[pt] Os modelos GAS (generalized autoregressive score) são modelos de séries temporais com parâmetros variantes no tempo, os quais possuem sua evolução ditada pelo vetor score ponderado da função de verossimilhança. A avaliação da verossimilhança nestes modelos é bastante simples, bem como incorporação de efeitos como assimetria, memória longa e outras dinâmicas. Por serem baseados no score da verossimilhança, exporta-se a estrutura completa da distribuição preditiva para o mecanismo de atualização dos parâmetros, e não apenas a média ou momentos de ordem superior. Estas características, somadas á capacidade de lidar com processos multivariados e não estacionários, tornam a classe em estudo uma nova alternativa para a construção de modelos com parâmetros variantes, particularmente para séries temporais não gaussianas. Nesta dissertação, foram desenvolvidos modelos GAS univariados para a análise das séries mensais de vazão do Rio Paraibuna (MG) e de fator de capacidade de uma usina é olica não divulgada do Nordeste, utilizando as distribuições gama e beta, respectivamente. Além disso, foi derivado um novo modelo GAS bivariado com marginais gama e beta para a modelagem conjunta dos processos de vazão e vento, de modo a explorar a complementaridade sazonal entre as séries. / [en] The GAS models (generalized autoregressive score) are time series models with time-varying parameters, which have their update mechanism drived by the scaled score of the likelihood function. The likelihood evaluation in these models is quite simple, as well as the incorporation of effects like asymmetry, long memory and other dynamics. Because they are based in the scaled score of the likelihood, it exploits the full structure of the predictive distribution to the update mechanism of the parameters, and not just mean or higher order moments. These characteristics, coupled with the ability to handle with multivariate and non-stationary processes, make the studied class a new alternative to the construction of models with time-varying parameters, particularly for non-Gaussian time series. In this dissertation, univariate GAS models were developed to analyze monthly series of streamflow of Paraibuna river (MG) and of capacity factor of a wind farm undisclosed in Northeast, using the gamma and beta distributions, respectively. In addition, a new bivariate GAS model with gamma and beta marginals was derived for the joint modeling of the streamflow and wind processes, in order to explore the seasonal complementarity between the series.

Dissertação(mestrado) - Universidade Federal do Rio Grande, Programa de Pós-Graduação em Engenharia Oceânica, Escola de Engenharia, 2006. / Submitted by Lilian M. Silva (lilianmadeirasilva@hotmail.com) on 2013-04-14T23:00:46Z No. of bitstreams: 1 acunha,i.c.pdf: 3231145 bytes, checksum: 59b7e3a2e51d332d1eb99c5b968beb88 (MD5) / Approved for entry into archive by Bruna Vieira(bruninha_vieira@ibest.com.br) on 2013-06-04T16:01:13Z (GMT) No. of bitstreams: 1 acunha,i.c.pdf: 3231145 bytes, checksum: 59b7e3a2e51d332d1eb99c5b968beb88 (MD5) / Made available in DSpace on 2013-06-04T16:01:13Z (GMT). No. of bitstreams: 1 acunha,i.c.pdf: 3231145 bytes, checksum: 59b7e3a2e51d332d1eb99c5b968beb88 (MD5) Previous issue date: 2006 / O objetivo deste trabalho é analisar o desempenho de um gerador eólico de pequeno porte. Para isto foi instalado um aerogerador de velocidade variável com potência nominal de 250 W. O aerogerador utiliza o sistema de estol ativo para controle de rotação e proteção, maximizando a eficiência aerodinâmica, minimizando a complexidadee os custos de fabricação do sistema os quais poderiam ser impeditivos à geração de energia com estes equipamentos em função da sua pequena capacidade de geração. Para monitoramento do sistema foi instalada uma torre anemométrica contendo dois anemômetros de três conchas, um sensor de direção do tipo leme direcional e um sistema de aquisição e armazenamento de dados (data logger), um amperímetro tipo alicate utilizado para medição da corrente elétrica e um voltímetro para medição da tensão, ambos com um sistema de armazenamento de dados e um medidor de energia. Com os dados de vento medidos no local e a potência convertida, calculada através da tensão e corrente elétrica produzida pelo aerogerador foi construída acurva de potência deste e comparada com a curva de potência fornecida pelo fabricante, onde concluímos que o desempenho deste foi muito próximo do desempenho