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  • 151.
    Bäckberg, Erik
    et al.
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Wissmach, Toni
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    IPv6 latensprestandastudie över Internet2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis is about a comparison of latency between IPv6 and IPv4 in a live environment, the Internet. When IPv4 was developed in the 1980s it was not foreseen how great the need for IP addresses would be. For this reason, the Internet Engineering Task Force began to develop IPv6 in the 1990s. IPv6 extends the number of available IP addresses manifold and eliminate the need for NAT. The protocol was also optimized for more efficient package handling with fewer fields in the header. Migration to IPv6 from IPv4 is inevitable, the question is whether there will be differences in latency.

    This report is based on a hypothesis that IPv6 should perform better than IPv4 in form of latency since low response time is fundamental when it comes to for example online games, live video streaming and web surfing. Measurements from Sunet and Telia have been performed with ping and traceroute against 55 nodes that support both protocols. IPv6 does not show any clear indication of lower latency than IPv4. The performance measured differed significantly depending on which ISP was used.

  • 152.
    Bäckström, Joakim
    et al.
    University West, Department of Engineering Science.
    Falck, Mari
    University West, Department of Engineering Science.
    Förslag på reviderat arbetssätt för att säkerställa att underhållsåtgärder upptäckta vid felavhjälpning blir genomförda2023Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Då entreprenörer utför felavhjälpningar och schemalagda underhåll i Vattenfall Eldistribution AB nät upptäcks regelbundet fel och brister. Dessa brister ska de enligt serviceavtal rapportera in och göra en beställning på arbete, ett åtgärdsförslag med hjälp aven applikation. Det sker regelbundet att dessa brister inte blir inrapporterade korrekt vilket leder till felaktigheter i budget, kvarvarande noteringar i SCADA-systemet som inte avslutas och att underhåll inte utförs. Detta är ett problem som har pågått under många år och som är svårt att få ordning på.

    Detta examensarbete är ett uppdrag från Vattenfall Eldistribution AB och behandlar processer för drift och underhållsåtgärder och har till syfte att analysera brister i de befintliga processerna och ger förslag på åtgärder. Analysen baseras på intervjuer med drift- och underhållspersonal.Det resultat som framkommit av utredningen, visar att det krävs både tid och budgetvanaför att skapa dessa beställningar genom applikationen, vilket gör inrapporteringen omständlig för många tekniker. Det blir informationsöverlämningar vilket är ineffektivt då beställningen inte utförs direkt och det kan leda till att viss information försvinner eller glöms av. Flera alternativ som dellösningar har tagits fram och kan kombineras och användas beroende på vilken inriktning Vattenfall Eldistribution AB vill ta. Alla alternativ som tagits fram kräver någon form av större systemförändring

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  • 153.
    Börjesson, Erik
    University West, Department of Engineering Science, Division of Industrial Engineering and Management, Electrical- and Mechanical Engineering.
    Beredning av landsbygdsnät i Hassle, Mariestad2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The thesis deals with how preparation work is accomplished in rural networks, by field work, landowner contact, contracts and permit applications. The described preparation work is the basis for the implementation of the project from Ellevio AB.  The reconstruction is performed in order to secure the voltage and get a more weatherproofed network, but also to get rejuvenation of the network. The preparation work is done for PSN Kraftkonsult Eldistribution AB in Vedum and performed using their working methods. The preparation work is performed in the area of Hassle north of the town Mariestad. The project is divided into two interim stages. Stage one is called Hassle sub-station – Källtorp and the second one is Fåleberg – Nolhassle. These two stages are parts of one large reconstruction of the distribution network in the area by Ellevio AB in the near time. Due to the fact that a major rebuilding project of the E20 in the affected area the projector’s intended rout for the cable had to be changed. And it became 1100 m further. The result of the preparation work includes two new 10/04 kV substations, one new cable cabinet, 5850 meters of high-voltage cable and 500 meters low-voltage cable. All the cables will be placed in the ground and for the most they will be plowed down. Substations and cable cabinets will be placed strategically to create the strongest network as possible and for good availability for future maintenance.

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  • 154.
    Capriles, Claudia
    University West, Department of Engineering Science, Division of Industrial Engineering and Management, Electrical- and Mechanical Engineering.
    Kartläggning av kommunala utvecklingsplaner gällande laddinfrastruktur för elbilar2018Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Sweden aims to be completely fossil free by 2030. Politicians want to reduce fossil fuel cars while expanding the charging infrastructure for electric cars. The ownership of electric cars has increased by 73% in the last year. The charging infrastructure is increasing and now there are over 3,500 charging points in Sweden. It's possible to apply for investment support through State owned Klimatklivet, which offers financial support up to 50% of the cost of building new charging stations.

    The purpose is to investigate and compare different municipalities' plans regarding the development of charging stations for electric cars, and to compare their methods, strategies and infrastructure. The purpose is also to see which municipalities cooperate with each other and in what way.

    In order to investigate and compare the charging infrastructure in Stockholm, Gothenburg, Malmö, Borås and Trollhättan, interviews were conducted with those in charge of these selected municipalities.

    The result shows that the larger municipalities such as Stockholm, Gothenburg and Malmö have come quite a long way with the charging infrastructure issue, while the smaller municipalities haven't come as far in their development. The larger municipalities have staff who work with the issue and they have major projects in progress, which will be completed by 2018. Stockholm is moving ahead and is expanding their charging infrastructure onto city street buildings and residential neighborhood areas, while Malmö and Gothenburg are more careful and want to prioritize residential neighborhood areas over city streets as they want to continue giving precedence to bicycle- and bus lanes. The laws are the same but are interpreted differently. Common to all is that they often see legislation as an obstacle. Besides Stockholm, the other municipalities don't really know how to proceed. They don't know how to plan for- or who is responsible for developing the charging infrastructure.

    This is a new area which means that most municipalities are still trying to find their model. Better cooperation between municipalities could mean faster and more cost-effective development.

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  • 155.
    Carlander, Isabel
    et al.
    University West, Department of Engineering Science, Division of Computer, Electrical and Surveying Engineering.
    Holmberg, Malin
    University West, Department of Engineering Science, Division of Computer, Electrical and Surveying Engineering.
    Undersökning och exemplifiering av ett oriktat jordfelsskydd för detektering av dubbla jordfel i impedansjordade nät.2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis describes problems that might occur with detecting and disconnection of cables and lines that have suffered from cross-country fault in impedance grounded networks, furthermore how and if an undirected earth-fault relay could affect the way these faults are dealt with. When single-phase earth-faults occur, the network suffers from a dissymmetry. This dissymmetry leads to enhanced stress on the parts of the network which are healthy. This stress could cause other earth-faults to occur, for example on locations in the network where, for some reason the insolation has been compromised. These problems could lead to that the time it takes for the relays to disengage the faulty cables becomes too long or that unnecessary large areas of the network are disconnected. The purpose of this study is to illustrate these problems and to analyze in what way an undirected earth-fault relay could affect the outcome of these problems.

    By examining theoretical cases where earth-faults had occur, files from actual disturbances and by verifications tests with relays in the laboratory and Comtrade-files developed from PSCAD, these problems could be analyzed and were easy to survey. As a result of the study it was found that the undirected earth-fault relay both can contribute to better selectivity in the network and to faster disconnection in the event of cross-country faults. The undirected earth-fault relay should also be able to handle additional cases when earth-faults occurs, for example, where a simultaneous uncompensated power distribution network leads to that the directed earth-fault relay functions does not work.

    The earth-fault function is recommended to be used with DFT-measuring, as this prevents the relay from tripping for harmonics, transients and direct-current components. A good knowledge regarding the capacitive currents occurring in the network is crucial to set the relay correct and prevent from unselective tripping, but if set correctly, no conflict with other protective relay functions has been noticed.

    The problem with disconnecting cross-country faults mainly occurs where two-phase-measuring overcurrent protective relays are used, therefore, the transition to three-phase-measuring overcurrent-relays are recommended in places where the undirected earth-fault relay proves to be difficult to set up correctly.

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  • 156.
    Carlson, Christer
    et al.
    University West, Department of Engineering Science, Division of Computer and Electrical Engineering.
    Lundgren, Clas
    University West, Department of Engineering Science, Division of Computer and Electrical Engineering.
    Alternativa metoder för att öka strömmar vid fel och förbättra elkvalitet i lågspänningsnät2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In this study are rebuilding methods to improve existing low voltage networks (0,4 kV) investigated. The background, causing the need of improvement, is the existence of lines where the trigger condition is not satisfied. Due to the length of the line and its area a problem with power quality is also often present in these lines. The meaning in this context of not satisfying the trigger condition is that intended fuse will not disconnect in prescribed time of 5 seconds when a single phase fault to ground occurs at the line. Why this problem is emerged can depend of load increases by time, thus the fuse size has been increased which causes the demand of a higher fault current to disconnect. In this study a large part of the focus is placed in satisfying the trigger condition and a small part of the focus is placed in improving the power quality.

