Detta kandidatexamensarbete behandlar vågkraftverket “NoviOcean” och syftar till att skapa en rekommendation för de mätstorheter som bör övervakas, vilka mätprinciper som är lämpliga, samt eventuellt var sensorerna för dessa bör placeras. Först gjordes en informationssökning, för att förbättra förståelsen för hur vågkraftverket fungerar och vilka komponenter som ingår i konstruktionen. Detta gjordes dels genom att söka igenom företagets officiella dokument och dels med en genomgång med en tekniskt ansvarig från företaget, med en prototyp i mindre skala. Utöver detta undersöktes de förhållanden vågkraftverket kommer användas i, även här genom möten med ansvariga från företaget, för att öka förståelsen för vad produkten kommer utsättas för. När en komplett bild av vågkraftverkets funktion hade genererats påbörjades arbetet med att föreslå mätstorheter. Det första steget var att dela upp produkten i delsystem, för att strukturera upp arbetet. Detta gjorde det möjligt att sedan för respektive delsystem föreslå mätstorheter, som kan ge information om systemets prestanda, hälsa och miljön runtomkring. När de önskade mätstorheterna etablerats gjordes sedan ytterligare en informationssökning, för att undersöka vilka mätprinciper som ansågs vara lämpliga för produkten. Av dessa valdes en eller fler sensortyper ut, om det ansågs finnas mer än en lämplig lösning. Vissa sensorer kunde även placeras ut på enheten, då tillräckligt med information om det relevanta delsystemet ansågs finnas.' I stort anses den slutgiltiga rekommendationen av mätstorheter och mätprinciper uppfylla de krav som ställdes från företaget. En lista för respektive delsystem detaljerar de storheter och principer som anses lämpliga, med bilder och skisser för placering om detta bedömdes genomförbart. I bilagorna återfinns även mer specifika förslag för vidare arbete, för några av delsystemen. / This bachelor thesis report focuses on the Wave Energy Converter (WEC) “NoviOcean” and aims to recommend the physical quantities that should be measured aboard the unit, as well as the appropriate measuring principle for each quantity. An approximate position of each sensor was also recommended, if deemed possible. The first step was to complete a literature study, to form a better understanding of the product and its components. This was done in part by going through the company’s official documents and in part by interviewing the head of mechatronics, with a walk-through of a miniature prototype. Additional meetings with the company were also held, to better understand how and where the product is intended to be used and what conditions it will be exposed to. When the product and its function had been sufficiently understood, the work of suggesting measuring quantities began. The entire system was first divided into smaller sub-systems, to organize and simplify the process. A list of recommended quantities was then generated, that could provide information about the system’s performance, health and surroundings. Once finished, an additional literature study was performed, to understand what measuring principles would be appropriate for each quantity. The most suitable principle was then chosen from this list, unless there was more than one solution, in which case all options were included. Sensor placement could also be determined in some cases, provided that the relevant sub-system was sufficiently well defined. In conclusion, the final recommendation for measured quantities and measuring principles fulfills the demands placed by the commissioner of this report. A list of quantities and measuring principles was generated for each sub-system, with images and sketches detailing sensor placement, if applicable. For some systems, more specific sensor recommendations could be made, the results of which can be found in the appendix.

