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8597 Uppsatser om Power quality problems - Sida 1 av 574
Mätning i nätstationer - nyttor och problem
The purpose of this study has been to investigate advantages and problems with distributionsystem metering in substations. This report is a study in cooperation with Göteborg Energi.The analyses in this report are made for GENAB, a subsidiary company of Göteborg Energi.To analyse advantages and problems in advance is interesting information for GENAB. Theresult of the report could be based upon whether installation of metering in distributionsubstations will be implemented and in that case which kind of measurement that is relevant.The most relevant and strategic place to implement measurement is at the distributionsubstations on the secondary side (400V), this is due to the placement of the currenttransformers. The measurements in this study involve current, voltage, power, power factor,temperature, energy and power quality.Measuring instruments that are relevant to implement are intended to measure current,voltage, power, power factor, energy and, possibly, power quality in the same measuring unit.It is desirable to have a measuring instrument that measures both energy and power qualitybut since it is most often a cost question, it can be established that energy meters have a lowercost.Metering in distribution substations gives a better illustration of the power network. Thisresults in many advantages for GENAB.
Kvalitetssäkring
This thesis has been made in cooperation with Forsheda Stålverktyg AB which develops and manufactures injection moulds and diecasting tools. The main concern has been their Trading-system which provides them with considerable amount of quality lost function.Focus has to however be put on the analysis of the Trading-system due to the fact that this has previously meant various quality issues for the company.This thesis treats quality assurance of the Trading-system, identification of the problems in the process and improvements of these problems.Quality assurance is carried out when a company detects that their quality based costs become too high. Quality based cost are? the costs that would disappear if a company's products and its different operational processes were absolute? (Sörqvist, 2001 p.30, free translation from Swedish). High quality based costs often result in increased quality problems, which can lead to substantial economic loss for the company.This work has resulted in a thorough review of the Trading-system whereupon problems have been identified.
Datakvalitet : En fallstudie om kvaliteten i SJ:s underhållssystem
SJ is a government-owned passenger train operator in Sweden. SJ currently uses asystem called Ford for control and monitoring of maintenance. Technical andorganizational factors have given Ford the character of a monolithic system withoutflexibility and conditions to meet SJ's increased requirements.The main purpose of this master's thesis is to investigate how data quality can bedefined at SJ and to examine the data quality in Ford. This will give SJ an indication ofwhat their quality efforts should focus on in the future.The technical data quality parameters found are: accuracy, timeliness, completenessand consistency. The user centred data quality parameters are: accessibility,understandability and reliability.
Statuskontroll av Paradisskolans elektriska belastning
In this thesis is studied the electrical load of Paradisskolan with respect to power quality and energy consumption. The school's owner Trollhättans Tomt AB is also interested to know if they can reduce their costs by changing to smaller meter fuses. A recurring ground fault that?s been recorded from powerpanel A1A has been investigated. The school's equipped with an electrical bonding system, harmonic filters for the third harmonic currents, TN-S system from feeding transformer and groundfault monitoring.
Undersökning av elkvalitet i distributionsnät med omfattande vindkraftselproduktion
The goal for this master thesis project has been to investigate the power quality in adistribution grid, which has a high fraction of dispersed power production due towindmills. The study has been done on a grid in Laholm South of Halmstad, whereapproximately 45 windmills are connected to the distribution grid owned by SHKEnergi. The investigation has been focused on to two radialy fed 20 kV lines, wheretwelve windmills are connected.Voltage variations have been studied by creating a model of the grid in the simulationprogram SIMPOW. The largest deviation that has been found in any point of the gridis ±1.9 % of the nominal voltage. This deviation is a result of varying powergeneration from the windmills and the voltage regulation at the connection point ofthe line.
Värmning av avloppsvatten med spillvärme för att förbättra kvävereningen -Temperaturens inverkan på kvävereningen
The goal for this master thesis project has been to investigate the power quality in adistribution grid, which has a high fraction of dispersed power production due towindmills. The study has been done on a grid in Laholm South of Halmstad, whereapproximately 45 windmills are connected to the distribution grid owned by SHKEnergi. The investigation has been focused on to two radialy fed 20 kV lines, wheretwelve windmills are connected.Voltage variations have been studied by creating a model of the grid in the simulationprogram SIMPOW. The largest deviation that has been found in any point of the gridis ±1.9 % of the nominal voltage. This deviation is a result of varying powergeneration from the windmills and the voltage regulation at the connection point ofthe line.
Att möta vampyren : Hur kan Twilight behandlas i skolan?
This essay discusses how popular literature in general and Stephanie Meyer?s Twilight-series in particular can be useful in the classroom, despite, or rather, thanks to, its inherent problems concerning gender roles, relationships and the power systems within them. The essay takes a reader and teacher centered approach in describing both the problems of Twilight and the ways these problems can be worked with in the context of the school subject Swedish in upper secondary school. It makes an inventory of Twilight?s problematic aspects, and attempts to use them in conjunction with the governing documents of the Swedish school system.