    The traditional solution to solve above problem is to expand the medium voltage network, closer to the customer, or reinforce the low voltage network, two comparative expensive solutions.

    The studied methods are named alternative as either the methods are less known or entire new which are not fully developed so far. Respective method consists of a device that by design, and chosen point of connection at the line, is considered to afford a gained single phase fault to ground current. Four devices are studied and named

    Isolertransformator (eng. Isolating transformer), Sparkopplad transformator (eng. Auto transformer), Magtech Voltage Booster and Black box. The devices are studied in computer aided simulations with the program PSCAD/EMTDC and the result shows that all devices increase the fault current. The device Isolertransformator affords the highest gain. Further an economic comparison is performed regarding purchase cost and no-load losses, the result is that the devices Sparkopplad transformator and Black box has the lowest costs and losses

  • 157.
    Carlson, Joakim
    University West, Department of Engineering Science, Division of Industrial Engineering and Management, Electrical- and Mechanical Engineering.
    Ny generatorbrytare och styrsystem till kontrollerande avbördningsskydd vid Strömmens vattenkraftstation2020Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis is divided into two separate parts where implementation of new electrical equipment at Strömmens hydro power plant is presented. The first part is about how to implement a new generator circuit breaker into the existing low voltage switchgear. The second part is about the control system for the dam overtopping protection system (DOPS). The powerplant needs a new control system for DOPS that will fulfill the demands of a secure and reliable installation.

    After 35 years of operation some of the electrical equipment has reached its physical lifetime expectancy. Employees at Vattenfall has noticed abnormal heat temperatures radiating from the current generator circuit breaker. The conclusion is that a retrofit solution can be installed into the existing circuit breaker compartment. This will provide a cost effective alternative and ensure continued operation of existing control and protection systems. A detailed presentation of the installation is presented in section Results of the report.

    The report will present the concept of a new control system for DOPS. Due to several reasons the decision has been made to base the new control system on electromagnetic relays. The thesis presents a circuit diagram describing the connections and the implementation of the new control system. Appendix D shows how the new control system can be added to the starter circuit of the hydraulic motor, controlling the spillway gate.

  • 158.
    Carlsson, Henric
    et al.
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Danielsson, Fredrik
    University West, Department of Engineering Science, Division of Production Engineering.
    Lennartson, Bengt
    University West, Department of Engineering Science, Division of Production Engineering.
    General Time Synchronisation Method for PLC Programs Aiming at Virtual Verification and Development2008In: 17th IFAC World: Congress Proceedings of the 17th World Congress. The International Federation of Automatic Control. Soel, July 6-11, 2008, p. 4440-4445Conference paper (Other academic)
    Abstract [en]

    The latest state-of-the-art Computer Aided Production Engineering (CAPE) simulation technology offers OPC integration for PLC verification. A critical drawback with this technology has been identified and described within this paper. A new time synchronisation method and a simulation architecture are therefore presented and proposed. The time synchronisation method together with the architecture can be used when verifying and developing real-time dependent control logic for industrial control system, e.g. PLC with CAPE tools. The method described in this paper is general and should work on any PLCs that are compatible with the IEC 61131-3 standard. A test case was also carried out, showing that by disregarding time synchronisation it is impossible to verify real-time dependent PLC functions together with CAPE tools in a reliable way. However, the test case also shows that by applying the proposed time synchronisation method together with the described simulation architecture a successful industrial verification method is achieved

  • 159.
    Carlsson, Henrik
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Reliable Virtual Commissioning2012Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Virtual commissioning is a technique for programming, optimising and verifying industrial automated production, such as robot controllers and programmable logic controllers (PLC), off-line in a simulated environment. Compared with traditional robot off-line programming and simulation, the scope is wider and can include an entire production cell.

    Robot simulation is a well-established technique and widely used in industry today, much thanks to the RRS interface that enables simulated robot control systems to be integrated in the simulation software. A more general interface for industrial control system integration is OPC that has been an industrial de facto standard for connection between industrial control systems and regular PCs. State-of-the-art production simulation tools often include the possibility to connect an industrial control system via OPC. However, OPC suffers a major drawback when it comes to production simulation, there is no mechanism that synchronises the industrial control system with the simulation and this could lead to unreliable results from the simulation.

    Another obstacle for virtual commissioning is the amount of time that needs to be spent during the simulation model building phase, since virtual commissioning includes more signals. This does not only take more time, but it is also an error prone process that might lead to unreliable results.

    In this thesis problems related to the OPC interface and the modelling process are discussed, and suggestions how these issues can be solved are presented so reliable virtual commissioning can be achieved.

  • 160.
    Carlsson, Henrik
    et al.
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Nilsson, Jim
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Danielsson, Fredrik
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Lennartson, Bengt
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering. University West, Department of Engineering Science, Division of Production Systems.
    Automated Generation of Discrete Event System Simulation Models for Flexible Automation2011In: The 21st International Conference on Flexible Automation and Intelligent Manufacturing: Taichung, Taiwan, June 26-29 2011, 2011, p. 825-832Conference paper (Refereed)
    Abstract [en]

    Flexible automation cells with rapid product changes are an important competitive advantage for industries today. These cells can increase a company’s productivity and thereby increase their profits. A flexible cell shall be able to handle different products with none or minimal changes to the cell itself. A powerful tool, which can be used to analyse and verify such cells, is discrete event system simulation. Problems such as potential bottlenecks, deadlocks, answers to "what-if" questions and the level of resource utilisation can be gathered. The drawback of discrete event system simulation is that the modelling task is both time consuming and difficult to accomplish. Furthermore, state-of-the-art discrete event system simulation tools that are used in the industry today are not suitable for flexible automation. If the production scenario is changed, e.g. introduction of a new product, the simulation and modelling has to be redone and this is both time consuming and tedious. In this paper a new approach will be presented that enables discrete event simulation models to be generated automatically. The models are generated from information retrieved from a PLM/PDM database system, which is shared among other engineering tools such as robot simulation, CAD and process planning. Hence, when the cell and the database are updated a new model can easily be generated. The database is also connected to the real cell so up-to-date data can be retrieved from the real cell. The model generator described in this paper was implemented and tested in a discrete event system simulation tool and showed promising results. With this approach it is possible to handle flexible automation cells more effectively in a process planning stage.

  • 161.
    Carlsson, Henrik
    et al.
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Svensson, Bo
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Danielsson, Fredrik
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    A General Virtual Manufacturing Concept for Programming, Verification and Optimisation of Complex Control Functions2008In: Proceedings of the 18th International Conference on Flexible Automation and Intelligent Manufacturing, FAIM 2008: June 30th - July 2nd, 2008, University of Skövde, Sweden / [ed] Leo J. de Vin, Skövde, 2008, p. 668-675Conference paper (Refereed)
    Abstract [en]

    This paper describes a general virtual manufacturing concept for industrial control systems. Our virtual manufacturing concept provides a distinct advantage; programming, verification and optimisation of complex real-time dependent control functions described by real control code, which can be directly transferred to the real manufacturing system. To achieve this distinct advantage, a time synchronised virtual manufacturing system is a necessity. The aim of this paper is thus to present and to describe in detail, our proposed virtual manufacturing concept. To the authors’ knowledge no such general virtual manufacturing concept, i.e. one that can correctly handle complex real-time dependent control functions, currently exists. To summarise previous work related to virtual manufacturing and industrial control systems, several critical issues have been identified. The virtual manufacturing concept proposed in this paper addresses these issues. To verify that our concept can manage these critical issues found and further is suitable in industrial applications a virtual manufacturing test case is also presented. The test case, that includes motion control (i.e. servo), complex control functions, real control systems etc., was carried out with success.