This report covers a bachelor thesis project to design a concept for a levelling system to a point absorbing wave energy converter that uses a winch with a chain, which has restricted capabilities to bending and thus requires a system which compensates for this. First of all, a literature study was made to see if there were any technologies that could be used, and also a wide search for information about the wave conditions in the Baltic sea were performed to find what requirements would be necessary for the concept to be able to withstand the conditions faced there. Following this, several brainstorming sessions were had to get ideas for different types of constructions that could solve the problem. After multiple ideas had been conceptualized, they were rated in a Pugh matrix with five different criteria which were: 1. mechanical complexity 2. complexity of required motion control 3. complexity of the structure 4. amount of potential critical weak points 5. mass of the system and lastly 6. how symmetrical it could be made. The concept that was deemed most viable out of all them is a cradle that holds the winch-drum and is controlled by a motor to compensate for one angular shift, and this is paired with a mooring system that limits the yawing motion of the entire buoy and thus removes the need for the compensation of that angle. This concept was then modelled in Solid Edge and following this; a stress analysis was made to determine the forces that would act upon the system. These were then used to determine whether the system would live up to the requirements or not with fatigue calculations. Lastly a list of recommended future work is presented. / Denna rapport täcker ett kandidatarbetsprojekt för att utforma ett koncept för ett nivelleringssystem till ett punktabsorberande vågkraftverk som använder en kedjevinsch med begränsad kapacitet till böjning och därmed kräver ett system som kompenserar för detta. Först gjordes en litteraturstudie för att se om det fanns teknik som kunde användas, och även en bred sökning efter information om vågförhållandena i Östersjön gjordes för att hitta vilka krav som skulle vara nödvändiga för att konceptet skulle kunna motstå dessa förhållanden. Efter detta hölls flera brainstormingssessioner för att få idéer för olika typer av konstruktioner som kunde lösa problemet. Efter att flera idéer hade konceptualiserats, bedömdes de i en Pugh-matris med fem olika kriterier som var: 1. mekanisk komplexitet 2. komplexitet för krävd rörelsekontroll 3. Strukturellkomplexitet 4. Antalet potentiella svaga punkter 5. Massan på systemet och slutligen 6. Hur symmetriskt systemet kunde göras. Det koncept som bedömdes vara mest genomförbart av dem alla var en vagga som håller vinschtrumman och styrs av en motor för att kompensera för en vinkelförskjutning, och detta är kombinerat med ett förtöjningssystem som begränsar girrörelsen för hela bojen och tar således bort behovet av kompensation av den vinkeln. Detta koncept modellerades sedan med Solid Edge och efter detta gjordes en kraftanalys för att bestämma krafterna som skulle agera på systemet. Dessa användes sedan för att bestämma om systemet skulle uppfylla kraven eller inte med utmattningsberäkningar. Till sist presenteras en lista med framtida arbete som rekommenderar.

In this study, several wave parameters are downloaded or calculated from spectral wave data, and their interdependence is investigated. A literature review is carried out to summarize these dependencies. The literature study is followed by a statistical analysis of the relations between the calculated wave parameters. This statistical analysis is done both for all wave data, resulting in a global expression for the relations, and for the different seas and oceans, resulting in a deeper analysis about local differences and how these differences should be taken into consideration when using wave parameter relations in specific water bodies.

