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3028 Uppsatser om Power measurement - Sida 2 av 202
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.
Tidssynkroniserade mätningar i vattenkraftstationer
Vattenfall and Svenska Kraftnät perform start-up tests, where hydropower generators are used to power up the electrical grid in case of a blackout. To monitor the electrical grid, Phasor Measurement Units (PMU) are used. Each PMU is individually equipped with a GPS-receiver to precisely timestamp the data relative to the official time UTC. During the test, it is also of interest to timestamp the measurement signals from individual hydropower generators to later compare with PMU-data, and thus study the power grids impact on the generator. The aim is to work out an appropriate method to make these measurements and to build a data acquisition system, capable of timestamp data relative to UTC, from a generator in one of Vattenfalls hydroelectric power stations. The problem is that the generator is located in an underground station which hampers the reception of GPS-signals and wiring should be avoided if possible. Time synchronization has been solved by using Vattenfalls network, which is synchronized by the network protocol NTP.
Flödesmätning i vattenkraftverk : Studie av alternativa mätmetoder
Flow measurement is one of the greatest challenges in order to calculate efficiency in hydropower. Most hydropower plants in Sweden use differential pressure methods for flow measurement. These methods are dependent on constant conditions in the waterways. A change in these conditions, like turbine improvements, prevents differential pressure methods to verify efficiency improvements. Since efficiency improvements can?t be verified by one measurement system, another method, which isn?t affected by changing conditions, can be used.
Osteometriska Mätningar : För artbedömning av får, get och svin utifrån mått av revben
Ribs from sheep, goat and pig are rarely assessed to species due to the fact that they are very similar in their morphology and size. The ribs are instead considered unidentifiable although it is possible to see what kind of bone it is. If these ribs would be identified to species not only would species assessment degree of archaeological source material increase, the relationship between meat-rich and meat poor regions would change.To find out whether there are morphologically measurable differences between sheep, goat and pig ribs, three measurement points on each rib has been defined and measured. At each measurement point two measurements were measured, one medial-lateral measurement and one cranial-caudal measurement. The ratio between the medial- lateral measurement and the cranial-caudal measurement was calculated for each point.
Value creation from a gender perspective – a case study of Caran
Caran has a strong belief that women leaders affect the financial profitability positive. Since women leaders are intangible resources it is very difficult to calculate its exact value. The authors found that one of their measurement methods can’t be used to calculate the value of women leaders. The other measurement method can calculate significance between women and men leaders and provides an index to be compared to other groups. But there is no prove that women are better creating value than their men colleagues, the figures indicate that women add more value due to their lower wages.
Det permanenta mätfelet: En studie i förändringen av det permanenta mätfelet
This thesis studies the relationship between book values and market values in different assets and liabilities in Swedish Large Cap companies balance sheets. The aim is to find out if the relationship, the permanent measurement bias, has changed during since Mikael Runstens doctoral thesis from 1998 called The Association between Accounting Information and Stock Prices. Although some changes in the permanent measurement bias are found, this probably is due to other aspects than the introduction of IFRS..
Ström- och temperaturkontroll
Storing kinetic energy in a flywheel allows for more efficient driving of electricvehicles. Research in this area is in progress at Uppsala University, where a flywheelwith magnetic bearings encased in a vacuum chamber is being constructed. To makethis possible methods for measuring the current through the electromagnets in thebearings and temperatures in the flywheel need to be developed. This has been thepurpose of this report. The current measurement resulted in a resistive method, andthe implementation of eight measurement circuits in the system.
Value creation from a gender perspective ? a case study of Caran
Caran has a strong belief that women leaders affect the financial profitability positive. Since women leaders are intangible resources it is very difficult to calculate its exact value. The authors found that one of their measurement methods can?t be used to calculate the value of women leaders. The other measurement method can calculate significance between women and men leaders and provides an index to be compared to other groups.
Analys av mätdata från nätstationer
Fortum has in a pilot project installed metering equipment with wireless communication in secondary substations in Stockholm. So far, the collected data are used only in specific projects.This master thesis was carried out at Fortum Distribution AB in Stockholm during 2013. The purpose of this study is to simplify and enhance the use of data in for example network planning process, by giving suggestions on how data can be managed and giving examples of analyzes that collected data can be used for.The electricity meter which Fortum has installed is a EDMI-Mk10A which is set to measure max/average/min values with a one hour time resolution of the following parameters: voltage (per phase), current (per phase) andactive power and active and reactive energy.In order to analyze the collected data an analysis tool is required. During this thesis two customized tools in Microsoft Excel have been developed, one for sorting data and one for analyzing.One aim of the thesis is to show examples of what collected measurement data can be used for. This work shows an example of analysis of active power, power factor, voltage, occurrence of interrupts and the relationship between outdoor temperature and power.This master thesis has among others resulted in the following advice: Expand the number of secondary substations with measuring equipment.
