In the master thesis the concept of Programmed Modulation is investigated for motor drives with Three-Level NPC inverter. Programmed Modulation operates with pre-calculated PWM switching-patterns, which enables the facility of off-line optimization of the converter switching-instants. The Optimization objectives are several, two commonly known are Selective Harmonic Elimination and Synchronous Optimal Modulation. The latter optimization focuses on generating a switching-pattern that will reduce the phase current harmonics. A reduction of harmonic components in the phase currents, means that a reduction in switching frequency is possible. The switching loss component, compared to the total loss in IGBTs increases as the voltage level increase. A reduction in switching losses opens for an increase in the nominal current limit in IGBTs. Hence, reductions in switching frequency gives an increase in power density.Conventional current control strategies cannot be used in a switching-pattern based drive system without sacrificing the optimality of the applied switching-pattern. A novel approach is therefore required to obtain dynamic control. For this has the stator flux trajectory control method been chosen and tested. A simulation model, specially built for Programmed Modulation, is proposed in this thesis. The model has a Stator Flux Trajectory Controller (SFTC) that calculates manipulation of the optimal switching-pattern, the manipulations are added to the original optimal switching-pattern to control the actual stator flux in the drive system. This SFTC is also used to eliminates, fast, deviations between the actual stator flux and a calculated optimal stator flux. This effectively eliminates the currents transient that otherwise could arise after a switching-pattern exchange, due to mismatch between optimal flux and actual flux trajectory.The modulation strategy has been simulated, results shows that fast dynamic control is obtained by controlling the alpha- and beta-components of the stator flux, in rotor field oriented coordinates. Combined with the use of Synchronous Optimal Modulation switching-patterns is this a very promising modulation strategy that have the required qualities for medium voltage drives. The simulation model needs further development, suggestions are given in the further work section.

Rapporten omhandlar utviklinga av relévernmodellar for bruk i ATPDraw. ATPDraw er eit simuleringsprogram for elektriske kretsar, og inneheld per i dag ikkje modellar av relévern.Fyrste del av rapporten tek for seg grunnleggande teori og virkemåte til dei vanlegaste typane relévern, samt diskré signalbehandling. Relévern omtala er overstraumvern, differensialvern og impedansvern. Av signalbehandling er det sett på omgjering av diskré signal til effektivverdiar og frekvenskomponentar, med amplitude og fase.I andre del av rapporten er resultata frå utviklingsarbeidet presentert. Kjeldekode for kvar modell er forklart, og flytskjema er vist for dei modellane med omfattande kode. Her er det også forklart kort om korleis modellane kan nyttast i ATPDraw.Til slutt er nokre av modellane verifisert mot eit fysisk relévern. Relévernet som vart nytta til verifisering var eit impedansvern levert av Siemens, modellnummer 7SA610. På bakgrunn av relévernets funksjonalitet vart kun modellane av impedansvern utan effektpendlingsfunksjon og overstraumvern samanlikna.Modellane presentert i denne oppgåva har som funksjon å etterlikne reelle relévern. Verna vart bygd opp frå grunnleggande teori om virkemåte funnen i diverse litteratur og artiklar. Denne virkemåten, presentert i fyrste del, er oppnådd på alle modellar. Av verifiserte modellar viser det seg at overstraumverna og signalbehandlingsmodellane har ein virkemåte tilsvarande reelle relévern, medan impedansvernmodellen har eit lite avvik. Dette kjem truleg av at relévernet nyttar seg av ytterligare filtrering.

The society's dependency of a reliable power supply is increasing, and properly identifying the distance to the stability limits of the power system and avoiding large disturbances is thus becoming increasingly important. In this thesis, a system integrity protection scheme (SIPS) for voltage instability is proposed. First, six voltage stability indicators are studied and compared, and their performance is tested in several power system models. They are first tested in a two-bus system where the load impedance is gradually increased until the load-side voltage reaches zero. The performance of the indicators is then tested under circuit contingencies in models of the IEEE Reliability Test System and of the Norwegian power system. From the results, the most reliable indicators seem to be the ones that are based on local measurements (SDI, ISI and VSIscc).Several actions to mitigate voltage instability are described and tested in the power system models, including load shedding, switching of reactive compensation equipment, increasing AVR set points and increasing the active power generation. Of the unconventional actions, increasing AVR set points appears to be the most effective mitigation action.A SIPS is proposed based on the above mitigation actions, voltage stability indicators and signals from activation of OELs. The principle behind the scheme is to avoid load shedding as far as possible by using indicator values and OEL activation signals to initiate preventive mitigation actions to relieve the situation when the system is approaching instability. This also reduces the necessary amount of load to shed to stabilise the system.Simulations show that the proposed SIPS works as long as it has an adequate amount of mitigation actions available. In the simulations in the model of the Hammerfest/Skaidi region in Northern Norway, there was a general lack of possible mitigation actions, providing no alternative other than shedding large amounts of load to prevent voltage collapse after critical contingencies.