apresentado pelo fabricante, sendo em algumas situações superior. O gráfico do coeficiente de potência deste aerogerador foi construído a fim de verificar a relação entre a potência real convertida e o potencial eólico disponível para as diversas velocidades do vento experimentadas. Com os dados de vento tratados estatisticamente utilizando a função densidade de probabilidade de Weibull e a curva de potência, foi calculada aenergia convertida pelo aerogerador e o seu fator de capacidade, o qual representa a relação entre a energia convertida pelo aerogerador em um certo intervalo de tempo e a energia existente no vento para o mesmo intervalo. Foi concluído que o aerogerador possui um desempenho aceitável para as velocidades do vento a que o mesmo foi submetido durante a operação. / This study aims to analyze the performance of a small wind turbine. Thus, it was set up a wind turbine of variable speed with nominal power of 250W. The wind turbine uses the active stall system to control rotation and protection, maximizingthe aerodynamic efficiency, minimizing the complexity and the manufacturing costs of the system, which could be hindering for energy production with such equipment once it has a small generation capacity. In order to monitor the system it was installed an anemometric tower with two anemometers of three shells, a direction sensor with directional rudder and a data acquisition and storing system (data logger), an amperimeter pincers-typeused for measuring electric current and one voltmeter for tension measuring, both with a data storing system and an energy gauger. With the data from wind measured in the place and the power converted, calculated by tension and electric current produced by the wind turbine, it was built its power curve and compared with power curve provided by the marker, where weconcluded that the performance of this wind turbine was very close to the performance shown by the marker, and on some occasions even higher. The graphic of the power coefficient of this wind turbine was constructed in order to examine the relation between the real power converted and the wind power available for the different wind velocities. With the data from the wind statistically seen using the function of Weibull`s density of probability and the power curve, it was calculated the converted energy by the wind turbine and its capacity factor, which represents the relationship between the wind turbine converted energy and the available wind energy at the same time interval. We conclude that, by the power coefficient that the wind turbine performs acceptable within the wind speeds under which it was submitted during the operation.

The recent worldwide economic crisis, climate change and global warming have emphasized that the need for low carbon emissions while also ensuring the economic feasibility. In this paper, wind power potential of ETD in KTH was investigated. The technical and economical feasibility of tower mounted small scale standalone wind turbine installation is conducted. The potential of wind power production was statistically analysed. The average wind speed data of four-season interval of one year period (2011) which its measurement was taken on the roof top of the ETDB, and this was adopted and analysed in order to find out the potential of wind power generation. The Rayleigh distribution probability was applied to calculate the wind speed distribution at KTH, by doing so the annual wind power potential at the area and annual energy production of the chosen wind turbine was estimated, after the selection of a proper wind turbine have been made upon the site conditions. Therefore, the study result shows that installation of the wind turbine at 24 meters hub height for this particular area will have a better performance of annual energy production, capacity factor, carbon savings and better economical value than the current turbine installed at 17 meters height at the ETD. The economic evaluation shows that the turbine can save an electricity bill of US$3661.05 per year and cover 1.84% of the electricity consumption of the ETD by reducing its respective CO2 emission from the electricity use at the department. Moreover, the payback period of the turbine installation with the inclusion of the green certificate is approximately 14 years which is more feasible if it is considered for small wind turbines too, which is already in practice for renewables including wind power in Sweden.

