Large-scale Offshore Wind Farms Research Articles

Fatigue distribution optimization for offshore wind farms using intelligent agent control

ABSTRACTA novel control approach is proposed to optimize the fatigue distribution of wind turbines in a large‐scale offshore wind farm on the basis of an intelligent agent theory. In this approach, each wind turbine is considered to be an intelligent agent. The turbine at the farm boundary communicates with its neighbouring downwind turbines and organizes them adaptively into a wind delivery group along the wind direction. The agent attributes and the event structure are designed on the basis of the intelligent agent theory by using the unified modelling language. The control strategy of the intelligent agent is studied using topology models. The reference power of an individual wind turbine from the wind farm controller is re‐dispatched to balance the turbine fatigue in the power dispatch intervals. In the fatigue optimization, the goal function is to minimize the standard deviation of the fatigue coefficient for every wind turbine. The optimization is constrained such that the average fatigue for every turbine is smaller than what would be achieved by conventional dispatch and such that the total power loss of the wind farm is restricted to a few percent of the total power. This intelligent agent control approach is verified through the simulation of wind data from the Horns Rev offshore wind farm. The results illustrate that intelligent agent control is a feasible way to optimize fatigue distribution in wind farms, which may reduce the maintenance frequency and extend the service life of large‐scale wind farms. Copyright © 2012 John Wiley & Sons, Ltd.

A General Probabilistic Forecasting Framework for Offshore Wind Power Fluctuations

Accurate wind power forecasts highly contribute to the integration of wind power into power systems. The focus of the present study is on large-scale offshore wind farms and the complexity of generating accurate probabilistic forecasts of wind power fluctuations at time-scales of a few minutes. Such complexity is addressed from three perspectives: (i) the modeling of a nonlinear and non-stationary stochastic process; (ii) the practical implementation of the model we proposed; (iii) the gap between working on synthetic data and real world observations. At time-scales of a few minutes, offshore fluctuations are characterized by highly volatile dynamics which are difficult to capture and predict. Due to the lack of adequate on-site meteorological observations to relate these dynamics to meteorological phenomena, we propose a general model formulation based on a statistical approach and historical wind power measurements only. We introduce an advanced Markov Chain Monte Carlo (MCMC) estimation method to account for the different features observed in an empirical time series of wind power: autocorrelation, heteroscedasticity and regime-switching. The model we propose is an extension of Markov-Switching Autoregressive (MSAR) models with Generalized AutoRegressive Conditional Heteroscedastic (GARCH) errors in each regime to cope with the heteroscedasticity. Then, we analyze the predictive power of our model on a one-step ahead exercise of time series sampled over 10 min intervals. Its performances are compared to state-of-the-art models and highlight the interest of including a GARCH specification for density forecasts.

Stochastic Optimization Model for Electric Power System Planning of Offshore Wind Farms

In the coming years, an extensive development of large-scale offshore wind farms (OWFs) is foreseen in Europe. Electric power systems of OWFs need to be optimized in order to minimize investment and operational costs. This paper proposes a comprehensive decision support model that covers the three key factors that characterize the design of ac electric power systems of OWFs: investment costs of the components, system efficiency, and system reliability. Stochasticity of wind speed and reliability of the main system components are also considered. The main decisions concern the layout and the cross-sections of cable connections and the location of the central collection point for the medium voltage cables. GAMS language has been used to implement the model. It has been validated using a real OWF. An application example has also been carried out to explain the extension of the model to OWFs with dc power systems. The proposed model is useful for basic engineering design and as a decision tool for planning the electric power system of OWFs.

새만금 고군산군도의 풍자원 측정 및 분석

Saemankeum is well known for its high speed wind, and it is known that the blueprint of a future city around Saemankeum, including new industrial complex, has been planned. As a result, large-scale offshore wind farm, on the basis of the measurement of wind resource for a long time, can be considered, so that generated electricity can be used to meet the energy demand near the wind farm. Wind speed in Kokunsando of Saemankeum is measured and analyzed with its statistical distribution and wind directions. The probability of wind power resource over Kokunsando of Saemangeum is reviewed with the measured data in one island of Kokunsando. According to measured data, the shape and scale factor of Weibull distribution of wind speed are obtained, and then power density is analyzed as well. Through this study, it is clear that the Saemangeum area has a fluent and abundant wind power source to develop the wind farm in Korea.

Taiwan's First Large-Scale Offshore Wind Farm Connection—A Real Project Case Study With a Comparison of Wind Turbine

The west coast and islands of Taiwan have abundant wind resource, which offers a great opportunity for large-scale offshore wind power generation. In Taiwan, the first stage of the offshore wind farms at the Jhang-Bin and Penghu areas has been planned. In particular, the Jhang-Bin wind farm will become the first and one of the largest wind farms in Taiwan. Therefore, its impacts on system operation and security have to be investigated and studied in advance. Following a general connection design discussion, this paper is consist of four major system impact analyses: load flow, fault current, voltage variation, and transient stability. Moreover, three types of typical wind turbines have been adopted in this paper in order to compare their performances on the wind farm integration system. From the simulation results, some significant conclusion and recommendations have been extracted, which would contribute to the first offshore wind farm development in Taiwan.

Effect of Low-Voltage-Ride-Through Technologies on the First Taiwan Offshore Wind Farm Planning

Penghu, Taiwan, has the potential to be one of the most valuable sources of wind energy in the world. A 59-km submarine cable that connects Taiwan to Penghu Island is currently in the planning phase, and a large-scale offshore wind farm around Penghu will be developed. This will be the first offshore wind farm to be planned in Taiwan and will have a significant role in the development of renewable energy in this country. In the initial planning phase, various transient impact analyses must be performed. Low-voltage-ride-through (LVRT) capability is one of the most critical items to be analyzed. The main target of this paper is to investigate the effect of LVRT technologies on the first Taiwan offshore wind farm planning. It begins by investigating the development of LVRT technologies, and then discusses the effect of grid strength on the preferred LVRT installation. The critical range of faults that can disconnect the wind farm from the grid with and without LVRT has been studied. Finally, the effect of LVRT characteristics on the transient stability of the power system in Taiwan is evaluated and the strategy of replacing the LVRT installations with reactive power compensation elements is proposed.

