In this thesis, a model has been developed to analyze the behavior of wave energy converter arrays in the frequency domain. This development serves the purpose of establishing an in-house model tool for array modelling for CorPower Ocean. A literature review has been conducted to compare various modelling approaches and prior studies on different configurations of wave energy converter arrays have been examined. The literature review is followed by theory that includes linear wave theory and the equation of motion. Following this, the model is introduced, accompanied by behavior validation in comparison to similar models. The selected case studies for this thesis are divided into two parts. Firstly, the investigation of different layout configurations with 16 Wave Energy Converters: 1) Circular configuration, 2) Double Circular configuration, 3) Double Row configuration (2x8), 4) Square Grid configuration (4x4), and 5) Randomized layout. The second chosen study case involves investigating layout 3) Double Row configuration (2x8) with four different distances between each Wave Energy Converter, 50, 100, 150, and 200 meters. The results demonstrate the presence of interactions within the wave energy converter arrays. The Double row layout exhibits the largest power outputs but power drops at certain waveperiods were also observed. Additionally, the results of different distances between the Wave Energy Converters demonstrate that larger spacings result in reduced interactions.

Thesis (PhD (Agric) (Agricultural Economics)--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: A complex and volatile decision-making environment and constant pressure on product prices, due to the cost-price squeeze, complicates decision-making for grain farmers in the Western Cape. Furthermore, available alternative crops and cultivation practices are limited due to local soil and climatic conditions. The farm system itself is complex due to the interdependence of a variety of factors and the synergy resulting from specific sequences of cash and pasture crops. The aim of this research project was to establish a method that would contribute to identifying strategies to advance the profitability of grain production. Research in the grain industry is traditionally specialised within specific fields, such as, agronomy, soil science, entomology, agricultural economics, etc., causing a fragmentation of knowledge. To ensure that the systems nature of a complex farm is accommodated, various related research domains should be acknowledged and incorporated. The use of expert group discussions, as a research method, is suitable, firstly, for gathering information in a meaningful manner and, secondly, to stimulate individual creativity by presenting alternative perspectives provided by various participating experts. In support of expert group discussions, simulation models in the form of multi-period whole-farm models were developed. This type of modelling supports the accurate financial simulation of farms, while the user friendliness and adaptability thereof can accurately accommodate typical farm interrelationships, and quickly measure the financial impact of suggested changes to parameters. Suggestions made by experts during the group discussions can thus be quickly introduced into the model. The financial implications are instantly available to prevent further exploration of non-viable plans and to fine-tune the viable plans. Participants in the group discussions represent fields of expertise such as agronomy, soil science, entomology, plant pathology, the agricultural chemical industry, agricultural mechanisation. Also represented are professionals such as extension officers from local agribusinesses, local producers and agricultural economists. The dynamics of the group discussions are supported by each participant’s specific strengths and perspectives. For each relatively homogeneous production area of the Western Cape, a typical farm budget model was developed, which served as the basis for the group discussions. The budget models measure profitability in terms of the IRR (internal rate of return on capital investment) and affordability in terms of expected cash flow. For the Swartland, the homogeneous areas identified were Koeberg/Wellington, the Middle Swartland and the Rooi Karoo, and for the Southern Cape, the homogenous areas identified were, the Goue Rûens, Middle Rûens and Heidelberg Vlakte. A model of a typical farm in the Wesselsbron area was developed for comparison with the Western Cape farms. For each area the expected impact of climate change, fluctuating product and input prices, and the possible impact of partial conversion to bio-fuel production were evaluated in terms of expected impact on profitability. Various area-specific strategies were identified that could enhance the profitability of grain production: most of the strategies focused on optimising machinery usage and expanding or intensifying the livestock enterprise. The repeated successful use of the model in support of the expert groups in all the chosen study areas illustrates the value thereof for identifying and evaluating plans to increase the profitability of small grain production. / AFRIKAANSE OPSOMMING: 'n Komplekse en wisselvallige besluitnemingsomgewing, en konstante druk op produkpryse weens die koste/prys knyptang bemoeilik besluitneming op graanplase in die Wes-Kaap terwyl die beskikbare alternatiewe verbouingsgewasse en -praktyke beperk is weens plaaslike grond en klimatologiese eienskappe. Die boerderystelsel self is kompleks weens die interafhanklikheid van die dele