A new concept for extracting renewable power has been developed at KTH Electric Power and Energy Systems, this time regarding wave power. Unlike other wave energy converters this concepts generator opens up the possibility to be operative also during low speed and at the same time preserve high power density and efficiency. This solution needs to be sealed since its components don’t withstand the ambient environment; this is therefore the purpose of the project. Several problems exist with the sealing solutions that currently are available, that is why it exists a need to produce a custom sealing solution for this concept. Some of the problems are, for example, leakage and fatigue failure that lead to unacceptably short life expectancy. The issues discussed in the report and the project, are whether there are any loads acting on the seal that are specifically critical, if there is any way to easily reduce these, if there are any solutions that are denser than the current ones (which also have approved properties of strength and life expectancy as a result of the requirements imposed on them), if these solutions would be applicable in all seas and if these solutions are also economically applicable. To answer this, most conceptualizations have been conducted using brainstorming where potential solutions were evaluated based on the extensive information retrieval, to finally reach out and outline the most promising final concepts. These were then modeled using the 3D-modeling software Solid Edge to finally be analyzed using the Ansys software. The results and conclusions from both the search for information and the detailed analyzes were that the critical loads are stresses that arise from compression, expansion and bending of the buoy, which can be reduced by creating an inner structure in the seal which causes loads to occur more continuously. There are also sealing solutions that are completely dense as they enclose the part of the wave power concept that needs to be sealed, so-called gaiter solutions. In addition, these solutions are applicable in all seas, both from a material perspective, but also from a dimensioning one such as the possibility of adjusting the length of the seal during the manufacture along varying wave heights of where it is to be applied. Regarding the last question, which addresses economic applicability, no sufficiently accurate results could be generated and hence no conclusions could be drawn. / Ett nytt koncept för att utvinna förnyelsebar energi har framtagits på KTH Elkraftteknik, denna gång handlar det om vågkraft. Till skillnad från flera andra vågkraftverk så öppnar detta koncepts nyframtagna generator upp för möjligheten att vara verksamt även vid låga hastigheter samtidigt som det bibehåller hög krafttäthet samt verkningsgrad. Denna lösning av generatorn är i behov av att tätas då dess ingående komponenter inte tål den omgivande havsmiljön, detta är därför syftet med projektet som genomförts. Flertalet problem existerar med de lösningar som för nuvarande finns att tillgå, varför det finns behov av att ta fram en skräddarsydd tätningslösning till detta koncept. Dessa problem är exempelvis läckage och utmattningsbrott vilka leder till att livslängden hos tätningarna blir oacceptabelt kort. De frågeställningar vilka i rapporten och projektet behandlas är ifall det finns några belastningar verkande på tätningen som är specifikt kritiska, ifall det finns något enkelt sätt att reducera just dessa, ifall det finns några lösningar som är tätare än de som finns att tillgå idag (som också har godkända egenskaper gällande hållfasthet och livslängd till följd av de krav som ställs på dem), ifall dessa lösningar skulle vara applicerbara i alla hav och ifall dessa lösningar är ekonomiskt tillämpbara. För att besvara detta har flertalet konceptgenereringar utförts med hjälp av brainstorming där potentiella lösningar utvärderats baserat på en omfattande informationssökning, för att till sist komma fram till och skissera upp de mest lovande slutkoncepten. Dessa modellerades därefter upp med hjälp av 3D-modelleringsprogrammet Solid Edge för att slutligen analyseras med programvaran Ansys. Resultaten och slutsatserna från både informationssökningen och de utförliga analyserna var att de kritiska belastningarna är de spänningar vilka uppstår till följd av kompression, expansion och böjning av bojen, vilka kan reduceras genom att skapa en inre struktur i tätningen som leder till att belastningarna sker mer jämnt. Det finns även tätningslösningar vilka är helt täta då de inkapslar den del av vågkraftskonceptet som behöver tätas, så kallade damasklösningar. Dessa lösningar är dessutom applicerbara i alla hav både ur ett perspektiv gällande material men också ett dimensioneringsmässigt sådant, där möjligheten finns att justera tätningens längd vid tillverkningen utefter den varierande våghöjden där denna ska appliceras. Gällande den sista frågan vilken behandlar den ekonomiska tillämpbarheten kunde inga tillräckligt träffsäkra resultat genereras och därav inga slutsatser dras.

Detta projekt undersöker olika alternativ av design utav transmissionskedja för ett vågkraftverk. Designen av koncepten kan delas in i två grupper, en grupp med styva länkar och rörliga leder och en annan grupp med stela leder och böjflexibla länkar. Analysen genomförs genom att undersöka olika tvärsnitt och olika material. De material som länkarna undersöks för är kolstål, rostfritt stål, aluminium, glas- och kolfiberkomposit. Analyserna utförs analytiskt för transmissioner med stela leder och böjflexibla länkar och för styva länkar med rörliga leder används Solidworks tillsammans med Ansys Workbench. En transmission med rörliga leder togs fram och idén baserades på en rullkedja. Denna design klarar de ställda kraven men det skapas problem i kontakteringen mellan kedjelederna där det blir koncentrationsspänningar och mycket slitage. I nuläget finns det inte några bussningar eller lager som klarar kraven som ställs på kedjan. I den andra gruppen med stela leder och böjflexibla länkar togs det fram två koncept. Den första har ett rektangulärt tvärsnitt och den andra ett runt. Den med det runda tvärsnittet klarar inte kraven då både böj- och dragspänningarna inte kan hållas tillräckligt låga samtidigt.Konceptet med det rektangulära tvärsnittet, som liknar ett band, klarar alla krav förutom utmattningskravet. Då bandet är tillverkat i stål blir bandets bredd för stor för bojen. Då bandet är tillverkat i aluminium uppfylls inte utmattningskravet. Fiberkompositer tappar mer än 50 % av sin styrka efter 10 miljoner repetitioner vilket gör att de måste bytas ut med jämna mellanrum för att undvika brott. / This project examines different options of designs of transmission chains for a wave power plant. The different designs can be divided into two groups, one group that contains chains with stiff links and moving joints and another group with stiff joints and bend flexible links. The analysis is carried out by examining different cross sections and different materials. The links are evaluated with carbon steel, stainless steel, aluminum, glass and carbon fiber composite. The analyses are preformed analytically for the group with stiff joints and bend flexible links and the group with stiff links and moving joints are examined with Solidworks together with Ansys workbench. One transmission with stiff links and moving joints was made inspired by a roller chain. This design meets the requirements, but problems occur in the contact between the links, where it appears concentration stresses and a lot of wear. At present there are no bearings that meet the demands on the chain.In the second group with stiff joints and bend flexible links, two designs were developed. The first one has a rectangular cross section and the other one has a round. The circular cross section does not meet the requirements, since both bending and tensile stresses cannot be kept low enough at the same time. The design with the rectangular cross section meets all the requirements except the fatigue requirement. After 10 million repetitions the fiber composites loses more than 50 % of its strength, which means that they needs to be replaced periodically to avoid fracture.

