<p>Följande rapport beskriver ett projektarbete i att ersätta en automatisk spännings regulator (AVR) till en gammal ASEA dieselgeneratoranläggning. Generatorn är installerad på M/S Calmare Nyckel som tillhör Sjöfartshögskolan i Kalmar. Generatoranläggningen används enbart i utbildningssyfte.</p><p>Den AVR som ska ersättas är en ASEA UTWH310. Det är ett väldigt gammal anläggning och vi uppskattar att den härstammar från 60-talet. Problemet med den gamla regulatorn är att när systemet har körts en stund så är det inte längre möjligt att reglera den reaktiva effekten. Vi blev tillfrågade att ersätta det gamla systemet, därför har vi inte gjort något försök att laga det.</p><p>Regulatorn matar ström till en liten DC generator, mataren, som är ansluten till den större AC generatorn med remdrift. Mataren magnetiserar sedan rotorn i AC generatorn. För att få klarhet i hur systemet fungerade så gjorde vi några testkörningar. Vi tog reda på nödvändiga parametrar för att kunna ersätta den gamla anläggningen.</p><p>Eftersom vi inte hade någon tidigare erfarenhet av den här typen av projekt, så hade vi lite problem att hitta en leverantör av den nya AVR utrustningen. Som tur var kom vi i kontakt med Subtron AB, ett litet företag från Enköping. De var mycket hjälpsamma, och de hade både kunskapen och utrustningen som vi behövde.</p><p>Vi beslutade oss för att beställa Leroy-Somers R 448 AVR. Det är en enkel AVR men fullt kapabel att utföra det vi efterfrågar. Vi beställde också en del kringutrustning till installationen. Efter att ha testkört den nya utrustningen och kommit fram till att den fungerade utmärkt så utfördes installationen sedan på några dagar.</p> / <p>This following report describes a project in replacing the Automatic Voltage Regulator (AVR) in an old ASEA diesel generator system. The generator is installed on M/S Calmare Nyckel which belongs to Kalmar Maritime Academy. The Generator system is solely used for educational purposes.</p><p>The AVR that is being replaced is an ASEA UTWH310. It is a very old system and we assume its from some where around 1960. The problem with the old AVR is that when the system has been running for a while there is no longer possible to control the reactive power. We were asked to replace the old system, so not much effort has been put on trying to repair it.</p><p>The AVR feeds current to a small DC generator, feeder, witch is connected by a strap drive to the larger AC generator. The feeder then excites the rotor in the AC generator. To find out how the system actually worked we made some test runs. We measured necessary variables to be able to replace the old system.</p><p>Because we had no formerly experience in this type of project, we had some troubles in finding a supplier of AVR equipment. Luckily we came in contact with a small company called Subtron AB from Enköping. They were very helpful and had both the equipments and the knowledge that we needed for our project.</p><p>We decided to order Leroy-Somers R 448 AVR. It is a simple but fully capable AVR to preform what we asked for. We also ordered some auxiliary equipment for the installation. After a test run with the new equipment, we found out that it worked very well. The installation process was then made in a few days.</p>

Examensarbetet har utförts på uppdrag av NEA Gruppen och är en elkvalitetsanalys av VBG Groups maskinhall. Målet med analysen var att uppvisa elkvaliteten i maskinhallen. Perfekt elkvalitet kan definieras som total frånvaro av elektriska störningar. Av elektriska störningar är det framförallt spänningsstörningar, såsom kortvariga spänningsvariationer, spänningsosymmetrier, spänningstransienter och likspänningskomponnenter, som orsakar mest besvär för elnät och anslutna laster. Även övertoner, som kan delas i spännings- och strömövertoner, påverkar elsystem på ett negativt sätt. Analysen visar att maskinhallens spänning är stabil. Detta var väntat då kortslutningseffekten är hög jämfört med anläggningens storlek. Det matande nätet kan alltså anses starkt. Maskinhallens laster alstrar strömövertoner av framförallt ordningstalen 5 och 7 men eftersom det matande nätet är starkt ger dessa inte upphov till några spänningsövertoner som ligger utanför rekommenderade gränser. I maskinhallens ena inmatningspunkt, T1A15, finns ett kondensatorbatteri anslutet för reaktiv effektkompensering. Vid den andra inmatningspunkten, transformatorstation T3, finns idag ingen kompenseringsutrustning. Behovet är inte heller stort då belastningsgraden av T3 idag är under 10%. Man kan dock se att den reaktiva effekten redan nu är lika stor som den aktiva vilket medför att effektfaktorn är ca 0,7 och inom en nära framtid kommer fler laster att anslutas till T3 vilket innebär att ett kondensatorbatteri kan vara en lönsam investering. Maskinhallens belysning alstrar strömövertoner av framförallt ordningstal tre. Övertoner av detta ordningstal har egenskapen att de ger upphov till strömmar i neutralledaren, i värsta fall så stora att neutralledaren blir överbelastad. Någon risk för överbelastning av neutralledaren för maskinhallens belysningsgrupp finns dock inte. Totalt sett är anläggningens elkvalitet god och inga akuta åtgärder behöver vidtas.

