Wind power in the Danish liberalised power market-Policy measures, price impact and investor incentives

International Nuclear Information System (INIS)

Munksgaard, Jesper; Morthorst, Poul Erik

2008-01-01

Wind power has a strong position at the Danish electricity market, mainly caused by high feed-in tariffs in the 1990s. Investments in new wind-power installations on land, however, have declined dramatically after the Danish electricity market was liberalised in 1999. First, the paper describes how policy measures directed towards wind power have been redesigned to match the liberalised market. Then, we estimate the impact of the redesigned tariffs on the electricity prices. Finally, we assess whether the new tariffs make an incentive to invest in wind power. The paper concludes that the new tariffs not by itself make evidence for the actual Danish recession in new wind-power installations after the electricity reform. The main causes could include a combination of problems in spatial planning, high risk aversion of new wind turbine investors and perhaps more favourable support schemes in other countries

Early warnings of extreme winds using the ECMWF Extreme Forecast Index

DEFF Research Database (Denmark)

Petroliagis, Thomas I.; Pinson, Pierre

2014-01-01

The European FP7 SafeWind Project aims at developing research towards a European vision of wind power forecasting, which requires advanced meteorological support concerning extreme wind events. This study is focused mainly on early warnings of extreme winds in the early medium-range. Three synoptic...... regimes. Overall, it becomes clear that the first indications of an extreme wind event might come from the ECMWF deterministic and/or probabilistic components capturing very intense weather systems (possible windstorms) in the medium term. For early warnings, all available EPS Extreme Forecast Index (EFI......) formulations were used, by linking daily maximum wind speeds to EFI values for different forecast horizons. From all possible EFI schemes deployed for issuing early warnings, the highest skill was found for the Gust Factor formulation (EFI-10FGI). Using EFI-10FGI, the corresponding 99% threshold could provide...

Extreme winds in the Western North Pacific

Energy Technology Data Exchange (ETDEWEB)

Ott, S.

2006-11-15

A statistical model for extreme winds in the western North Pacific is developed, the region on the Planet where tropical cyclones are most common. The model is based on best track data derived mostly from satellite images of tropical cyclones. The methods used to estimate surface wind speeds from satellite images is discussed with emphasis on the empirical basis, which, unfortunately, is not very strong. This is stressed by the fact that Japanese and US agencies arrive at markedly different estimates. On the other hand, best track data records cover a long period of time and if not perfect they are at least coherent over time in their imperfections. Applying the the Holland model to the best track data, wind profiles can be assigned along the tracks. From this annual wind speed maxima at any particular point in the region can be derived. The annual maxima, in turn, are fitted to a Gumbel distribution using a generalization Abild's method that allows for data wind collected from multiple positions. The choice of this method is justified by a Monte Carlo simulation comparing it to two other methods. The principle output is a map showing fifty year winds in the region. The method is tested against observed winds from Philippine synoptic stations and fair agreement is found for observed and predicted 48 year maxima. However, the almost biasfree performance of the model could be fortuitous, since precise definitions of 'windspeed' in terms averaging time, height above ground and assumed surface roughness are not available, neither for best tracks nor for the synoptic data. The work has been carried out under Danish Research Agency grant 2104-04-0005 'Offshore wind power' and it also covers the findings and analysis carried out in connection with task 1.6 of the project 'Feasibility Assessment and Capacity Building for Wind Energy Development in Cambodia, The Philippines and Vietnam' during 2005-06 under contract 125-2004 with EU

Analysis of the energy production of Danish wind turbines 1981-1992

International Nuclear Information System (INIS)

Godtfredsen, F.

1995-10-01

A study of 1981-1992 energy production from Danish wind turbines has been carried out. The study is based on production data from the greater part of Danish wind turbines, as reported by the turbine owners and published in the magazine Naturlig Energi. The study shows a significant rise in the average energy production from 55 kW turbines erected in the early eighties to modern 150-500 kW turbines erected in 1992. The average yearly energy production of new turbines raised from rather more than 400 MWh per square meter swept rotor area in 1981 to 750-900 MWh in 1992. The main reasons for this increase are the development of larger wind turbines (with larger generator capacity, rotor area and hub height), more efficient turbines. (au) 18 tabs., 14 ills., 8 refs

New developments in the Danish Wind Energy Policy

Energy Technology Data Exchange (ETDEWEB)

Lemming, J. [Danish Energy Agency, Copenhagen (Denmark)

1996-12-31

Wind energy resources in Denmark are among the best in Europe. In recent years there has been a rapid growth in number of wind turbines connected to the grid in Denmark. By the end of 1995 more than 3800 wind turbines were installed on-shore with a capacity of over 600 MW. The total production of electricity from these turbines in 1995 was more than 1200 GWh, corresponding to approximately 3.6 % of the Danish electricity consumption. For several years Denmark has pursued an energy policy with an increasing weight on environmental aspects and new and renewable energy sources like wind energy. Therefore wind energy already plays an important part as supplement to the traditional sources of fuel in the electricity production, and the share of wind energy and other renewables is expected to increase significantly in the years to come. 1 ref., 9 figs.

Strategy for Danish wind energy research; Startegi for dansk vindenergiforskning

Energy Technology Data Exchange (ETDEWEB)

NONE

2004-07-01

The objective of the strategy for Danish wind energy research is to support future prioritizations - primarily as regards publicly funded programs. Most recent energy political objectives formulated in 2004 by the Danish Ministry of Economic and Business Affairs state: 'The objective of the governmental energy policy is to create efficient energy markets within a framework that secures cost efficiency, security of supplies, environmental considerations and efficient use of energy. The markets must be transparent and the competition must be fair. This will secure the energy consumers the lowest possible energy prices.' The wind energy strategy mirrors user needs and is, among other things, based upon a number of interviews with interested parties and a hearing on the strategy draft. (BA)

Extreme gust wind estimation using mesoscale modeling

DEFF Research Database (Denmark)

Larsén, Xiaoli Guo; Kruger, Andries

2014-01-01

, surface turbulence characteristics. In this study, we follow a theory that is different from the local gust concept as described above. In this theory, the gust at the surface is non-local; it is produced by the deflection of air parcels flowing in the boundary layer and brought down to the surface...... from the Danish site Høvsøre help us to understand the limitation of the traditional method. Good agreement was found between the extreme gust atlases for South Africa and the existing map made from a limited number of measurements across the country. Our study supports the non-local gust theory. While...... through turbulent eddies. This process is modeled using the mesoscale Weather Forecasting and Research (WRF) model. The gust at the surface is calculated as the largest winds over a layer where the averaged turbulence kinetic energy is greater than the averaged buoyancy force. The experiments have been...