  • 162.
    Carlsson, Henrik
    et al.
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Svensson, Bo
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Danielsson, Fredrik
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Lennartson, Bengt
    Chalmers University of Technology, Department of Signals and Systems.
    Methods for Reliable Simulation-Based PLC Code Verification2012In: IEEE Transactions on Industrial Informatics, ISSN 1551-3203, E-ISSN 1941-0050, ISSN 1551-3203, Vol. 8, no 2, p. 267-278Article in journal (Refereed)
    Abstract [en]

    Simulation based PLC code verification is a part of virtual commissioning, where the control code is verified against a virtual prototype of an application. With today’s general OPC interface it is easy to connect a PLC to a simulation tool for e.g. verification purposes. However, there are some problems with this approach that can lead to an unreliable verification result. In this paper, four major problems with the OPC interface are described, and two possible solutions to the problems are presented: a general IEC 61131-3 based software solution, and a new OPC standard solution

  • 163.
    Carlsson, Konrad
    et al.
    University West, Department of Engineering Science.
    Bertauskas, Lukas
    University West, Department of Engineering Science.
    An analysis of agentless automation tools and their suitability for network device management2022Independent thesis Basic level (university diploma), 5 credits / 7,5 HE creditsStudent thesis
    Abstract [en]

    The overall focus of this paper is to identify the more suitable agentless automation tool for network automation, here we compare Puppet Bolt and Ansible, which are both rather popular in the networking world. But which one is actually more suitable from the perspective of installation, initial setup, user friendliness and suitability for networking device configuration? This is the question that is answered here. During the writing of this paper, we have both invested several hours of our time in learning these tools, documenting our experiences and using this experience in constructing this paper while staying highly objective. During the testing phase of this paper, a decision was made to push NTP server configurations to the target devices (Cisco routers). This configuration consists of an IP address of an NTP server for the hosts to use as their source for time calibrations. All necessary changes were made to make the tools functional. Playbooks/Manifests were created to be as similaras possible to each other to make this paper as objective as possible. The same type of modules were used in the creation of these Playbooks/Manifests, again to make the comparison as objective as possible. The only difference between these configuration files was the language in which they were written (XML for Bolt and YAML for Ansible). Their purpose was the same.Installation and user-friendliness was also compared during the testing phase. Ansible turned out to be the most user friendly tool with the best online support, easiest configuration and the snappiest operation. 

  • 164.
    Carlsson, Mattias
    University West, Department of Engineering Science, Division of Computer, Electrical and Surveying Engineering.
    Systemanalys av eldistributionssystem på Preemraff Göteborg2017Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    On behalf of the technology department at Preemraff, a system analysis of the electrical distribution system has been performed. The work consists of two parts, and its main purpose is to give a better knowledge of the plants status. In the first part, a model of the refinery’s electrical distribution system is built in a program for network analysis. The model is intended to help Preemraff’s technology department in both the daily operation but also for expansion projects and changes in the electrical distribution system. In the second part of the work, an analysis of a limited part of the plant is performed. The analysis consists of verification of short-circuit currents, selectivity and simulation of voltage drop during start of electrical motors. A rough check of free capacity in respective part of the plant is also performed.

    Theory to give the reader understanding of the various components function and mutual interaction is presented. Existing standards and their calculation methods are discussed. Additional attention is paid to calculation of short-circuits. The technical configuration of the electrical plant is introduced, followed by a description of the modelling with respect to suppositions and some special cases.

    The results show that the short-circuit currents are in an acceptable level in most part of the plant. In one switchgear, the short-circuit current are somewhat exceeded. Start of electrical engines does not contribute to a voltage drop above acceptable levels in the part of the plant that was investigated. With respect to selectivity the plant has the potential to achieve selective disconnection at most of the investigated points. It is shown that the present operation mode, with switched on breakers between the switchgears A- and B-side prevent selective disconnection. The selectivity analysis is performed with the premise that A- and B-side is sectioned. With those premises, it shows that some adjustment is needed to achieve good selectivity.

    The electric distribution system is mainly constructed to permit redundancy for the n-1 criteria. The results show that a few switchgears are loaded to the point that their transformers will be overloaded with a single transformer fault.

    At the end of the report, proposal on operation diversions that is considered to optimize the plant is given. Suggestions on investments that would improve the plant in an energy term perspective is also given.

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  • 165.
    Carse, Eddie
    et al.
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Garsallawi, Naman
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Wennström-Juslin, Christina
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Förslag till övervakningslösning med värmekameror för Magnetgärdets transformatorstation2010Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The substation called Magnetgärdet is located in Ludvika, Sweden and it is owned by Västerbergslagens Energi AB. The substation has recently been renovated and is now placed indoors, which reduces the influence of weather on the station. To decrease the need for personal supervision and increase the availability of the station a monitoring solution is needed.

    The purpose of this degree thesis is to examine if it is possible to monitor the condition of critical items in the station with infrared cameras. To determine this, theory on condition monitoring, thermography and thermal imaging cameras has been compiled together with relevant measurements and tests. The results are then discussed to see if a possible solution can be presented. Important criteria for making condition monitoring with infrared cameras possible have also been formulated in this degree thesis.

    The conclusion is that it is possible, but a complicated system is required. The solution we have given is based on different parts interplaying with each other and it should become a powerful monitoring system. It is however uncertain whether infrared cameras are the only and best tools, therefore other tools should be considered. It might be possible to use thermistors with, or instead of infrared cameras.

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  • 166.
    Celaschi, Minna
    University West, Department of Engineering Science.
    En energiutredning av värmekabelför frostskydd2009Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Denna rapport behandlar en energiundersökning av värmekablar på uppdrag av INEOS ChlorVinyls anläggning i Stenungsund. Eftersom miljön får en större och större betydelse i dagens samhälle försöker alla sektorer i samhället minska sin energiförbrukning. År 2006 använde svensk industri 157 TWh energi och 35,8 % av detta var elenergi. Den kemiska industrin står för 8 % (2006) av Sveriges industriers energiförbrukning och räknas som en energiintensiv bransch. Fabriken i Stenungsund har länge haft ett mycket förmånligt elavtal vilket har gjort att de inte har varit lönsamt att bry sig om att göra relativt småskaliga effektiviseringar. Men nu med ökade energipriser är det aktuellt att titta på vad som kan göras och till vilket pris. Syftet med utredningen är att undersöka om ett annorlunda upplägg av termostaterna som styr värmekablarna gör att man kan spara energi genom att värmen bara ligger på när det verkligen behövs. Genom undersökning och jämförelse av olika termostater koms det fram till att det inte finns noggrannare termostater på marknaden än de som sitter i fabriken. Termostaten till VKB14 är dock felvald. Med hjälp av temperaturstatistik och ett medelvärde av antal timmar under en viss temperatur över de två vintersäsongerna har effektåtgången för VKA14 och VKB14 räknats ut. Genom mätningen av när kontaktorn slår till i VKB14 har det utlästs att detta skåp ligger till 38 % av tiden när temperaturen i intervallet är så hög att det inte borde vara till alls. Om man utgår från att skåpet gör av med 20 000 W när det är igång i onödan, ger detta att det förbrukar 1,3 gånger mer energi per år än vad som behövs vid en temperaturinställning på +5°C.

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  • 167.
    Chacko, Vishal
    University West, Department of Engineering Science.
    Developing an Offline program for a weld path of a CAD model for a Friction Stir Welding robot: Feedback control system to reduce defects in material flow2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This study aimed to make a specific type of welding, called Friction Stir Welding (FSW), better when welding along curved paths using offline programming. The goal was to reduce two common problems: metal ejection and flashing. Welding along curves might become difficult due to friction, overheating, and down-pressure can cause these issues. The study wanted to find ways to make the welding process smoother and prevent these problems along the curve. To tackle this challenge, the study tried different methods by changing theparameters such as welding speed, tool speed, and force applied. The goal was to find the best combination of settings to reduce metal ejection and flashing.The experiments showed that making some changes to the welding parameter by monitoring the changing path in feedback. By adjusting the force and speed at specific points, the welding process becomes better and good quality. This meant the metal stayed in place and didn't fly out as much. However, the study also found that changing one thing could sometimes cause other problems. For example, adjusting the force could make the robot less stable. So, finding the right balance was important.In the future, using sensors and smart computer programs could help make welding along curves even better. These technologies can keep an eye on the welding process and make quick adjustments to prevent problems. In conclusion, this study worked on making curved welding better by changing welding parameter settings. It found that small changes can make a big difference in reducing metal ejection and flashing. The study also showed that new technologies could make curved welding even smoother and more reliable in the future.

  • 168.
    Chakina, Marina
    University West, Department of Engineering Science, Division of Production Systems.
    The future optimal sensor system for the industrial Autonomous Mobile Robotics (AMR)2021Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Sensor systems of industrial Autonomous Mobile Robots (ARM) constitute the main part of its information and measurement systems. The purpose of these systems is to form and provide information about the state of objects and processes in the environment and about the robot itself. This information is required for the functioning of the robot.

