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A voltage dip is a short duration reduction in voltage magnitude due to a short duration increase in current magnitude. Causes of dips are, among others, electrical faults, large motor starting, transformer energizing and failure of power-electronic converters. Voltage dips are considered as a very important power quality issue because they lead to trip or malfunction of sensitive loads especially in industrial process installations and subsequently they lead to high costs. In this thesis the overall aim is extracting additional information from large voltage dip monitoring databases. An important step to this end is providing efficient characterization methods for voltage dips. Voltage dip characterization aids by describing voltage dip events (a set of voltage waveforms with high time resolution) as a limited number of values such that this set gives as much as possible information about the dip. This thesis contributes to the voltage dip characterization development through three different methods. The first method consists of a systematic way for comparison different sets of voltage dip characteristic. With this method, both real-measured and synthetic voltage dips are applied to generic models of sensitive loads. The best set of characteristics, for representing the voltage dip, is the one best enables the reproduction of the behaviour of equipment when exposed to real-measured voltage dips. The second method compares 12 different sets of characteristics for describing three-phase single-events.. The method determines the most efficient and feasible way that gives more realistic characteristics as well as comparable with existing standard methods. The proposed set of characteristics has been proposed for inclusion in international standard documents. The third method enables the extraction of dip characteristics based on machine learning approaches. It is applicable for characterization of multi-stage voltage dips in particular and for single-stage (normal) voltage dips as well. The proposed method uses the space-phasor model of three-phase voltages as an input data for k-means clustering algorithm. Then the calculated data are modeled as a general form of an ellipse by exploiting logistic regression algorithm. Finally the optimized obtained ellipse parameters are applied to calculate single-segment characteristics for each individual stage of a multi-stage voltage dip. Further, all proposed methods are implemented in an Matlab environment and validated by applying them to a large number of real-measured voltage dips in actual HV and MV power networks and some suitable synthetic voltage dips.

With the number of interconnected devices, many of which being wireless, exceeding the human population, there is a need to power resource-constrained devices through means other than disposable batteries. Harvesting ambient energy from the vicinity of the device is one solution.SKF, a producer of rolling element bearings, produces approximately one billion bearings per year. If parts of the produced bearings could be self-sucient devices powered through ambient energy, the smart integration of electronics in mechanical systems could be achieved. A scenario in which rolling element bearings are embedded with electronics is presented, through which the development of new services, data collection, data transfer and data interpretation can be realized. This scenario is the key motivation for thisthesis.This thesis presents some of the most common sources of energy used for harvesting energy in rotating environments and discusses how dierent transduction methods can convert ambient energy into electrical energy. Finding a general, robust and cost-eectivetechnology that can be applied to or in the vicinity of a rotating system is one of the main focuses of this thesis. The investigated technologies should be applicable to a dirty and encapsulated industrial environment; therefore, certain energy sources, e.g., sun light and radio frequencies, are not investigated. Advancements in vibrational energy harvesting are also presented in the form of a parameterized SPICE model of a piezoelectric vibrationharvester that can be simulated in conjunction with non-ideal and non-linear circuit models. The SPICE model is used to verify the performance of a novel energy harvesting circuit that actively extracts energy from a piezoelectric transducer. The harvesting circuit enables the enforcement of greater electrical damping on the mechanical system, thereby enabling more electrical energy to be extracted. For weak electromechanically coupled piezoelectric harvesters, the circuit can increase the power output by more than 300% compared to a full-wave rectifying bridge. The simulation results with the modeledharvester under the dened operating conditions in conjunction with the active harvesting circuit indicate that an average of more than 1 mW of power can be extracted, which is assumed to be sucient for powering a resource-constrained embedded device. / Godkänd; 2015; 20150211 (hagfre)