Det finns inom Vattenfall Eldistribution AB ett intresse att automatisera felsökning i elnätet. Syftet med detta examensarbete är att utreda möjligheten att utplacera feldetektorer i Vänersborgs centrala elnät. Ett förslag på en optimal placering av feldetektorerna utifrån ett tekniskt och ekonomiskt perspektiv presenteras. Den föreslagna placeringen av feldetektorer bygger på det befintliga signalkabelsystems struktur. Signalkabelsystemet för Vänersborgs centralort finns dokumenterat i Vattenfalls dokumentationssystem. Samhällskostnader har beräknats och sammanställts för berörda ledningar. I beräkningsmodellen har olika alternativ med utplacerade feldetektorer simulerats. Alternativen utvärderas därefter i relation till felsökningstid, felfrekvens och samhällskostnad. Med framtagen beräkningsmodell erhålls samhällskostnaden för varje ledning, för ett genomsnittligt avbrott. Beräkningsmodellen visar även hur samhällskostnaden reduceras vid alternativa utplaceringar av feldetektorer. För det optimala alternativet med utplacerade feldetektorer i Vänersborgs centralort har den reducerade samhällskostnaden ställts i relation till investeringskostnaden. Därefter har den ekonomiska besparingen kunnat fastställas. Det har visat sig enligt detta examensarbete, att det med avseende på samhällskostnader och kundnytta är en bra investering att installera feldetektorer. Med den föreslagna optimala placeringen av feldetektorer, passeras återbetalningstiden för investeringen efter sex till sju år. Det genererar samtidigt en förhöjd kundnytta. Ett minskat antal provinkopplingar medför dessutom att kablar och elapparater inte på samma vis utsätts för höga kortslutningsströmmar, vilket resulterar i en längre livslängd för elnätet.

<p>This thesis investigates simulation of synchronous machines using a novel Magnetic Equivalent Circuit (MEC) model. The proposed model offers sufficient detail richness for design calculations, while still keeping the simulation time acceptably short.</p><p>Different modeling methods and circuit alternatives are considered. The selected approach is a combination of several previous methods added with some new features. A detailed description of the new model is given. The flux derivative is chosen as the magnetic flow variable which enables a description with standard circuit elements. The model is implemented in dq-coordinates to reduce complexity and simulation time. A new method to reflect winding harmonics is introduced.</p><p>Extensive measurements have been made to estimate the traditional dq-model parameters. These in combination with analytical calculations are used to determine the parameters for the new MEC model.</p><p>The model is implemented using the Dymola simulation program. The results are evaluated by comparison with measurements and FEM simulations. Three different operation cases are investigated; synchronous operation, asynchronous start and inverter fed operation. The agreement with measurements and FEM simulations varies, but it is believed that it can be improved by more work on the parameter determination.</p><p>The overall conclusion is that the MEC method is a useful approach for detailed simulation of synchronous machines. It enables proper modeling of magnetic saturation, and promises sufficiently detailed results to enable accurate loss calculations. However, the experience is that the complexity of the circuits should be kept at a reasonable low level. It is believed that the practical problems with model structure, parameter determination and the simulation itself will otherwise be difficult to master.</p>

The main performance objective in an electric power grid entails timely and efficient generation and delivery to the time-varying electricity demand. As the electricity industry is witnessing proliferation of the mainstream renewables, the minute-by-minute variations in wind and solar power generation may result in temporary electricity scarcity that jeopardizes grid stability and quality of service. The evolving electricity markets are aimed at incentivizing the conventional generators to reinforce their operating flexibility. This dissertation concerns the goal of enhancing the dynamic response rates of interconnected controllable resources by means of a multi-layered fuel input control of electrically coupled heterogeneous energy conversion components. Both power engineering and large-scale control contributions are made in support of this enhancement. First, improved fuel input controls are designed to enable flexible physics-based energy conversion dynamics required by the interconnected grid. To efficiently utilize the resources load-following and regulation problems are stated. The efficacy of proposed fuel input control designs in enhancing the dynamic response rates is illustrated on IEEE 14-bus system. Second, the problem is formalized as multi-input multioutput time-varying trajectory tracking based on a decentralized spatiotemporal composite control design. The concepts of vector-Lyapunov function and singular perturbation are invoked to formalize model decompositions, over space and time, respectively. Next, the assumptions for model simplifications are relaxed and the problem of parametric uncertainty is addressed. A minimumcost resilient co-design approach is introduced for storage-sensors-communication channels in a complex electric power grid. The notion of selective strong structural fixed modes is explored as a characterization of feasible decentralized control laws for an arbitrary system realization satisfying a pre-specified structure. Finally, it is proposed that planning of generation portfolio must be driven by the objective of maintaining adequate operating flexibility in the system. The goal is to ensure sufficient ramp capacity to sustain the significant integration of intermittent renewable resources.

