SummaryElectromagnetic compatibility (EMC) and electromagnetic interference (EMI) are topics which have been of concern to electrical industry for many years. Excessive generation of electromagnetic noise and interference, resulting inadequate EMC, is one potential source of interaction and performance degradation which may reduce operational effectiveness of the devices. Because of this, EMC testing services and regulation imposed by governments have forced product designer to pay close attention electromagnetic interference level of their products.For improving oil and gas production recovery, from mature fields and for exploitation of deep and ultra-deep offshore reservoirs new downhole technologies are required. Electrification of downhole applications has proven to be very promising and the technologies are designed for deployment in harsh environments. This master thesis deals with the study of EMI problems for downhole drive train system especially caused by EMI phenomena. The two aspects of EMI and EMC are studied, the manner in which how EMI can generate and propagate then affect receptor or victim intentionally and unintentionally are discussed. Followed by types of EMI phenomena (voltage dip, electrostatic discharge (ESD), surge, fast transient and rapid voltage change (dv/dt)) their occurrence and adverse effects of them are studied. dv/dt, overvoltage and EMI filter types are studied and designed. Compressions are made by their performance, size, power loss and cost. To verify their performance simulation model are made for downhole drive system to filter dv/dt and overvoltage at the motor terminals.After having the theoretical base, practical pre-compliance conducted EMI measurements are made for single phase chopper and three phase inverter.The influence of EMI such as reverse recovery current of diode, stray or leakage inductance, gate drive resistance, heat sink grounding, duty cycle and switching frequency are investigated on the single phase chopper. An LfCf harmonic filter is designed and placed between the inverter and motor terminals and differential mode EMI noise is measured in the system.

För att öka skyddet mot elektriska fält i processnätet på Stora Enso Skoghalls bruk utreds det i denna rapport om det går att direktjorda processnätet som i dagens läge endast är skyddsjordat. Eftersom det tidigare endast funnits skyddsjord vill företaget veta om kabeldimensioneringen är tillräcklig så att de skydd man har mot kortslutningsströmmar även fungerar i ett direktjordat nät. I ett direktjordat nät blir den minsta kortslutningsströmmen cirka gånger mindre än icke direktjordat nät då kortslutning kan ske mellan fas och nolla (fasspänning). Nollan finns inte i ett icke direktjordat nät och kablarna är kan alltså vara för långa eller för klena så att en fasspänning inte klarar att driva tillräckligt stor ström vid kortslutning genom kabelns impedans förr att skydden skall lösa ut. Eftersom en nydragning av alla de kilometervis utlagda kablarna skulle bli en så ofantligt kostnad och att tiden för stoppet av processen skulle bli för lång är detta inte ett alternativ. Den här utredningen kommer att visa maximala kabellängden mellan de olika ställverken och motorerna i det befintliga nätet för att man skall kunna direktjorda det. / To increase the protection against electrical fields in the distribution net on Stora Enso’s mill in Skoghall it will be investigated if it’s possible to use direct earth instead of only protective earth as of today. Because the net only has protective earth the company wants to know if the dimensions of the cables are enough to meet the lesser shortcut voltage in a net with direct earth. The smallest shortcut current when using direct earth occurs between one phase and the zero and will be aproximately times less than when using non direct earth where there is not a zero and the shortcut can onlyu occur between two phases. This means that when building a non direct eart net you can use longer or thinner cables with more resistance than you could using direct earth. New cables are not an alternative when the cost would be to great and the downtime of the machines would be too long. This inquiry will show the maximum cabel length from the different protections to the different engines can be if you want to use direct earth and be sure that the fuses will burn when an error occurs.

Klimatförändringar börjar allt mer få en viktig roll i allas vardag och för energibranschen har arbetet med att minska miljöpåverkan bara börjat. Branschen har sedan en tid tillbaka premierat fjärrvärme som bra miljöval för uppvärmningskälla för bostäder och lokaler. Faktum kvarstår dock att beroende på hur fjärrvärmesystemet ser ut så påverkar näten miljön olika. I denna rapport behandlas det lokala energibolaget Halmstads Energi och Miljös fjärrvärmesystem genom en optimering av systemkostnaden. Utifrån optimeringen studeras sedan skuggpriser, drift och miljöpåverkan för systemet. Studien behandlar även de stora fördelarna med att energibolaget samarbetar med en eventuellt kommande energikrävande industrier, i detta fall en etanolfabrik. I och med samarbetet bildas ett energikombinat där fjärrvärme, el och etanol tillverkas. För analysen används ett energisystemperspektiv som får större geografiska gränser än bara Halmstad. Undersökningen av systemet görs med hjälp av datorprogrammet MODEST som är ett energioptimeringsprogram som utvecklats på Linköpings Tekniska högskola. Modellen av Halmstads fjärrvärmenät baseras och valideras mot driftsäsongen 2005 och har visat sig stämma med verkligheten bra. Resultatet visar att Halmstad Energi och Miljö planerade effekthöjningar används fullt ut men att det nätet kommer få stora effekttoppar inom en snar framtid. Energikombinatet som analyseras visar sig både ha ekonomiska som miljöfördelar för både energibolaget och en etanolfabrik. Spillvärmen som kan utvinnas kan även den minska användningen av topplastanläggningarna i fjärrvärmenätet.

