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467 Uppsatser om Low voltage grid - Sida 19 av 32

K2 : Finns det ett behov hos företagen i dagsläget?

Sedan 2003 har Bokföringsnämnden (BFN) arbetat med ett projekt innehållande redovisningsförenklingar. 11 juni 2008 beslutade BFN att ge ut allmänna råd och vägledning för mindre företag, K2. (BFNAR 2008:1) De företag som innefattas i K2 är en stor grupp med 96 % av alla svenska aktiebolag. Kritik som BFN har fått är att enheten jobbar under knappa resurser och att de största företagen inom K2 kommer att ha svårt att redovisa med en rättvisande bild.Hur är kunskapen om och behovet av BFNAR 2008:1 för det övre segmentet inom kategorin K2 i dagsläget?Syftet med denna uppsats är att undersöka behovet hos företag i det övre segmentet inom kategorin K2 samt att se hur kunskapen och attityden är till BFNAR 2008:1.

Elektrisk integrering och projektering av förnybar energi i svagt lokalt elnät

För att en kvalitativ och driftsäker kraftomvandling från vind till elkraft skall erhållas ställs krav på en mängd olika faktorer. Klimatologiska och tekniska faktorer kräver korrekt dimensionering och anpassning av omvandlingstekniken för att största möjliga energimängd skall kunna omvandlas på ett driftsäkert och energieffektivt vis som vindkraftsägare, nätägare kräver. Vinden är som bekant en oberäknelig kraftkälla. Variationerna i styrka och tid kan innebära en hel del driftoptimeringsproblematik med efterverkningar för vindkraftsverket, nätet och belastningen. Konsekvenserna kan bero på vilken typ av teknik som är installerad i de olika delarna av energisystemet och i områdets elnät.

Implementering av Constant Fraction Detection vid avståndsmätning

This thesis is performed at Saab Bofors Dynamics in Karlskoga and investigates a technique for ranging with laser pulses. The investigated technique is called Constant Fraction Detection (CFD). Described briefly, the received laser pulse is split into two equal parts, where one part is delayed half the pulse width and inverted. This signal is added to the original pulse. The resulting curve has the shape of a laying S and the detection of the zero level is used to stop the time measurement.

Tillförlitlighet i Stockholms elnät : En analys med hjälp av Tekla NIS

Outages in the electric grid can be costly for society. Because of this, reliability is one of the parameters used to regulate network companies. Reliability in electrical grids can be measured with SAIDI, system average interruption duration index, which for Fortum Distribution has increased in Stockholm?s distribution network (11 kV) in the early 2000?s.By using outage data for Stockholm from 2011-2013, sets of parameters to be used for reliability calculations in the network information program Tekla NIS were derived. Two different options for investment were then analysed: changing old cables with high fault frequencies, and installing automatic switching in distribution substations.

Utvärdering av dimensionell stabilitet i PWR-patroner i Ringhals

Dimensional stability is an important aspect of fuel mechanical design and licensing of new fuel designs for nuclear power plants. Dimensional changes within the reactor can affect the safety margins against overheating of the cladding and the pellets, therefore it is crucial that the dimensional changes are kept to a minimum.The profits per produced kiloWatt hour continue to decrease for the Swedish nuclear power plants. Some reactors are even operated with a calculated loss. To reduce fuel costs and thereby improve the profit some reactors are operated with higher uranium enrichment, so that the assemblies can reach a higher average burnup. This increases the neutron fluence to the pellets, cladding an spacers.

Jämförelse av verklig och modellerad elproduktion från en solcellsanläggning : En utvärdering av två simuleringsverktyg.

This thesis has been carried out in New Zealand in collaboration with the University of Waikato. In association with Dr. Mike Duke the purpose of this work is to investigate whether two different software for modeling of photovoltaic systems are useful in the teaching of solar energy.The next ten years grid-connected photovoltaic systems are assumed to increase and therefore also a rising demand for people with engineering knowledge are to be predicted. For engineer students with a focus on solar energy a more practical teaching with design software´s can be a good method to make the students comprehend more when it comes to large scale photovoltaic systems and be more prepared for working life.The software´s used is called Transient System Simulation (TRNSYS) and Photovoltaic Systems (PVSYST) which are both well used throughout the world. To assess the reliability of the software´s, a reference solar power plant at 16.1 kWp installed capacity are used, which consists of photovoltaic modules from four different manufacturers.

Mobil kommunikation och högre tillgänglighet vid längre elavbrott : Exemplet stormen Dagmar och 4G-kommunikation inom smarta elnät

To be able to secure a safe and reliable power supply is becoming increasingly important since society depends on services and functions that need continuous power supply. The delivery rate in Swedish power supply is 99.98 % which insists on a high availability. During the past decade several storms has passed Sweden which resulted in large amount of tree felling leading to extended power outages. During these storms many socially critical activities, such as electric utility company Fortum, experienced disruption in mobile communication which affected the crisis management. This paper has investigated Swedish mobile operators? crisis management at Hi3G, Tele2 and TeliaSonera with a case study of the storm Dagmar that hit Sweden during December in 2011.

