "REAL TIME MONITORING OF IMPACTS OF POWER QUALITY ON INDUSTRIAL MOTOR EFFICIENCY". Thesis, 2022. http://dspace.dtu.ac.in:8080/jspui/handle/repository/19706.

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This work focused on Impacts of power quality on an online induction motor in a real time basis. The work involves creating variable conditions in the input power supply and analyzing its impacts on motor performance specially efficiency. Input power supply is modulated in two aspects, first one is voltage fluctuation and second one is voltage unbalance. For the conduct of test a 10 HP induction motor is selected which is run under test condition for half an hour. During test input supply voltage is varied on both sides of the rated voltage of the motor with the help of servo voltage stabilizer. In process voltage unbalance condition was also implied on the motor by varying the voltage across three phases. All measurement parameters during test are recorded with the help of Fluke 438 II Power quality and motor analyzer. The test results have indicated that motor efficiency deteriorates whenever there is a deviation from rated voltage of the motor. It also shown the same trend when voltage unbalance is increased. Thus, it implies that power quality plays a major role in the performance of the motor.

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Muthige, Mavhungu Sydney. "Ambient air quality impacts of a coal-fired power station in Lephalale area". Thesis, 2014.

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Lephalale Municipality is a predominantly rural Municipality with 38 villages, two townships (Marapong and Onverwacht) and one town, Lephalale. Lephalale, formerly known as Ellisras, is a town situated in the “heart of the Bushveld” in Limpopo province. The town is growing rapidly and more industries are becoming concentrated within this small town. The construction of Medupi power station which is underway and other projects such as the expansion of Grootegeluk mine (coal 3 and 4 projects), and road developments in the area; have led to concern about the ambient air quality of the area. Other possible future projects are the Coal to Liquid project by Sasol and the Coal Bed Methane project by Anglo American Thermal Coal. The purpose of this study is to determine the ambient air quality impact of the Matimba power station in the Lephalale area. The AERMOD model and ambient air quality data obtained from Eskom’s Grootstryd and Marapong monitoring stations were used to assess the ambient air quality of Lephalale. Sulphur dioxide and Nitrogen oxides were investigated. Both the model’s results and the ambient air quality monitoring data indicated that the power station contributes to high -ground level concentrations of Sulphur dioxide. AERMOD simulated the nitrogen oxides results as nitrogen dioxide. From the study it is concluded that the power station is not the only source of nitrogen oxides. Nitrogen oxides concentrations were associated with low-level sources. The relationship between the criteria pollutants in this study was assessed. The study found that there is no relationship between sulphur dioxide and nitrogen oxides. This finding was used to support the idea that sulphur dioxide and nitrogen oxides are from different sources. It was also established that seasonality has an influence on the ground level concentrations of pollutants in the area.

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48

"Distributed Photovoltaic Generation in Residential Distribution Systems: Impacts on Power Quality and Anti-islanding". Master's thesis, 2013. http://hdl.handle.net/2286/R.I.17741.

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abstract: The past few decades have seen a consistent growth of distributed PV sources. Distributed PV, like other DG sources, can be located at or near load centers and provide benefits which traditional generation may lack. However, distribution systems were not designed to accommodate such power generation sources as these sources might lead to operational as well as power quality issues. A high penetration of distributed PV resources may lead to bi-directional power flow resulting in voltage swells, increased losses and overloading of conductors. Voltage unbalance is a concern in distribution systems and the effect of single-phase residential PV systems on voltage unbalance needs to be explored. Furthermore, the islanding of DGs presents a technical hurdle towards the seamless integration of DG sources with the electricity grid. The work done in this thesis explores two important aspects of grid inte-gration of distributed PV generation, namely, the impact on power quality and anti-islanding. A test distribution system, representing a realistic distribution feeder in Arizona is modeled to study both the aforementioned aspects. The im-pact of distributed PV on voltage profile, voltage unbalance and distribution sys-tem primary losses are studied using CYMDIST. Furthermore, a PSCAD model of the inverter with anti-island controls is developed and the efficacy of the anti-islanding techniques is studied. Based on the simulations, generalized conclusions are drawn and the problems/benefits are elucidated.
Dissertation/Thesis
M.S. Electrical Engineering 2013

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49

Tsai, Hsin-ting, i 蔡欣庭. "Review of the Impacts on Power Quality and System Stability to Power Systems by New Energy Systems :Wind Power﹐Photovoltaic and Fuel Cell". Thesis, 2008. http://ndltd.ncl.edu.tw/handle/01099639640694189342.

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碩士
國立中正大學
電機工程所
97
Energy demands from human beings are increasing. Electricity usage is also rising from year to year. Nowadays, most electricity comes from the conversion of fossil and hydro energies. Fossil energy storage is limited on earth and using fossil energies would produce green house effect. Sustainable energy conversion technologies are developing around the globe to replace the dependence on fossil-based generation. New electricity generation technologies, e.g. wind turbine, photovoltaic, fuel cell and etc., are penetrating in the power system network in a great increasing rate. In this thesis, based on published works, we discuss on the power quality problems that may be induced by the integration of these new energy generation systems into power systems. Several mitigation methods to the power quality problems are listed and their operations are discussed. In addition, when new energy generations are integrated into power systems, the impacts of transient stability when fault occurs, or switch-in or switch-off these new energy sources are analyzed. Counter-control methods are also discussed.

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50

LEE, TSUNG-MING, i 李宗明. "IMPACT OF MINIMUM SHORT-CIRCUIT CURRENT ON POWER QUALITY REGULATION". Thesis, 1995. http://ndltd.ncl.edu.tw/handle/39971275542595082074.

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碩士
國立清華大學
電機工程研究所
83
The harmonic or three-phase unbalance current injection into the Taiwan Power (Taipower) system due to customer''s nonlinear load can cause the voltage distortion at Taipower''s substation. This voltage distortion also varies with the system impedance of Taipower.For example,during the base-load duration, because the system impedance is high (or the three-phase short-circuit current,abbreviated by 3-φ SCC, is low),the injection current can cause a higher voltage distortion than that caused by the same current during the peak-load duration. As the system impedance (or 3-φ SCC)is variational,the power utility has to specify the minimum 3-φ SCC based on which to regulate the harmonic or 3-φ unbalance current injected into the utility system. Presently,Taipower adopts a rule-based approach to specify the yearly minimum 3-φ SCC.For a theoretical soundness, Tsing-Hua University has proposed a statistical approach to the same specification. Our research comprises of two major parts.In the first part,we simulate the traction load of Taiwan high-speed railway (HSR) system which is now under planning.With the load evaluated,we then estimate the maximum 3-φ voltage unbalance factor at each HSR substation on basis of the station''s minimum 3-φ SCC specified by the Taipower''s rule-based and the Tsing-Hua''s statistical approaches respectively. In the second part,we simulate the load of Taipei mass rapid transit (MRT) system,and estimate the harmonic distortion limits to be imposed on each MRT substation .In this estimation,we also uses the minimum 3-φ SCC specified by the Taipower''s and the Tsing-Hua''s approaches respectively,and compare the impact of these two approaches on the MRT harmonic distortion limits.

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