The three phase permanent magnet synchronous generator with full scale converter arrangement has gained significant market share in win energy turbine topology. This is because of the advancement in production of superior magnetic properties and steady decline in price of the magnets. Permanent magnet synchronous generators are of compact in size and light in weight. They become attractive for offshore wind application. But offshore wind energy system has to be not only light weight and compact in size but also reliable operation. The majority of failures of wind turbines are the electrical systems. To increase the reliability of the ordinary three phase wind energy system, a six phase wind energy system is proposed: a six phase permanent magnet synchronous connected to six leg converter. To harness the maximum energy from the wind, the viable option is using variable speed wind turbine. Variable speed operation of drive is achieved by suitable control of generator-converter system.This project deals with the design, simulation and implementation vector control of six phase permanent magnet synchronous generator-converter system. Step by step approach is used to tackle the problem. First the dynamic modeling of six phase permanent magnet in different references frames is studied. Then the time average and switching model of a six leg converter is presented. The different modulation technique of six leg converter is studied. Last the design or tuning of control parameters for the speed and current controllers are done. Dc link voltage control design is also done.After having the theoretical base, the majority of the work is done in preparation of laboratory setup, understanding of FPGA platforms and fighting with sporadic practical problem.Finally, it is of great personal success to be able to model, and control in the laboratory a low speed Non Standard Six Phase PMSG having 33.27 degree separations between the phase groups.

<p>Hydroware Elevation Technology AB sells control and regulation equipment for hydraulic elevators. The company now wants to investigate the possibility of changing their present softstarters to frequency inverters to supply power to their pump engines. They also want to investigate the possibility of future use in so called ”intelligent” houses.</p><p>The purpose of this report is to investigate these possibilities.</p>

<p>Fläkt Woods har ett fläktlab i Växjö där man utför kund och leveransprover av axiella fläktar.</p><p>Befintlig anläggning är i dag bristfällig när det gäller driftsäkerhet och personsäkerhet. Även möjligheten att köra varvtalsreglerat är idag begränsad.</p><p>Uppgiften är att projektera en ny anläggning omfattande en ny jordkabel, mellan- och lågspänningsställverk, transformatorer, kopplingsutrustningar och frekvensomriktare.</p>

The goal of the thesis is to analyze an existing Axial Flux Permanent Magnet motor used for Shell Eco Marathon from the Norwegian University of Science and Technology (NTNU). The existing machine has been analysed and modified to achieve improved power density at high efficiency with lowered weight.A detailed literature study on AFPM machine topologies, winding and magnet arrangements is covered. The magnet arrangement of the existing machine has been transformed from conventional North-South to Halbach array. The preliminary analytical calculations were done by using analytical expressions. After that, for an improved design, an efficiency-based optimization has been used to improve the obtained parameters from analytical calculation. This optimization has been performed with the help of fmincon solver in the Matlab optimization tool. The optimized values after being compared with the analytical calculation, has been used to run Finite Element Method simulations.The new design with optimum performance parameters displays an improvement of overall efficiency with decreased weight in comparison. The new machine has a 97.2% efficiency and weights only 6.24 kg. In comparison with the existing machine, the weight of the new machine is almost half with improved efficiency.KeywordsAxial Flux, Permanent Magnet, Synchronous Motor, Ironless Stator, Halbach.

