The construction of traditional large-scale central power plants and the extension of power lines in Taiwan have tremendous difficulties in terms of land acquisition and environmental protection for a long time. In addition, one potential risk of energy supply is that over 95% of energy source is imported overseas. Therefore, the most important goal of Taiwan energy policy is to cut down the amount of energy import. To achieve the goal, it is important to explore innovatively local energy source by developing renewable and clean energy. Around the available renewable energy technologies, wind power technique is the most mature one in addition to hydraulic power generation. However due to limited land resources and restrictive regulations, it is expected that wind farm development in Taiwan can only be located offshore, instead of inland. Besides, a multi-functional wind farm site, which involves ocean farm ranch, is desirable to bring mutual benefits for both developers and local stake holders. The current study has used System Dynamics(SD) to analyze the influence of Multi-functional offshore wind farm on economic. We discuss the change of fish catch with building offshore wind farm¡Aand the change of economic output in open ocean with offshore wind farm combine marine ranching. It is therefore easy for the decision makers to comprehend the economical benefit difference if an offshore multi-functional wind farm were to develop in the future. The result of this study is building offshore wind farm will reduced the fishing revenue in a short time¡Abut the total fishing revenue will increased in a long time. The Multi-functional offshore wind farm has better economic output than offshore wind farm.

The interest in the utilization of offshore wind power is increasing significantly. Due to the shortage of in-land locations for wind farm and the wind speed offshore is potentially higher than that of onshore, which leads to a much higher power production. In this thesis a large offshore wind farm is modeled using Matlab simulation package. In the simulations active stall regulated wind turbines driving fixed speed asynchronous generators are used. Two different types of interconnections are modeled and compared, one is the Voltage Source Converter (VSC) based HVDC link and the other one uses high voltage AC (HVAC) cable interconnection. Transmission faults are simulated in each system and the transient response are examined. Three phase fault and single line to ground fault are used to compare the performance of the VSC based HVDC interconnection system and HVAC interconnection. It is found that compared to the traditional HVAC transmission, the VSC based HVDC transmission would have better performance under various system disturbances.

Wind power, as a source of renewable energy, is growing very fast. Especially so, is consideration given to offshore wind farms where expansion is due in part to limited social and visual impact, reduced noise effect of turbines, and at the same time higher production of offshore wind turbines. Maintenance is always a considerable and costly part of the wind power investment, especially for offshore projects, but it could not improve as fast as the increasing wind industry in the world. The operation and maintenance management of wind farms should have always a reliable and structured planning to have an economical investment. At the beginning of the growth of wind industry, companies tried to transfer responsibilities of the failure and loss of production to the insurance companies, but it cannot be continued any more. These days even the insurance companies ask about regular inspection or condition monitoring. In other words, they ask for a reliable strategy for operation and maintenance. Both preventative and corrective maintenance are used in offshore wind farms. Preventive maintenance is usually performed at the first sign of failure, and in so doing it helps reduce costs associated from lost production. Having a perfect preventive maintenance program is not easy and it usually needs more inspection and online monitoring. To select a suitable strategy, data should be gathered from different stakeholders who are involved in the project. The stakeholders could be turbine designers, construction companies, transportation companies, operation staff, etc. The reason is that each group has the data which could help to define a reliable strategy of maintenance. Reliability includes measurements, e.g., failure rate, repair time, and availability. Reliability is the ability of components or system to perform their function under given operational condition and for a predicted period of time. However always preventive maintenance especially for offshore wind farm is faced with uncertainty due to bad weather, access difficulty, and logistic limitation. Reliability Centered Maintenance (RCM) is a systematic qualitative technique that balances preventive and corrective maintenance. It chooses the right preventive maintenance activities for the right component at the right time to reach the most cost efficient solution. This research points out that RCM, as an experienced methodology in other industries, could be a good method for scheduled preventive maintenance in offshore wind power for purposes of lowering cost while improving reliability and safety. RCM implementation is always facing with uncertainty. Engaged uncertainty to RCM is known as Reliability and Risk Centered Maintenance RRCM and it could lead maintenance process to an optimal preventive schedule with minimum uncertainty.

Abstract   The permit application process for offshore wind farms (OWF) in Sweden conceivably requires a comprehensive and transparent complement within risk management. The NETEP framework (covering risks concerning navigation, economics, technology, environment and politics), based on a futures planning mechanism (STEEP) has consequently been brought forward as a structure for the application of FMECA (Failure Mode, Effects, and Criticality Analysis) methodology to the permit application process of the Swedish offshore wind farm sector. FMECA, originating from the aeronautical and automobile industries, presents a systematic method for the prediction of future failure in a product, part or process, to evaluate the consequences of that failure and to suggest possible measures for its mitigation or eradication. Its application to attitude and acceptance, safety and environmental effect remains, however, limited which creates the research gap for this thesis. Three Swedish offshore wind farm (OWF) projects in the Baltic Sea area (Lillgrund, Taggen and Trolleboda) were put forward as case studies for use in the evaluation of the proposed FMECA-NETEP methodology, which was approached in two stages. The first evaluation stage results showed that the model accommodates the precautionary principle, the consideration of stakeholder viewpoints, the mitigation of negative effects, the analysis of alternative sites, the observation of relevant legislation and the utilisation of contemporary research. In the subsequent stage of evaluation, the factor for incorporation into the adapted model was intra- and inter-sector cumulative impact. Results showed that positive cumulative impact cannot be illustrated by the model whereas neutral and negative cumulative impact can.  The model’s added value is that it facilitates decision making by providing a rigorous, transparent and structured methodology, the holistic approach of which provides a sound basis for the incorporation of contemporary research.

