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  • 1.
    Alameddine, Raged
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Dashtbozorg, Sajad
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Utredning av för- och nackdelar med TN-S respektive TN-C system2016Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In this report analysis the advantages and disadvantages of the TN-C (four conductor system) and TN-S (five conductor system) system. There are different opinion about which system is most appropriate to use in the distribution network and the building main lines. With the help of literature studies and contacts with various power companies and electric companies different opinion have been discussed . TN-C is the most appropriate option in the distribution network and TN-S should be used in the building main lines. This for achieving high and stable electrical environment. This thesis will facilitate the choice of technology and hopefully increase the knowledge about the subject.

  • 2.
    Al-Breihi, Mohammed
    KTH, School of Technology and Health (STH).
    Utveckling av laboration om trefastransformatorn: En studie om transformatorer2014Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This degree project was carried out on behalf of the unit for Computer

    and Electrical engineering at the School of Technology and Health, KTH.

    This study about transformers, their function and uses, the way they’re

    built, how the core and windings, which are the most important parts of a

    transformer, are made and what kind of materials are used to make them.

    Several types of transformers and their functions are described. A crucial

    part of the study has been to search for different ways to develop

    transformers to make them environmentally safer and to increase their

    life-span. As such this work describes different transformer oils, what

    advantages and disadvantages they have compared to mineral oils, what

    properties they have and in what way they’re less harmful for the

    environment. HVDC units transform high voltages from Alternating

    Current to Direct Current to lessen the resistive losses and energy losses

    which lead to a cleaner environment.

    The theory examination of the transformer is the basis for the formation

    of a lab for educational use, among others in a course about electrical

    power that’s included in Bachelor of Science in Electrical Engineering at

    KTH.

  • 3.
    Björklund, Johan
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Prestandautvärdering av permanentmagnetmotor2014Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The project was to evaluate a synchronous three-phase permanent magnet motor with brushless outrunner. It is supposed to be a part of an electric drive system for equipment onboard sailing boats. The goal was to investigate the performance of the motor and find the construction weaknesses and to come up with suggestions how to optimize the performance of the motor.

     

    Tests and measurements were made with a test setup that consisted of inverter, motor and a generator connected to the shaft. The generator stator winding had a short circuit when the load current reached 106,1 A and the tests therefore had to end. The copper wire used in the windings temperature became to high and the isolation of the wire melted.  The tests showed that the motor could handle up to 92,1 A with an efficiency of 70%. It was how much current the winding could withstand together with the power losses that was the limiting factor of the motor construction.

     

    Forced cooling with water cooled stator or improving the winding wires ability to handle higher currents by increasing the cable area are both alternatives to get a better efficiency and motor performance.

  • 4.
    Cronebäck, Alexandra
    KTH, School of Technology and Health (STH), Data- och elektroteknik.
    Input interface requirements on board mounted DC/DC converters2013Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis has been carried out on behalf of the department of Power Modules at Ericsson.

    In a telecom system interface A is a physical point between the power supply system and the telecommunication equipment described in a European standard called ETSI EN 300 132-2. This interface is also described in the American standard ATIS-0600315.2007. For board-mounted products, such as DC/DC converters, a well-defined input interface description is lacking.

    The goal of this thesis was to evaluate if the requirements in the standards ETSI EN 300 132-2 and ATIS-0600315.2007 are viable for the input interface of DC/DC converters. A part of this goal was also to investigate and analyze how the systems, in which the DC/DC converters operate, works.

    To be able to determine if any of the two standards, ETSI and ATIS, are viable for use for the input interface, both were reviewed and described with focus on voltage levels and transients.

    In the information gathering phase it became clear that an extended limitation was needed. Therefore, in order to investigate what happens from interface A to the input interface of DC/DC converters, the system used in this thesis is the EBS LOD (Ericsson Blade System – Low Ohmic Distribution). EBS is one of the systems in Core sites.

