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314 Uppsatser om Voltage disturbances - Sida 12 av 21

Simulering av vindkraftverk och närliggande elnät vid Risholmen i Göteborg i SimPowerSystems

With background in the rapidly growing need to find solutions for sustainable energy production and the increasing interest for wind power, this report was written. With take-off point from the wind power plant Big Glenn, which has been built in the harbour of Gothenburg, a model of the adjacent power grid has been created in Simulink/SimPowerSystems. Parameters for the power grid and its components has been provided by Göteborg Energi Nät, that has also been the supplier of measurement data of produced power, the power need from loads in the vicinity, voltage levels, current values and also the variation of power factor at the wind power plant.The SimPowerSystems model has been used to perform simulations of power flow in the grid. These simulated values have then been compared to the measured values to verify the functionality of the model. Further, the model has been used to perform simulations of a grid fault, which causes a voltage drop.

Molecular analysis of insecticide resistance in pollen beetle (Meligethes aeneus)

The escalating usage of pyrethroids has resulted in an increased awareness about resistance towards pyrethroids in insects. Pyrethroids inhibit voltage-sensitive sodium channels (VSSC) in nerve cell membranes and are composed of synthetic molecules based on pyrethrins present in pyrethrum extracts from Chrysanthemum species. VSSC are transmembrane proteins that are important for electric signalling over the membrane in insects. Mutations in the gene encoding the sodium channel have proved to be a common reason for resistance against pyrethroids. Pyrethroid resistance among pollen beetles is spread all over Sweden and also abroad and is increasing.

Partiell Urladdning- Mätmetoder och detektering med fokus på HVDC- kablar

Detta arbete behandlar mätmetoder för detektering av partiella urladdningar (kallad PD från engelska benämningen Partial Disharge) i HVAC- och HVDC- högspänningskablar. HVAC står för ?High Voltage Alternative Current? och HVDC står för ?High Voltage Direct Current?. När en viss hög spänningsnivå överskrids i kabeln uppstår olika typer av partiella urladdningar och dessa skadar kabelns isoleringsmaterial. PD- intensiteten ökar med tiden och om de tillåts fortlöpa under en längre tid kan de med tiden helt bryta ned isoleringsmaterialet vilket leder till ett fel.

Den bäcknära zonen vid små skogliga vattendrag i Värmland : generell beskrivning, förekomst av traktorspår samt kvicksilverhalter i körpåverkat ytvatten

Forest streams and the associated riparian zones are sensitive to disturbances and changes that occur within these riparian areas. Particularly sensitive are small streams of low order, which will have large impacts down-stream. The disturbances that occur in the riparian zones are reflected quickly in the stream. Driving with forestry machines in the riparian zone will have detrimental effects to the soil and water. Driving the machines will lead to changes in the mineral soil composition, resulting in the reduction of porosity, less infiltration, compaction, and an increased bulk density.

Undersökning av energibesparande metoder för multiplikator

In this thesis a number of energy saving methods for a multiplier on algorithmic level are investigated. For the investigation a multiplier is constructed in VHDL, after which the circuit's performance is investigated. A number of techniques for reduced power consumption are introduced in the circuit and are then evaluated. The conclusions are that all investigated methods, pipelining, interleaving and voltage scaling, should be maximally made use of in order to minimize the power consumption..

Modellering och styrning av flis till en sulfatkokare

At the Skoghall pappermill, sulphatepaper pulp is produced in a continuous digester originally from 1969. To be able to maintain a high level of production there is a need for a process with few disturbances. Variations in how well the wooden chips are packed in the digester is one form of disturbance. Today there are no available measurements on how well the chips are packed. Instead this is regarded as being constant.

Optimerad styrning av kondensatorbatterier - Ny möjlighet att minska förluster med elektronisk brytteknik

Transmission of reactive power is well known to cause active power losses. Thus, newcomponents who can help minimizing these expensive reactive power flows are ofgreat interest to the power distribution companies. ABB Corporate Research hasdeveloped the first electronic power breaker. One possible application for thisbreaker is transient-free switching of capacitor banks. This could prove a usefuldistribution voltage complement to the switch-sync technique, mainly applied to transmissionvoltage level.

Impact of Eucalyptus plantations on pasture land on soil properties and carbon sequestration in Brazil

Soil organic carbon (SOC) stocks and fluxes in forest ecosystems are influenced by natural and human disturbances. In the tropical regions the highest impacts on disturbance in forest C cycles are related to human activities such as conversion of natural lands to cropland and pasture areas and to forest plantations. The disturbances in the forest C cycles will release CO2 emissions to the atmosphere triggering global warming. In this study the focus was set in subtropical soils in Brazil, south extreme region of Bahia. The aim of the study was to investigate whether reforestation of Eucalyptus plantations under former pasture areas will help mitigate climate change through carbon sequestration.

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.

I vilken utsträckning kan hästar enbart utfodras med grovfoder?

Horses are grazers with a digestive system that is adapted for a high fiber diet. Forage is a fiber rich feed that includes grass and legumes. A deficiency of forage and an excess of grains may cause gut disturbances and stereotypic behavior. The aim of this literature study was to summarize information on the horse?s capacity to consume forage-only diets with focus on the horse?s need of energy and protein.

Modellering och simulering av hovrande helikopter

At the department of Electronic Warfare Assessments at the Swedish Defence Research Agency in Linköping one of the activities is modelling and simulation of the duel between a robot and a target. The aim with this Master's thesis is to develop a simulation model of an hovering helicopter. First a theoretical description of the forces and moments acting on an helicopter is given. Then the equations of motion are derived. These equations are simplified to be valid only for a hovering helicopter and the result is a mathematical model.

Patienters beskrivning av att vårdas på isoleringsrum -en litteraturstudie

Background: Every day patient´s get isolated in hospitals as a consequense of infection control purposes. Physical isolation can result in lack of human contact and a new unknown environment for the patient. Those two factors can easily cause stress within the patient and create anxiety for the future. Aim: The aim of the study was to describe patient´s experience of being nursed in an isolation room. Method: The method that was used was a literature research, where earlier research findings were read and put together.

Internetbaserad kognitiv beteendeterapi för personer med bipolär sjukdom -en pilotstudie

En betydande andel individer med bipolär sjukdom upplever kvarvarande, subkliniska symtom mellan egentliga sjukdomsepisoder. Sådana restsymtom är förenade med sänkt livskvalitet och förhöjd risk för återfall i sjukdomsepisoder. Syftet med föreliggande studie var att undersöka huruvida en kort, internetadministrerad behandling är genomförbar och kan ge en minskning av depressiva restsymtom, genom interventioner riktade mot sömn och emotionsreglering. För detta syfte användes en single-subject design med upprepade mätningar (n=4). Studiens resultat visar att behandlingen är genomförbar och att den, för vissa individer, kan ge en minskning av depressiva restsymtom.

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..

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