<p>This thesis tries to explain the changes in the control of power electronic converters that are possible by the use of communication. Many of the renewable energy sources such as photovoltaic panels are geographically dispersed. The power rating per generator is therefore typically low. If this kind of energy source should dominate an electrical grid, the number of generators must be high. There should also be means of controlling this large number of generators simultaneously and safely. The cost of safe communication may be too high compared to the power contribution of a single generator. The Internet offers a low-cost solution, but it cannot guarantee real-time properties. Similarly to the Internet itself, it is shown how communication errors can be detected and handled in a safe manner by the end-system, in this case the generator. The generator can detect a communication timeout, and change control algorithms in order to guard itself and the connected electricity grid. When necessary, it can also disconnect and work as a local standalone power supply. In order to be able to supply all kinds of loads, the generator (in this case an inverter) is primarily voltage controlled. This results in challenges concerning current distortion. The use of feed-forward for cancellation of common grid voltage harmonics is discussed, simulated and measured. An anti-islanding algorithm for voltage controlled inverters is also developed, simulated and measured in this thesis. A DC/DC-converter for optimized connection of a photovoltaic panel is built, exploiting the photovoltaic panel properties to reduce the size and the losses significantly. Although most contributions are connected to details and parts of the system, the interactions between communication and control are emphasized.</p>

<p>The theme of this thesis is the supply of capacity during peak demand in restructured power systems. There are a number of reasons why there is uncertainty about whether an enegyonly electricity market (where generators are only paid for the energy produced) is able to ensure uninterrupted supply during peak load conditions.</p><p>Much of the public debate in Europe has been about the present surplus generation capacity. However, in a truly competitive environment, it is hard to believe that seldom used capacity will be kept operational. This is illustrated by developments in Sweden. For this reason, the large surplus of generation capacity in the European Union may vanish much faster than generally assumed. In the USA, much of the debate has been about California. During the last three summers, California has occasionally experienced involuntary load shedding and prices have been very high during these periods. To some extent, the Californian situation illustrates the relevance of the subject of this thesis: in a deregulated system generators may not be willing to invest in peaking capacity that is only needed occasionally, even though prices are very high during these periods.</p><p>A good solution to the problem of providing peaking power is pivotal to the success of power market restructuring. Solutions that fail to create the right incentives will result in unacceptable load shedding and can endanger the whole restructuring process. On the other hand, solutions that pay too much for investments in peaking power will lead to generation capacity surpluses and thus represent a societal loss.</p><p>Why is peaking capacity a problematic issue in energy-only markets?</p><p>Traditionally, probabilistic methods are applied to calculate the required generation capacity to obtain a desired level of reliability. In a centrally planned system, this level of generation capacity is developed in a least-cost manner. A single utility or central authorities can thus control the level of reliability directly. This is not possible in a market-based system, if suppliers are only paid for the energy produced.</p><p>Under the assumption of certainty and continually varying prices, generators fully recover their variable and investment costs under ideal market conditions. When uncertainty is taken into account, generators will cover their expected costs. However, revenues will be extremely volatile, especially for peaking generators. Combined with a risk-averse attitude, it is unlikely that investments will be sufficient to maintain the traditional level of reliability in an energyonly market. Consequently, one would expect reserve margins to decline in such markets. This effect is very clear in Sweden that deregulated in 1996, and less explicit in a number of other cases like Norway, California and Alberta.