    The report describes the construction of EBS where in the PFM (Power Fan Module), backplanes and various boards are important parts. Furthermore some key principles within Core sites, such as HOD (High Ohmic Distribution), LOD, Two-wire system and Three-wire system, are also described in order to explain how the EBS system works.

    EBS (including PIM (Power Interface Module)) was modeled in OrCad PSpice, with both one board and 26 boards, and was simulated with different transients at an input to the system. The simulation results show that the high voltages never reach the DC/DC converter and that they therefore are well protected from transients in an EBS LOD system.

    In order to determine whether the standards ETSI and ATIS are viable for the input interface of DC/DC converters, it is concluded that more investigations, tests and simulations are needed.

  • 5.
    Duvheim Bruce, Adam
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Indreeide, Ole Martn
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Beräkning av återmatad bromsenergi på Malmbanan2015Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Energy is a limited recourse and the use of energy has to be as effective as possible to avoid harmful effects on the environment and to cut spending. Reusing the energy the ore train uses to climb the mountains of northern Sweden through regenerative breaking leads to a more effective use of energy. Calculation of energy uses the trains’ stored energy and the losses during its journey along Malmbanan. This results in a total power save of 20 % for single track and between 20 % and 21 % for double track. Traffic on double track can increase but the relationship between regenerated and consumed energy will be the same. Regenerating energy on the railway reduces today’s negative impact on the environment and leads to savings in energy cost for the company.

  • 6.
    Eriksson, Niklas
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Lifvendahl, Patrik
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Utbildningssimulator av funktioner i spårfordon: Hårdvarusimulator med felsökning på dörrsystem2015Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This report is a description of a developed educational simulator over rail vehicles and its components. The simulator is a hardware-based prototype over a door system on rail vehi- cles. System specialists and technicians will use the prototype. The Simulator should give the user a technical demonstration on how components work in a door system. The proto- type consists of motor, switch, relay and sensor. The components are used for illustration of the functions in a door system on a rail vehicle. The educational simulator is controlled with a control unit and with pushbuttons for manual control. For demonstration of the boarding security an optical sensor is used as symbolize for the obstacle detection.

    The educational simulation has two embedded common faults: cable fault and ground fault. The instruction manual consists of a circuit diagram and is used for troubleshooting. The circuit diagram over the door system is used to find the faults and to correct them. The fault analysis includes the factors, which is the reason for the most common faults to occur in a rail vehicle. Door system receives diagnostic code from a door computer that control priori- tizing for arrangements that will be made. 

  • 7.
    Ezzeddine, Kassem
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Oskarsson, Robert
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Analys av kondensatorbatteriers tillkopplingsfenomen: Undersökning av de kopplingsfenomen som uppstår vid tillkoppling av kondensatorbatterier och deras påverkan på närliggande komponenter2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Many electrical devices need reactive power to operate. Transmission of reactive power occupies a proportion of the available capacity in the power system and therefore capacitor banks are used near to the end user to generate reactive power. Thus, the reactive effect is generated and consumed in a separate part of the power system. Capacitor banks switching causes transients which may damage the surrounding components.

    Based on the real substation Stallbacka in Trollhättan, this study has analysed capacitor banks switching transients within the medium voltage level. The analysis has covered the size of these transients according to different conditions and scenarios. The result showed that the transients in this case never reached serious levels, thus there was no impact on the components. It is not clear whether the transients affect the power quality because there are no defined limits. 

    A calculation tool to the predicted transients was supposed to be created in the process. This calculation tool was never completed due to the unmanageable solution that was obtained.

  • 8.
    Gabrail, Philip
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Samuelsson, Sam
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Analys av fältfördelning i kabelavslut av linjära och icke linjära material: Analysis of the field distribution in cable termination by linear and nonlinear material2016Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Nowadays XLPE high voltage cables are used in transmission and distribution of electrical power and has an important role in the electrical system. Power transmission that occurs over long distances is diverted from one point to another and is done with the help of cable terminations. These cable terminations have some vulnerabilities that affect the entire power system.