Wind energy development in China (WED) — The Danish-Chinese collaboration project

DEFF Research Database (Denmark)

Xu, Zhao; Rosenberg, H.; Sørensen, Poul Ejnar

2009-01-01

This paper reports the large scale bilateral development program- the Danish-Chinese wind energy development program (WED). The paper starts with overview of electric energy production and consumption in the two counties with special focus on wind energy status. Next, the detailed objectives...

Danish offshore wind. Key environmental issues - a follow-up

Energy Technology Data Exchange (ETDEWEB)

NONE

2013-02-15

This follow-up to the Danish environmental monitoring programme on large-scale offshore wind power builds on the result of the former programme of 2006 and focuses on updated knowledge on harbour porpoises, water birds and fish communities, and on the cumulative effects of wind farms. The scientific quality of the projects in this follow-up has been assessed by experts from the International Advisory Panel of Experts on Marine Ecology (IAPEME), who have commented on the results in an independent evaluation which is reproduced in this publication. (LN)

The Danish large wind turbine program. [feasibility of wind power in a utility grid

Science.gov (United States)

Pederson, B. M.

1979-01-01

A brief description of the Danish wind energy program and its present status is given. Results and experiences from tests on the Gedser windmill (200 kW) are presented. The key results are presented from the preliminary design study and detailed design of two new WECS (630 kW each) is described.

Regional tendencies of extreme wind characteristics in Hungary

Science.gov (United States)

Radics, Dr.; Bartholy, Dr.; Péliné

2009-09-01

Human activities have substantial effects on climate system. It has already accepted that change in the long-term climatic mean state will have significant consequences in the global economy and society, but the most important effects of climate change may come from changes in the intensity and frequency of climatic extremes. It is therefore of great interest to document the extremes of surface wind that could assist in estimating the regional effects of climate change. The research presented is based on 34-year-long (1975-2008) wind (speed, direction, and wind gust) data sets of 36 Hungarian synoptic meteorological stations. After processing (including digitalisation of old instrumental records, quality control and homogenisation of wind time series) the measured wind data sets, time series and complex wind climate analysis were carried out. Spatial and temporal distributions of mean and extreme wind climate characteristics were estimated, wind extremes and trends were interpolated and mapped over the country. Finally, measured and reanalysed (ERA40) wind data were compared over Hungary, in order to verify not only the validity of ERA40 reanalysed data sets, but the adaptability of climate simulation results in estimation of regional climate change effects.

Integration of Wind Power into the Danish Power System

DEFF Research Database (Denmark)

Rácz, Viktor J.; Yadav, Priyadarshini; Vestergaard, Niels

Wind energy is a major player in the Danish electricity market with an ambitious goal to pursue 50% of the electricity market by 2020. This paper examines the economic impacts of increasing integration of large-scale wind power to the existing electrical grid. Firstly, we survey the literature...... the price of electricity. We have observed the degree of influence of the fossil fuel prices, total demand, wind power production and import on the electricity price and the individual co-efficiency for the years 2000, 2005 and 2010, according to the energy mix. Using a grid management model for the Western...... Denmark region, we simulate the effect of an increase in wind penetration level on the electricity generation costs and on the CO2 emissions at various penetration levels. The results show that as the wind penetration level increases the cost of electricity production rises thus, reducing the CO2 emission...

Danish-Czech wind resource know-how transfer project. Final report

Energy Technology Data Exchange (ETDEWEB)

Rathmann, O.; Noergaerd, P.; Frandsen, S.

2004-06-01

The course of the Danish-Czech Wind Resource Know-how Transfer Project is reported. The know-how transfer component of the project has consisted in performing a wind resource training work-shop for about 13 individuals from the Czech Republic, ranging from scientists to wind farm project developers, and in donating modern software for evaluating wind resources. The project has also included a review of a Czech overview-study of wind speeds inside the country as well as an investigation of the electricity tariffs and their impact on wind energy utilization in the Czech Republic. A problematic existing Czech wind farm project, locked up in a no-production situation, was also addressed. Not until the purchase by a new owner-company, which initiated the necessary repair and maintenance, the wind farm resumed normal operation. As its last task, the present project assisted in consolidating future operation through a helping package consisting of a training course for the wind farm technicians and in a package of relevant spare parts. (au)

Wind energy development: Danish experiences and international options

International Nuclear Information System (INIS)

Frandsen, S.; Hasted, F.; Josephsen, L.; Nielson, J.H.

1989-01-01

In Denmark, wind energy makes a visible contribution to energy planning. Since 1976, over 1,800 wind turbine units have been installed in Denmark, representing a capacity of ca 140 MW out of a grid capacity of 8,000 MW. These units are all grid-connected and the unit sizes range from 55 kW to 400 kW. The installed wind energy capacity represents a substantial development of technologies for wind energy utilization during the last 15 years, involving participation from research institutes, electric utilities, private industry, and the national energy administration. A considerable improvement of the technical and economic performance of wind turbines, along with increased reliability and durability, has been strongly supported by comprehensive government programs. In 1985, another large construction program was initiated which will add 100 MW wind power capacity by the end of 1990. Parallel with commercial development, Danish utilities have developed and constructed a number of megawatt-size wind turbines on a pilot basis. In general terms the wind energy resources in Denmark are rather good, and many suitable sites exist, but installed wind energy capacity is limited by the high population density. Consequently, research is being conducted on the feasibility of offshore wind turbines. In other countries, wind energy developments similar to those in Denmark are taking place. In communities with no connection to the national grid, special attention should be paid to hybrid systems such as wind-diesel and hydro-wind systems. A substantial transfer of technology is required for facilitating significant development of hybrid systems in developing countries. 11 refs., 7 figs., 2 tabs

