Svenska Kraftnät is (together with the other transmission system operators of the Nordic power system) responsible for keeping balance between the generated and demanded power in the Nordic power system. Spontaneous load variations and system disturbances, however, lead to power imbalance followed by frequency variations. The frequency deviations can be limited to an acceptable level by the spinning reserve, mainly by hydro power control. But there are also other system properties which have a great influence on the frequency and system stability. The frequency and voltage dependence of the loads have a direct influence on the power balance.

The technological legacy from the early electrification of the Swedish railroads has resulted in a power grid with a lower grid frequency than the national power grid from which it is fed. Energy transfer between these power grids with different frequencies requires substations, adapting the grid frequency for the rail road power grid. For this purpose, a feeding power grid has been built, stretching across the country from Boden in the north to Tälle/Häggvik in the south.Power transfer in the Swedish power grid results in voltage angle differences which increase with increasing loads and transfer distance. These voltage angle differences are transferred from the power feeding substations to the rail road power grid, will in some extent cause loss of energy due to unwanted power flows from north to south.To minimize the losses due to this phenomenon, a power management system called EFS 132 kV has been developed and implemented. The system minimizes the unwanted power flows and controls the desired power flow for a good distribution of loads between the power feeding substations.This thesis investigates the extent of the transmission losses avoided due to the EFS 132 kV that coordinates the idling angles to a common reference point.The results indicate that EFS 132 kV affects the power flow, especially between the northern substations through an improved load distribution.

The purpose of the project was to design an electric bicycle to offer thetarget group youth an attractive alternative to mopeds. The basis for theproject was user studies in which young people were interviewed andobserved in their daily environment.The project resulted in a product, designed with the focus of integratingthe battery to the shape, to create a wholeness that is simple andintuitive.!The product is easy to use and operate, with an automatic transmissionengine.! A smart modular system allows the user to choose design withmudguards, rear rack, or without. The battery design is based on "cradleto-cradle" to maximize the battery life and minimize environmentalimpacts.It was very fun and rewarding to have the opportunity to present theresults for the youth who showed great interest in the product.The project was conducted in collaboration with Designit and Cycleurope..

The purpose of this study is to investigate how much of the estimated annual electric energy production from Swedish wind power that actually was produced, as well as the history of this agreement over time. The aim is to also examine if there are properties that have caused some group of wind power plants to produce more or less, compared to their estimated production. Operational data on wind turbines collected by the Swedish Energy Agency was analyzed. A survey was made among owners of wind power plants with a nominal power of at least 2 MW. Two different methods for normal year correction of production data were used and compared.

This master thesis describes the development of an UPS module. UPS is an acronym for Uninterruptable Power Supply. The UPS module has been developed at the company AerotechTelub AB. The UPS module delivers the necessary voltage and current in case of a power interrupt. If a power interrupt occur, the computer system has one to three minutes available to store data and shut down correctly.

Gtherm is an innovation company who has an unique air heat exchanger underdevelopment. The purpose of this thesis is to provide data of suitable motors for theheat exchanger and to find suitable motor suppliers.A motor specification was designed. It is an important basis for the search of suitablemotors. A compilation was made of nine motor suppliers and the suitable motorsfrom those. The compilation can be used by GTherm in their choice of suppliers andmotors.The compilation of the demands on the motor and analysis of suppliers indicated thatthere were no standard motors available to GTherms air heat exchanger.

Linux is a growing operating system in embedded systems. Today, Linux is not only in heavy servers but also in cell phones, PDAs, cameras and other devices running on battery power. While current technology is more energy efficient, more and more technologies are implemented into a single unit resulting in an overall increase of power consumption.Low power consumption is an increasingly important feature of a system today. Lower power consumption means lower costs, less environmental impact, and longer life for applications that runs on batteries.This work compiles methods to reduce power consumption of Linux systems. The work includes examining whether the available opportunities are platform-specific or of a more general nature.

The assignment given to us by NCC was to compose a degree project based on ground excavations for power cables. The aim of the study was to examine suitable excavation methods depending on different possible terrain conditions. The amount of previously written material within this subject is nearly non- existent and therefore there is a genuine interest by the NCC to receive a compilation of different production methods. The greater part of this study is based upon interviews with several companies active within this area of expertise. The technique of placing the electricity grid beneath ground for safety is today getting more and more common.

Since 1996 the Swedish households have ten folded their volume of loans for own homes that is attached to a floating interest rate. Also in 1996 the Swedish electric market was deregulated. These two facts have increased the volatility in the household expenses for these two commodities. This thesis studies the risk for homeowners attached to the exposure against the electric and the credit market. The risk model used is Cost-at-Risk which is usually used by public authorities for analysing the risk involved with national debt.

AbstractAuthor: Ellinor Carlsson and Renate HöjdTitle: "When you can make a difference and when you can´t" the power relation between psychiatricdisability social worker and client [translated title]Supervisor: Eva SkogmanAssessor: Norma MontesinoOne branch of the social works field of research is the relation between social worker andclient. Research has shown that the power and inequality in the relation between helper andperson being helped is needed for the helper to provide help. Power is often mentioned undernegative circumstances such as social workers abuse of their power position, violating theperson being helped. However, Michel Foucault suggests that power is something neutral thatexists in every social interaction. The negative aspects of power are effects of the parties notreaching agreement.

There is always a need for more effective ways to store energy in order to reduce the human impact on the environment. One step on the way can be the use of flywheels as kinetic energy storage devices. Low frictional losses are essential for a flywheel to be effective. To minimize these losses active magnetic bearings (AMB) can be used to keep the shaft centered instead of the more conventional ball-bearings. AMBs use actuators and a fast control system that needs correct and noise-free measurement data of the shaft position and the current in the actuators to work properly.This thesis explains the process of constructing power electronics and a current measurement system for active magnetic bearings (AMB).

The purpose of this project was to study how the interference between two antennas in a MIMO system affects the linearity of the power amplifiers powering the antennas. For the MIMO system, two power amplifiers and twoantennas were constructed and designed using the software ADS and a software defined radio was constructed using the platform USRP and the software LabVIEW. The result was that the interference between the antennas affectsthe linearity of the power amplifiers powering the antennas adversely and a reasonable theory was that the interaction decreases inversely proportional tothe square of the distance..

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.

To achieve the goal of fossil independency in the Swedish vehicle fleet in 2030, it would be important to substantially increase the proportion of electric vehicles, both BEV:s (Battery Electric Vehicles) and PHEV:s (Plug-in Hybrid Electric Vehicles). The Swedish Energy Agency has funded numerous research and development projects about electric vehicles in recent years. An important task for the Swedish Energy Agency is to allocate state funds to those projects with the greatest potential to contribute to increased establishment of electric vehicles in society. The purpose of this work is mainly to understand the efforts and measures that can make the market for electric vehicles to grow. The report can contribute to a better understanding of how far the research on electric vehicles has come and what has to be done in the future to promote the establishment of electric vehicles. Another aim for this report is that it should serve as a basis for future decisions by the Swedish Energy Agency on which projects that will be funded with state funds.

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.