    The theoretical part of the report was carried out with the help of FEM software Comsol Multiphysics. Results showed that the highest field concentration occurs at the insulation of the cable and caused malfunction and vulnerabilities. In the linear case for the electrical part resulted a high permittivity that the potential and the electric field was reduced, which showed the same result for low conductivity. For the nonlinear material the conductivity changes with the electric field and time.

    The temperature of the linear case showed that at high temperatures the material became more conductive. In the nonlinear case the conductive material was reduced. This could be controlled with different threshold value (Eb) which cannot in the linear case.

    The practical part was done in E.ON:s laboratory for different type of cable terminations that were tested with 33kV. Some of the tested cable terminations were used for testing purposes and was picked out of operation because of a malfunction in the cable. An attempt to control field concentration was carried out in the laboratory and resulted to a reduced field  istribution in the cable termination. The result of the practical part showed how the field concentration was distributed in the cable termination and that the field distribution led to the collapse of the cable.

  • 9.
    Gerkens, Rick
    et al.
    KTH, School of Technology and Health (STH), Data- och elektroteknik.
    Berg, David
    KTH, School of Technology and Health (STH), Data- och elektroteknik.
    Elkvalitéproblem vid varvtalsstyrd motordrift i industrimiljö2013Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Harmonics caused by variable speed drives create problems in industrial systems. The purpose of this study is to identify these problems and give recommendations to avoid them. The study was conducted as a bachelor thesis at the Royal Technical University in Stockholm, Sweden for the consultant company Ramboll Energy. A literature review was combined with electrical power quality measurements on variable speed motor operations conducted at Sandvik Mining in Sandviken, Sweden.

    Electrical quality problems caused by variable speed drives origin mainly from frequency inverter control that gives a non-linear current usage which, if the grid is not strong enough, affects voltage quality. Examples of problems are production downtime, disruption and malfunction of equipment and increased wear of equipment.

    This study shows that when making changes in systems containing harmonics, future harmonic levels can be approximated in some cases. Measurements before the change provide input data to model the system, describing the load as a harmonic current generator. With some assumptions on the grid impedance, calculating an approximation on harmonic after the change is possible.

    This study has used a simplified model for the prediction of harmonic levels after a change in the system. The purpose is to propose a cost effective way to approximate so that information on how to prevent problems …in the decision making. Electrical power quality problems could be prevented more often and not doing that is a waste of economical, environmental and social resources.

  • 10.
    Grip, Johan
    et al.
    KTH, School of Technology and Health (STH), Data- och elektroteknik.
    Djampou, Serge
    KTH, School of Technology and Health (STH), Data- och elektroteknik.
    Elkraftsystem för fälttest av Polygeneration system EXC2013Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In a modern society electricity is a key component for the development of the individual, industry, and society. Natural disaster areas where the electricity has been knocked out face great trials in order to get vital public functions working again. With the help of the mobile eco-friendly energy device Emergency Energy Module (EEM) electricity needs can be eased.

    The goal of thesis was to produce an electrical power system description for the upcoming Export container (EXC), and to generate a correct circuit diagram for the existing Emergency energy module (EEM).

    The electric power description must take into account EXC's specifications and include Bills of Material (BoM) and circuit diagram. The problems lies in getting the various sources of energy (solar, wind and biomass gasifier) to work together in a power system where DC, AC, three-phase and single-phase are mixed. Great emphasis is also given to obtain a flexible electricity systems that can be relatively easily changed for different customer needs.

    The making of this thesis was carried out initially with a gathering facts phase. This was followed by a review and analysis of the EEM's electrical system which resulted in a circuit diagram and a manual.

    Weaknesses in EEM's electrical system was considered to be the lack of overvoltage protection and residual current device, measuring point 5 was misplaced, measuring equipment should for safety reasons be firmly attached and 1-phase generator should be used in biomass gasifier to remove uneven load problems. The existing Power router, whose task is to control the energy flow in the system, was limited because it could only receive one AC power source, handle only one-phase and had a relatively low maximum output power of 5.5 kW.