</p><p>Pricing and Consumer Preferences</p><p>The theory of electricity pricing was originally developed for vertically integrated utilities, but elements from this theory are also valuable in a restructured context. Many authors have agreed on the presence of a capacity element in the optimal price during peak-load conditions, while price should equal marginal cost during low-load conditions. An important assumption is that prices have to be stable. More recently, spot pricing of electricity has been advocated. A number of papers have been written about how to efficiently include security considerations in the spot price.</p><p>Because the availability of capacity cannot be directly controlled in an energy-only spot market, the probability of occasional capacity shortages increases. It is important to be prepared for this situation. The core of the problem is that demand is de facto inelastic in the short-term because of traditional tariff systems. It is shown that considerable economic gains are obtained when demand elasticity can be utilized, even if only minor shares of demand are elastic in the short-term. Better utilization of demand elasticity was also profitable in traditional systems, but after restructuring the gain is much larger: the alternative is not expensive generation but random rationing, which is unacceptable in modern society.</p><p>It is possible to go one step further. Consumers have different preferences for the use of energy and reliability. Some consumers have a low tolerance about being disconnected, while others are more willing to accept this. This will be reflected by their willingness to pay for reliability. A better solution would emerge if consumers could buy electricity and reliability more or less as separate commodities, based on their preferences.</p><p>In the context of pricing it should be pointed out that ”profile-based settlement” that allows small consumers to freely choose their supplier without hourly metering is detrimental with respect to the correct pricing of capacity. It should only be used in the initial phases of opening a market.</p><p>Improved utilization of system resources</p><p>Even in the short-term, demand and the availability of generation and transmission resources are uncertain. Therefore, it is necessary to have reserves available in a power system. When capacity becomes scarce, it is difficult to satisfy the reserve requirements. If these requirements are strict, the only possibility is to resort to what can be called ”preventive loadshedding” to satisfy the reserve requirements. This is obviously an expensive solution, but there are no obvious ways of balancing the (societal) cost of preventive load shedding against reduced system security. In this thesis, a model is developed for unit commitment and dispatch with a one-hour time horizon, with the objective of minimizing the sum of the operation and disruption costs, including the expected cost of system collapse. The model is run for the IEEE Reliability Test System. It is shown that under conditions where there is not enough capacity available to satisfy the reserve requirements, large cost savings can be obtained by optimizing the sum of the operation and disruption costs instead of using preventive load-shedding. In the model, it is also possible to directly target reliability indexes like the Loss of Load Probability or Expected Energy not Served. It is shown that increased reliability (in terms of the values of the indexes) can be obtained at a lower cost by targeting the indexes directly instead of resorting to reserve requirements. This is especially the case if flexible load-shedding routines are developed, making it possible to disconnect and reconnect the optimal amounts of load efficiently.</p><p>The use of alternatives to fixed reserve requirements as a means to maintain system security does not solve the problem about how to ensure the availability of peaking capacity. However, in a situation with occasional capacity shortages, it gives the System Operator a tool to find the optimal balance between preventive load shedding and system security, which can result in significantly lower disruption costs in such cases. More research and development in this area is necessary to develop methods and tools that are suitable for large power systems.</p><p>Ancillary Services</p><p>Investment in peaking capacity is insufficient in restructured systems because expected revenues are too low or too uncertain. If generator revenues are increased, the situation improves. One way to obtain this is to create markets for ancillary services. In the thesis, a model is developed for a central-dispatch type of pool. In this model, markets for energy and three types of ancillary services are cleared simultaneously for 24 hours ahead. Market prices are such that volumes and prices are consistent with the market participants. self-dispatch decisions . i.e. given these prices, market participants would have chosen the same production of energy and ancillary services as the outcome of the optimization program. With this model, it is shown that markets for ancillary services increase generator revenues, but this effect is partly offset by lower energy prices. This shows that markets for ancillary services can contribute to improving the situation, but given the remaining uncertainty, this is hardly enough to solve the problem.