På bilar med insprutningsmotorer behövs oftast någon typ av justering av bränsletryck då olika typer av belastning behöver olika mycket bränsle. Mängden bränsle motorn får styrs till viss del av spridarnas öppentider samt storleken på spridarmunstyckena. Men öppentiderna kan inte vara hur långa som helst samt storleken på spridarmunstyckena kan inte vara allt för stor heller då man bara har en viss tid på sig att trycka in bränsle under insugstakten[1] samt att man inte vill trycka in allt för mycket bränsle heller beroende på belastningen på motorn. Just för den anledningen används oftasten bränsletrycksregulator för sänka bränsletrycket när belastningen är låg och höja bränsletrycket när belastningen är hög. De flesta bränsletrycksregulatorer som sitter som standard på bilar är inte justerbara utan har oftast bara ett fast arbetsområde som styrs med hjälp av vakuum. Börjar man ta ut mer effekt ur en motor kommer det att behövas mer bränsle och ett sätt att få in mer bränsle men ändå behålla spridare och bränslepump är att byta ut den fasta bränsletrycksregulatorn mot en justerbar vilket innebär att man kan ändra arbetsområdet för bränsletrycket och därigenom få in mer bränsle under samma öppentid på spridare, vilket kan behövas vid t.ex överladdning. Den här rapporten kommer gå igenom hur ett trådlöst övervakningssystem för kontroll av bränsletryck kan konstrueras.

Rapporten presenterar övertonshalter på spänningen vid två procesställverk och ett och huvudställverket vid Södra Cells anläggning i Mönsterås. Mätningarna är viktade mot Energimarknadsinspektionens standard EIFS 2013:1. Det utvärderas även om övertoner från procesställverken sprider sig till överliggande huvudställverk. Dessutom utvärderas det om strömtransformatorer som sitter monterade i procesställverken har tillräcklig mätnoggrannhet för framtida övertonsmätningar.

Power distribution networks are recognized as the constituent part of power systems with the highest concentration of failure events. Even though the faults in distribution networks have a local effect when compared to the generation and transmission sides, major contingency escalation events are being more frequently reported from this section. The various aspects regarding the reliability and performance of distribution networks are identified as an important topic. Integration of new technologies, automation and increased penetration of distributed generation is expected to make improving and even sustaining high reliability standards a complex task.   This thesis presents developed approaches to quantify and analyze the complex correlated failure probabilities of different failure modes in distribution networks. A theoretical simulation model that relates to real world data to measure false tripping probabilities is developed and tested. More simplified approaches that utilities can exercise with readily available data in fault registers are also established.  Optimal configurations that could improve system performance and respective investment costs are analyzed and savings in system reliability at the cost of grid investments are modelled. The optimization helps in prioritizing the most critical investments by considering the system impact of reconfigurations focusing on meeting customer demands and respecting transfer capacities of weak links. The value of existing networks and willingness of the grid owner in investing can be integrated into suggestive alterations to assist decision making in planning and maintenance allocation.   The thesis makes both system specific and generalizable observations from detailed data collection from power utilities. The observations and results have potential in aiding future research by giving important understanding of the reliability impacts of network structures and of control and protection equipment. / Eldistributionsnätet är den del av elnäten som leder till flest kundarbrott trots att felhändelserna oftast är mycket lokala jämfört med händelse på genererings och transmissions sidan. Alltså identifieras de olika aspekterna beträffande pålitlighet och prestanda för distributionssystem som viktiga ämnen. Integration av ny teknik, automatisering och ökad penetration av distribuerad produktion förväntas göra förbättringar och rent av upprätthållande av höga tillförlitlighetskrav till en komplex uppgift.   Denna avhandling presenterar metoder för att kvantifiera och analysera de komplexa och korrelerade sannolikheterna för olika fellägen i distributionsnätet. En teoretisk simuleringsmodell baserrad på verkliga data för att mäta sannolikheter för felaktiga brytarkommandon utvecklas och testas. Mer förenklade tillvägagångssätt där elnätsföretag kan använda lättillgängliga data i felregister presenteras också. Optimala konfigurationer som kan förbättra systemprestandan och investeringskostnader analyseras och minskningar i systemets tillförlitlighet genom minskade kostnader för nätinvesteringar modelleras. Optimeringen bidrar till att prioritera kritiska investeringar genom att påvisa systemets inverkan av omkonfigurationer. Optimeringen tär hänsyn till kundernas krav och att bevara överföringsförmågan hos svaga länkar. Värdet av befintliga nät och villigheten hos nätägaren att investera kan undersökas som förslag, till ändringar, som stöd detta för beslut om planering och underhåll.   Avhandlingen gör både systemspecifika och generaliserbara observationer från en detaljerad datainsamling från elnätägare. Observationerna och resultaten har potential att hjälpa framtida forskning genom att ge en viktig förståelse för tillförlitlighetseffekter från nätverksstrukturen och från kontroll- och skyddsutrustning. / <p>QC 20171004</p>

This is a report of our examination project in electronics carried out for Bofors Test Center in Karlskoga. The task was to construct an electronic devise for starting up different kinds of measuring systems in exact time during test sequences. The modules that are used today are old and unreliable. Our goal was to construct a prototype, which later on is supposed to be developed into a useful system.