    Whit the help of the analysis improvement suggestions above and with EXC's specification taking into account was then an electric power system for EXC constructed. with associated BoM, circuit diagram, specifications for subsystems and proposals for candidates that meet these.

    The electrical system is recommended to be built around the Power router Quattro which provides great opportunities for flexibility in terms of being able to scale up the system if such more power would be desired by the customer, or if there is a need for 3-phase systems. A variety of programming settings can then be made which facilitates the construction of specific electrical systems for varying customer needs.

  • 11.
    Gustavsson, Robert
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering. KTH.
    Lind, Alexander
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering. KTH.
    Utvärdering av energiförbrukning av ett IoT-system för övervakning av hundars rörelsemönster2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Tracy Trackers is currently developing an AI platform which purpose is to monitor a dog's movement pattern. The platform consists of hardware with accelerometer, gyroscope, temperature and humidity sensors attached to the dog. The hardware is connected to a mobile through Bluetooth. A study was conducted to investigate which batteries that are available on the market and which ones that fit best for the prototype. The aim of the study was to find a rechargeable battery with long operat-ing hours that is economically and environmentally viable for future production. Hardware for monitoring the battery voltage characteristics was built to determine differences between kinds of batteries and if there was an optimal type of battery for the specific product. The sensors used by the prototype were studied using os-cilloscopes and a self-constructed circuit in order to be able to determine power consumption at different sampling frequencies. Furthermore, a circuit was built for filtering out certain frequencies to determine the current consumption of the DC-components. The current consumption measured by the tests in this study refers to what draws current in the prototype. The developed hardware can be used for measurements of future prototypes

  • 12.
    Johansson, Charlie
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Frid, Martin
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Inomhuspositioneringssystem: Personlig navigation inomhus via mobiltelefon2015Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The GPS is used today for personal navigation, however GPS performs less well in an in-door environment due to the dependency of line of sight. The IPS, Indoor Positioning Sys-tem, will complement the function of the GPS and open doors for new applications. In this thesis studies of methods and techniques are made to enable IPS for a portable device. These techniques and methods are verified that they could be implemented in a smartphone.A prototype was designed to examine the possibility to navigate in an indoor environment. The prototype was built on a RSSI-based radio fingerprinting method over Bluetooth. This method was integrated with a dead reckoning system using an IMU to follow the motions of the user. Tests and simulations are performed along with the results presented in tables and figures. The result shows that it is possible to navigate using the prototype with a mean error of 0.26m. Results are also showing that two methods are to prefer, as they will com-plement each other’s weaknesses.

  • 13.
    Lundmark, Staffan
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Ekholm, Gustav
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Successiv transponering av luftledningar för högspändväxelström2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Three phase high voltage alternating current overhead line systems are associated with losses along the lines and disrupting magnetic fields surrounding the conductors. These negative effects could possibly be combated by twisting the conductors. The twist was achieved by gradually shifting the conductors positions (transposition) over each span of transmission line. A test circuit with a stainless steel wire was made. Geometric and electromagnetic modelling of a successively transposed power line was performed. A miniature three phase overhead line model was constructed.. The model was based on the results from the geometric modeling and data from a real △-configured power system application. Experiments were made with both the steel wire circuit and the overhead line model. Voltage drops in the circuit with a straight - and twisted wire was measured with an oscilloscope. Magnetic flux around the overhead line models were measured with a solenoid. The results from the experiments showed that twisting the conductors resulted in an increase in inductance and a decrease in capacitance. Regarding the magnetic fields, indications of an overall decrease was observed with the twisted configurations compared to the straight. Twisted overhead lines could be viable when an overall decrease in magnetic field is needed. Due to uncertainties in the magnetic field measurements, more extensive experiments should be conducted in order to solidify the results of this work.