Offshore wind resources at Danish measurement sites

Energy Technology Data Exchange (ETDEWEB)

Barthelmie, R J; Courtney, M S; Lange, B; Nielsen, M; Sempreviva, A M [Risoe National Lab., Dept. of Wind Energy and Atmospheric Physics, Roskilde (Denmark); Svenson, J; Olsen, F [SEAS, Haslev (Denmark); Christensen, T [Elsamprojekt, Fredericia (Denmark)

1999-03-01

In order to characterise wind and turbulence characteristics at prospective offshore wind energy sites, meteorological observations from a number of purpose-built offshore monitoring sites have been analyzed and compared with long wind speed time series. New analyses have been conducted on the data sets focussing on meteorology, turbulence, extreme winds and wind and wave interactions. Relationships between wind speed, turbulence and fetch are highly complex. Minimum turbulence intensity offshore is associated with wind speeds of about 12 m/s. At lower wind speeds, stability effects are important while at higher winds speeds wind and wave interactions appear to dominate. On average, turbulence intensity offshore at 48 m height is approximately 0.08 if no coastal effects are present. However, the effect of the coastal discontinuity persists in wind speed and turbulence characteristics for considerable distances offshore. The majority of the adjustment of appears to occur within 20 km of the coast. (au)

Effects of the North Atlantic Oscillation and wind waves on salt marsh dynamics in the Danish Wadden Sea

DEFF Research Database (Denmark)

Kim, Daehyun; Grant, William E.; Cairns, David M.

2013-01-01

Long-term eustatic sea-level variation has been recognized as a primary factor affecting the hydrological and geomorphic dynamics of salt marshes. However, recent studies suggest that wind waves influenced by atmospheric oscillations also may play an important role in many coastal areas. Although...... this notion has been conceptually introduced for the Wadden Sea, no modeling attempts have been made yet. As a proof of concept, this study developed a simulation model using the commercially available STELLAA (R) software, based on long-term data on water level and sedimentation collected at a back......-barrier marsh on the Skallingen peninsula in Denmark. In the model, the frequency (number year(-1)) of wind-driven extreme high water level (HWL) events (> 130 cm Danish Ordnance Zero) was simulated in terms of the North Atlantic Oscillation (NAO) index. Then, surface accretion (cm year(-1)) and submergence...

Danish-Czech wind resource know-how transfer project. Interim report 2002

Energy Technology Data Exchange (ETDEWEB)

Rathmann, O.; Noergaerd, P.; Frandsen, S.

2003-12-01

The progress of the Danish-Czech Wind Resource Know-how Transfer Project is reported. The know-how transfer component of the project has consisted in performing a wind resource training workshop for about 13 individuals from the Czech Republic, ranging from scientists to wind farm project developers, and in donating modern software for evaluating wind resources. The project has also included a review of a Czech overview-study of wind speeds inside the country as well as a study of the electricity tariffs and their impact on wind energy utilization in the Czech Republic. A problematic existing Czech wind farm project, locked up in a no-production situation, was also addressed. However, this situation turned out to be related to problems with economy and owner-ship to a higher degree than to low wind resources and technical problems, and it was not possible for the project to point out a way out of this situation. (au)

Wind turbines in Danish waters - a survey of the authorities' interests, evaluations and recommendations

International Nuclear Information System (INIS)

1995-02-01

The document produced by a committee under the Danish Ministry for Energy and the Environment aims at meeting the current need for clarifying potentials for placing wind turbine arrays in Danish waters. It deals with (a) marine areas which are of especial interest, a fact which would be a barrier for the establishment of wind turbine arrays, and with (b) marine areas in connection with which permission to establish such arrays is only granted after serious consideration of local needs and interests. In connection with (a) special interests are defined: areas with a bird-life protected by European Union (EU) legislation, conservation areas, land where raw materials can be mined etc., places where buildings or ruins etc, of cultural/historical interest are to be found, military training grounds, principal shipping routes, cable and piping locations, or areas where a bridge is planned to be built. In connection with (b), local interests are defined as fishing areas, places included in landscaping projects, areas where there are large numbers of birds, harbours, areas near airports, radio or navigations systems etc., areas where raw materials are to be found, places where Stone Age habitations exist, marine areas where private yachts are sailed, military training areas, etc. A number of Danish fjords are mentioned as being included in the survey which should result in the choice of Danish waters where wind farm arrays could be established. (AB) 15 maps

Integration of electric drive vehicles in the Danish electricity network with high wind power penetration

DEFF Research Database (Denmark)

Chandrashekhara, Divya K; Østergaard, Jacob; Larsen, Esben

2010-01-01

/conventional) which are likely to fuel these cars. The study was carried out considering the Danish electricity network state around 2025, when the EDV penetration levels would be significant enough to have an impact on the power system. Some of the interesting findings of this study are - EDV have the potential......This paper presents the results of a study carried out to examine the feasibility of integrating electric drive vehicles (EDV) in the Danish electricity network which is characterised by high wind power penetration. One of the main aims of this study was to examine the effect of electric drive...... vehicles on the Danish electricity network, wind power penetration and electricity market. In particular the study examined the effect of electric drive vehicles on the generation capacity constraints, load curve, cross border transmission capacity and the type of generating sources (renewable...

Analysis of power curves of Danish and foreign wind turbines

International Nuclear Information System (INIS)

Petersen, H.

1995-12-01

This report describes an analysis of power curves for a number of wind turbines, 30 Danish and 17 foreign - European - wind turbines. The investigation is limited to wind turbines of 150 kW capacity and greater, and to wind turbines for which a power curve is available. The power curves are transformed into a common, uniform presentation in order to facilitate the succeeding treatment, which primarily is the calculation of the production of electrical energy yielded per year. From the known data of the wind turbine, equipped generator power and rotor area and the area swept by the blades, the specific electrical production is calculated in three terms: yield per square meter of rotor area, yield per kW generator power and yield per square meter and per kilowatt generator power. Based on these findings a number of comparisons are established, such as comparisons of conceptual designs and technical- economical evaluations. (au)

Estimation of extreme wind speeds in the mixed strong wind climate of South Africa

CSIR Research Space (South Africa)

Kruger, AC

2010-08-01

Full Text Available wind-generating mechanisms for Australia. Annual extreme wind speeds are generated by different mechanisms, forthcoming from thunderstorm activity and the passages of extratropical low pressure systems, which were identified. Separate extreme value...

