The purpose of this master thesis is to implement and validate a Power System Stabilizer (PSS) to a generator at Trängslet hydropower station in Dalarna, Sweden. Problems with local rotor oscillations can occur at the hydropower station when power is transferred on a new power line (130 kV) from Northern to Southern part of Dalarna. To ensure good operation properties on this power line Fortum Generation AB and Fortum Distribution AB wants to activate a PSS on a generator.There have been investigations in which situations and what equipment that contributes to rotor oscillations. When this is known the PSS is tuned to damp these oscillations by choosing a good set of parameters. The most important parameters for good performance are to choose amount of gain and phase compensation.

This paper investigates the automatic stabilizer and the underlying factors behind its function. The paper includes both a literature review and an empirical analysis. The literature review discusses the IS-LM and Mundell-Fleming models and different ways to quantify the automatic stabilizer. Based on the theory, the relationship between volatility in GDP and the size of the automatic stabilizers is then analyzed with the help of regressions. Our main result shows a negative relation between these two variables.

The power system modelled in this thesis work has been developed for simulationwhen e.g. the production in some part of the power system is changed. The powersystem has been modelled according to the swing mass of the system, the frequencydependency of the load and the turbine governor. The model determines the systemfrequency, the period of regulation and the power exchange between the differentsubsystems in the Nordic synchronized system.In this model the system frequency is assumed to be the same in all different parts ofthe power system and the voltage conditions in the power system are neglected. Forthat reason power swings does not occur between different subsystems in the powersystem, which usually occur as a result of the swinging connection between thetransmissions line.

Orust Kretsloppsakademi is a nonprofit organisation, with a goal of annually generate the same amount of electrical energy that is consumed. Orust is an island on the west coast of Sweden, north of Gothenburg. The population of 15 000 reaches 40 000 during summer, due to the large amount of vacationer. The total electricity demand is 174 GWh a year with a maximum power need of 32 MW. This report presents an analysis for the plausibility of their plan and from a power system stability perspective, the effects on the electrical grid.The conclusion is that the restraints for development of power generation from wind, solar and wave generation, are the power systems capability to transfer power, primarily in the transformers of the grid.

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 this report was to investigate what characterizes a good psychosocialwork environment, and whether it may have impact on a vessel's safe voyage. Thisreport is proposed to increase the understanding of what creates a good psychosocialwork environment and its potential effect on safety at sea. In order to find out thesuccess factors for a good work environment group interviews were conducted in socalledunstructured focus groups. During these conversations, the participants discussedfreely by the question "what is a good psychosocial work environment for you?? Thesuccess factors were thereafter applied on selected accident reports, to investigate theextent to which they were represented and taken into account.The results of the study show three categories of factors: colleagues, communicationand competence, where colleagues are the main contribution to a good psychosocialwork environment.

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.

Syftet med examensarbetet är att digitalt tillämpa en stabilisering av pendlingar i den aktiva effekten hos en synkrongenerator för vattenkraft kopplad till ett distributionsnät.Implementeringen är tänkt att ske i en PLC som redan hanterar andra delar av magnetiseringen.Effektstabiliseringen görs genom att en motverkande styrsignal skickas till magnetiseringsutrustningen vilken i sin tur påverkar generatorns uteffekt. Denna motverkande styrsignal kan tas fram på olika sätt.Två modeller, av IEEE standardiserade, för effektstabilisering undersöks, PSS1A och PSS2B.En Simulink-modell över ett distributionsnät med generator byggs upp för att testa effektstabiliseringen.Diskretisering av den ena standarden utförs för att digital implementering ska kunna ske. Tester utförs även på denna modell för att kunna validera dess funktion i jämförelse med den kontinuerliga.Den tidsdiskreta modellen görs om till ett matematiskt uttryck tillämpbart i PLC:n.Jämförelse sker mellan simuleringarna och den tillämpade modellen genom mätningar..

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.

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.

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.

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..

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.