    A sensitive device or a sensor is a primary transducer that reacts to the value to be detected (temperature, pressure, displacement, current, etc.) and converts it into another value, convenient for further use, giving a signal about its presence and intensity. This signal can be of any physical nature, determined by the principle of operation of the sensitive device. It is preferable that it is electrical, since most technical systems in which it will be used are electrical. However, there are systems of a different nature, for example, completely pneumatic, designed to work in conditions that do not allow electricity. In these cases, signals of a different nature must be used.

    Requirements for sensor systems substantially depend on the level of the control system at which their information is used. Sensor systems used at control levels operating in real time should have the highest performance, with the inevitable simplification of this information. On the contrary, at the strategic level of controlling the behaviour of the robot, the most complete information is required, possibly to the detriment of performance.

    Robotics is a complex and fascinating method for investigation of the surrounding space. A profound moment within the history of most robotics is that the expected value a robot performed a task below the influence of software package or electronics.

    This work is devoted to the study of the possibilities of modernization and improvement of the navigation system of mobile robots in order to move in a space with obstacles. The research was carried out at the Industrial In-novation Arena in Skövde (Sweden).

    The aim of the work is to develop the most sensitive sensor system of the robot to ensure easy movement in space with movable and fixed obstacles.

    In this report, two methods will be used, the main method - Ullmans method and the evaluation method to select the optimal solution - Quality function deployment (QFD) method.

    Based on the QFD, it was concluded that the most optimal is to use Simultaneous Localization and Mapping method (SLAM). For a more accurate result, further research in the laboratory will be required.

  • 169.
    Changala, Mayani
    University West, Department of Engineering Science, Division of Computer and Electrical Engineering.
    Investigation of power quality in the auxiliary and distribution networks at Kafue Gorge Power Station in Zambia2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Zambia Electrical Supply Company (ZESCO) Limited has partly replaced electrical components from analogue to digital in the auxiliary system at Kafue Gorge Power Station. Later, it was discovered that there was an increase in component breakdowns in the parts of the monitoring system connected to the auxiliary system. The company seeks baseline data for Power Quality to help determine the cause of these frequent breakdowns.

    Unilyser 902 and PQ Secure were used to monitor and analyse the power quality outlook in both the auxiliary and distribution systems. Data was collected on 3 deferent points of the systems. These points were different both in space and electrically and were connected to loads with different electricalcharacteristics. There were inconsistences in the data collection procession such as deferent lengths in times of motoring per point and difficulties in reaching one of the pre-selected points. Furthermore, the monitoring instrument could not be correctly configured because a correct IP address could not be obtained. This led to inconsistencies in data collection such as failure to obtain certain power quality parameter readings. No particular power quality issues could be pin pointed in the system that could be linked to the problem at the station. However, due to the above mentioned challenges in the data collection process, these results were inconclusive for the purpose of the study. The results arrived at cannot serve as baseline data for trouble shooting the system. More concrete and updated monitoring of power quality is needed to draw conclusion about the wellbeing of the system from the power quality point of view.

    In view of the above, it was recommended that permanent power quality monitors are more suitable tools for the purpose as they give more updated data. The updated data can be relied upon and compared with other points monitored at the same time and this gives a more fair understanding of instantaneous and non-repetitive events in the power system

  • 170.
    Chapuzet, Nathan
    University West, Department of Engineering Science, Division of Production Systems.
    The implementation of digital solutions in factories: How to facilitate the implementation of digital solution, such as supervision, with different old PLCs and devices using different communication protocols2021Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Nowadays companies aim to become more and more competitive. More production with less wastes of time, energy, matter is the aim of these new tools which are composing the industry 4.0. This new era of digitalization has already started.This paper will present the technologies and concepts necessary to understand the setting up of a digital solution, and its implementation in a factory which would have evolved step by step, by enlarging and creating new sections, with different PLCs.

     It will be explained how the different communication protocols, due to the different brands of PLCs, are creating problems in the communication when it is about implementing a digital solution. It will also propose several potential solutions, and several solutions will be proposed and compared. Also, the reasons of the chosen final solution will be explained. These results have been obtained by consulting several studies concerning the new technologies about industry 4.0, but also by going directly on the field, to notice the problems and applicable solution beyond the theoretical aspect. Interviews on several occasions with the actual leader of the market for the implementation of digital solution is composing a solid and precious testimony about what could be done to implement such solutions for now. Indeed, papers are presenting technologies which could be developed, or already existing, as the one which will revolutionize the interconnectivity, but it seems that this is for a near future, while the actual reality seems to be different. The final decision which has been taken will be explained regarding the methodology followed to solve the problem. It will be presented that a solution which is more appealing is not always the optimal solution, depending of the company configuration, needs and long term goal. This document will present the explaining why and how to determine the corresponding solution for a specific company.

  • 171.
    Charles Murgau, Corinne
    et al.
    University West, Department of Engineering Science, Division of Production Engineering.
    Pederson, R.
    Luleå University of Technology, Division of Material Science.
    Lindgren, L. E.
    Luleå University of Technology, Division of Material Mechanics.
    A model for Ti-6Al-4V microstructure evolution for arbitrary temperature changes2012In: Modelling and Simulation in Materials Science and Engineering, ISSN 0965-0393, E-ISSN 1361-651X, Vol. 20, no 5, p. 055006-Article in journal (Refereed)
    Abstract [en]

    This paper presents a microstructure model for the titanium alloy Ti-6Al-4V designed to be used in coupled thermo-metallurgical-mechanical simulations of, e.g., welding processes. The microstructure evolution is increasingly taken into consideration in analyses of manufacturing processes since it directly affects the mechanical properties. Thermally driven phase evolutions are accounted for in the model. A state variable approach is adopted to represent the microstructure with the objective to integrate the microstructure changes with a thermomechanical model of manufacturing process simulation such as welding. The model is calibrated using the literature data and also validated against a cyclic temperature history during multi-pass welding.

  • 172.
    Chavez Andersson, Carina
    et al.
    University West, Department of Engineering Science, Division of Industrial Engineering and Management, Electrical- and Mechanical Engineering.
    Jacobsen, Sofie
    University West, Department of Engineering Science, Division of Industrial Engineering and Management, Electrical- and Mechanical Engineering.
    Effektivisering av ärenden för anslutning av solcellsanläggningar2022Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The department of grid connections at Vattenfall Eldistribution AB currently has a large number of cases regarding connection of solar panels to the power grid. These cases may require rebuilding on the power grid, this process has a delay today due to, for example, a high influx of cases, time-consuming customer contact and that the case may need to be reviewed by several departments. This delay creates dissatisfied customers and puts pressure on the administrators. 

    The intention of this master thesis is to develop a working method that the administrators can use for inquiries regarding connection of solar panels before the rebuilding is concluded.This is to shorten the time that it takes for a case to go from a request to a connected solar panel. The results show suggestions about improvements of the current working method. During the interviews in the thesis, obstacles were found in the current work process that provided inspiration for further solution proposals in the processing process.

    A proposal to achieve a more unitary way of working in case management is to introduce a strict interval for the result of dimensioning calculation. This also entails a reduction in departments that are involved in the case process as not as large rebuilds may need to be made and at best avoided completely.

    The administrators today have a close customer contact which takes up much of their working time when customers demand an update in their case. A proposal to reduce the time-consuming customer contact is to create a page under My page on Vattenfall Eldistribution´s website. The update page shall inform the customer about the case process with a time aspect and present the stage in which customer’s case is.

    In order to avoid rebuilds because of additional power in the power grid, a solution may be to procure batteries as a substation. However, Vattenfall Eldistribution does not present anything about this on their website. One proposal is to set up an information page aboutsubstations and how customers should proceed to arrange it

  • 173.
    Chavier, Emmanuel
    University West, Department of Technology, Mathematics and Computer Science, Division for Mechanical Engineering.
    Investigations of POSEYE: a photogrammetry position measuring system2005Report (Other (popular science, discussion, etc.))
    Abstract [en]

    In this report, we present a photogrammetric system that can be used during welding operation with a robot. It should be able to give the position and the orientation of the Tool Center Point with a high accuracy (less than 0.5 mm). After a view on the historic of PosEye®, we describe its two different ways of working: using active or passive markers. We then explain one way to improve the accuracy of the sensor by taking in account the distortion of the image due to the projection. This part is followed by investigations on a so-called “flash collar” which permits to fix diodes when we use passive markers. We finish by some tests to have a better idea of the accuracy of the sensor. This accuracy is only available for the position, as it has been realized on a Coordinate Measuring Machine which is only able to give information on its position.