Recently wind resource assessment studies have become an important research tool to identify the possible wind farm locations.  In this thesis work technical analysis was carried out to determine the wind resource potential of two candidate sites in Eritrea with help of suitable software tools. The first site is located along the Red Sea cost which is well known for its wind resource potential, whereas the second site is located in the central highlands of Eritrea with significant wind resource potential. Detailed wind resource assessment, for one year hourly weather data including wind speed and wind direction, was performed for the two candidate sites using MS Excel and MATLAB. The measured wind data at Assab wind site showed that the mean wind speed and power density was 7.54 m/s and 402.57 W/m2 , whereas the mean wind speed and mean power density from Weibull distribution was 7.51 m/s and 423.71 W/m2 respectively at 80m height. Similarly, the measured mean wind speed and mean power density at Dekemahre wind site was obtained to be 5.498 m/s and 141.45 W/m2, whereas the mean wind speed and mean power density from Weibull distribution was 5.4859m/s and 141.057W/m2 respectively. Based on the analysis results Assab wind site classified as wind class-III and Dekemhare as wind class-I.  Wind farm modeling and Annual Energy Production (AEP) estimation was performed for E-82 & E-53 model turbines from Enercon Company with the help of MATLAB and Windpro software. The analysis revealed that Assab wind farm was an ideal site for wind energy production with capacity factor (CF) 53.4% and 55% for E-82 and E-53 turbines respectively. The gross and net AEP for turbine E-82 at Assab wind farm was 469.5 GWh and 446.025 GWh respectively with 95% park efficiency. Similarly, the analysis showed that the CF in Dekemhare site was very low with typical value 14.2% and 15.26% for E-82 and E-53 turbines respectively. The gross and net AEP of that site for model turbine E-53 was 53.5 GWh and 50.825 GWh respectively with 5% wake loss. Finally, a simplified economic analysis was carried out to determine the economic feasibility of possible wind power projects in both sites by assuming investment cost 1600 €/kW for E-82 turbine and 2000 €/kW for E-53 turbine. The total wind farm investment cost was found to be 215.85 and 107.93 Million Euro for E-82 and E-53 model turbines respectively. The levelized cost of energy at Assab and Dekemhare wind farm for E-82 model turbine was 0.0307 €/kWh and 0.5526 €/kWh respectively. The analysis result show that the levelized cost of energy in Dekemhare wind fasrm was much higher than that of Assab wind farm.

An exponentially growing global population, power demands, pollution levels and, on the other hand, rapid advances in means of communication have made the public aware of the complex energy situation. The Kingdom of Saudi Arabia has vast open land, an abundance of fossil fuel, a small population but has always been among the front-runners where the development and utilisation of clean sources of energy are concerned. Several studies on wind, solar and geothermal sources of energy have been conducted in Saudi Arabia. Solar photovoltaic (pv) has been used for a long time in many applications such as cathodic protection, communication towers and remotely located oil field installations. Recently, a 2MW grid-connected pv power plant has been put online and much larger solar desalination plants are in planning stage. Wind resource assessment, hub height optimisation, grid-connected wind farm and hybrid power system design were conducted in this study using existing methods. Historical daily mean wind speed data measured at 8 to 12metres above ground level at national and international airports in the kingdom over a period of 37 years was used to obtain long-term annual and monthly mean wind speeds, annual mean wind speed trends, frequency distribution, Weibull parameters, wind speed maps, hub height optimisation and energy yield using an efficient modern wind turbine of 2.75MW rated power. A further detailed analysis (such as estimation of wind shear exponent, Weibull parameters at different heights, frequency distribution at different heights, energy yield and plant capacity factor and wind speed variation with height) was conducted using wind speed measurements made at 20, 30 and 40metres above ground level. As a first attempt, an empirical correlation was developed for the estimation of near-optimal hub height (HH = 142.035 * (α) + 40.33) as a function of local wind shear exponent (α) with a correlation coefficient of 97%. This correlation was developed using the energy yield from a wind turbine of 1 000kW rated power and wind speed and local exponent for seven locations in Saudi Arabia. A wind-pv-diesel hybrid power system was designed and specifications were made for a remotely located village, which is being fed 100% by diesel power generating units. The proposed system, if developed, will offset around 35% of the diesel load and therefore will result in decreased air pollution by almost the same amount. The developed wind speed maps, the frequency distributions and estimated local wind shear exponents for seven locations and energy yield will be of great help in defining the further line of action and policy-building towards wind power development and utilisation in the kingdom. The study also recommends conducting a wind measurement campaign using tall towers with wind measurements at more than one height and estimating the local wind shear exponents and developing a wind atlas for the kingdom. The study further states that a grid-connected wind farm of moderate capacity of 40MW should be developed using turbines of varying rated powers. The wind speed data was also analysed using wavelet transform and Fast Fourier Transform (FFT) to understand the fluctuation in wind speed time series for some of the stations. It is also recommended that policy-makers should take firm decision on the development of hybrid power systems for remotely located populations which are not yet connected with the grid. There are two challenges which need research: one is the effect of dust on the moving and structural elements of the wind turbines and the second is the effect of high prevailing temperatures on the performance and efficiency of the same. / Thesis (PhD)--University of Pretoria, 2012. / Mechanical and Aeronautical Engineering / PhD / Unrestricted

This thesis deals with usage of each kind of RES under conditions of Czech republic and their usage at areas placed in. Consequently supplied RES output power at time and its influence on reliability of supply in EPS CZ. Way of operation of RES from point of view of requirement on regulation and control of operation of EPS is more studied on operation of different kinds of wind power plants, which due to its variable output power affects not only EPS CZ. At final caption, economic influence of RES to EPS is reviewed as a unit, increasingly claims on regulation, increasingly benefit on support of RES. All these influences increase price of electricity for end user.