Gravo-Aeroelastic Scaling for Extreme-Scale Wind Turbines

Energy Technology Data Exchange (ETDEWEB)

Fingersh, Lee J [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Loth, Eric [University of Virginia; Kaminski, Meghan [University of Virginia; Qin, Chao [University of Virginia; Griffith, D. Todd [Sandia National Laboratories

2017-06-09

A scaling methodology is described in the present paper for extreme-scale wind turbines (rated at 10 MW or more) that allow their sub-scale turbines to capture their key blade dynamics and aeroelastic deflections. For extreme-scale turbines, such deflections and dynamics can be substantial and are primarily driven by centrifugal, thrust and gravity forces as well as the net torque. Each of these are in turn a function of various wind conditions, including turbulence levels that cause shear, veer, and gust loads. The 13.2 MW rated SNL100-03 rotor design, having a blade length of 100-meters, is herein scaled to the CART3 wind turbine at NREL using 25% geometric scaling and blade mass and wind speed scaled by gravo-aeroelastic constraints. In order to mimic the ultralight structure on the advanced concept extreme-scale design the scaling results indicate that the gravo-aeroelastically scaled blades for the CART3 are be three times lighter and 25% longer than the current CART3 blades. A benefit of this scaling approach is that the scaled wind speeds needed for testing are reduced (in this case by a factor of two), allowing testing under extreme gust conditions to be much more easily achieved. Most importantly, this scaling approach can investigate extreme-scale concepts including dynamic behaviors and aeroelastic deflections (including flutter) at an extremely small fraction of the full-scale cost.

Extreme Winds from the NCEP/NCAR Reanalysis Data

DEFF Research Database (Denmark)

Larsén, Xiaoli Guo; Mann, Jakob

2009-01-01

wind. We examined extreme winds in different places where the strongest wind events are weather phenomena of different scales, including the mid-latitude lows in Denmark, channelling winds in the Gulf of Suez, typhoons in the western North Pacific, cyclones in the Caribbean Sea, local strong winds...

Danish wind turbines: Technical-economic feasibility of commercial models

International Nuclear Information System (INIS)

Falchetta, M.

1992-01-01

This feasibility study examines the principal technical and economic (investment-manufacturing-installation-operation unit costs, supply and demand) characteristics of wind turbines being commercialized in Denmark. The general configuration of the 150 to 450 kW range machines currently being manufactured can be described as that of a three bladed fibreglass rotor, of from 24 to 35 meters in diameter, and mounted on a tower of from 29 to 41 meters in height. The electrical system consists of one asynchronous generator or a two generator system with a power ratio of 1 to 5 between the two generators. The cost analysis reveals that the Danish wind turbines are competitively priced, with per kWh costs varying from $0. 0675 to $0. 040 for operating wind speeds ranging from 5 to 7 m/sec, and that their overall design and performance characteristics make them suitable for Italian site conditions

A review of Danish integrated multi-energy system flexibility options for high wind power penetration

DEFF Research Database (Denmark)

Wang, Jiawei; Zong, Yi; You, Shi

2017-01-01

The current status of wind power and the energy infrastructure in Denmark is reviewed in this paper. The reasons for why Denmark is a world leader in wind power are outlined. The Danish government is aiming to achieve 100% renewable energy generation by 2050. A major challenge is balancing load...

Wind structure during mid-latitude storms and its application in Wind Energy

DEFF Research Database (Denmark)

Larsén, Xiaoli Guo; Du, Jianting; Bolanos, Rodolfo

2015-01-01

in Denmark. The extreme wind and wave conditions in the coastal area for wind energy application are important but have rarely been studied in the literature. Our experiments are done to the Danish coasts where the mid-latitude depression systems are causes of the extreme wind and wave conditions....... The numerical modeling is done through an atmosphere-wave coupled system, where the atmospheric model is the Weather Research and Forecasting (WRF) model and the wave model is the Simulating WAves Nearshore (SWAN) model. Measurements from offshore stations, Horns Rev and the FINO platform, as well as satellite...... and the modeling will be presented. Here the “key” is referring both to the application of wind energy and the wind-wave coupling system. The various parameterization of the interface parameter for the atmospheric and wave modeling, the roughness length, has been examined. Data analysis reveals the importance...

Operational experience of extreme wind penetrations

Energy Technology Data Exchange (ETDEWEB)

Estanqueiro, Ana [INETI/LNEG - National Laboratory for Energy and Geology, Lisbon (Portugal); Mateus, Carlos B. [Instituto de Meteorologia, Lisboa (Portugal); Pestana, Rui [Redes Energeticas Nacionais (REN), Lisboa (Portugal)

2010-07-01

This paper reports the operational experience from the Portuguese Power System during the 2009/2010 winter months when record wind penerations were observed: the instantaneous wind power penetration peaked at 70% of consumption during no-load periods and the wind energy accounted for more than 50% of the energy consumed for a large period. The regulation measures taken by the TSO are presented in the paper, together with the additional reserves operated for added system security. Information on the overall power system behavior under such extreme long-term wind power penetrations will also be addressed. (org.)

Large-scale integration of off-shore wind power and regulation strategies of cogeneration plants in the Danish electricity system

DEFF Research Database (Denmark)

Østergaard, Poul Alberg

2005-01-01

The article analyses how the amount of a small-scale CHP plants and heat pumps and the regulation strategies of these affect the quantity of off-shore wind power that may be integrated into Danish electricity supply......The article analyses how the amount of a small-scale CHP plants and heat pumps and the regulation strategies of these affect the quantity of off-shore wind power that may be integrated into Danish electricity supply...

How good are remote sensors at measuring extreme winds?

NARCIS (Netherlands)

Sathe, A.R.; Courtney, M.; Mann, J.; Wagner, R.