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  • 174.
    Chmeis, Ali
    et al.
    University West, Department of Engineering Science, Division of Computer, Electrical and Surveying Engineering.
    Halaoui, Mahmoud
    University West, Department of Engineering Science, Division of Computer, Electrical and Surveying Engineering.
    Modernisering av belysningsanläggning för kontorslokal2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Lighting is a big need in our daily lives. In recent years, the field of lighting has achieved significant improvements in energy consumption, brightness, environmental aspects and the lifetime of light sources. The outdated lighting systems are phasing out and are now being replaced by LED lamps.

    The thesis is based on establishing a more energy efficient lighting installation for an office premises in Gothenburg that has an area of 220 sq.m. and consists of 12 rooms. The work has been carried out with the entrepreneur Ljusproffsen Future Group Svenska AB, which has received a request from the customer to upgrade the lighting system to LED. The replacement to LED aims to contribute to a financial saving for the customer.

    An inventory for all light sources in the office premises has been established with a calculation of the total energy consumed. After that, a new lighting layout has been proposed using the DIALux evo lighting calculation program and the reduced energy consumption that can be achieved. The LED illumination covers all the requirements of the Occupational Safety and Health Act regarding workplaces and offices.

    The energy consumption has been reduced from approximately 2844W to 1581W. This corresponds to a decrease of 44%. The annual energy consumption is estimated at 6 324kWh based on 4000 hours of lighting each year. The life of the LED installation is 50,000 hours for the selected luminaires compared to the previous ones which have a lifespan of 20,000 hours. LED lights have proved to be a good choice for saving energy. The total luminaire light flow for the premises has increased with 21 000lm.

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  • 175.
    Choquet, Isabelle
    et al.
    University West, Department of Technology, Mathematics and Computer Science, Division for Mechanical Engineering.
    Javidi-Shirvan, Alireza
    University West, Department of Engineering Science, Division of Mechanical Engineering.
    Nilsson, Håkan
    Chalmers University of Technology, Department of Applied Mechanics, .
    Magnetic field models for high intensity arcs, applied to welding: A comparison between three different formulations2013In: ASM Proceedings of the International Conference: Trends in Welding Research 2013, Chicago, IL: ASM International, 2013, p. 876-885Conference paper (Refereed)
    Abstract [en]

    Most simulation studies done to deeper understand high-intensity welding arcs address axi-symmetric configurations and use the electric potential formulation. This formulation involves the assumption of a one-dimensional magnetic field. The assumption is justified in its original frame: rather long arcs (about 10 mm), and when the electrode tip is excluded from the computational domain. However, arcs applied to welding are shorter, and the electrode geometry is important to take into account. The present work questions the assumption of a one-dimensional magnetic field for simulating short welding arcs. We have compared three different approaches for modeling the magnetic field: three-dimensional, two-dimensional axi-symmetric, and the electric potential formulation. These models have been applied to water cooled anode Gas Tungsten Arc Welding (GTAW) test cases with truncated conical electrode tip (tip radius of 0.5 and 0.2 mm) and various arc lengths (2, 3 and 5 mm). For the axi-symmetric cases studied in the present work, the three- and two-dimensional models give exactly the same results. The one-dimensional simplification of the magnetic field turns out to have a significant unfavorable effect on the simulation results. For axi-symmetric welding applications, it is argued that the two-dimensional axi-symmetric formulation should be used. Copyright © 2013 ASM International® All rights reserved.

  • 176.
    Christensen, Johan
    et al.
    University West, Department of Engineering Science, Division of Computer, Electrical and Surveying Engineering.
    Lund, Hannes
    University West, Department of Engineering Science, Division of Computer, Electrical and Surveying Engineering.
    Undersökning av objektorienterad JavaScript i praktiken2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Javascript is a well-used programming language that is mostly used in web development. The development in javascript is not that obvious though; this is because javascript differs from similar programming languages in many aspects. The purpose of this thesis is to ana-lyze javascript projects and find out if any kind of object-oriented javascript is applied, and also check for different design patterns used. The report's findings show that there are few projects that use most of the techniques of object-oriented javascript, and that only a few design patterns are used.

  • 177.
    Christensson, Johan
    et al.
    University West, Department of Engineering Science, Division of Industrial Engineering and Management, Electrical- and Mechanical Engineering.
    Jönsson, Tobias
    University West, Department of Engineering Science, Division of Industrial Engineering and Management, Electrical- and Mechanical Engineering.
    Beredningshandling för nytt bostadsområde i Sunningebergen2020Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis includes a project planning for the power grid distribution 0,4 / 10 kV in Sunningebergen, Uddevalla Kommun. Sunningebergen is an area outside the center of Uddevalla in Herrestad.

    The preparation in this report is a planning before finalizing the detailed plan for the area Sunningebergen. The preparation will be done by Uddevalla Kommun Elnät AB. The project includes a detailed plan developed by Uddevalla Kommun which contain facts about households and community services that will be in the area.

    The thesis gives an insight in power grid preparation and how the preparation of the area Sunningebergen will be. To fulfill the requirements, rules, and guidelines set by the electricity grid companies to maintain a good power quality to the costumers, a secure and stable electricity grid are in need

    In the report there is 0,4 / 10 kV maps over the area and it also includes a costing table. Sunningebergen will have a max capacity of 2040 kVA. The total capacity of the three transformer substations will be on 2400 kVA. This means that the area will have a load on 85% of max capacity. The high voltage grid has before the connection of Sunningebergen a peak load of 20 000 kVA as compared to the total capacity 36 000 kVA. There will be 2.2 km of transmission line. In the low voltage system, there will be fifty-two cabinets from ABB's CDC-series, 5,5 km feeder and 5,2 km of supply service line connection. The calculation for the preparation has been done with EBR's P1 calculation catalog. The total cost is estimated to be 6,1 million SEK.

  • 178.
    Christiansson, Anna-Karin
    University West, Department of Technology.
    A unified framework for mixed continuous/discrete-time H_infinity -control2003Doctoral thesis, monograph (Other academic)
  • 179.
    Christiansson, Anna-Karin
    et al.
    University West, Department of Engineering Science, Division of Production Engineering.
    Danielsson, Fredrik
    University West, Department of Engineering Science, Division of Production Engineering.
    Heralic, Almir
    University West, Department of Engineering Science, Division of Production Engineering.
    Ottosson, Mattias
    University West, Department of Engineering Science, Division of Production Engineering.
    Hurtig, Kjell
    University West, Department of Engineering Science, Division of Production Engineering.
    Automation of a robotised metal deposition system using laser melting of wire2008In: 18th International Conference on Flexible Automation and Intelligent Manufacturing (FAIM 2008): Skövde, 30 June-2 July, 2008, p. 122-129Conference paper (Other academic)
    Abstract [en]

    This paper presents a system for full automation of free-form-fabrication of fully dense metal structures using robotized laser melting of wire. The structure is built of beads of melted wire laid side by side and layer upon layer governed by synchronized robot motion. By full automation is here meant that the process starts with a product specification of a component, and ends in a geometrically validated dense metal component fulfilling industrial material requirements. Due to the complexity of this flexible manufacturing system, a number of different disciplines are involved. This paper discusses mainly the system design, which includes how off-line programming is used for automatic generation of code and how feedback control is used for on-line adjustment of parameters based on desired building properties. To meet industrial needs, the project is carried out in a close cooperation between research and development activities in academy and industry.

  • 180.
    Christiansson, Anna-Karin
    et al.
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Lennartson, B.
    Chalmers University of Technology, Control Engineering Lab, Göteborg, Sweden .
    Toivonen, H.
    Åbo Akademi University, Department of Chemical Engineering, Åbo, Finland.
    Mixed continuous/discrete-time output feedback H∞ control: A unified approach1999In: European Control Conference, ECC 1999 - Conference Proceedings, 1999, p. 4077-4082Conference paper (Refereed)
    Abstract [en]

    A Riccati equation (RE) based solution to the H∞ optimal control problem for mixed continuous/discrete-time systems is presented. The results unify a number of recently penetrated H∞ control problems. In the infinite-horizon case a periodic behaviour is assumed, and it is shown how the related continuous RE with jumps can be replaced by an equivalent discrete periodic RE. A related algebraic RE, which involves the system behaviour during one period, then can be formulated and solved by standard methods. Typical applications are control of continuous-time or discrete-time periodic systems, as well as multirate and sampled-data control, including mixed continuous and sampled-data measurements. © 1999 EUCA.