</p><p>Capacity Subscription</p><p>Because consumers have preferences for two goods: electricity and reliability, they should ideally have the choice of purchasing the preferred amount of each of these. Traditionally this is not possible . reliability is a public good, produced or obtained by a central authority on behalf of all consumers. Technological progress is presently changing this. Capacity subscription is a method that allows consumers to choose their individual level of reliability, at the same time creating a true market for capacity. It is based on the concept of selfrationing. Consumers anticipate (for example on a seasonal basis) their need for capacity at the instant of system-wide peak demand. Based on this anticipation, they procure their desired level of capacity in a market, where generators offer their available capacity. Demand is limited to subscribed capacity by a fuse-like device that is activated when total demand exceeds total available generation. In this way, the capacity payment only influences the market when demand is close to installed capacity, and does not distort the energy price in other periods. Demand is not limited when there is ample capacity. Demand will never exceed supply, because it can be limited in an acceptable way when this situation occurs. Moreover, both consumers and suppliers can adapt to situations with scarce or ample capacity, and the price of capacity will reflect this situation. There is one problem with the method: as consumers do not reach their subscribed capacity simultaneously, there will be a capacity surplus at the instant the fuse-devices are activated. Two methods to solve this problem are analysed, and it is shown that the problem can be solved optimally by giving consumers who prefer this the opportunity to buy power in excess of their subscription on the spot market.</p><p>Policy evaluation</p><p>Six alternative policies to assess the peaking power problem are analysed based on the following criteria:</p><p>- Static efficiency: the welfare-optimal match of consumption and supply</p><p>- Dynamic efficiency: the ability to create incentives for innovation</p><p>- Invisibility: with invisible strategies, each market actor pursues his or her own objectives without worrying about anyone else.s</p><p>- Robustness: a robust policy is less sensitive to deviations from assumptions</p><p>- Timeliness: the ability of a policy to be employed at the right time</p><p>- Stakeholder equity: the degree to which all the involved parties are treated equitable</p><p>- Corrigibility: the extent to which a policy can be corrected once it is employed</p><p>- Acceptability: the degree to which the policy is acceptable to all parties</p><p>- Simplicity: ceteris paribus simple strategies are preferable over more complicated strategies</p><p>- Cost: the cost of implementing the policy</p><p>- System security: the policy.s ability to obtain an acceptable level of system security</p><p>The policies are, in short (an example is given in parentheses):</p><p>- Capacity obligation: suppliers are obliged to keep sufficient capacity (PJM)</p><p>- Fixed capacity payment: a fixed payment is offered for available capacity (Spain)</p><p>- Dynamic capacity payment: capacity payment is based on the Loss of Load Probability (England and Wales)</p><p>- Energy-only: no explicit payments or obligation (Scandinavia, California)</p><p>- Proxy prices: very high administrative prices are used as a proxy to the Value of Lost Load when load shedding is necessary (Australia)</p><p>- Capacity subscription: cf. the description above (not implemented)</p><p>As could be expected, no single policy performs best on all criteria. The obligation and fixed payment methods do not perform well on market efficiency criteria, as essentially they are not market-based policies. The proxy prices policy is a reasonable policy on most criteria. It is easy, cheap and quick to implement. Because there is little experience with the method so far, there is some uncertainty with respect to if it is effective. One can anticipate that the threat of having to buy power at rationing prices will motivate market participants to avoid coming in a buying position in such cases, and that this will stimulate the adaptation of innovative solutions, especially on the demand side.</p><p>The capacity subscription policy looks very promising on the issues of efficiency, robustness and system security. This is especially true for dynamic efficiency: consumers will weigh the cost of capacity against the cost of innovative load control devices, and if the price of capacity is high, a market for such technology will emerge. However, there is a considerable threshold prior to the introduction of capacity subscription, caused by the implementation costs and complexity.</p><p>The conclusion on policies is thus that in an early stage after restructuring it may be appropriate to resort to the capacity obligation or payment method if the capacity balance is tight at the time of transition. For the medium-term, or if there is ample capacity initially, it is sensible to introduce proxy market prices to transfer the risk of a capacity deficit to market participants, with due attention being paid to the appropriate price level. Capacity subscription can be a long-term objective.</p>