2011-01-01

This article describes some preliminary efforts within the SafeWind project, aimed to identify the possible added value of using wind lidars to detect extreme wind events. Exceptionally good performance is now regularly reported in the measurement of the mean wind speed with some wind lidars in flat

Wind energy development in the light of Danish experiences

International Nuclear Information System (INIS)

Frandsen, S.

1991-01-01

Wind energy will undoubtedly play a significant role in the future energy supply being a nonpolluting energy source, which on a technical basis has proved to be an economically feasible and thus a realistic alternative to traditional power production. This conclusion may be drawn from Danish experiences where energy planning comprises a visible contribution from wind energy. Since 1976 more than 3200 wind turbine units have been installed in Denmark, representing a capacity of roughly 340 MW out of a grid capacity of 8,000 MW. These units are all grid-connected and the unit sizes range from 55 kW to 450 kW. The installed wind energy capacity represents a substantial development of technologies for wind energy utilization during the last 15 years, involving participation from many sides: research institutes, electric utilities, the national energy administration, and private industry. The development has implied a considerable improvement of the technical and economic performance of wind turbines along with increased reliability and durability. The successful development has been strongly supported by comprehensive government programmes, i.e. establishment of a national wind energy research programme, establishment of the Riso Test Station for Windmills and a subsidy scheme for private turbine owners. The improved economic performance is partly the result of a development in rotor size of commercially available wind turbines. In 1981 the largest commercial wind turbine size in Denmark was 55 kW, while today it is close to 500 kW. In the same period the average energy production per installed unit capacity almost doubled, due to enhanced aerodynamic rotor design, increased tower height and improved overall design and production methods. (author) 7 figs., 3 tabs., 13 refs

The selective dynamical downscaling method for extreme-wind atlases

DEFF Research Database (Denmark)

Larsén, Xiaoli Guo; Badger, Jake; Hahmann, Andrea N.

2012-01-01

A selective dynamical downscaling method is developed to obtain extreme-wind atlases for large areas. The method is general, efficient and flexible. The method consists of three steps: (i) identifying storm episodes for a particular area, (ii) downscaling of the storms using mesoscale modelling...... and (iii) post-processing. The post-processing generalizes the winds from the mesoscale modelling to standard conditions, i.e. 10-m height over a homogeneous surface with roughness length of 5 cm. The generalized winds are then used to calculate the 50-year wind using the annual maximum method for each...... mesoscale grid point. The generalization of the mesoscale winds through the post-processing provides a framework for data validation and for applying further the mesoscale extreme winds at specific places using microscale modelling. The results are compared with measurements from two areas with different...

Calculation of extreme wind atlases using mesoscale modeling. Final report

DEFF Research Database (Denmark)

Larsén, Xiaoli Guo; Badger, Jake

This is the final report of the project PSO-10240 "Calculation of extreme wind atlases using mesoscale modeling". The overall objective is to improve the estimation of extreme winds by developing and applying new methodologies to confront the many weaknesses in the current methodologies as explai...

Extreme pressure differences at 0900 NZST and winds across New Zealand

Science.gov (United States)

Salinger, M. James; Griffiths, Georgina M.; Gosai, Ashmita

2005-07-01

Trends in extremes in station daily sea-level pressure differences at 0900 NZST are examined, and extreme daily wind gusts, across New Zealand, since the 1960s. Annual time series were examined (with indices of magnitude and frequency over threshold percentiles) from the daily indices selected. These follow from earlier indices of normalized monthly mean sea-level pressure differences between station pairs, except the daily indices are not normalized. The frequency statistics quantify the number of extreme zonal (westerly and easterly), or extreme meridional (southerly or northerly), pressure gradient events. The frequency and magnitude of extreme westerly episodes has increased slightly over New Zealand, with a significant increase in the westerly extremes to the south of New Zealand. In contrast, the magnitude and frequency of easterly extremes has decreased over New Zealand, but increased to the south, with some trends weakly significant. The frequency and magnitude of daily southerly extremes has decreased significantly in the region.Extreme daily wind gust events at key climate stations in New Zealand and at Hobart, Australia, are highly likely to be associated with an extreme daily pressure difference. The converse was less likely to hold: extreme wind gusts were not always observed on days with extreme daily pressure difference, probably due to the strong influence that topography has on localized station winds. Significant correlations exist between the frequency indices and both annual-average mean sea-level pressures around the Australasian region and annual-average sea surface temperature (SST) anomalies in the Southern Hemisphere. These correlations are generally stronger for indices of extreme westerly or extreme southerly airflows. Annual-average pressures in the Tasman Sea or Southern Ocean are highly correlated to zonal indices (frequency of extreme westerlies). SST anomalies in the NINO3 region or on either side of the South Island are

Dynamic model of frequency control in Danish power system with large scale integration of wind power

DEFF Research Database (Denmark)

Basit, Abdul; Hansen, Anca Daniela; Sørensen, Poul Ejnar

2013-01-01

This work evaluates the impact of large scale integration of wind power in future power systems when 50% of load demand can be met from wind power. The focus is on active power balance control, where the main source of power imbalance is an inaccurate wind speed forecast. In this study, a Danish...... power system model with large scale of wind power is developed and a case study for an inaccurate wind power forecast is investigated. The goal of this work is to develop an adequate power system model that depicts relevant dynamic features of the power plants and compensates for load generation...... imbalances, caused by inaccurate wind speed forecast, by an appropriate control of the active power production from power plants....

Analysis of technological innovation in Danish wind turbine industry - including the Test Station for Windturbines dual roll as research institution and certification authority

International Nuclear Information System (INIS)

Dannemand Andersen, P.