The present thesis is an attempt to investigate the interference effects on the magnitudes of the ultimate failure loads for a group of closely spaced strip footings and strip plate anchors. On account of an increase in the number of different civil engineering structures, footings and anchors are often need to be placed very close to each other. In such a situation, the ultimate bearing capacity/pullout capacity of an interfering footing/anchor becomes significantly different from that of a single isolated footing/anchor. The effect of interference on the magnitude of failure load is usually expressed in terms of an efficiency factor (%y); where £,y is defined as the ratio of the magnitude of the failure load for a strip footing/anchor of a given width in the presence of other footings/anchors to that of the magnitude of the failure load for an isolated single strip footing/anchor having exactly the same width. No rigorous analysis seems to have been carried out so far in literature to investigate the interference effect for a group of footings and anchors. In the present study, it is intended to use rigorous numerical upper bound limit analysis in combination with finite elements and linear programming in order to determine the collapse loads for the problems of both isolated and a group of footings and anchors. Three noded triangular elements are used throughout the thesis for carrying out the analysis for different problems. The velocity discontinuities are employed along the interfaces of all the elements. The plastic strains within the elements are incorporated by using an associated flow rule. The Mohr Coulomb yield surface is linearised by means of an exterior regular polygon circumscribing the actual failure surface so that the finite element formulation leads to a linear programming problem. In solving the different problems taken in this thesis, computer programs were developed using 'MATLAB' with the usage of 'LINPROG' - a library subprogram for doing the necessary optimization. The bearing capacity factor Ny for an isolated single rigid strip footing placed on a cohesionless ground surface has been computed and its variation with respect to the footing-soil roughness angle (8) has been examined in detail. It is clearly noted that an increase in 8 leads to a continuous increase in Ny. The solution is also obtained for a perfectly rough footing without considering any velocity discontinuity surface along the footing-soil interface. With 5 = <|), the magnitude of NY becomes almost the same as that for a perfectly rough footing. The size of the plastic zone increases with an increase in the values of 8 and <j). The obtained values of Ny for 5=0 and § compare quite favorably with the solutions reported earlier in literature. The ultimate bearing capacity for a group of two and an infinite number of multiple interfering rough strip footings placed on a cohesionless medium has been computed; all the footings are assumed to be perfectly rigid. It is specified that the footings are loaded simultaneously to failure exactly at the same magnitude of the failure load. For different clear spacing (S) between the adjacent footings, the magnitude of the efficiency factor (£,y) is determined. In the case of two footings, the value of E,y at S/B = 0 becomes exactly equal to 2.0, and the maximum ^occurs at a critical spacing (Scr). For S/B < Sor/B, the ultimate bearing pressure for a footing becomes equal to that of an isolated footing having the width (2B+S), and the ground mass encompassed between the two footings deforms mainly in the downward direction. In contrast, for S/B > Scr/B, ground heave is noticed along both the sides of the footing. As compared to the available theories in literature, the analysis presented in this thesis provides generally lower values of ^y for S/B > Scr/B. ' In the case of a group of multiple strip footings, the value of £y is found to increase continuously with a decrease in S/B. The effect of the variation of spacing on §y is found to be very extensive for small values of S/B; the magnitude of ^y