  • 14.
    Orrevad, Gustav
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Ömsesidig koppling mellan parallellgående friledningar2015Independent thesis Basic level (university diploma), 180 HE creditsStudent thesis
    Abstract [en]

    Parallel overhead power lines induce voltage in one another, which in turn drives a current. In this report an investigation is made in how asymmetrical short circuits on an overhead power line influence the cur-rent in a parallel overhead power lines due to the inductive coupling be-tween the power lines and which hazards it can cause for the electrical delivery dependability as well as high voltage workers.The aim with this bachelor thesis is to increase the accuracy in fault cur-rent calculation in the Vattenfall electricity grid as well as to increase the knowledge within Vattenfall of the phenomena of inductive coupling and the hazards which comes with it.The report could ascertain that inductive coupling can lead to danger for electrical delivery dependability and that there exists a need of analysis on specific parallel overhead power lines within the Vattenfall electricity grid.

  • 15.
    Papadakis, Alexander
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Falge, Emil
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Sensorbaserad riskbedömning av belastningsbesvär2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Musculoskeletal disorders (MSD) is a rising problem in society leading to several socio-economic problems. In combination of the trend of an aging population, MSD can cause even more challenges in the future. Expanding the knowledge of ergonomics is a good way to reduce the risk of stress injury. Today, a visual assessment of ergonomics is primarily used. These observations are individual and not consistent. Availability of cheaper and smaller Inertial Measurement Unit (IMU) has increased the possibility of using objective measurements instead of subjective observations.

    In this thesis work, the Texas Instruments SensorTag CC2650 was used as a sensor, because it is cheap and has many built-in sensors where the 9-axis motion sensor was the most sought one. A web-based development environment called Node-RED was used to develop a prototype and the sensor was connected to a smartphone along with Texas Instruments own application. The data from the sensor was sent from the smartphone to the web application. Measurements were performed on an arm to measure the load on a shoulder, when the hand's position passed the height of the shoulder it indicates that there is a risk of musculoskeletal disorders after an amount of time. To calculate the angle of the arm, sensor fusion of an accelerometer and a gyroscope were used together with a complementary filter.

    Developed system was evaluated by series of tasks exposing the shoulder to a higher risk e.g., painting compare to lower risk tasks e.g., paper sorting. It turned out that measurement are useful for assessment of the risk. However, there are known limitations like low sampling rate of 5Hz (due to limitation in the android app from Texas Instruments). Adding magnetometer to the sensor fusion and evaluation of reliability of calculations are the next natural steps for future work.

  • 16.
    Papp Aminnejad, Benjamin
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Wieweg, Daniel
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Magnetfält i elkraftanläggningar: Ett projekteringsverktyg i Excel för bedömning av magnetfält från elkraftsutrustning på lågspänningssidan2015Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The exposure of ELF (Extremely low frequency) magnetic field generated by today’s electrical power system, is something that is relatively new to the human body and it is constantly increasing as more technology is developed. As there is no clear answer on how the field actually affects the body, a measure of caution is applied to ensure that the exposure levels are kept down to make sure no harm is done. With the help of previous research in the field, measured values from different locations and approximate calculations, a tool was developed in Excel to estimate the magnitude of the magnetic fields. The tool provides information about the magnitude of magnetic fields from transformers, switchgears, switchboards, powerlines and busbars. The user enters a number of parameters and the tool provides output data with the magnitude of the magnetic field at different distances from the source. This is presented in the form of a table and a graph for each equipment. Since the magnetic field is generated depending on the currents direction, the actual geometry of the electrical system needs to be taken in consideration when calculating the exact magnetic field. This requires an advanced simulation software to be accurate. With this tool, designers have the opportunity to estimate the magnetic fields at an early stage of development.