<p>After decades of power generating units increasing in size, there is currently a growing focus on distributed generation, power generation close to energy loads. Investments in large-scale units have been driven by economy of scale, but recent technological improvements on small generating plants have made it possible to exploit the benefits of local power generation to a larger extent than previously. Distributed generation can improve power system efficiency because heat can be recovered from thermal units to supply heat and thermally activated cooling, and because small-scale renewables have a promising end-user market. Further benefits of distributed generation include improved reliability, deferral of often controversial and costly grid investments and reduction of grid losses. The new appeal of small-scale power generation means that there is a need for new tools to analyze distributed generation, both from a system perspective and from the perspective of potential developers. In this thesis, the focus is on the value of power generation for end-users. The thesis identifies how an end-user can find optimal distributed generation systems and investment strategies under a variety of economic and regulatory scenarios. The final part of the thesis extends the analysis with a bottom-up model of how the economics of distributed generation for a representative set of building types can transfer to technology diffusion in a market.</p><p>Four separate research papers make up the thesis. In the first paper, Optimal Investment Strategies in Decentralized Renewable Power Generation under Uncertainty, a method for evaluation of investments in renewable power units under price uncertainty is presented. It is assumed the developer has a building with an electricity load and a renewable power resource. The case study compares a set of wind power systems with different capacity and finds that capacity depends on the electricity price and that there under uncertain prices can be a significant value in postponing investment until larger projects are profitable. In the second paper, Combined Heat and Power in Commercial Buildings: Investment and Risk Analysis, a Monte Carlo simulation program to find the value and risk characteristics of combined heat and power units is presented. Using historical price data to estimate price process parameters, it is shown that uncertain prices should not be a barrier for investment, since on-site generators can adapt to uncertain prices and reduce the total energy cost risks. In, Optimizing Distributed Generation Systems for Commercial Buildings, which uses a mixed integer linear program, distributed generation portfolios that maximize profitability are tailored to a building's energy load. Distributed generation with heat recovery and thermally activated cooling are found profitable in an office and a health care building, using current generator data and energy tariffs from California. With the fourth paper, Distributed Energy Resources Market Diffusion Model, the analysis is taken a step further to predict distributed generation market diffusion. Market penetration is assumed to depend on economic attractiveness and knowledge and trust in the technologies. A case study based on the U.S. commercial sector depicts a large market for reciprocating engines and microturbines, with the West and Northeast regions driving market diffusion. Technology research and outreach programs can speed up and change the path of capacity expansion.</p><p>The thesis presents three different models for analyzing investments in distributed generation, all of which have benefits and disadvantages. Choice of model depends on the specific application, but the different approaches can be used on the same problem to analyze it from different viewpoints. The cases in the thesis indicate that distributed generation can reduce expected energy costs while at the same time improve cost predictability. Further, the thesis identifies several important factors and potential barriers to distributed generation adoption. Analyzing distributed generation from the end-user perspective is important also for policy makers, because of the importance of estimating how the market will react to potential policy measures. The thesis shows that small-scale generating capacity has the potential to increase in the near future. Further research should increase the understanding of economic and environmental issues related to distributed generation, while policy makers should aim to construct and implement measures that make it attractive for end-users to invest in efficient local generating capacity.</p>