QuikSCAT 위성 데이터를 이용한 한반도 주변의 해상 풍력자원 평가

In order to investigate the offshore wind resources, the measured data from the QuikSCAT satellite was analyzed from Jan 2000 to Dec 2008. QuikSCAT satellite is a specialized device for a microwave scatterometer that measures near-surface wind speed and direction under all weather and cloud conditions. Wind speed measured at 10 m above from the sea surface was extrapolated to the hub height by using the power law model. It has been found that the high wind energy prevailing in the south sea and the east sea of the Korean peninsula. From the limitation of seawater depth for piling the tower and archipelagic environment around the south sea, the west and the south-west sea are favorable to construct the large scale offshore wind farm, but it needs efficient blade considering relatively low wind speed. Wind map and monthly variation of wind speed and wind rose using wind energy density were investigated at the specified positions.

Offshore wind power development as affected by seascape values on the German North Sea coast

In Germany, the first permits have now been issued for the construction of large-scale offshore wind farms in the German Exclusive Economic Zone (EEZ). This paper focuses on perceptions of the local seascape and the role of aesthetic seascape qualities in shaping local attitudes to offshore wind farming. Based on a survey of local residents in the districts of Dithmarschen and North Frisia, it shows that aesthetic seascape perception alone cannot account for local attitudes to offshore wind farming. Three main aspects seem to come together to determine these attitudes: deeply held convictions of the sea as a natural space, deeply held views of the local landscape and linked to this local identity, and also perceptions of renewable energies in combination with attitudes to issues such as climate change and sea level rise. The paper draws some conclusions on the future of the sea as a natural space or energy space.

British wind continues to surge forward

Construction of the first turbine at the UK’s first large-scale offshore wind farm was completed in August. National Wind Power's North Hoyle Offshore Wind Farm, located 7.5km off the North Wales coast between Prestatyn and Rhyl in Denbighshire, is the first to be constructed of 17 seabed sites released for development by the Crown Estate in 2001 in 'Round One' of the UK’s offshore wind farm programme. A further seven of the ‘Round One’ sites already have the necessary planning consents and are due for construction in 2004–6. Secretary of State Patricia Hewitt recently launched the next phase of offshore wind energy development, 'Round Two', to be developed in three strategic areas around the UK. Together with continued development onshore, wind power in the UK is now set to generate around 8000 megawatts of clean green electricity by 2010 or three-quarters of the UK Government's targets for renewable energy. This is a short news story only. Visit www.re-focus.net for the latest renewable energy industry news.

An aggregate model of a grid-connected, large-scale, offshore wind farm for power stability investigations—importance of windmill mechanical system

An aggregate model of a large-scale offshore wind farm, comprising 72 wind turbines of 2 MW rating each, is set up. Representation of the shaft systems of the wind turbines shall be taken into account when a simplified aggregate model of the wind farm is used in voltage stability investigations. Because the shaft system gives a soft coupling between the rotating wind turbine and the induction generator, the large-scale wind farm cannot always be reduced to one-machine equivalent and use of multi-machine equivalents will be necessary for reaching accuracy of the investigation results. This will be in cases with irregular wind distribution over the wind farm area. The torsion mode of the shaft systems of large wind turbines is commonly in the range of 1–2 Hz and close to typical values of the electric power grid eigenfrequencies why there is a risk of oscillation between the wind turbines and the entire network. All these phenomena are different compared to previous experiences with modelling of conventional power plants with synchronous generators and stiff shaft systems.

95/06385 First industrial scale CYMIC at Rauma

Construction of the first turbine at the UK’s first large-scale offshore wind farm was completed in August. National Wind Power's North Hoyle Offshore Wind Farm, located 7.5km off the North Wales coast between Prestatyn and Rhyl in Denbighshire, is the first to be constructed of 17 seabed sites released for development by the Crown Estate in 2001 in 'Round One' of the UK’s offshore wind farm programme. A further seven of the ‘Round One’ sites already have the necessary planning consents and are due for construction in 2004–6. Secretary of State Patricia Hewitt recently launched the next phase of offshore wind energy development, 'Round Two', to be developed in three strategic areas around the UK. Together with continued development onshore, wind power in the UK is now set to generate around 8000 megawatts of clean green electricity by 2010 or three-quarters of the UK Government's targets for renewable energy.This is a short news story only. Visit www.re-focus.net for the latest renewable energy industry news.

95/06379 Advanced turbines hold the key to economic IGCC

Construction of the first turbine at the UK’s first large-scale offshore wind farm was completed in August. National Wind Power's North Hoyle Offshore Wind Farm, located 7.5km off the North Wales coast between Prestatyn and Rhyl in Denbighshire, is the first to be constructed of 17 seabed sites released for development by the Crown Estate in 2001 in 'Round One' of the UK’s offshore wind farm programme. A further seven of the ‘Round One’ sites already have the necessary planning consents and are due for construction in 2004–6. Secretary of State Patricia Hewitt recently launched the next phase of offshore wind energy development, 'Round Two', to be developed in three strategic areas around the UK. Together with continued development onshore, wind power in the UK is now set to generate around 8000 megawatts of clean green electricity by 2010 or three-quarters of the UK Government's targets for renewable energy.This is a short news story only. Visit www.re-focus.net for the latest renewable energy industry news.