  • 17.
    Strand, Mathias
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Standardisering av processer och aktiviteter inom kontrollanläggningar och elmontage2015Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In this thesis, a study has been carried out for the consulting company ÅF, and their work method within documentation and control facilities to investigate whether there were any potential for efficiency improvements. The investigation has largely involved interviews with operating consultants within the control facility on substations. The consultants worked as electrical designers and produced drawings mainly for control equipment. The results of the interviews were analyzed to draw conclusions about the efficiency potentials within the business. Different offices in the business were examined and the work approach varied between the offices. One difference was the CAD-software used and a suggestion was to use the same program. Efficiency improvement potentials were also by re-using electrical schematics to some extent from previous projects and another suggestion was to establish databases where electrical schematics can be gathered and shared between the different offices.

  • 18.
    Svensson Marcial, Alexander
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Gatu, Andreas
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Justerbar modell av transmissionsledning för elkraftsöverföring2014Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Detta examensarbete har utförts på uppdrag av Terco. Tercos PST 2220 Transmission Line and Distribution Module fungerar som en fysisk modell av ett verkligt transmissions- eller distributionsnät där fem olika typer av nät med avseende på längd, spänningsnivå och skenbar effekt är möjliga. Idag finns ett behov av en modell där användaren kan ställa in dessa parametrar så att modellen mer precist kan spegla vilka egenskaper det specifika nätet har. Här undersöks hur längden och dess inverkan på en ledning kan varieras i en modell. En presentation av hur transmissions- och distributionsnät fungerar och beskrivs teoretiskt lägger grunden till den modell och de två approximationer som kan beskriva ett helt näts egenskaper. Då R, L och C komponenterna behöver kunna varieras för att fysiskt kunna realisera denna teoretiska modell undersöks vilka metoder som detta kan genomföras på. För detta undersöks två tillvägagångssätt, kaskadkopplad pi-modell och variabel aktiv-passiv reaktans. Flera aspekter som utrymme, kostnad och variabilitet gör att variabel aktiv-passiv reaktans är att föredra. Dess funktion som en varierbar spänningskälla, uppbyggd av switchar styrda med reglerteknik och pulsbreddsmodulering gör att komponenterna R, L och C och dess egenskaper och inverkan på en transmissionslinje kan åstadkommas. Resultatet är att de nödvändiga R,L,C komponenterna går att variera i storlek för att kunna ingå i en varierbar transmissionsledningsmodell. Resultatet och målen säkerställs med simuleringar där variabel aktivpassiv reaktans visas kunna vidareutvecklas och praktiskt testas för att modellera transmissions- och distributionsnät med olika längd.

  • 19.
    Westerberg, Rickard
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Lösningsalternativ för strömförsörjningsproblem på Nockebybanan och Tvärbanan2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Abstract

    Several problems regarding power supply of Nockebybanan and Tvärbanan tram lines have been detected. The goal of this work has been to investigate and solve some of these problems. One of the problems was that so called relay protections were breaking the current too often, even when there was no fault. The protections also often break the power supply because of current transients, which can arise when a pantograph passes a section delimiter or in the winter when there is hoarfrost on the catenary.

    The result of the investigation and analysis shows different solutions, of which one appropriate procedure for reducing the number of breaks in the rectifier stations, is to limit the current in the trams so that they are not able to use as much current. This procedure was not possible to develop for the tram manufacturer alredy to the autumn of 2017, only a power limitation was the option for the short time perspective. An investigation of the settings of the relay protections was proposed as a procedure to reduce the number of breaks and was done by Siemens. The aim was to investigate if the relay protection could be readjusted so that the number of breaks could be reduced. The investigation showed that the so called derivative protection could be readjusted a bit. In this thesis work, it was also proposed that the lapse when a tram passes a section delimiter should be investigated, and was done so by the tram manufacturer. Their result was supposed to be finished after the completion of this thesis work. Options for operating trams when there is hoarfrost on the catenary is investigated and a relatively simple solution is to let a roller apply glycerol on the overhead line, preventing hoarfrost.

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