approaches infinity at S/B = 0. For all the values of S/B ground heave is invariably observed on both the sides of the footings. The magnitudes of ^Y for given values of S/B and <|) for the two footings case are found to be smaller than the multiple footings case. The vertical uplift capacity of an isolated strip anchor embedded horizontally at shallow depths in sand has been examined; the anchor plate is assumed to be perfectly rigid and rough. The collapse load is expressed in terms of a non-dimensional uplift factor FY, the value of which needs to be known before calculating the failure load for an interfering anchor. The magnitude of Fr is found to increase continuously with increase in both embedment ratio (k) and the friction angle (<|>) of sand. Even though the analysis considers the development of plastic strain within all elements, however, at collapse, the soil mass just above the anchor is found to move as a single rigid block bounded by planar rupture surfaces; the rupture surfaces emerging from the anchor edges are seen to make approximately an angle <|> with the vertical. The vertical uplift capacity of a group of two and an infinite number of multiple interfering rigid rough strip anchors embedded horizontally in sand at shallow depths has been examined. At collapse, it is specified that all the anchors in the group are loaded to failure simultaneously exactly at the same magnitude of the failure load. For different clear spacing (S) between the anchors, the magnitude of the efficiency factor (£Y) is determined. On account of interference, the magnitude of 4y is found to reduce continuously with a decrease in the spacing between the anchors. For all values of X and §, the magnitude of ^y for the multiple anchors case is found to be always smaller than that for the two anchors case. In contrast to a group of footings under compression, the magnitude of ^v for a group of anchors is found to decrease invariably with an increase in $ for a given value of S/B. For S > 2c/tan<j) , the uplift resistance of anchors in the group becomes equal to that of an isolated anchor, and no interference is seen to exist; where d is the depth of anchor. By examining the nodal velocity patterns, it was noted that in the event of collapse, a wedge of soil mass just above the anchors and encompassed within linear rupture surfaces moves vertically upward almost as a single rigid unit with the velocity same as that of the anchor plate itself. On this basis, a closed form solution of the problem has been developed. The results from the closed form solution for the group of two anchors as well as for multiple anchors are found to provide an excellent comparison with the rigorous upper bound numerical solution especially for the value of § greater than or equal to about 35°. For all the problems taken in this study, it has been seen that an upper bound limit analysis in combination with finite elements and linear programming is a very useful numerical tool for determining the magnitudes of collapse loads.

Hydrogen, as a form of storage for the excess energy from renewable sources, is a technically and economically viable option. However, the technology is not mature enough to compete with the other renewable energy possibilities. In this thesis, a study based on coupling two 330 kW wind-turbines with an NELP. 40 electrolyzer this connection should improve the utilization of wind power. In this thesis are two options of energy utilization. The energy produced by the wind-turbine is stored in the form, of hydrogen and is then delivered for consumption at variable power through a fuel cell, second option is use of produced hydrogen as alternative fuel for cars. This study is a general introduction for the wind energy system with hydrogen storage. Future studies should be more complex and detailed in order to understand and model the system with greater accuracy and to increase the possibility for the utilization of wind energy to generate hydrogen. This would enhance wind power competitiveness and sustain the continuously changing world energy demands.