Förstudie för kvalitetssäkringav glidande förband vid Hissmoforsvattenkraftsstation : -Specifikt för aggregat G6 och G7
Jämtkraft AB which is a power production company in Sweden has bought two newhydro power units to their station in Hissmofors. The two new generators are using aconcept with sliding stator feet to handle the thermal expansion.The concept with sliding stator feet on hydro electric generators has not beenworking satisfactory on many hydro power stations in Sweden and has caused a lot ofcosts due to long downtimes.The new station in Hissmofors is very important for Jämtkraft AB, and therefore theywant to know how to make sure that the sliding stator feet are working as theyshould. According to theories and a simplified model of the generator the stator feetdisplacement should be around 1 -1,6 mm.The generators are delivered with a surveillance system that will measure thedisplacement of the sliding stator feet. The signal from the system isn?t accessible forJämtkraft AB but it will alarm when the sliding stator feet are malfunctioning.To secure the function of the sliding feet a logger for the surveillance system or adifferent measurement system must be used; if both systems are used Jämtkraft cansecure the function of the surveillance system..
Pengar, press & partiledare : En studie om porträtteringen av makt i svenska tidsskrifter
We have studied how power is portrayed in Swedish journals by analyzing eight portraits of Swedish persons with economic or political power. We have studied how they and their power are described by the journalist in text and picture. We wanted to see which picture the journalist shows of people with power, what properties they are given by the journalist and how this picture is shown by the texts and the pictures. We have also looked if there are any differences between people with political power and people with economic power. We have under our studies noticed that the persons with power are described as very successful and special and this picture are shown in a very clear and unproblematic way..
Undersökande journalistik : En analys av Uppdrag gransknings dokumentär om IKEA
This essay is about power in the classroom. It is about the power dimension of the student-teacher relationships that arise in that space. The overall aim has been to investigate which categories are fruitful in a power analysis of these relationships. My aim has therefore been to develop power categories and to use them to identify and to categorise cases of power interaction that take place between those particular actors in that particular setting.In order to gather material for my study I have both read literature that approaches the study of the student-teacher relationships from a power perspective and done a series of observations in a high school.My theoretical frame comprises a concept of power and a series of power categories. These categories include strength, authority, inducement, coercion, violence, resistance as well as to possess power, to have power, to exert power, the scope of power and the base of power.
Scenarioanalys över Sveriges elproduktion år 2050 : Kan Sverige försörja sig med 100 % förnybar
The aim of this report was to investigate if Sweden can have 100 % renewable electricity production in the year 2050. The conclusion is that it is possible but under certain conditions. For instance wave power must be in commercial use. When wind power and solar power represent a large percentage of the electric production there will be a lack of electric power during the winter but during the summer there will be a surplus of electric power. Both the surplus and the lack of electric power need to be taken into account.
Del projekt inom ClampCal - Utvärdering av mätmetoder för temperatur, viskositet och densitet samt röregenskaper
The dissertation were performed on SP, Technical Institute of Sweden.
The dissertation were carried out on the measurement technical department, this dissertation is a part of a bigger project, project ClampCal.
One of SP?s returning assignments are flow-measurement. When flow-measurement is performed, the flow has to be stopped so that a meter can be installed in the pipes where measurement is going to take place. At every stop there is time delay in the flow which causes the customers to loose money. This is why SP wanted to find a better solution so that measurement can be done without any stops in the flow.
Usage of a so-called Clamp-on meter was considered, but since the measurement uncertainty is too large it takes some investigation on the parts where the largest uncertainties occur and thus find a solution that can diminish the uncertainty as much as possible.
The parts that were considered to have an opportunity to reduce measurement uncertainties were the fluid temperature, its characteristics and the pipe geometry and its characteristics.
For the fluid temperature a Pt100-sensor with four different radii for various pipes was used.
Design och framtagande av mätanordning för ström och effek på trefas ledare : Josi Periferi strömmeter
The assignment is issued by Scania Maintence AB seeking a new approach to detect power changes in their industrial processes. The work has taken place at Ångströmslaboratoriet and tests have been performed at Scania AB Södertälje.Today?s society consumes enormous amount of energy. In both economically and environmental view, it is important that the processes are effective, with high power factor. There are many ways to measure power in the industry, what they all have in common is that the installation is advanced, requires time and planning.