1993-01-01

The overall aim of this thesis is to examine the interactions between the Danish wind turbine industry and the Test Station for Wind Turbines. Because these interactions are concerning technological innovation, it follows that the innovation processes within the enterprises must be analyzed and modelled. The study is carried out as an iterative model-developing process using case study methods. The findings from some less structured interviews are discussed with literature and forms a basis for models and new interviews. The thesis is based on interviews with 20 R and D engineers in the Danish wind turbine industry, 7 engineers at The Test Station and 7 people involved in wind power abroad (American and British). The theoretical frame for this thesis is sociology/organizational theory and industrial engineering. The thesis consists of five main sections, dealing with technology and knowledge, innovation processes, organizational culture, innovation and interaction between the Test Station's research activities and the companies' innovation processes, and finally interaction through the Test Stations certification activity. First a taxonomy for technology and knowledge is established in order to clarify what kind of technology the interactions are all about, and what kind of knowledge is transferred during the interactions. This part of the thesis also contains an analysis of the patents drawn by the Danish wind turbine industry. The analysis shows that the Danish wind turbine industry do not use patents. Instead the nature of the technology and the speed of innovation are used to protect the industry's knowledge. (EG) (192 refs.)

Turbulence and turbulence-generated structural loading in wind turbine clusters

DEFF Research Database (Denmark)

Frandsen, Sten Tronæs

2007-01-01

of the model is that it became part of the Danish standard for wind turbine design DS 472 (2001) in August 2001 and it is part of the corresponding international standard, IEC61400-1 (2005). Also, extreme loading under normal operation for wake conditions and the efficiency of very large wind farms......Turbulence - in terms of standard deviation of wind speed fluctuations - and other flow characteristics are different in the interior of wind farms relative to the free flow and action must be taken to ensure sufficient structural sustainability of the wind turbines exposed to “wind farm flow......”. The standard deviation of wind speed fluctuations is a known key parameter for both extreme- and fatigue loading, and it is argued and found to be justified that a model for change in turbulence intensity alone may account for increased fatigue loading in wind farms. Changes in scale of turbulence...

Windmills in Danish waters - an investigation of the visual effects related to the positioning of wind turbines on the sea bed

International Nuclear Information System (INIS)

1994-12-01

Investigations have shown that the visual consequences of setting up wind turbines on the sea bed are much greater than those following location on the land. One option is to locate them so far out to sea that they can hardly be seen from the coast but the investigation showed that it is impossible to place them anywhere in Danish coastal waters where they would be out of view from the land. Although it should be possible to locate windmills in coastal waters in such a way that it could be aesthetically acceptable, it is feared that local attitudes could be tentative. The general conditions of significance for evaluating the aesthetic effects of locating wind turbines at sea are described and the main principles of regional planning in coastal areas are explained in addition to the potentials for being able to judge the visual consequences from a viewpoint that is placed out at sea. Various examples of marine positionings of wind turbines at different distances from the coastline are described and evaluated. It is asserted that some Danish marine locations for wind turbines can be found that will have only limited visual consequences. Some of these are near to the coast and a considerable number of wind turbines could be placed there. The document is illustrated with large coloured photographs and maps of Danish coastal areas. (AB)

Normal and Extreme Wind Conditions for Power at Coastal Locations in China.

Science.gov (United States)

Gao, Meng; Ning, Jicai; Wu, Xiaoqing

2015-01-01

In this paper, the normal and extreme wind conditions for power at 12 coastal locations along China's coastline were investigated. For this purpose, the daily meteorological data measured at the standard 10-m height above ground for periods of 40-62 years are statistically analyzed. The East Asian Monsoon that affects almost China's entire coastal region is considered as the leading factor determining wind energy resources. For most stations, the mean wind speed is higher in winter and lower in summer. Meanwhile, the wind direction analysis indicates that the prevalent winds in summer are southerly, while those in winter are northerly. The air densities at different coastal locations differ significantly, resulting in the difference in wind power density. The Weibull and lognormal distributions are applied to fit the yearly wind speeds. The lognormal distribution performs better than the Weibull distribution at 8 coastal stations according to two judgement criteria, the Kolmogorov-Smirnov test and absolute error (AE). Regarding the annual maximum extreme wind speed, the generalized extreme value (GEV) distribution performs better than the commonly-used Gumbel distribution. At these southeastern coastal locations, strong winds usually occur in typhoon season. These 4 coastal provinces, that is, Guangdong, Fujian, Hainan, and Zhejiang, which have abundant wind resources, are also prone to typhoon disasters.

Model of analysis of maximum loads in wind generators produced by extreme winds

International Nuclear Information System (INIS)

Herrera – Sánchez, Omar; Schellong, Wolfgang; González – Fernández, Vladimir

2010-01-01

The use of the wind energy by means of the wind turbines in areas of high risk of occurrence of Hurricanes comes being an important challenge for the designers of wind farm at world for some years. The wind generator is not usually designed to support this type of phenomena, for this reason the areas of high incidence of tropical hurricanes of the planning are excluded, that which, in occasions disables the use of this renewable source of energy totally, either because the country is very small, or because it coincides the area of more potential fully with that of high risk. To counteract this situation, a model of analysis of maxims loads has been elaborated taken place the extreme winds in wind turbines of great behavior. This model has the advantage of determining, in a chosen place, for the installation of a wind farm, the micro-areas with higher risk of wind loads above the acceptable for the standard classes of wind turbines. (author)

Is the distribution and abundance of waterbirds altered in and around Danish Offshore wind farms?

DEFF Research Database (Denmark)

Petersen, Ib Krag

programmes for Horns Rev 1 and the Nysted offshore wind farms were initiated, and after the erection of the turbines post-construction monitoring programmes were initiated. Data from these investigations will be touched upon. At Nysted offshore wind farm common eiders (Somateria mollissima) avoided flying...... and the near surroundings. Common scoters (Melanitta nigra) initially showed signs of avoidance, but in the spring of 2007 birds were seen in densities within the Horns Rev 1 wind farm that was equal to the densities found around the wind farm. Very recent findings from Horns Rev 2 indicate that this have......In 1999 a Danish demonstration programme concerning offshore wind farms was initiated. The aim was to evaluate environmental and technical aspects in relation to introducing these new structures at sea. Aarhus University was involved in ornithological investigations in that respect. Monitoring...

