Simulation is a vital tool during development of JAS 39 Gripen, since money and time can be saved.The Auxiliary and Emergency Power System, AEPS, is a subsystem of the secondary power system in Gripen. It has the function of providing the aircraft with electrical and hydraulical power before activation and after deactivation of the main engine. The system also functions as backup in case of a safety critical problem in the main power supply system. The system basically consists of a control unit and an auxiliary gearbox. The gearbox is driven by an air turbine.

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..

Denna rapport beskriver arbetet med utvecklingen av en ny modell för kaplanturbiner. Utvecklingen bygger på två kopplade differentialekvationer som under arbetets gång anpassats och implementerats i turbinmodellen.Modellen beskriver hur vattenflöde och turbinmoment påverkas av avvikelsen från den optimala kombineringskurvan för vinklarna på turbinens ledskena och löphjul, och är anpassad för ett referensaggregat med tillgängliga provdata. Även övriga enheter i vattenkraftaggregatet modelleras och sätts samman med frekvensregulator och elnät för att simulera aggregatets reglerstabilitet i önätsdrift.Verifieringen av turbinmodellen sker genom försök att återskapa de befintliga verkningsgradskurvorna med hjälp av modellen. Resultatet visar en god följning av de verkliga kurvformerna, dock med något lägre maximal verkningsgrad.Verifieringen av önätmodellen sker genom att prova stabiliteten i nätfrekvens och turbineffekt vid stegpålastningar. Resultatet ger en stabilare reglerstabilitet än i verkligheten, men uppfyller ändå förväntningarna på en fungerande modell.This report describes the development of a new kaplan turbine model.

This report is a Master?s Thesis performed by Andreas Adolfsson and David Jacobsson atChalmers University of Technology. The purpose of this master?s thesis is to evaluate anew method for load-shedding, the voltage controlled underfrequency load-sheddingdeveloped by ABB. This report presents a comparison between conventionalunderfrequency load-shedding and this new method for load-shedding.

Wind power is expanding rapidly in Sweden. Increasing amounts of wind power sets higher requirements on balancing power and grid expansions and would affect the whole Swedish electricity system. The aim of this report is to examine the factors affecting the wind power expansion in Sweden. How many wind power plants projects will obtain building permissions and what costs and revenues can be expected? How much balancing power will be required and does a changing geographical distribution of the wind power plants reduce the need of balancing power?A survey of the county board?s official applications has been made and out of all the applications, corresponding to 80 TWh produced per year, about half of the applications are expected to obtain a permit with a major portion of them located in the north of Sweden.Especially older wind power plants, deriving revenue from Nord pool, find themselves today in a complicated financial situation.

Chalmers University of Technology today have numerous computers which are never powereddown, at the same time there is a need for more computation power for researchers.Hence, we have investigated the possibility to use the computers for computing power andsecondly, if there is no work to be done, to put them into power saving mode.We have made a thorough study where we compared different distributing systems andin the end HTCondor was chosen as the best to implement. HTCondor is an excellent systemfor opportunistic use of computing power, i.e. make use of computers that no one elseis currently using. The system is used at several universities around the world with goodresults and would be excellent at Chalmers, where there is a need for such a system.Our implementation shows that HTCondor is well capable of handling unused computingpower. HTCondor can handle most file types that may be run on the system.

An important process for grid companies in order to reduce power losses in electricity distribution grids is to figure out where and how they appear. This report describes the factors that cause power losses in low voltage distribution grids and methods for how they could be measured and analyzed. Measurement data for consumed and injected energy were collected for twelve low voltage distribution grids owned by Gävle Energi AB in order to analyze the size of the power losses and how the measurement uncertainty affects the collected data. Then models of three of the grids were created in MATLAB in order to analyze the data and the power losses were calculated to be compared to the collected data. Curve fitting were also used as a method in order to analyze the power losses from collected data.The results show that the losses in the studied grids are low.

Most of the portable electronic devices use a battery as a primary power source. Nowadays, when the applications are becoming smaller and smaller and more power efficient, the designer needs to concentrate more on reducing power consumption, using secondary power sources and introducing power storage devices. Multiple power source availability and a power storage device on the board will make the applications much more useful and efficient in everyday use. This thesis proposes a power supply unit (PSU) for wireless sensor platforms which is capable of supplying a sensor node with energy from multiple sources, as well as status information from the PSU. Present power storage devices, like electric double-layer capacitors (EDLCs) and batteries, have become more and more common as their characteristics have developed.