  • 181.
    Christiansson, Anna-Karin
    et al.
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Lennartson, Bengt
    Chalmers University of Technology, Control Engineering Lab, Göteborg, Sweden.
    Low order sampled-data H∞ control2003In: Decision and Control, 2003. Proceedings. 42nd IEEE Conference on, 2003, Vol. 3, p. 2308-2313 Vol.3Conference paper (Refereed)
    Abstract [en]

    A method for obtaining low order sampled-data H∞ controllers is presented. The method is mainly based on a parametric static feedback controller for a plant that is augmented with the controller dynamics. The design of a full-order controller is a convex problem, while the optimisation problem for lower order controllers is non convex. The proposed method starts with design of a full-order sampled-data controller using Riccati equations. Then this controller is reduced by an ordinary model reduction technique, and the reduced controller is used as an initial value for an iterative procedure using linear matrix inequalities (LMIs) in the search for an optimal controller. The matrix inequalities are in fact linear in either the Lyapunov matrix or the static controller matrix, why the solution to the non convex problem fundamentally is given by a bilinear matrix inequality (BMI). The order of the controller is reduced until the closed loop performance degrades too much. Simulations are shown for the control of a time delayed SISO-plant where the controller order can be reduced from 8th to 3rd order. Results are also shown from control of a MIMO-model of a jet engine where the reduction is successful from 15th to 4th order. It is argued that the non convexity is handled efficiently since the procedure uses a model reduction of the full-order controller as initial value.

  • 182.
    Christiansson, Anna-Karin
    et al.
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Lennartson, Bengt
    Chalmers University of Technology, Control Engineering Lab, SE-41 2 96 Goteborg, Sweden .
    Toivonen, H.
    Åbo Akademi University, Department of Chemical Engineering, FIN-20500 Abo, Finland .
    Continuous-, discrete- and sampled-data- H∞ˆž control - a unified framework2000In: IEEE Proceedings: Conference on Decision and Control (CDC), ISSN 0191-2216, Vol. 2, p. 1936-1941Article in journal (Refereed)
    Abstract [en]

    We present a unified and general framework for H∞-control in both continuous time, discrete time and combinations of these. The general result is a hybrid continuous-/discrete-time H∞ˆž-controller. Using a compact hybrid notation, the work shows a close relationship between the continuous-and discrete-time solutions. In fact, the pure continuous and discrete time equations may be obtained as two similar interpretations of the general result. There are no assumptions made on certain system matrices being zero or normalised, e.g. D11 = 0. The method is Riccati equation (RE) based, and it is shown how the continuous REs can be "lifted" into discrete ones reflecting the system behaviour during the period. Typical applications are control of continuous-time or discrete-time periodic systems, as well as multirate and sampled-data control, including mixed continuous and sampled-data measurements.

  • 183.
    Christiansson, Anna-Karin
    et al.
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Lennartson, Bengt
    Chalmers University of Technology, Control Engineering Lab, Göteborg, Sweden.
    Toivonen, H.T.
    Åbo Akademi University, Department of Chemical Engineering, Åbo, Finland..
    Sampled-data H∞ˆž-control for time-varying hybrid systems2001In: Dynamics of continuous, discrete and impulsive systems, ISSN 1201-3390, E-ISSN 1918-2538, Dynamics of Continuous, Discrete and Impulsive Systems Series B: Applications and Algorithms, ISSN 1492-8760, Vol. 8, no 4b, p. 427-444Article in journal (Refereed)
    Abstract [en]

    This paper presents sampled-data H∞ˆž-control of linear mixed continuous-time and discrete-time systems, including a mix of continuous-time and discrete-time performance signals and disturbances. However, neither continuous-time control signals nor continuous-time measurements are included. The sampling may well be multirate, i.e. different signals may be sampled by different rates, as long as a periodic pattern is repeated over the period, consisting of a number of sampling steps. In fact, the results are applicable even to arbitrary linear time-varying systems. The sampled-data system is discretised such that the continuous-time performance is reflected in the discretised or "lifted" system. This lifted system is combined with discrete-time updates at the sampling instants to achieve the sampled-data controller. The "hold-states" case is presented as a special application, when there is also a hold circuit at the controller output. The continuous-time Riccati equations with discrete-time updates then can be replaced by one discrete-time static feedback and filter Riccati equation respectively, which also reflect the intersample behaviour. Furthermore, convergence results between the discretised Riccati solutions and the corresponding continuous-time solutions are shown, when the sampling interval decreases towards zero. Simulations are shown when the results are applied to the control of a MIMO jet-engine model.

  • 184.
    Christiansson, Anna-Karin
    et al.
    University West, Department of Technology, Mathematics and Computer Science, Division for Electrical Engineering and Land Surveying.
    Ottosson, Mattias
    University West, Department of Technology, Mathematics and Computer Science, Division for Electrical Engineering and Land Surveying.
    Sensor and control system for metal deposition using robotised laser welding.2006In: 16th International Conference on Computer Technology in Welding and Manufacturing: Kiev, Ukraine, 2006, p. 328-332Conference paper (Refereed)
  • 185.
    Claesson, Niclas
    University West, Department of Engineering Science, Division of Automation Systems.
    Modernisering av montageanvisningar för utomhusställverk 40-400kV2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Since the construction of the main and regional power line networks in Sweden during the 1940-80s, the power lines and the outdoor switchgear have just been undergoing general management during this time. In the middle of the first decade in the 21 century, demand for the construction of new power lines and outdoor switchgear took place. This was mainly due to increased power consumption from customers and that society have become more energy intensive.

    This thesis deals with general operating instructions as to how the procedure for lifting steel and apparatus are done and how these are to be fixed in an outdoor switchgear. The thesis is also dealing with how to install power lines, mount clamps and conductors for apparatus. The work also focuses on procedures how to receive goods, self inspection of these and how to store them. The thesis also contains what safety equipment and tools might be needed for the job.

    The methods for how to build outdoor switchgear today and back in the days are mainly the same. Today you have more advanced tools like lasers which helps you measure distances more easily and is reducing the number of measures needed. With mobile work platforms and 4-wheelers today you can be more mobile than back in the days when you only had tractors and mobile cranes.

    With good planning and the use of risk analysis methods like FMEA "Failure Modes and Effects Analysis" before starting a work, you can minimize the work casualties and accidents dramatically. With FMEA you can evaluate the risks and prevent them before they happen. With standardized work and instructions you minimize work casualties and accidents since you have instructions to follow and would not risk to miss any important stage of the work that will cause injury or casualty. This will increase the safety and quality of the work. Toyotas principles can be used in most professions and not just the car industry. With more companies using standardized work you will increase safety and quality of work which will decrease the number of casualties and accidents for the people working.

  • 186.
    Colliander, Henrik
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Prestandajämförelse mellan WireGuard och OpenVPN med Raspberry Pi 32019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Historically, private communications between two remote offices were established by using a dedicated link, also known as a leased line.

    There are some huge drawbacks with this solution, the costs are often unreasonable when you want to maintain private communications between offices after expanding the company to different countries, thus the solution is only viable for large companies. Leased lines also have low flexibility and requires a lot of time and resources to install.

    A better solution to this problem is to make use of virtual private networks (VPNs). A VPN is a private network that is established over a public infrastructure between two nodes, such as the Internet. The virtual private network created between the nodes is called a tunnel where the payload often is entirely encrypted to ensure confidentiality.

    This study was made to compare the performance of two different open source VPN protocols, the older but reliable OpenVPN and a more recent one called WireGuard which has the goal to eventually replace OpenVPN and IPSec according to their website.

    Experiments were done in a lab environment using the two different VPN-solutions running on a Raspberry Pi 3 to evaluate and compare the performance by measuring throughput, packet loss, delay and jitter. The results showed that WireGuard had better performance overall compared to OpenVPN. However, considering WireGuard currently is in an early stage of development, implementations should mainly be used for personal use at your own risk. If you want to use an open source VPN protocol, OpenVPN is still an excellent choice and a reliable solution.

  • 187.
    Collin, Johannes
    et al.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Ljunggren, Robert
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Utvärdering av GENAB’s projektmodell inom elnät via kapitalbaskalkyl hänfört till nyckeltalet COP2021Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    To determine the efficiency of GENAB´s (Göteborg Energi Nät AB) project, the key figure COP (Capex OutPerformance) is used, which is a ratio between the capital that a project generates through standard values provided by the Energy Market Inspectorate and the project's total cost. If the value of the quota is 1.0, the project has generated as much capitalas it cost. If the COP number is above 1.0, the project generated more capital than it cost, and if the number is below 1.0, the project cost more than the generated capital. A COP number equal to 1.0 or above is desirable but this is not always possible. There are times when electricity network companies have to carry out projects despite the COP number being very low, it is mainly connection obligations that form the basis for executing these projects despite the low COP number. GENAB experiences uncertainty about assessments in the investment stage about how the outcome of the COP number will be for projects and wishes to supplement old projects with COP numbers and to provide a compelling indication of favorable project conditions. Based on processed results, the authors find indications that projects that contain capital base from all technical categories of low voltage, high voltage, control cables and station equipment are projects that are most likely to be profitable. The results also show that the affected rural projects that were included in the analysis are never profitable, while urban projects are most likely to be profitable. The authors wish to be able to give GENAB a generalization of the types of projects that are profitable and not, and thereby create the opportunity to optimize the investments made in the network.  