Wave energy is one of the possible solutions for meeting the future energy demand in a clean and sustainable way. Extracting large amounts of energy, a wave energy device would be subjected to extreme and fatigue loads from the waves. Designing such a device, a trade off needs to be done between making a device that is strong enough to withstand the loads and on the same time not too heavy making it inefficient and too costly. Having good estimations of extreme and fatigue loads are therefore critical when designing an efficient wave energy device. This thesis has aimed to create a tool that can be used between the already existing hydrodynamic and solid mechanic models available at CorPower Oceean. The goal has been that the tool shall extract the extreme and fatigue loads from the hydrodynamic model and format them in a way so that they can be used in the solid mechanical model. Four different tools have been created and compared for calculating fatigue using amplitude and spectral methods, where the amplitude methods also are able to estimate extreme loads. The fatigue tools have been evaluated against each other in a simple example showing that the estimated accumulated fatigue damage can be decreased by using several variables. An application of the tools has been done on a critical sub system of the wave energy device developed by CorPower Ocean. Where in this application critical points against extreme loading and fatigue have been localized. A new design has been suggested based on the strength analysis from the first one. Increasing the number of variables and using the tools developed in this thesis can significantly improve the fatigue damage estimations of the system. What fatigue method to use depends on the details for each case.

Detta examensarbete syftar sig till att undersöka olika konceptuella lösningar utav en transmissionslina för ett vågkraftverk. De tre olika konceptuella lösningarna är; ett rep av materialet HMPE (High Modulus Polyethylene), en transmissionslina baserad på KONE Ultrarope samt en transmissionskedja baserad på elastomera lager. Dessa har indelats i nämnd följd enligt koncept A, koncept B och koncept C. Analysen av dessa grundar sig i befintlig information och kunskap. Från dessa koncept har sedan koncept A valts att studeras vidare för optimering, vilket gjordes genom bedömning enligt Pughmetoden. Verktyget Solid Edge har använts vid framtagandet av koncept A och B. Vid optimeringen för koncept A så konstruerades en trumma för att minimera nötning, maximera repets livslängd samt för att uppnå de satta kraven. / This bachelor’s thesis aims to examine different conceptual solutions of transmission lines for a winch-based wave power plant. The different concepts are; a rope of the material HMPE (High Modulus Polyethylene), a transmission line based on KONE Ultrarope and a transmission chain based on elastomeric bearings. These have then been divided in that order into concept A, concept B and concept C. The analyses of these are based on existing information and knowledge. From these concepts, concept A has been chosen to be further analyzed and optimized. Concept A was chosen by following the method of a Pugh matrix. The modeling software Solid Edge has been used when developing concepts, A and B. Concept A was optimized by designing a drum that minimize abrasion, maximize the life of the rope and was also adjusted for reaching the specific requirements.

Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2011. / Please refer to full text to view abstract.