Specificering av produktionstransformatorer : Rekommenderade avsteg från IEC 60076 för att vid upphandling beskriva en robust enhet

As break downs of production transformers are costly and often result in long outages it is essential for reliability of operation that the transformers are manufactured to be robust. The aim of this M.Sc. thesis is to investigate if deviations should be made from the standard IEC 60076 ? Power Transformers in order to describe a robust large power transformer for procurement.The investigation has been conducted in three stages. In the first stage a definition of the term robust was developed in consultation with the client Vattenfall Vattenkraft.

Trådlös energiöverföring via elektromagnetisk induktion

This paper describes a method for wireless energy transfer via near-field electromagnetic inductionthat is inexpensive, simple and can be applied to almost any type of system, regardless of size andenergy demands.The method uses a primary unit consisting of an oscillator, amplifier and inductive coil thattransfers energy to a secondary unit consisting of a coil, rectifier and voltage regulator. Two typesof oscillators and several amplifier designs were realized and evaluated together with a multitudeof flat coils of both monofilar and bifilar type.The results show that it is important to use an oscillator whose frequency is dependent on theinductance of the connected transmission coil, such as the Colpitts oscillator. This is preferable toan oscillator with a preset frequency, such as a Schmitt-trigger oscillator..

Konstruktion och utvärdering av Current Conveyors

Normally the operational amplifier is used as a component in active filter design. The goal for future components in filter design is large bandwith and the use of low supply voltages. The use of current-mode instead of voltage-mode circuits gets a step closer to the required performance. A component that use current as the signal conveying part is the current conveyor. In this report a comparative study between two current conveyor structures of second generation (CCII) is performed.

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.

Snake Grid och andra objektanpassade projektioner för svensk infrastruktur

I detta examensarbete undersöks tillämpligheten av speciellt anpassade kartprojektioner för projektering, byggnation, drift och underhåll av långsträcka objekt inom svensk infrastruktur. Speciellt intresse ägnas åt Snake Grid-projektionen som utvecklats av University College London i samarbete med Network Rail, som bygger och underhåller det brittiska järnvägsnätet.I samband med att man i Sverige satsar på utbyggnad och uppgradering av järnvägsnätet med höghastighetsspår, uppstår även ny mätningstekniska utmaningar då anläggningarna blir allt mer komplicerade, och toleranserna allt snävare. Projekteringen av anläggningarna utförs oftast i programvaror som antar att bygget kommer att utföras i ett tredimensionellt rum med rätvinkliga axlar, med norr och öst i ett plan och lodriktningen vinkelrätt mot detta plan. Problem uppstår när detta antagande om en platt jord möter verkligheten med en krökt jordyta och kuperad terräng.Den klassiska lösningen på problemet är att arbeta med kartprojektioner, för att på så sätt lokalt eller regionalt approximera en platt jord vid kartering och projektering. Storleken på det område som kartprojektionen är giltig för och lokala höjdförhållanden bestämmer hur stora avbildningsfelen, i form av skalförskjutningar, som mest blir i kartan.

Det självförsörjande passivhuset

The housing sector uses 40 % of the energy in Sweden and half of the electricity usage. Theuse of energy is the main reason to the increasing rate of carbon dioxide in the atmosphere.This is the main motive but also a wish of higher safety, that is a higher rate of selfsufficientenergy production in Sweden, we want to decrease the need of using fossil fuel. Now whenthe energy price rise, the interest in energy issues increase and more people discuss thepossibility of reducing the usage of fossil fuel. A change to renewable energy such as sun,wind and water is the only solution where we can get a sustainable development.One way to contribute to a better use of energy is to build in the principle of passive house.The house is being built with a thick and tight insulation. If you use a heat-exchanger withhigh degree of efficiency and a final heating battery on the ventilation system, the heat fromlamps, devices and the ones living in the house should be enough to fulfil the criteria ofliving.

Peltierelement - spillvärme till el : Peltier element - waste heat into electricity

The purpose of this thesis has been to determine experimentally how good a peltierelement is to convert waste heat from wood burning. Three different peltier elementswere used in a comparison study. The comparison was mainly done to know howmuch power could be obtained from each element. Even, a circuit with a step-upfunction has been created to give a higher output voltage than the peltier elementitself. The result of the experiments was a low output power, the highest valuereached 2.18W.

Konstruktion av styrelektronik till testfixtur

The focus of this thesis is primarily in electronic construction and describes the design process for a microcontroller circuit board from concept development to prototyping. The client develops test fixtures for automated testing of products within the electronics industry and needs a new controller circuit for the test fixtures that can handle controls and basic testing. An investigation into the needs of such a system is conducted and a prototype printed circuit board assembly is manufactured.The prototype is developed with focus on protection against electrostatic discharges and overvoltage. Among the functions that are included are voltage measurements, communication interfaces and control of input and output currents. Firmware for the prototype is developed and configured to communicate with a PC through USB interface for control and collecting of measurements..

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