  • 188.
    Cámara Ortiz, Héctor Miguel
    University West, Department of Engineering Science, Division of Production Systems.
    Design of a PLC system for continuous beer fermentation control2020Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    With the intent of contributing to the research of alternative fermentation process of beer, a PLC-driven system was designed, programmed and simulated. The resultant system includes a user friendly HMI and a modular structure. The proposed configuration of modules includes two fermentor stages, four buffers and a clean-in-place module. The configuration proposed is intended to be capable of starting-up and controlling both primary and secondary fermentation in a continuous stationary state, as well as perform automated cleaning.

    The HMI allows the user to operate the system in seven different run modes. Initialization, Steady state, Batch mode, Change of beer style, Manual mode, Auto clean and, Settings control. Each run mode has different intended functions and enable or disable different elements in the system. The designed HMI also allows the user to continuously visualise and monitor all of the system variables, as well as customizing each of the programed PID temperature controls contained in each module.

    The proposed modular structure was embedded into the PLC programs, the HMI and the simulation. This structure was carefully designed to allow both the programmer and the user the flexibility to increase or decrease the amount of modules as well as their relative positions in the system with a few minor changes in code and a drag-and-drop action in the visualisations of the HMI.

    There is still much to learn about the continuous fermentation process before the technology is ready to become commercially available. However, the present work intends to provide an approach to address the practical complexity of controlling the process and allow researchers to iterate faster between experiments.

  • 189.
    Dafgård, Anton
    et al.
    University West, Department of Engineering Science.
    Junhav Land, Hugo
    University West, Department of Engineering Science.
    Förbättring av nätstruktur i området Forshälla.2023Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    When a lot of new construction occurs in an area, the power grid structure must be analyzed to ensure that the existing network can handle the new power demand. In Forshälla, summer cottages have been converted into permanent residences, new residential areas have been built along the coast, and households are installing solar panels and electric vehicle chargers in their homes. In this thesis, the 10 kV power grid for the Forshälla area will be analyzed, and a proposal will be developed for improvements to the power grid structure. The Forshälla distribution station will receives six new switching compartments, which will lead to more switching options in the area. Cable with an area of 50/95 mm2 is replaced with 150 mm2 cable to ensure a stable and reliable power supply for customers. Currently, the Forshälla area has 2447 customers distributed over 1889 connection points, with 843 of the customers residing in urban areas and 1604 people in rural areas. There are a total of 128 substations, 116,5 km of 10 kV medium voltage cable, and 265,8 km of 0,4 kV power cable within the area. In the development of results and methodology, the energy companies planning, and preparation handbook has been used to plan and structure the work as efficiently as possible. The authors proposal for the new power grid structure includes laying 19,36 km of new medium voltage cable, of which 3,5 km is replaced power lines and the remaining is replaced underground cable. Two of the six new switching compartments in the distribution station are used to balance load currents and create more switching options in the network. Five junction boxes have been demolished, five network and two series satellite stations will be built. The maximum voltage drop decreases from 5,50 % to 3,30 % during normal operation. The total cost for the proposed new power grid structure is approximately 7,7 Mkr. Calculations regarding slow voltage changes that occur when connecting solar cells meet the requirements of ±10 % imposed by EIFS 2013:1. Conductor impedances for the solar power systems were neglected in the calculations, which may cause the actual value to deviate slightly from the results presented in the report.  

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  • 190.
    Daher, Amir
    et al.
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Nadjati-Yazdi, Artin
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Optimization of warehouse logic and structure2021Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Products flow in and out of different warehouses all over the world every day all the time, while the technology is improving, warehouses remain as they are unless major developments occur in the industry which require the modern warehouses to follow. Major changes in warehouses cost a fortune for the companies which require the owners to find changes that cost as little as possible while resulting in as high efficiency in the warehouse as possible. The purpose of this project is to find ways to optimize the current logic in the Warehouse Management System named Warehouse Administration Service System or WASS. By analyzing the WASS-systems database, reading the WASS-manual, creating tools to visualize the warehouse both theoretically and practically, interviewing workers, then shortcomings and optimizations can be found. The resultis that the current logic in the warehouse is very unoptimized by analysing the warehouse with the help of visualizing the warehouse and feedback from an interview. Improvements are suggested from analysing the heatmap and through visualizing the issues the improvements can be implemented. By creating a visualization of the optimal structure which can be used as areference for implementing a better structure in the actual production. The visualization tool and the heatmaps can help future warehouses that log goods inwards and outwards find shortcomings in their A,B,C-structure and improve their warehouse logic.

  • 191.
    Danielsson, Fredrik
    University West, Department of Technology, Mathematics and Computer Science.
    Off-line programming, verification and optimisation of industrial control systems2002Doctoral thesis, monograph (Other academic)
  • 192.
    Danielsson, Fredrik
    et al.
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Haijun, Xing
    University West.
    Svensson, Bo
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    A Simulation-Based Optimization Approach for Holonic Manufacturing Systems2012In: Flexible Automation and Intelligent Manufacturing, FAIM 2012: Helsinki, 10-13 June / [ed] Hasse Nylund, Satu Kantti, Ville Toivonen, Seppo Torvinen, Tampere University, Finland: Tampere University of Technology, 2012, p. 515-522Conference paper (Refereed)
    Abstract [en]

    Holonic Manufacturing System (HMS) is an integrated multi-agent technology that represents the developing direction in the automation field. HMS can be represented as a non-hierarchical manufacturing architecture with no or limited supervision. However, it is a challenge for a single holon in a non-hierarchical system to make globally optimal decisions. This paper presents a simulation-based optimization method for HMS by introducing a new wizard holon. A wizard holon collects the necessary information from the entire HMS and uses Discrete Event System (DES) simulation to evaluate the cost of different decisions. Since a non-hierarchical approach is used the wizard input is only treated as an advice to achieve more globally optimal decisions. The decisions are still taken by the local holon. Even for an experienced operator it might be hard to predict the outcome of a decision in a critical situation. Hence, wizard advices are valuable for all types holons, including machines, robots, and operators.

  • 193.
    Danielsson, Fredrik
    et al.
    University West, Department of Technology, Mathematics and Computer Science.
    Hansbo, Anita
    University West, Department of Technology, Mathematics and Computer Science.
    Control system verification by emulation: an application to off-line pressline throughput rate orpimization2002In: Journal of Advanced Manufacturing Systems, ISSN 0219-6867, E-ISSN 1793-6896, Vol. 1, no 2, p. 159-172Article in journal (Refereed)
    Abstract [en]

    This study is part of a research project aims at off-line programming and verification of industrial control systems. In this paper, an off-line method for press line throughput rate optimization and control system verification is proposed, implemented and evaluated. The main tool is a virtual press station, developed by the first author, consisting of an emulated control system for a feeder/extractor robot which communicates with 3D-simulated production equipment. Moreover, several virtual press stations have been coupled and synchronized in a virtual press line. An important feature of the system is that the virtual robot controller is emulated, yielding an exact representation of the control logic and the possibility to run the entire system in virtual real time. The application considered is a sheet metal forming process where it is difficult to achieve maximum capacity utilization. There is much to gain if the control logic is improved and the throughput rate is increased. For this purpose, an automated robot motion optimization method is implemented and evaluated, using the virtual press line.

  • 194.
    Danielsson, Fredrik
    et al.
    University West, Department of Technology, Mathematics and Computer Science.
    Moore, P
    Eriksson, P
    Validation, off-line programming and optimisation of industrial control logic2003In: Mechatronics (Oxford), ISSN 0957-4158, E-ISSN 1873-4006, Vol. 13, no 6, p. 571-585Article in journal (Refereed)
    Abstract [en]

    This article proposes a classification of different methods for validation, off-line programming and optimisation of control logic. The classification is an overview of different methods available and includes advantages and disadvantages for each method. The method overview points out a superior method, control system emulation, which is the most cost-effective and flexible method. The control system emulation method is also general and may be applied to validate and optimise control logic in various applications. Further, the method is compared with several other methods for validation of industrial control systems. However the method requires a standardised system architecture. This article proposes such architecture for the control system emulation method. Here, a control system emulator has also been implemented with the specific system architecture described in this article. An application case is also provided to demonstrate an approach to the integration of a control system emulator into a virtual manufacturing system.