Potential of Offshore Wind Energy and Extreme Wind Speed Forecasting on the West Coast of Taiwan

Directory of Open Access Journals (Sweden)

Pei-Chi Chang

2015-02-01

Full Text Available It is of great importance and urgency for Taiwan to develop offshore wind power. However, relevant data on offshore wind energy resources are limited. This study imported wind speeds measured by a tidal station and a buoy into the software WAsP to estimate the high-altitude wind speeds in the two areas. A light detection and ranging (Lidar system was set up near the tidal station and buoy. High-altitude wind speeds measured by the Lidar system were compared with the WAsP-estimated values, and it was discovered that the two data sets were consistent. Then, long-term wind speed data observed by buoys and tidal stations at various locations were imported into WAsP to forecast wind speeds at heights of 55–200 m on the west coast of Taiwan. The software WAsP Engineering was used to analyze the extreme wind speeds in the same areas. The results show that wind speeds at 100 m are approximately 9.32–11.24 m/s, which means that the coastal areas of west Taiwan are rich in wind energy resources. When a long-term 10-min average wind speed is used, the extreme wind speed on the west coast is estimated to be between 36.4 and 55.3 m/s.

Integration and control of wind farms in the Danish electricity system. Final report

Energy Technology Data Exchange (ETDEWEB)

Bak-Jensen, B. (ed.); Suwannarat, A.; Chen, Z. (Aalborg Univ.. Dept. of Energy Technology, Aalborg (Denmark)) (and others)

2009-07-01

The objective of this project have been to establish and develop a generic model for power balancing studies of the Danish power system as is expected to look like in 2025, with a lot of new wind farms integrated. That is, the objective has been to describe the wind-farms interaction with other power generating units, and the wind farms ability to act as a power plant with regard to the power control and the wind farms ability to maintain the power system stability. Therefore, a dynamic model has been set up, which can reflect the active power balancing in case of wind power fluctuations in the system with a huge wind farm penetration. The set up of the Danish network grid includes the interconnections to Norway, Sweden and Germany and takes into account the power production from the central power plants, the decentralized combined heat and power plants, the power production from the wind turbines on-land as well as off-shore and the load. Also the new Great Belt link is simulated; to see how the usage of this link could optimize the power balance situation. The power production from the different units is controlled by an automatic generation controller, where the different units are controlled by use of a so called participation factor, which determines how the power producing units participate in balancing the power. The participations factors should reflect the market behavior and the unit commitment for the power plants. Therefore, the participation factors are made time dependent, to be able to reflect this market behavior in the future use of the model. Further, the possibility to use balance, delta and gradient control in the wind farms is included together with the possibility to include planned power production from the thermal units. In this report different scenarios have been set up, to show the different possibilities with the model. The primary focus has been to see what could happen if a storm is coming up, and the wind turbines suddenly disconnects

Wind farm projects as joint ventures between a Danish utility and private cooperatives

International Nuclear Information System (INIS)

Moerup-Petersen, V.; Pedersen, S.

1992-01-01

Four cases on successful cooperation between the Danish utility, NESA A/S, and private wind cooperatives are described. In two cases the utility was invited to share the projects prepared by the cooperatives. In the third case the project was developed by the utility. The fourth and most ambitious project, where construction work is just about to start, both parties are involved on a 50/50 basis. The experience gained from the different projects is described. The paper discusses the advantages and disadvantages of joint projects for both parties. Different models on cooperation are outlined. Mainly based on NESA's experience, the joint concept is recommended by the Danish Ministry of Environment. The aim is to get the optimal utilization of the limited siting possibilities in Denmark. The future perspectives of joint projects are anticipated. (au)

Collision risks at sea: species composition and altitude distributions of birds in Danish offshore wind farms

Energy Technology Data Exchange (ETDEWEB)

Blew, J.; Hoffmann, M.; Nehls, G. [BioConsult SH (Germany)

2007-07-01

This study investigates the collision risks of birds in operating offshore wind farms, focussing on all bird species present in the direct vicinity of the wind farms, their altitude distribution and reactions. The project was conducted jointly by BioConsult SH and the University of Hamburg in the two Danish offshore wind farms Horns Rev (North Sea) and Nysted (Baltic Sea) in the framework of a Danish-German cooperation and financed by the German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU). Data were collected between March 2005 and November 2006, using a ship anchored at the edge of the offshore wind farms. In this way, bird species of all sizes could be considered. Daytime observations yielded data on species composition, flight routes and potential reactions of the birds. Radar observations provided altitude distributions inside and outside the wind farm area and also reactions. The results shall help to further describe and assess the collision risk of different species groups. Since data analysis is still running, exemplary results will be presented here. 114 species have been recorded in Nysted and 99 in Horns Rev, approximately 65% of which have been observed inside the wind farm areas. Migrating birds seem to avoid flying into the wind farms, whereas individuals present in the areas for extended time periods utilize areas within the wind farms. While a barrier effect exists for species on migration, resident species probably have a higher collision risk. Raptors migrating during daylight frequently enter the wind farm area on their flight routes, correcting their flight paths in order to avoid collisions. Radar results show that during times of intensive migration, the proportion of birds flying at high altitudes and thus above windmill height is higher than in times of low migration intensity. Consequently, there is a lower proportion of migrating birds flying within the risk area. Data will be further analysed to

Offshore Variability in Critical Weather Conditions in Large-Scale Wind Based Danish Power System

DEFF Research Database (Denmark)

Cutululis, Nicolaos Antonio; Litong-Palima, Marisciel; Sørensen, Poul Ejnar

2013-01-01

of the variability for the 2020 Danish power system, one can see that in the worst case, up to 1500 MW of power can be lost in 30 minutes. We present results showing how this issue is partially solved by the new High Wind Storm Controller presented by Siemens in the TWENTIES project.......Offshore wind power has a significant development potential, especially in North Europe. The geographical concentration of offshore wind power leads to increased variability and in the case of critical weather conditions it may lead to sudden and considerable loss of production. In this context......, the chances of losing several GW of wind power due to critical weather conditions in a very short time period could potentially jeopardize the whole system’s reliability and stability. Forecasting such events is not trivial and the results so far are not encouraging. When assessing the impact...

