This thesis presents an assessment of a modular flap-type wave energy converter. Comparisons are made to an equivalent width rigid device. All quoted relative difference results here use the rigid device as the reference point. The variables that are evaluated are the power capture and surge and yaw foundation loads. The power capture is evaluated at both module and device level, while the foundation loads are assessed just at the device level. The investigation is carried out through testing of a 30th scale physical model in a wave tank. A key output from the work is the development of the physical model. The model consists of six flap modules, mounted on a common base structure. Each module contains a highly controllable and compact power take off system. The devices are tested in a range of conditions, primarily consisting of regular waves of different period and direction. The damping strategy employed is the simplest approach available, setting the achievable damping level on each module to be the same. For the modular device in head-on regular waves, the results show that the power capture increases significantly moving from the outer to the central modules. On average, the central pair of modules produce 68 % of the total mean power, the inner modules 25 % and the outer modules only 7 %. Between the devices, it is shown that the power captures in head-on waves are similar, with a mean relative difference of -3 %, with +/-5 % uncertainty. Thus, no statistically significant change in power capture is shown. In off-angle waves, the mean relative difference is –1 %, with +/-4 % uncertainty. However, for the highest wave direction that was tested in, 27.5 degrees, the modular device outperforms the rigid flap, by 10 %, with uncertainty of +/-1 %. The surge foundation loads are shown to be very similar for the two devices - in head-on waves, the mean relative difference is +2 %. Depending on the level of applied damping, however, significant differences in the yaw foundation loads are shown. Using damping where the power capture is maximised, the yaw loads increase by a mean of 10 %; using damping where the power to load ratio is instead maximised, the modular yaw loads are 26 % lower. Finally, the economics of the power production is estimated through division of the power capture with a cost metric, the foundation loads. While this does not provide a full techno-economic assessment, it effectively captures the interdependency of the power capture and foundation loads for the devices. The mean relative differences in the power per load ratios of the devices are found to be similar across the wave conditions. In the head-on waves, the differences are between –8 and –0.4 %, depending on damping strategy; in the off-angle waves, the differences are between –6 and +10 %. For both sets of wave conditions, the modular flap performs better when the damping is set to maximise the ratio of power capture to foundation loads. The work concludes that the modular and rigid devices produce power and experience foundation loads at similar levels in head-on waves. Given the high power capture efficiency, nearshore location, simple mode of operation and high survivability of the flap-type WEC, this suggests that the modular device is a viable stand-alone concept. The work also finds that in off-angle waves, some benefits can be achieved with an appropriately damped modular system, notably in improved power capture and reduced yaw foundation loads. These could reduce the sensitivity that flap-type devices have in off-angle waves and allow expansion of the width and hence capacity of machines. Further work should extend the wave conditions tested in, by using more irregular and directional waves, and investigate more damping strategies and geometries. Economic assessment should also be carried out.

Vid konstruktion av utomhusställverk behöver laster beräknas för dimensionering av fundament, stativ och grundbultar. Dessa beräkningar är tidskrävande och kräver god kunskap i standarder för ställverk. Utvecklandet av ett Exceldokument som beräknar krafterna som verkar på fundament, stativet och grundbultar, samt en ställverksmall med tillhörande stålritningar underlättar och försnabbar arbetet.  Beroende på vilken nätspänning ställverket är konstruerat för, förändras säkerhetsavståndet mellan apparater och till marken. Därför behövs det olika mallar för olika spänningar. Apparaterna som används blir tyngre och större vid högre spänningar därför måste stålet dimensioneras därefter. Dessa mallar är gjorda i Solidworks och består av sammanställning med alla stativ och apparater, samt en fundamentplan som alla delar är parade med för att enkelt kunna ändra utformningen av ställverket.  Standarder för mekanisk dimensionering av ställverkskonstruktion har följts för att göra ett exceldokument som beräknar dimensionerande laster på ställverkets stativ och fundament.  Genom att ange mått från ställverksritningen och teknisk information från beställaren i Exceldokumentet så beräknas böjspänning och vridskjuvspänning i stativen, normal- och skjuvspänning i bultar och hålkantstryck på fotplåten.  Exceldokumentet förväntas spara ca 12 timmar vid beräkning av spänningar i stativ och fundament. För ställverksmallen är förhoppningen att spara ca 80 timmar.  På grund av tidsbrist slutfördes endast en utav de nio påtänkta mallarna. Exceldokumentet skulle kunna vidareutvecklas till att beräkna vindlast på stativen och kortslutningskrafter men med minimal tidsbesparing. / During the construction of outdoor substation, loads need to be calculated to design the foundations, frames, and anchor bolts. These calculations are time-consuming and require a good understanding of standards for substations. The development of an Excel document that calculates the forces acting on the foundations, frames, and anchor bolts, along with a substation template and associated steel drawings, facilitates and speeds up the work. Depending on the voltage for which the substation is designed, the safety clearance between the equipment and the ground changes. Therefore, different templates are needed for different voltages. The equipment used becomes heavier and larger at higher voltages, so the steel must be dimensioned accordingly. These templates are created in Solidworks and consist of an assembly of all frames and equipment, as well as a foundation plan where all parts are paired to easily modify the design of the substation. Standards for the mechanical design of substation structures have been followed to create an Excel document that calculates the design loads on the substation frames and foundations. By entering some measurements from the substation drawings and some technical information from the client into the Excel document, the bending stress and shear stress in the frames, normal and shear stress in the bolts, and edge pressure on the base plate are calculated. The Excel document is expected to save approximately 12 hours when calculating stresses in the frames and foundations. For the substation template, the hope is to save around 80 hours. Due to time constraints, only one out of the planned nine templates was completed. The Excel document could be further developed to calculate wind loads on the frames and short-circuit forces, but with minimal time savings. / <p>Betygsdatum 2023-06-07</p>