daarvan en die sinergisme verkry deur byvoorbeeld die spesifieke orde van opeenvolging van kontant- en weidingsgewasse in die wisselboustelsel. Hierdie navorsingsprojek se doel is om 'n werkwyse te vestig wat die identifisering van strategieë te ondersteun wat moontlik die winsgewendheid van graanproduksie kan bevorder. Navorsing in die graanbedryf is tradisioneel gespesialiseerd binne 'n spesifieke navorsingsveld soos agronomie, grondkunde, entomologie en landbou-ekonomie. Dit gee daartoe aanleiding dat elk van hierdie velde op dimensies van die boerderystelsel fokus asof dit in isolasie bestaan. Om te verseker dat die stelselsgeaardheid van 'n komplekse boerdery effektief verreken word behoort navorsing erkenning te gee die interafhanklikheid van die dimensies van 'n boerdery. Ekspert groepbesprekings is 'n navorsingsmetode wat eerstens geskik is om kennis sinvol byeen te bring en tweedens om kreatiwiteit by deelnemers te stimuleer deur die blootstelling aan nuwe perspektiewe van kundiges van ander spesialiteitsvelde. Ter ondersteuning van die ekspert groepbesprekings is simulasiemodelle in die vorm van multi-periode geheelboerderybegrotings ontwikkel. Die tipe modellering ondersteun die akkurate simulasie van boerderye terwyl die gebruikersvriendelikheid en aanpasbaarheid daarvan die tipiese interverwantskappe van 'n boerdery akkuraat weergee en die impak van aanpassings aan die parameters van die boerdery model vinnig kan meet. Voorstelle deur die deelnemende eksperts kan dus vinnig aangebring word en die finansiële implikasie is dadelik beskikbaar. Deelnemers aan die ekspertgroepbesprekings het velde verteenwoordig soos agronomie, grondkunde, entomologie, die landbou chemiese bedryf, landbou meganisasie, plantpatologie, voorligtingsbeamptes van plaaslike agribesighede, plaaslike produsente en landbou-ekonome. Die dinamika van die groepbesprekings word ondersteun deur elke deelnemer se spesifieke sterkpunte en perspektief. Vir elke homogene produksiegebied in die Wes-Kaap is 'n aparte begrotingsmodel van 'n tipiese plaas vir daardie area ontwikkel. Hierdie modelle het gedien as die basis van die groepbesprekings. Die modelle meet die winsgewendheid van boerderye oor die langtermyn deur middel van die IOK (interne opbrengskoers op kapitaal investering) en die bekostigbaarheid in terme van verwagte kontantvloei. Binne die Swartland is die Koeberg/Wellington, Middel Swartland en Rooi Karoo as homogeen geïdentifiseer en vir die Suid-Kaap die areas van die Goue Rûens, die Middel Rûens en die Heidelberg Vlakte. 'n Tipiese plaas model is ook vir die Wesselsbron area ontwikkel om te vergelyk met die Wes-Kaap areas se modelle. Vir elke area is die verwagte impak van klimaatveranderings, fluktuerende produk- en insetpryse en die moontlike impak van 'n biobrandstofbedryf geëvalueer in terme van die verwagte impak op winsgewendheid. Verskeie area spesifieke strategieë is geïdentifiseer wat moontlik die winsgewendheid van graanproduksie kan bevorder. Die meeste strategieë fokus op die optimalisering van masjineriegebruik en die uitbreiding of intensifisering van die veevertakkings. Die herhaalde suksesvolle gebruik van die modelle ter ondersteuning van die ekspertgroepe in al die gekose studie areas illustreer die waarde daarvan vir die identifisering en evaluering van planne om die winsgewendheid van kleingraanproduksie te verhoog.

Grid connection of wave energy is one of the crucial remaining areas of development towards the commercialization of this renewable energy technology. One of the major challenges with the grid connection of the wave energy technology is power variability. The rapidly changing voltage and power production from very high peaks to lows, increases the complexity for the wave farm developers to reach an agreement with the grid owners to satisfy the grid compliance. Correspondingly, electrical network designs of the offshore wind sector also differ on some key features which includes the power variability, cable lengths, power ratings, connection layouts, sea depths and transmission distances. These differences present new challenges to engineers in adapting technology and knowhow from the wind industry wherever applicable; whereas in parts of the network where power ratings are <2 MW, new designs need to be derived. Hence, power system dynamic modelling of variable emerging wave energy puts a great field of research. CorPower Ocean AB is in the process of developing a 300-kW point absorber type Wave Energy Converter (WEC) that is a commercial fullscale prototype. In this regard, the thesis will discuss the topics of optimization of offshore wave energy electrical networks for farms primarily focused on a 10 MW rating. The modelling for RMS simulation, network efficiency, voltage profile and power quality analysis has been simulated on DIgSILENT PowerFactory. Grid connection compliance for voltage levels, voltage flicker and power factor has been evaluated against local site regulations and parameters for optimal efficiency and better power quality with respect to grid connection is discussed. The impact of grid impedance angle and the wave front incidence angle on the rating of wave farm being connected is also evaluated. The study leads to an optimized electrical layout of a wave farm which can tackle problems such as voltage flicker and varying power. The study also leads to the understanding of better layout for the point absorber with least transmission losses. This study can also be generalized for bigger wave farms in the future which will reduce the complexity and time for wave farms engineers while planning.