Wind power has become a major supplier of electricity in the European market in the last years. In 2020, 13% of electricity generated on the European continent was wind energy (onshore and offshore) and these shares are projected to increase in the next years due to reasons such as climate change and the energy security aspect. While an increased share of renewable electricity in the electricity mix has a lot of benefits, it also comes with challenges. One of these challenges are the electricity market design and the offtake mechanisms that find application. If national expansion goals for wind energy are to be achieved, wind power plants need to be profitable and hence be an attractive and competitive investment. If wind farms are running within the prevalent merit order system where the energy source with the highest marginal cost sets the electricity price, there is a risk of low or even negative income at times of high wind or solar irradiation. The unforeseeable and potentially low revenues also lead to worse conditions in the financing of wind projects, resulting in high financing costs. To counteract this challenge, governments have set up policy frameworks and subsidies and owners of wind farms have adopted different offtake mechanisms such as pay-as-produced PPAs (power purchase agreements) and baseload PPAs. Additionally, many operators hedge their assets, meaning that risks are reduced by deployment of different offtake mechanisms. All of this is where this study ties in. The objective was to evaluate how the design of markets and offtakes and their respective pricing level and predictability impact the best turbine fit in North and Central Europe. To get to an answer, two key onshore markets within the region have been chosen and characterized, namely Germany and Sweden. Two different turbine types, one with a low capacity factor but high rated power and one with a lower rated power but high capacity factor, have been examined in these markets in order to evaluate which turbine type performs better. A third turbine type which is a new concept in the technology demonstrator stage has been added to the study to assess its performance as compared to the existent turbines. The evaluation has been performed in form of a Use Case Analysis and Sensitivity Study. Finally, the results have been compared and generalized into key takeaways that can be transferred into other markets in the region of North and Central Europe. The study finds that different market characteristics and offtake mechanisms do in fact impact turbine selection and the best turbine fit. Important factors that have been found in this research are the key financial metric (NPV and IRR), market constraints such as a grid constraint, and offtake mechanisms and the predictability of revenues that comes with the offtake. The main impacts on wind turbine selection that can be tied to offtake mechanisms are the payment received per unit of electricity and the level of security that comes with the offtake mechanism. Constant incomes improve financing conditions, meaning that resources from crediting institutes are granted at better conditions if the income can be anticipated. For both markets, the optimal turbine fit varies depending on the boundary conditions. High capacity factor turbines have been found to be a better fit if the developing company considers the IRR as focal financial metric. If the NPV is the focal metric, the results are less clear: While low capacity turbines are a better fit for sites with low revenues from electricity pricing and lower wind conditions, turbines with high rated power benefit from high and secured electricity pricing and high wind speeds where rated power is reached. The German EEG as a special case promotes installation of high capacity turbines due to high and constant revenues per MWh. While the overall Value Pool (payment per MWh of electricity) is higher for Germany, business cases in Sweden benefit from higher turbine lifetimes. / Vindkraft har under de senaste åren blivit en viktig leverantör av el på den europeiska marknaden. År 2020 var 13 % av elproduktionen på den europeiska kontinenten vindkraft (på land och till havs) och dessa andelar förväntas öka under de kommande åren på grund av orsaker som klimatförändringar och energisäkerhet. Även om en ökad andel förnybar el i elmixen har många fördelar, kommer den också med utmaningar. En av dessa utmaningar är elmarknadens utformning och de uttagsmekanismer som tillämpas. Om de nationella utbyggnadsmålen för vindkraft ska kunna uppnås måste vindkraftverken vara lönsamma och därmed utgöra en attraktiv och konkurrenskraftig investering. Om vindkraftsparkerna drivs inom det rådande merit order-systemet, där den energikälla som har högst marginalkostnad sätter elpriset, finns det risk för låga eller till och med negativa intäkter vid tillfällen med mycket vind eller solinstrålning. De oförutsägbara och potentiellt låga intäkterna leder också till sämre villkor för finansiering av vindkraftsprojekt, vilket resulterar i höga finansieringskostnader. För att motverka denna utmaning har flera regeringar inrättat politiska ramverk och subventioner och ägare av vindkraftsparker har infört olika uppköpsmekanismer såsom PPA (Power Purchase Agreement) med betalning efter produktion och PPA för basbelastning. Dessutom säkrar många operatörer sina tillgångar, vilket innebär att riskerna minskas genom användning av olika upptagningsmekanismer. Målet var att utvärdera hur utformningen av marknader och upptag samt deras respektive prisnivå och förutsägbarhet påverkar den bästa turbinanpassningen i Nord- och