<p>OKG AB äger de tre kokvattenreaktorerna Oskarshamn 1, 2 och 3. Kärnkraftverket ligger i Simpevarp norr om Oskarshamn. Examensarbetet har utförts på Oskarshamn 1 inom ett projekt som kallas CEM. Oskarshamn 1 togs i drift 1972 och kan leverera en elektrisk effekt på 491 MW.</p><p>Examensarbetet behandlar underhållsaspekter som bör tas hänsyn till vid projektering och konstruktion av det nya automatiskt gasturbinsäkrade 6,3 kV ställverket i system 642. Ställverket är huvudfördelningsställverk inom Oskarshamn 1 och ska bytas ut på grund av hög ålder samt brist på reservdelar.</p><p>I syfte att uppnå hög driftsäkerhet och tillgänglighet för det nya ställverket har aspekter som förbättrar dess funktionssäkerhet, underhållsmässighet och underhållssäkerhet specificerats. Förslag på ny lastfördelning samt uppställning av ställverkets fack ges också.</p><p>Resultatet av examensarbetet är de framtagna underhållsaspekter som kan tillämpas vid projektering och konstruktion av ställverket. De viktigaste underhållsaspekterna som tagits fram är att utrustningen ska vara personsäker, det ska finnas tillräckligt med utrymme i facken för att kunna utföra underhållsarbete samt att fullständig dokumentation ska levereras samtidigt som utrustningen. Ett förslag till ny lastfördelning av ställverkets belastningar har utförts utifrån en teknisk specifikation. Förslaget på uppställning av ställverkets fack tyder på att tillräckligt utrymme finns i befintliga ställverksrum.</p> / <p>OKG AB is the owner of the three boiling water reactors Oskarshamn 1, 2 and 3. The nuclear power plant is located in Simpevarp north of Oskarshamn. The thesis has been carried out at Oskarshamn 1 within a project called CEM. Oskarshamn 1 started to produce electricity in 1972 and can today deliver an electrical power of 491 MW.</p><p>The thesis considers maintenance aspects which are to be taken into consideration before planning and construction of the new automatic gas turbine secured switchgears in system 642. The switchgears are the main distribution switchgears within Oskarshamn 1 and are to be replaced because of high age and lack of spare parts.</p><p>In purpose to achieve high availability performance and availability for the switchgears, aspects which improves the reliability, maintainability and maintenance supportability has been specified. Suggestion of new distribution of the loads between the busbars and arrangement of the cubicles has also been carried out and specified.</p><p>The results of the thesis are the specified maintenance aspects which can be used when planning and constructing the switchgears. The most important maintenance aspects are that the equipment has high personnel safety, that there is enough space in the cubicles to perform maintenance and that a complete documentation is delivered together with the equipment. Suggestion of new load distribution between the busbars has been carried out with the help of a technical specification. The suggestion of new arrangement for the switchgears implies that there is enough space in the existing electrical room for the switchgears.</p>

<p>In this bachelor thesis, cable fault locators are studied for use on the overhead electrode lines in the HVDC (High Voltage Direct Current) Light project Caprivi Link. The cable fault locators studied operates with the principle of travelling waves, where a pulse is sent in the tested conductor. The time difference is measured from the injection moment to the reflection is received. If the propagation speed of the pulse is known the distance to the fault can be calculated. This type of unit is typically referred to as a TDR (Time Domain Reflectometer). The study is performed as a computer simulation where a simplified model of a TDR unit is created and applied to an electrode line model by using PSCAD/EMTDC. Staged faults of open circuit and ground fault types are placed at three distances on the electrode line model, different parameters of the TDR units such as pulse width and pulse amplitude along with its connection to the electrode line are then studied and evaluated. The results of the simulations show that it is possible to detect faults of both open circuit and ground fault types with a suitable TDR unit. Ground faults with high resistance occurring at long distances can be hard to detect due to low reflection amplitudes from the injections. This problem can somewhat be resolved with a function that lets the user compare an old trace of a “healthy” line with the new trace. The study shows that most of the faults can be detected and a distance to the fault can be calculated within an accuracy of ± 250 m. The pulse width of the TDR needs to be at least 10 μs, preferable 20 μs to deliver high enough energy to the fault to create a detectable reflection. The pulse amplitude seams to be of less significance in this simulation, although higher pulse amplitude is likely to be more suitable in a real measurement due to the higher energy delivered to the fault. The Hipotronics TDR 1150 is a unit that fulfil these requirements and should therefore be able to work as a line fault locator on the electrode line.</p>