Detta examensarbete har utförts på Örebro universitet och Västerdalarnas Mekaniska Industri AB (VMI) i Malung för Ehrlund Microphones.Ehrlund Microphones tillverkar mikrofoner med sin patenterade kapsel, som bland annat består utav ett triangulärt membran. Under examensarbetets tid var en ny mikrofonmodell under utveckling. Målet med examensarbetet var att bistå Ehrlund Microphones med utförandet av tester och mätningar, samt att komma med förslag till förbättringar på den nya konstruktionen. På VMI i Malung, där kapslarna tillverkas, finns ett mätlabb som är till för att mäta kapslarnas frekvenssvar. Mätutrustningen i detta labb har installerats och konfigurerats för den mätmetod som har tagits fram för att verifiera kapslarnas frekvensgång. Slutsatsen av undersökningen huruvida skyddsgallret påverkar mikrofonens frekvensgång, är att den volym luft som ryms innanför skyddsgallret har större betydelse för frekvensgången än vad den geometriska utformningen av gallret har. Med stor sannolikhet kommer den nya transistorbaserade mikrofonmodellen att ha ett bättre signal/brus-förhållande än vad som visas i detta arbete, eftersom testerna har utförts på en prototyp i utvecklingsskedet. / This degree thesis has been conducted at the University of Örebro and Västerdalarnas Mekaniska Industri AB (VMI) in Malung on behalf of Ehrlund Microphones. Ehrlund Microphones produce microphones with their patented capsule, containing a triangular membrane.During the course of this thesis, a new microphone model was under construction. The aim was to assist Ehrlund Microphones conducting tests, measurements and also coming up with ideas of how to improve the construction of the new microphone model. At VMI, where the capsules are produced, there is a lab designed to measure the frequency response of the capsules. The equipment in this lab has been installed and configured for the measurement method used, to verify the frequency response of the capsules. The conclusion of the examination whether the grille of the microphone influence the frequency response of the microphone in a noticeable way, is that the volume of air enclosed by the grille has greater influence on the frequency response than the shape of the grille. It’s most likely that the new transistor based microphone model will have an improved signal/noise-ratio, considering that the tests conducted in this essay were made on a prototype under development.

In this thesis, the potential of the gap discharge transducer is investigated as transducers in a time-of-flight gas flow measurement setup designed for harsh environments.In this thesis the gap discharge transducer is operated in two different modes, named spark discharge transducer and glow discharge transducer. The spark discharge transducer generates a spark over a gap while the glow discharge transducer generates a continuous glow discharge.Earlier studies show that the spark discharge transducer is very durable and a potent sound pulse emitter. This thesis continues these studies by incorporating the spark discharge transducer into a flow measurement system as a sound pulse emitter. Further more, the gap discharge transducer is investigated as a potential sound pulse receiver.As an emitter in a flow measurement system the spark discharge transducer was placed in a pipe with a variable flow in a laboratory environment. The transducer was set to generate sparks to create the sound pulse and standard piezoelectric receivers were used to capture the signal.As a receiver, the gap discharge transducer was tested in two experiments. In the first experiment the spark discharge transducer was placed in a vacuum chamber to test the dependence between breakdown voltage and pressure. The pressure change from a sound pulse might cause breakdown in the gap of the transducer if an initial voltage between the electrodes is set close enough to breakdown. The breakdown leads to a spark which can be used to determine when a sound pulse arrives. In the second experiment the transducer was set to generate a glow discharge. The glow discharge was then subjected to a sound source. The voltage and current of the glow discharge depends on the environmental conditions in the gap. Pressure changes from a sound pulse will then affect the air in the gap which in turn changes the voltage and current characteristics of the discharge. The change in voltage and/or current can then be used to determine when a sound pulse has arrived.The investigation shows that the spark discharge transducer is a potential sound pulse emitter in a flow measurement system and could be capable of determining a flow quite accurately. As a receiver, the spark discharge transducer show limited potential. The pressure change of a spark generated sound pulse requires the receiver to be set very close to the breakdown voltage. But that close to the determined breakdown voltage will very often cause the gap to breakdown spontaneously. The glow discharge transducer, on the other hand, show promising potential. The transducer is proven to be able to receive sound waves and has a sensitivity that is deemed compatible with the spark discharge transducer as a sound pulse emitter. / Godkänd; 2014; 20140917 (krikar); Nedanstående person kommer att disputera för avläggande av teknologie doktorsexamen. Namn: Kristoffer Karlsson Ämne: Industriell elektronik/Industrial Electronics Avhandling: Gap Discharge Transducers in a Transit Time Flow Measurement System Designed for Harsh Enviroments Opponent: Professor Per Lunde, Department of Physics and Technology, University of Bergen, Norge Ordförande: Professor Jerker Delsing, EISLAB, Institutionen för System- och rymdteknik, Luleå tekniska universitet Tid: Måndag den 17 november 2014, kl 12:30 Plats: A1545, Luleå tekniska universitet