Denna rapport beskriver arbetet med utvecklingen av en ny modell för kaplanturbiner. Utvecklingen bygger på två kopplade differentialekvationer som under arbetets gång anpassats och implementerats i turbinmodellen.Modellen beskriver hur vattenflöde och turbinmoment påverkas av avvikelsen från den optimala kombineringskurvan för vinklarna på turbinens ledskena och löphjul, och är anpassad för ett referensaggregat med tillgängliga provdata. Även övriga enheter i vattenkraftaggregatet modelleras och sätts samman med frekvensregulator och elnät för att simulera aggregatets reglerstabilitet i önätsdrift.Verifieringen av turbinmodellen sker genom försök att återskapa de befintliga verkningsgradskurvorna med hjälp av modellen. Resultatet visar en god följning av de verkliga kurvformerna, dock med något lägre maximal verkningsgrad.Verifieringen av önätmodellen sker genom att prova stabiliteten i nätfrekvens och turbineffekt vid stegpålastningar. Resultatet ger en stabilare reglerstabilitet än i verkligheten, men uppfyller ändå förväntningarna på en fungerande modell.This report describes the development of a new kaplan turbine model.

This master thesis was made to validate hydropower models of a turbine governor,Kaplan turbine and a Francis turbine in the power system simulator ARISTO atSvenska Kraftnät. The validation was made in three steps. The first step was to makesure the models was implement correctly in the simulator. The second was tocompare the simulation results from the Kaplan turbine model to data from a realhydropower plant. The comparison was made to see how the models could generatesimulation result that was similar to the reference power station.

As companies grow, their need for computing power will increase, which traditionally resulted in companies having to invest in more IT resources. Now, with cloud computing, companies can easily hire computer power over the Internet, on-demand. Cloud computing offers a highly scalable environment where companies can store data and host their services. This paper employs a qualitative study with interviews and literature studies to explore opportunities and challenges associated with cloud computing from a system developer perspective. The aim of the paper is to find out how cloud computing changes the conditions for system development. The paper contributes with four different opportunities and challenges that the system developer must handle to succeed in the world of cloud computing.

Since 2003 Saudi Arabia is under attack from domestic Al Qaida-cells which, by random shootings of westerners and bombings of compounds and official state buildings, is trying to challenge the stability of the royal regime. According to Al Qaida, the Royal family is attacked because of their friendly relations to the US and for not implementing Islam in the Saudi society as profound as they ought to. Political analyst finds it obvious that the Islamic Al Qaida-cells by terrorism is trying to erode the stability in the kingdom.An important foundation for stability for any government is legitimacy. The aim of this thesis is to examine the royal legitimacy strategy in the state bureaucracy of Saudi Arabia. The question at issue is: how has the royal family constructed the civil, military and religious bureaucracies to maintain and promote stability and legitimacy?The thesis focuses on the on three different units within these three bureaucracies and it surveys the way they are staffed and organized to strengthen and maintain legitimacy for the royal family.

The Russian-Georgian war of 2008 drastically changed Europe´s and Sweden´s political climate.Russiashowed that it is capable of successfully completing complex campaigns including ground, naval and air assets. However, not much has been said about the theoretical framework and doctrine of the Russian military of today. Even less has been researched about Russian use of air power and applied air theory. Are air power assets still considered primarily as support of ground offensives or has the theoretical framework changed?John A.

Nuclear power production carries potential risks both for the environment and for the work force. Different safety measures are employed and they stem from local rules as well as from regulatory authorities. This work describes the development of a safety promoting tool at Forsmark Power Plant, one of Sweden?s three Nuclear power plants. We describe the development of a computer based system for Pre-Job Briefing and Post-Job Debriefing.

Safe operation of a large synchronous power system as Nordel is not an easy task.There are several aspects to take into consideration. This thesis focuses on the problems due to voltage collapses in a transmission system.The ability to foresee an upcoming collapse is vital to maintain stable operation of the grid. The grid operator at Svenska Kraftnät (SvK) uses the computer program SPICA to predict the maximum transfer limit at specified transfer sections. SPICA uses actual states from the grid to predict the transfer limitation, and a quarter later a renewed estimate is produced and so on. This means that the operator can se his transfer limits vary every fifteen minutes.Our task in this project is to validate the accuracy of the limitations obtained by SPICA.