Utvärdering av en FPGA för rymdbruk
A new FPGA suitable for space applications has just reached the market. To investigate whether there are any possible flaws or limitations similar to those previously seen on FPGAs, an evaluation has to be done. This master thesis contains the evaluation of this new radhard FPGA with focus on possible design limitations and package related electrical phenomena.Areas evaluated: Ground-/VDD bounce, Cross talk, Rise time sensitivit, Power cycling, Power consumption, Place and route tool, Radiation hardnessThis report contains all steps in the evaluation. From method to measurements, comparisons, theory, results and conclusions. In the evaluation work, special effort has been made to develop designs that really stress the FPGA to find potential problems.
vindkraftens påverkan på elkvaliten
This thesis concerns how the power quality in the grid is affected by the connection of wind power plants. As things are at present, Fortum Distribution AB has a number of wind turbines and wind parks connected to the own grid. As the pressure on building and connecting additional wind power is increasing, so is also the interest of how the already existing wind power generation affects the power quality in the nearby distribution grids. The study is performed by direction of Fortum Distribution AB and is limited to the 10 kV/40 kV-grid in Bohuslän, Sweden. The methods for calculation of power quality are compared to the results of a number of measurements.
Energy efficient storage of biomass at Vattenfall heat and power plants
Storage of biomass is often associated with problems such as heat development, dry
matter losses and reduction of fuel quality. The rise in temperature can potentially
cause a risk of self-ignition in the fuel storage. Moreover, emissions from storage piles
can cause health problems in the surrounding. The dry matter losses and reduction of
fuel quality can have economical effects. The aim of this thesis project is to develop
guidelines on how to store large amount of biomass at Vattenfalls heat and power
plants in an optimal way.
Alkohol inom äldreomsorgen : Hur hanteras problematiken?
The purpose of our qualitative study is to investigate how the caretakers, in the elderly care,interpret and manage the issue of alcohol problems in elderly people. We have beenperforming semi-structured interviews on 9 people, on different levels in the elderly care.There were 3 elderly care managers, 1 nurse, 1 assistance administrator and 4 auxiliarynurses, who all, at some level, work with alcohol problems in elderly people. Thoseinterviews were performed singularly, with one exception: we interviewed an elderly caremanager and her 2 auxiliary nurses at the same time. To analyse our empirics, we have usedthe theories of Power and Ageism. Our study shows that the auxiliary nurses, who are theones who must deal with these problems, have great difficulties to perform their work becausethey have no qualified knowledge about alcohol problems.
En förstudie till kvalitetsutveckling på GD-tryck
The print- and mailroom at Gefle Dagblad (GD-tyck) is handling an increasing amount of commercial jobsalong with the newspaper production. Investments have above all been done in the mailroom to be able tooffer commercial costumers a higher degree of finishing and there are plans to expand further in the commercialmarket. GD-tryck is of the opinion that they need to secure the quality of their production to be ableto do such expansion, which is the reason why a quality system of some kind may be appropriate. Howeverthere are no plans to certify such a quality system according to ISO 9001:2000.In this exam report the present methods of working have been analysed from a quality perspective.Suggestions on how GD-tryck should be working with quality development is presented in the fields whereshortage of quality has been discovered. The suggestions taken together do not form a quality system butcan be looked at as ideas of approach to quality fields that have to be developed if a working quality systemshall be accomplished.Many of the quality fields that have been discussed do not have anything to do with technical qualitydirectly but are in some degree requirements for a working quality system.
Undervattensvågbrytare - En modellstudie
Today?s wind power plants are only compensated for their reactive power consumption at no-load. As the wind power plants grow bigger the amount of reactive power they need also increases. This is no longer a problem that can be ignored, especially as the net owners are beginning to charge the reactive power they transport.In this thesis a couple of different methods of compensation and their prices will be discussed and evaluated. Problems, such as self-excitation, that can occur if one fully compensates the wind power plant will also be brought to surface.
Tillförlitlighet hos trafikolycksklassificering
Today?s wind power plants are only compensated for their reactive power consumption at no-load. As the wind power plants grow bigger the amount of reactive power they need also increases. This is no longer a problem that can be ignored, especially as the net owners are beginning to charge the reactive power they transport.In this thesis a couple of different methods of compensation and their prices will be discussed and evaluated. Problems, such as self-excitation, that can occur if one fully compensates the wind power plant will also be brought to surface.
Kompensering av reaktiv effekt vid vindkraftverk
Today?s wind power plants are only compensated for their reactive power consumption at no-load. As the wind power plants grow bigger the amount of reactive power they need also increases. This is no longer a problem that can be ignored, especially as the net owners are beginning to charge the reactive power they transport.In this thesis a couple of different methods of compensation and their prices will be discussed and evaluated. Problems, such as self-excitation, that can occur if one fully compensates the wind power plant will also be brought to surface.