The increasing global participation of wind power in the overall generation ca- pacity makes it one of the most promising renewable resources. Advances in power electronics have enabled this market growth and penetration. Through a literature review, this work explores the challenges and opportunities presented by offshore wind farms, as well as the different solutions proposed concerning power electron- ics converters, collection and transmission schemes, as well as control and protection techniques. A novel power converter solution for the parallel connection of high power offshore wind turbines, suitable for HVDC collection and transmission, is presented. For the parallel operation of energy sources in an HVDC grid, DC link voltage con- trol is required. The proposed system is based on a full-power rated uncontrolled diode bridge rectifier in series with a partially-rated fully-controlled thyristor bridge rectifier. The thyristor bridge acts as a voltage regulator to ensure the flow of the desired current through each branch, where a reactor is placed in series for filtering of the DC current. AC filters are installed on the machine side to mitigate harmonic content. The mathematical modeling of the system is derived and the control design procedure is discussed. Guidelines for equipment and device specifications are pre- sented. Different setups for an experimental framework are suggested and discussed, including a conceptual application for hardware-in-the-loop real-time simulation and testing.

No description available.

Reef habitats built by the tubiculous polychaete Sabellaria spinulosa have been identified as a habitat with significant conservation importance, based on their historic decline across Europe and the assumption that, like many other biogenic reef systems, S. spinulosa reefs enhance biodiversity. Despite the high conservation status of this habitat very little work has been undertaken to explore the role that S. spinulosa reefs play in marine ecosystems, or their sensitivity to anthropogenic disturbance. Observations of the reproductive ecology and population dynamics of the reef building organism indicate that S. spinulosa exhibit life-history traits typically associated with r-strategists, indicating that this species is likely to have the ability to recover quickly following most anthropogenic disturbance events. A series of surveys on S. spinulosa reefs identified at the Thanet Offshore Wind Farm site, where the extent of the reef habitat was found to have increased between the pre-construction and post construction survey despite extensive cable laying and turbine installation, corroborates these findings. Detailed investigations into the macrofauna associated with S. spinulosa reefs in the eastern English Channel revealed that S. spinulosa reefs support macrofaunal communities that are comparable to those associated with adjacent muddy sandy gravel and gravelly muddy sand in terms of species composition, taxonomic breadth and beta-diversity. A consistent enhancement in species richness, abundance and biomass was identified in samples collected from S. spinulosa reefs when compared with adjacent sedimentary deposits, as well as a corresponding reduction in the equitability of species, indicating that some macrofauna are able to exist in higher densities within this habitat. The increase in macrofaunal biomass associated with S. spinulosa reefs was found to influence the diet of demersal fish species, with some species feeding on the reef organism itself while others feed on species found in high densities on the reefs. The high abundance of juvenile flatfish associated with this habitat also suggests that S. spinulosa reefs may provide an important nursery habitat.

No description available.

Offshore wind farm (OWF) construction in the UK is progressing rapidly alongside increasing spatial pressures on marine ecosystems and social and economic activities. A need for increased protection of habitats, species and ecological processes that support environmental and economic benefits is being met by designation of marine protected areas (MPAs). Mitigation and spatial planning solutions are required to enable protection of vital ecological habitats, features and processes and support sustainable economic development. A potential solution is to co-locate OWFs and MPAs. This study uses a multi-disciplinary approach to examine if evidence on the environmental effects of existing OWFs and associated effects on fishing activity (as an existing resource use) benefits MPA goals. Through a systematic review and meta-analyses of existing data, knowledge of OWF effects on species abundance and economic effects on fishing were identified as key evidence gaps. The ecological evidence need was approached through a case study of ecological effects of North Hoyle OWF, North Wales, UK, using existing pre and post-construction monitoring data, as well as primary baited remote underwater video data, collected 5 years later (8 years post-construction). Results suggested habitat and species recovered to a stable state that showed some community differences to pre-construction conditions. The presence of OWF monopiles is likely to have increased existing heterogeneity of substratum and increased opportunities for scavenging species. Species benefitting and disadvantaged by habitat provided within the OWF reflected meta-analyses trends. Extended baseline monitoring to provide confident identification of natural levels of variation in sediment and fauna was lacking. Analysis of fishing activity and landings before and after OWF construction in three UK case study regions approached effects on resource users. Fishing activity in the three case study areas showed broad scale similarity to national trends. Small-scale activity patterns indicated greater reductions in mobile (towed) fishing gear effort near to operating OWFs than in static gear activity (using pots or static nets). Semi-structured interviews conducted with fishermen in each region revealed loss of ground and disruption as negative effects from OWFs, in addition to existing pressures. Benefits including habitat creation and species augmentation, as well as reduction of cumulative lost ground, were identified by fishermen from co-location of MPAs and OWFs. Ecological effects of OWFs suggested benefits from habitat creation, species augmentation and potential for protection of sandbank habitats between monopiles. Mitigation requirements were identified to maximise these potential benefits to an MPA network.

With the rapid expansion of offshore wind power capacity in the world in the last decade, innovative offshore solutions are designed in order to meet the upcoming power capacity installations. As in all other energy sectors, offshore wind power has certain conditions that have to be met to increase the efficacy of the outcome.In this thesis, wake effect impact on the production results of Hexicon AB’s innovative floating and rotating offshore wind power platform project with 3 turbines located in the southern part of Sweden are analyzed through the application of “Analytical wake models” and the “Actuator Disc method”, with the help of WindSim.The results of Analytical models and Actuator Disc method were found to be independent of one another. Even though analytical wake models did not find any wake effect impact among the turbines, the results can be considered as logical. However, the Actuator Disc method created unexpected results which might stem from the WindSim – AD combination. It is therefore recommended to further explore these scenarios with other (more) advanced simulation tools.