Effective IT is vital in organization in the low resource settings of developingcountries. This also applies to public sector organizations. However, little researchhas been reported regarding IT implementation in higher education institution.Meanwhile, it is widely believed that information technology could boostdevelopment, strengthen and increase the competitiveness of the university amongothers.The focus of this report is to explain as well as improve the IT implementationprocess in public sector organizations, particularly in higher educationinstitution in developing countries. The motivation for studying the ITimplementation process is to be able to understand the underlying aspectsof the successful of IT implementation process in developing countries whichthen give the possibility to make any improvement on the organization.An action research approach in combination with case study method has beenperformed in one of Indonesia's public universities. Empirical data collectionwas done to support the research investigation including two-times of field work inwhich one of them was getting involved into the organization activity, two roundpre and follow-up semi-structural interviews, direct observation, discussion,meeting, document analysis and previous involvement in the institution. AnOnline Questionnaire was also performed to obtain the perception of researchparticipants regarding the proposed tools.A one initial cycle of action research was done and the study found severalfactors that possibly hamper the implementation process in the university andsuccessfully formulated several strategies that can be used to cope with thosefactors, e.g. limited human resources, lack of management commitment, lack ofclear job description among staffs, lack of appropriate planning and strategyfor systems development and implementation, ineffective communication &coordination, lack of funds, lack of rewards, and government policies.Intervention is then performed by introducing software project managementinto the organization as one of the formulated strategies. Even though theoutcome of the interventions not clearly visible at this time, it gives amotivation for the continuity of the interventions.In conclusion, it can be said that among other public sector organizations indeveloping countries, they share common barriers and challenges in general, andto deal with those challenges require substantial time and appropriate approach.

Det er ønskelig å øke driftsspenningen for krafttransmisjon ved bruk av høyspenningskabler, da en høyere driftsspenning vil gi lavere tap. Om man beholder samme tykkelse på isolasjonen og samtidig øker driftsspenningen, vil også det elektriske feltet i isolasjonen øke. Et økt felt vil gi en økt belastning på isolasjonen og kan føre til fremskyndet aldring og sammenbrudd. Det er flere faktorer om påvirker aldringen og dermed levetiden i et isolasjonssystem basert på polymerisolasjon (som her PEX) [1]. De viktigste faktorene under normal drift er forurensninger og urenheter. Dette er velkjente problemer og det tas strenge forhåndsregler under produksjon av slike isolasjonssystemer. På tross av dette er det praktisk umulig å unngå forurensinger når det produseres kabelisolasjon i store mengder.En annen angrepsvinkel er derfor å øke isolasjonssystemets toleranse ovenfor slike forurensninger. En måte å øke toleransen på er å sørge for god kontakt mellom isolasjons-materialet og en eventuell forurensning. Det er forsøkt oppnådd i dette prosjektet ved å øke kohesjonen mellom isolasjonsmaterialet og forurensningen ved å tilføre et heftemiddel. Dette er gjort ved å produsere testobjekter med tilsatt partikkelforurensning, for så å teste holdfastheten. Testobjektene har blitt tilsatt partikler behandlet på fire forskjellige måter:1)Referanse – Testobjekt uten tilsatte partikler.2)Ubehandlet – Testobjekt tilsatt ubehandlede partikler.3)Heftemiddel – Testobjekt tilsatt partikler behandlet med nanokompositter.4)Slippmiddel – Testobjekt tilsatt partikler behandlet med Chemlease PMR-90.Da det fra tidligere forsøk var kjent at denne typen testobjekt var hyppig utsatt for en defekt, ble laboratorie-arbeidet innledet med feilsøking av testobjektene [11]. Feilkilden viste seg å være vanskelig å finne, og nesten hele prosjektperioden ble benyttet på feilsøking. Under feilsøkingen ble flere av produksjonsparameterne variert, uten store forskjeller på resultatet. Defektene var stort sett av samme karakter uansett hvilke parametere som ble forandret.Det kan konkluderes med at ujevnheter i grenseoverflaten mellom indre halvleder og isolasjonsmaterialet medfører gjennomslag ved langt lavere påtrykt spenning enn det isolasjonssystemet er designet for å motstå. Når det gjelder feilkilder er det ennå ikke mulig å konkludere med noe, selv om høy mekanisk belastning på overflaten ved produksjon av råkopper virker som en sannsynlig feilkilde. Dette kommer høyst sannsynlig fra små ujevnheter som riper eller hakk i overflaten på støpeformene som følge av slitasje.Den resterende tiden ble benyttet til måling av PD, men det ble ikke nok tid til å gjennomføre tilstrekkelig med målinger. Det er og få testresultater fra de målingene som ble gjennomført, sannsynligvis grunnet de samme defektene som forhindrer måling av gjennomslagspenning. Det kan derfor ikke konkluderes med om heftemiddelet har noen effekt basert på PD målingene.