Radio measurement systems may have their performance significantly degraded due to environmental factors such as multipath, weather effects, and mechanical displacements. Characterization of these effects are therefore important in order to ensure functionality of the system. The characterization itself may also be the purpose of the system. This thesis contributes to the answer to the question of how to assess the effect of the environment on the propagation and reception of radio waves for three different applications.Traditionally the functionality of a radio measurement system has been assessed using either simulations assuming ideal conditions (e.g. free space) or measurements under controlled circumstances. There is no doubt that both these approaches are very useful when designing antennas and related hardware. In many applications it is also sufficient to assume ideal conditions and only use an a priori characterization. The applications considered in this thesis all operates in an environment that can be considered to be challenging. In these cases the environment needs to be taken into account in the design process of the system. Both simulations and measurement methods have been considered. The combination of electromagnetic simulation methods, such as the method of moments (MOM) or the partial element equivalent circuit (PEEC) method, with statistical methods, such as the Monte Carlo method, have been given special attention. The measurement systems considered, both for determining the performance of antennas and for detection of objects and transponders, are all assessed from a "challenging environment" point of view.The three application considered are multistatic radar using global navigation satellite systems (GNSS), measurement systems for antenna arrays in noisy conditions, and simulation of RFID systems with moving transponders. In the multistatic radar the focus is on detecting signals reflected in directions other than that of the primary reflection. The results shows that detecting these signals is possible even with the low signal levels involved. This is especially the case when reflecting objects are present which could scatter the signal in a specular way. By using the equivalent electric current method it is possible to estimate the complex far-field radiation pattern of antenna arrays even when the signals used have a low signal-to-noise ratio (SNR). This has been shown using simulation of a large antenna array and with measurements using a small array for GNSS receivers. When designing RFID systems it is important to be able to estimate the performance in terms of number of detected transponders with all movements of the transponders taken into account. This is possible by using a very simple model of the transponders (e.g. a magnetic dipole) in which case only one electromagnetic simulation is needed. This enables the use of the Monte Carlo method to take the random movements of the transponders into account using a low number of computations. The use of the PEEC method further enables a combined simulation of both the electromagnetic properties of the reader antenna and the electric functionality of the receiver circuit.Although the considered application are very different the obtained solutions are in many ways general. The fact that even the weak signals reflected in non-specular directions in a multi-static GNSS radar can be detected can be used in any application involving multi-path propagation or stray signals. The equivalent electric current method have here been considered for two radically different antenna arrays operating in a low SNR environment. Although the simulation approach chosen for the RFID simulations rely heavily on the simple magnetic dipole method it would work with any antenna at any frequency as long as the model of the antenna is sufficiently simple. / Godkänd; 2009; 20091106 (tore); DISPUTATION Ämnesområde: Industriell elektronik/Industrial Electronics Opponent: Professor Zvonimir Sipus, University of Zagreb, Kroatien Ordförande: Docent Jonas Ekman, Luleå tekniska universitet Tid: Torsdag den 10 december 2009, kl 10.00 Plats: D 770, Luleå tekniska universitet