Centraleuropa. För att komma fram till ett svar har representativa marknader inom regionen valts ut och karakteriserats, nämligen Tyskland och Sverige. Två olika turbintyper, en med låg kapacitetsfaktor men hög nominell effekt och en med lägre nominell effekt men hög kapacitetsfaktor, har undersökts på dessa marknader för att utvärdera vilken turbintyp som presterar bättre. En tredje turbintyp som är ett nytt koncept i teknikdemonstratorstadiet har lagts till i studien för att bedöma dess prestanda jämfört med de befintliga turbinerna. Utvärderingen har utförts i form av en användningsfallsanalys och en känslighetsstudie. Slutligen har resultaten jämförts och generaliserats till viktiga slutsatser som kan överföras till andra marknader i regionen Nord- och Centraleuropa. Studien visar att olika marknadsegenskaper och uppköpsmekanismer påverkar valet av turbin och vilken turbin som passar bäst. Viktiga faktorer som har hittats i denna forskning är det viktigaste finansiella måttet (NPV och IRR), marknadsbegränsningar som spetshöjd eller nätbegränsningar, och uppköpsmekanismer och förutsägbarheten av intäkter som kommer med uppköpet. De viktigaste faktorerna som påverkar valet av vindkraftverk och som kan kopplas till avsättningsmekanismer är den betalning som erhålls per enhet el och den säkerhetsnivå som följer med avsättningsmekanismen. Konstanta inkomster förbättrar finansieringsvillkoren, vilket innebär att resurser från kreditinstitut beviljas på bättre villkor om inkomsterna kan förutses. För båda marknaderna varierar den optimala turbinpassningen beroende på gränsvillkoren. Turbiner med hög kapacitet har visat sig passa bättre om utvecklingsföretaget betraktar internräntan som ekonomiska nyckeltal. Om NPV är det centrala måttet är resultaten mindre tydliga: Medan turbiner med låg kapacitet passar bättre för platser med låga intäkter från elpriser och lägre vindförhållanden, gynnas turbiner med hög nominell effekt av höga och säkra elpriser och höga vindhastigheter där nominell effekt uppnås. Det tyska EEG är ett specialfall som främjar installation av turbiner med hög kapacitet på grund av höga och konstanta intäkter per MWh. Medan den totala värdepoolen (betalning per MWh el) är högre för Tyskland, gynnas affärsfall i Sverige av högre livslängd för turbinerna.

This thesis is a study into the response and seismic safety of three-dimensional multi-storey concrete structures under concurrent orthogonal seismic excitations. It employs the nonlinear time-history method as its analysis tools. Time-history analyses rely heavily on their utilised earthquake records. Accordingly, this study examines the different approaches of selecting earthquake suites and develops a methodology of selecting representative earthquake scenarios. This methodology is credibly implemented in selecting a far- and a near field suites representative of the New Zealand seismic hazard. The study investigates the response of 6-, 9- and 12-storey concrete structures of different n-X-bays × m-Y-bays. Bidirectional responses of these considered structures are examined and consequently the current combination rules are scrutinised. Consequently this study strongly recommends the use of the 40-percent combination rule in lieu of the widely used 30-percent rule; and the use of time-history analysis in lieu of quasi/equivalent static and response modal analysis methods to avoid their strong dependence on combination rules. An intensive study is conducted employing the incremental dynamic analysis (IDA) technique to investigate structural demands of interstorey drifts, lateral storey drifts and storey accelerations. The study utilises the developed far-field suite and identifies the 50th and 90th percentile demands. Hence it provides easy-to-use expressions to facilitate rapid calculation of the structural demands and the effects of biaxial interactions. An implementation into the Demand and Capacity Factor Design (DCFD) format is presented that infers confidence in the performance levels of the considered structures. The study also draws attention to the importance of considering storey accelerations as their storey values reach as high as 10 × PGA. A sensitivity study is conducted by repeating the IDA investigation while using the developed near-field suite. Subsequently a comparison between the near- and the far-field results is conducted. The results were markedly similar albeit of less magnitudes until the (seismic hazard) intensity measure IM = Sa(T₁) = 0.4g when the near-field results show sudden flat large increase in demands suggesting a brittle collapse. This is attributed to the higher content of the higher mode frequencies contained in near-field ground motions. Finally, the study examines the (vectorial) radial horizontal shear demands in columns and beam-column joints of the previous far- and near-field studies. The combined radial shear demands in corner, edge and internal columns and joints are evaluated that roughly show a square-root proportional relationship with IM that exhibit somewhat brittle failure at IM ≥ 0.35g. Shears demands in the (4-way) internal columns and the (2-way) corner joints show highest magnitude in their respective class. The results suggest transverse joint shear reinforcement of 1.5, 1.0 and 0.5 of the longitudinal reinforcement of the neighbouring beam respectively for corner, edge and internal joints. An implementation of a proposed practical (and simpler) DCFD format shows satisfactory confidence in columns performance in shear up to IM = 0.35g, conversely to joints unsatisfactory performance in shear at the onset of inelastic behaviour (IM > 0.05g).