In this thesis, we present a prototype for search engine to show how such a semantic search application based on ontology techniques contributes to save time for user, and improve the quality of relevant search results compared to a traditional search engine. This system is built as a query improvement module, which uses ontology and sorts the results search based on four predefined categories. The first and important part of the implementation of search engine prototype is to apply ontology to define the meaning and the relations between the queries in default domain of the study. Next, categorization of the results is carried out in order to improve the quality of result search presentation based on categorization-list. The ontology used in this search engine prototype includes sample of terms in safety and security domain, which is capable to be modified in this domain, or can be substituted by another ontology in the other fields of study. The process is continued by searching the enriched query through the Web using Google interface application search engine. The application uses ranking algorithms to categorize and organize the results of Google search in four categories, i.e. History, Mechanism, Prevention, and Case study. The predefined categories can be substituted to the other categories based on user preferences in other studies using different categorizes.

This dissertation presents an analytical study on virtual synchronous machine-based power control in active rectifiers for micro grids supported by prototype modelling, simulation results and discussions.Popularity and demand of the distributed energy resources and renewable energy sources are increasing due to their economic and environmental friendliness. Concept of micro grid with an active rectifier (AR) interface has been found to be promising for smart integration of such distributed generation units. Having the presence of a synchronous generator (SG) in a micro grid introduces several advantages in terms of stability and reliability in the power system. This is mainly owed to the inertia, damping and load sharing properties of SG. This in return, gives rise to the question if an AR of a micro grid can imitate the behaviour of a synchronous generator, can the stability and reliability introduced by SG be replicated in a micro grid. A research on the state-of-the-art for uninterruptible power supplies (UPS) has been carried out to identify the implementation and the control strategies of redundancy and parallel operation as UPS has been an established technology over the last decades. The theoretical study on virtual synchronous machine (VSM) concept in the fall, 2011, has been extended in developing a model with classical inner current control and outer voltage control loops based on the synchronous reference frame.The complete active rectifier model has been able to emulate the inertia, damping and load sharing properties of a SG and redundancy and expandability of parallel UPS systems. It must be emphasized that due to the flexibility of the virtual machine parameters and the absence of magnetic saturation and eddy current losses, a much improved performance have been achieved with a VSM compared to a synchronous generator.Simulations have been carried out for single and parallel operation of active rectifiers in island and grid-tied modes with satisfactory stability, damping and power sharing features.Key words – Active rectifier, virtual synchronous machine, micro grid, uninterruptible power supply, load sharing, redundancy, island mode, grid-tied mode, synchronous reference frame

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.

Software innovations can offer organizations with competitive advantages. Research and development entities within the petroleum industry therefore seek to utilize IT capabilities to produce innovative software. Many factors may influence the success or failure of developing and implementing research-based software innovations in organizations. Of these issues the relation between software innovation and IT governance remains largely unexplored in the research literature.This study explores the effects IT governance has on the success or failure of research-based software development projects in an international petroleum company through an interpretive case study. The results of the study are twofold: 1) practical and 2) theoretical.The practical results show that the investigated petroleum company's emphasis on formalization has unfortunate side-effects on successful development and implementation of research-based software in the organization. IT governance, focused on stability of operations, is not well aligned with the corporate strategy of increased innovation. Moreover, the central IT department uses governance structures to guard the boundaries around the department.The theoretical results from the study presented that the impact of IS innovation or digital technology innovation on the research projects and how they can help the researchers to realize their ideas, remain unnoticed in the literature. Furthermore, In IS innovation literature, the organizations’ IS unit is the main responsible for IS innovation and it starts the innovation. However in the presented study R&D department had the main responsibility in innovation and it initiates innovation.

The capricious roman goddess Fortune is known for her strong power to influence or even decide the destiny of humans. In ancient Rome she was considered to be a good goddess, who brought the gifts of destiny and who also was seen as a possible ally. During the Middle Ages this position changed. Fortune was given two sides, a good and friendly one and a cruel impenetrable side. She was seen as one of God´s ministers and became an expression of divine providence. My purpose with this essay is to analyse three artworks of Fortune by Giovanni Bellini, Albrecht Dürer and Master MZ, but also some texts by the renaissance humanist Niccolò Machiavelli. When examining this representation I will try to determine the iconography of Fortune and see how or if the interpretations of her differs. The study has shown that the different representations of Fortune differ from one another of the artworks. However, there is one major resemblance that presents itself in each and every one of the artworks as well as in Machiavelli’s texts, the fact that Fortune is considered to be capricious. This attribute is frequent. In the works of art Fortune is depicted along with some kind of circular object like a ball or a sphere, a clear indication of instability. In Machiavelli’s texts Fortune is often, metaphorically or directly expressed, as capricious and unpredictable. According to Machiavelli, humans therefore have to be prepared, hold capability or virtù, to be able to resist her rapid changes. Like the humanist Machiavelli was it is likely that he represents the ancient view of Fortuna, although some medieval element cannot be omitted. Furthermore, in all of the selected works of art together, one can see elements of both an antique view of Fortuna as well as a medieval. Although the Renaissance was strongly influenced by ancient ideas and ways of life, it becomes clear that also some medieval features survived into the mindset of the Renaissance.