A wave energy park has been established on the Swedish west coast outside Lysekil and pioneer work about its interactions with the marine environment has been conducted. So far, little is known about the effects of offshore energy installations on the marine environment, and this thesis assists in minimizing environmental risks as well as in enhancing potential positive effects on the marine environment. The Lysekil research site is situated about two kilometres offshore and has been under development since 2005. During this time 26 “environmental devices”, without generators, consisting of a steel buoy attached via a wire to a foundation on 25 m depth have been placed out for ecological studies on macrofauna in surrounding sediments and on colonization of the foundations and the buoys. Sediment samples to examine macrofauna in the seabed have been taken during five seasons. Biomass, abundance and diversity of infauna in the test site were generally low, but higher than in a nearby control site. The species composition was typical for the area and depth. In addition to sediment analysis, the effect of wave power concrete foundations on the marine environment has been investigated by scuba diving. The surface orientation and its effect on colonization by sessile organisms was examined on the first five foundations, placed out in 2005, and observations of habitat use by fish and crustaceans were made. The results show a succession of colonization over time (three years of investigation) with a higher cover by sessile organisms on vertical surfaces. Mobile fauna abundance on and around the foundations was generally low. Three months after the deployment of the 21 new foundations in 2007, assemblages of mobile organisms were examined visually. Also here, mobile species exhibit a low density, but still higher than on surrounding soft bottoms. The edible crab used artificial holes in the foundations frequently. The foundations were placed in two different clusters, north and south, and the degree to which early recruits covered the foundations and the succession of epibenthic communities were documented during two years. Sessile organisms colonized the northern foundations more rapidly, producing a higher diversity which suggests that the placement of wave energy devices affects colonization patterns. Biofouling on buoys was examined and blue mussels, Mytilus edulis, dominated with a cover about 90%. Wave exposed buoys were particularly favoured by M. edulis which there had a higher biomass and larger shells compared to those on sheltered buoys. Biofouling on wave power buoys, independent whether these had a cylindrical or toroidal shape, was insufficient to markedly affect their energy production. Finally, the thesis incorporates a review describing wave power projects in general pointing out the need of future research on for instance no-take zones, marine bioacoustics and electromagnetic fields. The main conclusions are that large-scale renewable wave energy conversion will cause ecological impact primarily by adding new hard substrate to an area but not by harming organisms or decreasing biodiversity within wave power parks.

Thesis (MScEng (Civil Engineering))--University of Stellenbosch, 2008. / This thesis is an investigation of the wave power resource on the South African coast, focusing on the spatial distribution of wave power of the coastal region exposed to the highest wave power. The study’s main objective is to provide a detailed description of the spatial distribution of wave power to assist in the selection of locations for deployment of Wave Energy Converter (WEC) units in this zone. The study methodology employed to achieve this main objective entails an analysis of measured wave data recorded at wave recording stations distributed along the South African coast. The analysis provided a general description of wave power at locations for which wave data exist. From this analysis it was found that the South West Coast is exposed to the highest wave power, with an average wave power of approximately 40 kW per meter wave crest. The rest of the South African coast is exposed to average wave power between approximately 18 kW/m to 23 kW/m. The wave power characteristics on the South West Coast region (from Cape Point to Elands Bay) were therefore the focus of this thesis. The study objective was achieved by transferring deep sea wave data into the nearshore South West Coast study area with the Simulating WAves Nearshore (SWAN) wave model. The deep sea wave data was obtained from a 10 year period of available hindcast data. A simplified simulation procedure was required in order to make the study practically feasible. A sensitivity analysis was carried out to determine the validity of the simplified simulation procedure and it was found that the procedure slightly overestimate wave power in the shallower water regions due to the underestimation of energy dissipation processes. This overestimation was deemed acceptable for the dominant wave conditions and the simplified model was therefore applied in the study. An appropriate programming system was developed and used to transfer the available 10 year deep sea wave data into the selected South West Coast region. From this exercise spatial distribution of wave power and related statistical parameters were obtained for the study area. The accuracy of the modelled output was investigated by directly comparing it to wave data recorded during the overlapping recording period. It was found that the model slightly overestimates the monthly wave power resource compared to the measured data with a maximum overestimation of 9%; which is sufficiently accurate for the purpose of the study. The results of this investigation can be used for the identification of areas of high wave power concentration within the study area for the location of WEC units. Further numerical modelling is required for the detailed design of wave farms, especially if potential sites are located in shallow water (shallower than approximately 50 m). / Centre for Renewable and Sustainable Energy Studies