This thesis presents and discusses the development, design and testing of a lightweight current pulse source prototype used for condition assessment of line connectors. The thesis is a continuation of a student project conducted in the fall semester of 2014 with the title &quot;Condition Assessment of Line Connectors by Current Pulse Measurements - Effect of Reduced Pulse Rise Time And Connection Cable Cross Section&quot;. The student project looked into how weight and size could be removed from the present pulse source design, both by a reduced capacitor bank and by reduced connection cable cross section. The results from this project lead to the development of the lightweight pulse source prototype.The design and development is divided into three sections. Initially, the overall idea and generalization of the design is presented and discussed. Secondly, based on this conceptualization the design is broken down to each major component. These components were the battery, thyristor, capacitor bank, microcontroller, DC-DC Converter, and user interface. Their function and design criteria are presented and discussed in the thesis. The thesis also presents the circuit schematics of all the components designed specially for the prototype. Finally, the design is summarized and its weight and size compared to the present pulse source design. The measurements show that new pulse source prototype weights 7.6 kg compared to the 35 kg of the old design and is 47 dm^3 smaller. Note that the weight is measured without the connection cords and measurement equipment. enlargethispage{baselineskip}One of the major differences beside the size and weight is that the present pulse source uses a hardware based sequence control, while the prototype utilizes a microcontroller. This allows a much more flexible system since the behavior of the sequence control can be altered by rewriting the script. The microcontroller and script are presented in detail in the thesis and in the appendix.To verify the design, and to look into how the prototype operates during actual condition assessment measurements, a total of thirteen connectors were assessed. Three of these had an already known condition, while for the rest no prior condition assessment existed. The three connectors with a known state showed that it was possible to reproduce the results from the prior measurements using the pulse source prototype. The ten final connectors were meant to increase the number of measurements to see how the prototype handled during actual assessment tests. These measurements show that the prototype only needed a few alterations to it design to operate satisfactory. These alterations are presented and discussed in the thesis, while the condition assessment of all the connectors is presented in the appendix.In addition to the condition assessment measurements there were also conducted two separate experiments to define the battery capacity and setpoint accuracy of the prototype. The battery capacity test revealed that the battery capacity of the prototype is sufficiently large to supply the unit with power during continuous operation for at least four hours and ten minutes, and deliver 500 consecutive shots. The setpoint accuracy test indicated that the prototype&apos;s control sequence was able to reproduce the same current amplitude for the same setpoint with a deviation of only 26.4 A.All the tests performed on the prototype show that it works and operates as intended. Tests have shown that the prototype is able to produce and reproduce current pulses accurately up to and above 6000 A, and that the microcontroller based sequence control functions as intended.

Permanent Magnet (PM) machines can have difficulties dealing with unstable loads, which in worst case can make the machine to step-out of synchronous speed. This problem can be avoided by equipping the rotor with damper windings. During load variation the damper winding will induce a torque to dampen the impact of the load variation. To investigate the effects from using damper windings a numerical model of a PM machine was developed and studied in this thesis. The model is intended to operate with regards to load torque and the stator field. The stator configuration which was used in this thesis is very complex, which resulted in a lot of trial and error. Due to the complexity of the stator meant it had to be applied with a current density, which means that the voltage over the phases was not taken into account during the simulations. This simplification appears to have created an unnatural damping factor in the simulations.Simulations show that a high-conductive damper winding performs faster during load variations then a low conductive damper winding. The reason for this is that a low resistance will induce a high torque at low slip. The size of the windings also affects the performance but these are small and difficult to notice. Simulations show that the size of the damper winding should be between 5-10% of the size of the stator winding.

The conventional electrical system in place today sees our electrical devices powered by AC mains. But as renewable technologies such as solar photovoltaic and wind power become more prevalent at a household level, DC micro-grids could be a cheaper and more efficient alternative. New lighting devices (LED) can reduce the electricity consumption substantially. Two alternatives are envisioned in this paper: A stand-alone alternative in which there is no grid connection, that would require local storage (battery), and a grid-connection alternative. After reviewing and investigating relevant literature for this topic and writing theoretical part of thesis there were the fallowing tasks. One typical four member family household was described and hourly load curves for one year period, with typical summer and winter days, were made for this case. Next task that was completed was generating yearly energy production from solar panels, which the observed household contains, in INSEL software. With having those previously mentioned data, combined with necessary information about prices of all necessary components and prices from Croatian power system, it was possible to make feasibility and cost analysis where the two previously mentioned alternatives were investigated. With changing some parameters in that economical analysis several scenarios were observed. At the end conclusions were made about which one of those two options is more profitable and under what conditions. Also, suggestions were made for further work on this topic. This assignment is realized as a part of the collaborative project &#147;Sustainable Energy and Environment in Western Balkans&#148; that aims to develop and establish five new internationally recognized MSc study programs for the field of &#147;Sustainable Energy and Environment&#148;, one at each of the five collaborating universities in three different WB countries. The project is funded through the Norwegian Programme in Higher Education, Research and Development in the Western Balkans, Programme 3: Energy Sector (HERD Energy) for the period 2011-2014.