  • 195.
    Danielsson, Fredrik
    et al.
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Svensson, Bo
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Flexible Robotized Automation in Manufacturing Systems2011In: The 21st International Conference on Flexible Automation and Intelligent Manufacturing: Taiwan, 26-29 June 2011, 2011, p. 207-214Conference paper (Refereed)
    Abstract [en]

    Due to constant changes in the market there is a need for low-cost and low-volume manufacturing. Usually this type of production is difficult to automate due to the time it takes to become profitable and the inflexibility of such solutions. Therefore, flexible automation solutions need to be addressed together with cost effective aspects. In this paper, a new concept for the design of a flexible, robotized solution based on lean automation is presented and simulated. The proposed lean automation concept is formed of standardized robot stations, human-robot collaboration and cost effective level of automation. The main goals are flexible automated production system and reduced production cost. This paper shows that the proposed flexible lean automation concept has some key advantages compared to the traditional robot cells; a longer lifetime for the robot cell as well as being easier to re-balance, introduce new parts to and expand the cell. Further, it also shows that the proposed concept reduces the cost for automation of products with low volume.

  • 196.
    Danielsson, Fredrik
    et al.
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Svensson, Bo
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    He, Jun
    University West.
    Integration of humans into a multi-agent system2013In: ESM'2013 The 2013 European Simulation and Modelling Conference / [ed] Stephan Onggo and Antonin Kavicka, Ostend, Belgien: EUROSIS-ETI Publication , 2013, p. 257-259Conference paper (Refereed)
    Abstract [en]

    The aim of this paper is to describe on-going work in the integration of humans in automated manufacturing systems. The intention is to achieve a flexible manufacturing system to meet the rapid developing and changing of today’s industry. The approach is based on a control concept with multi-agents. Humans, which are considered as a valuable factor in industrial production, are proposed as flexible agent resources for the automated manufacturing system.

    A test case was performed on a manufacturing system where three different groups of humans where integrated in the system; inspection, carrier and recovery. The P-SOP agent generator was used to automatically generate IEC 61131-3 PLC control code for the system.

  • 197.
    Danielsson, Fredrik
    et al.
    University West, Department of Engineering Science, Division of Automation Systems.
    Svensson, Bo
    University West, Department of Engineering Science, Division of Automation Systems.
    Reddy, Dhanush
    University West, Department of Engineering Science, Division of Automation Systems.
    A genetic algorithm with shuffle for job shop scheduling problems2015In: Modelling and simulation 2015: The European simulation and modelling conference 2015, ESM 2015, October 26-28 Leicester, United Kingdom / [ed] Marwan Al-Akaidi & Aladdin Ayesh, Ostend: ESM , 2015, p. 363-367Conference paper (Refereed)
    Abstract [en]

    Job shop scheduling problems are computationally complex combinatorial optimization problems. Genetic algorithms have been used in various forms and in combination with other algorithms to solve job shop scheduling problems. A partially flexible job shop with precedence constraints increases this complex behaviour. There are two main parts to optimizing ajob shop, the routing and the scheduling. The objective here is to get consistent optimal makespan using a genetic algorithm. This paper firstly, presents a simulation approach for the considered partially flexible job shop scheduling problem. Which take into account the precedence constraints and reduce situations of deadlock. To solve the partially flexible job shop scheduling problem a genetic algorithm was used and improved. It utilise a genetic crossovers for routing and a new random shuffle feature is introduced for the scheduling. The computational results have shown that the algorithm performs well in terms of finding a consistent optimal schedule for the given problem

  • 198.
    Danyang, Cui
    et al.
    University West, Department of Engineering Science, Division of Industrial Engineering and Management, Electrical- and Mechanical Engineering. Department of Electrical Engineering Uppsala University Uppsala; Department of Engineering Science, University West, Trollhättan (SWE).
    Max, Lena
    University West, Department of Engineering Science, Division of Industrial Engineering and Management, Electrical- and Mechanical Engineering.
    Boström, Cecilia
    Department of Electrical Engineering Uppsala University Uppsala (SWE).
    Ekergård, Boel
    University West, Department of Engineering Science, Division of Industrial Engineering and Management, Electrical- and Mechanical Engineering.
    Design of Spoke Type Traction Motor with Ferrite Material for EV Application2022In: 2022 International Conference on Electrical Machines (ICEM): Proceedings 5-8 Sept. 2022, Institute of Electrical and Electronics Engineers (IEEE), 2022, p. 315-320Conference paper (Refereed)
    Abstract [en]

    Motor design for electric vehicle application using non-rare-earth permanent magnetic materials has become a research hotspot due to cost reduction and environmental issues. Among different motor topologies, permanent magnet synchronous motor (PMSM) with spoke-type ferrite magnets has great potential because of its competitive performance. In this paper, a novel design of a spoke-type synchronous motor using ferrite Y40 and non-magnetic steel material is presented, with optimizations on the overall structure and considerations on the effects of pole numbers. The performance of the designed motor verified with magnetic simulations shows that it has a high probability to be a candidate for replacing the conventional PMSM with rare-earth materials in Electric Vehicles (EV) application. © 2022 IEEE.

  • 199.
    Darefelt, Kristina
    et al.
    University West, Department of Engineering Science, Division of Industrial Engineering and Management, Electrical- and Mechanical Engineering.
    Vidén, Filip
    University West, Department of Engineering Science, Division of Industrial Engineering and Management, Electrical- and Mechanical Engineering.
    Projekthantering hos Vattenfall Eldistribution AB jämfört med andra nätbolag2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis work has been carried out on behalf of Vattenfall Eldistribution AB. The purpose of the work was to evaluate the improvement potential of the design process in the optimization department, with the aim of being able to provide suggestions for improvement of the process which ultimately can lead to a more efficient project flow. It is perceived in the department that there are non-value-creating activities at work that should be reviewed. In order to gain a deeper understanding of the process, the group has performed a network design according to the working process. The purpose of the work was to increase the electrical quality of the abonnee fields. Upon completion of the project, electricity quality could be increased for all customers in the area. For all subscribers except for one were the agreed limit values was within Vattenfall's guidelines. To make a comparison with other ways of working, a study inspired by benchmarking has been conducted at different network companies. Based on the analysis, data has been collected through qualitative interviews. The interviews have been recorded and transcribed. The material has since been sorted and analyzed using a qualitative data matrix. Following the interviews conducted, it was found that the working methods of the various companies largely resemble each other. However, some differences in the performance and view of economic calculations and key ratios could be observed. Differences can also be seen in the size of initiated projects. All participants in the benchmarking study stated that they overall are satisfied with the work process. Analysis of the collected material showed that for some aspects of the work process there is an improvement potential. After completion of work, the conclusion could be drawn that there are some elements in the process that contribute to non-value creation. This has been shown in the form of activities in which any form of forced interruption occurs in the process. Improving or eliminating these steps should provide a more efficient workflow. The management of calculations and key ratios is one of these factors. Proposals were made to clarify the information about the purpose and use of these for employees. Even the shortcomings found in the design tools can contribute to a slower process flow. For these, no proposals for improvement could have been provided, but it was still considered important to emphasize these inadequacies.  

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  • 200.
    Darefelt, Sofia
    University West, Department of Engineering Science.
    Resistiva nollföljdsströmmars påverkan på jordfelsskydd i impedansjordade nät2024Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Today more and more overhead lines are replaced by underground cables as a result of storms which have caused major interruptions in the power grid. Because of the cabling, the characteristics of the power grid change and the calculations for the relay protection settings that are made today need to be reviewed if they still can be performed in the same way as before. This to ensure correct and selective fault disconnection. This report, in a simplified way, explains how resistive zero-sequence currents flow in the grid and how they are measured by earth fault protection.

    A fictitious 22 kV grid has been studied and earth faults on two different cables in the grid are analyzed and discussed. Calculations are made with different sizes of the zero-point resistance resulting in different resistive zero-sequence currents in the grid. This is done both in normal operation and reserve power operation to be able to study differences that can occur. Discussions are made regarding misalignment, imbalance, angle error and measurement error, which have not been included in this work. The conclusion from the study performed is that it is difficult to parameterize a directional earth fault protection and a zero-point voltage protection correctly to be able to secure a correct disconnection in both normal and backup operation. This is because of the various resistive zero-sequence currents that arise in the grid. 

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