Extrapolation of Extreme Response for Wind Turbines based on FieldMeasurements

DEFF Research Database (Denmark)

Toft, Henrik Stensgaard; Sørensen, John Dalsgaard

2009-01-01

extrapolation are presented. The first method is based on the same assumptions as the existing method but the statistical extrapolation is only performed for a limited number of mean wind speeds where the extreme load is likely to occur. For the second method the mean wind speeds are divided into storms which......The characteristic loads on wind turbines during operation are among others dependent on the mean wind speed, the turbulence intensity and the type and settings of the control system. These parameters must be taken into account in the assessment of the characteristic load. The characteristic load...... are assumed independent and the characteristic loads are determined from the extreme load in each storm....

Wind power production: from the characterisation of the wind resource to wind turbine technologies

International Nuclear Information System (INIS)

Beslin, Guy; Multon, Bernard

2016-01-01

Illustrated by graphs and tables, this article first describes the various factors and means related to the assessment of wind resource in the World, in Europe, and the factors which characterize a local wind resource. In this last respect, the authors indicate how local topography is taken into account to calculate wind speed, how time variations are taken into account (at the yearly, seasonal or daily level), the different methods used to model a local wind resource, how to assess the power recoverable by a wind turbine with horizontal axis (notion of Betz limit). In the second part, the authors present the different wind turbines, their benefits and drawbacks: vertical axis, horizontal axis (examples of a Danish-type wind turbine, of wind turbines designed for extreme conditions). Then, they address the technology of big wind turbines: evolution of technology and of commercial offer, aerodynamic characteristics of wind turbine and benefit of a varying speed (technological solutions, importance of the electric generator). They describe how to choose a wind turbine, how product lines are organised, how the power curve and energy capacity are determined. The issue of integration of wind energy into the power system is then addressed. The next part addressed the economy of wind energy production (annualized production cost, order of magnitude of wind electric power production cost). Future trends are discussed and offshore wind energy production is briefly addressed

Extreme wind-wave modeling and analysis in the south Atlantic ocean

Science.gov (United States)

Campos, R. M.; Alves, J. H. G. M.; Guedes Soares, C.; Guimaraes, L. G.; Parente, C. E.

2018-04-01

A set of wave hindcasts is constructed using two different types of wind calibration, followed by an additional test retuning the input source term Sin in the wave model. The goal is to improve the simulation in extreme wave events in the South Atlantic Ocean without compromising average conditions. Wind fields are based on Climate Forecast System Reanalysis (CFSR/NCEP). The first wind calibration applies a simple linear regression model, with coefficients obtained from the comparison of CFSR against buoy data. The second is a method where deficiencies of the CFSR associated with severe sea state events are remedied, whereby "defective" winds are replaced with satellite data within cyclones. A total of six wind datasets forced WAVEWATCH-III and additional three tests with modified Sin in WAVEWATCH III lead to a total of nine wave hindcasts that are evaluated against satellite and buoy data for ambient and extreme conditions. The target variable considered is the significant wave height (Hs). The increase of sea-state severity shows a progressive increase of the hindcast underestimation which could be calculated as a function of percentiles. The wind calibration using a linear regression function shows similar results to the adjustments to Sin term (increase of βmax parameter) in WAVEWATCH-III - it effectively reduces the average bias of Hs but cannot avoid the increase of errors with percentiles. The use of blended scatterometer winds within cyclones could reduce the increasing wave hindcast errors mainly above the 93rd percentile and leads to a better representation of Hs at the peak of the storms. The combination of linear regression calibration of non-cyclonic winds with scatterometer winds within the cyclones generated a wave hindcast with small errors from calm to extreme conditions. This approach led to a reduction of the percentage error of Hs from 14% to less than 8% for extreme waves, while also improving the RMSE.

Extreme winds in the Western North Pacific

DEFF Research Database (Denmark)

Ott, Søren

2006-01-01

satellite images is discussed with emphasis on the empirical basis, which, unfortunately, is not very strong. This is stressed by the fact that Japanese and US agencies arrive at markedly different estimates. Onthe other hand, best track data records cover a long period of time and if not perfect......A statistical model for extreme winds in the western North Pacific is developed, the region on the Planet where tropical cyclones are most common. The model is based on best track data derived mostly from satellite images of tropical cyclones. The methodsused to estimate surface wind speeds from...... they are at least coherent over time in their imperfections. Applying the the Holland model to the best track data, wind profiles can be assigned along the tracks. Fromthis annual wind speed maxima at any particular point in the region can be derived. The annual maxima, in turn, are fitted to a Gumbel distribution...

Database on wind characteristics - Analyses of wind turbine design loads

DEFF Research Database (Denmark)

Larsen, Gunner Chr.; Hansen, K.S.

2004-01-01

the design load cases with relevance for to wind turbine structures. The present report constitutes thesecond part of the Annex XVII reporting. Both fatigue and extreme load aspects are dealt with, however, with the main emphasis on the latter. The work has been supported by The Ministry of Environment...... and Energy, Danish Energy Agency, The NetherlandsAgency for Energy and the Environment (NOVEM), The Norwegian Water Resources and Energy Administration (NVE), The Swedish National Energy Administration (STEM) and The Government of the United States of America....

Extreme wind atlases of South Africa from global reanalysis data

DEFF Research Database (Denmark)

Larsén, Xiaoli Guo; Kruger, Andries; Badger, Jake

2013-01-01

Extreme wind atlases of South Africa were developed using three reanalysis data and recently developed approaches. The results are compared with the maps produced using standard wind measurements over the region. It was found that different reanalyses with the same approach provide similar spatia...

Danish electricity supply. Statistik 1999

International Nuclear Information System (INIS)

2000-07-01

The Association of Danish Electric Utilities issues each year the statistical yearbook 'Danish electricity supply'. By means of brief text, figures, and tables a description is given of the electric supply sector. The total electric power consumption in 1999 is almost the same as in 1998. There has been a moderate consumption increase in the households and the service sector whereas the consumption in industry has decreased. 1999 is the first year with actual competition in the power-producing sector. The increased competition from the Scandinavian hydro-electric power plants and the growing number of privately owned wind turbines and other decentralised power plants result in a decline in the power production at the electric utilities of 10% compared to the year 1998. In 1999 electric power from renewable energy sources such as wind, biomass, and waste covers close to 10% of the total Danish power consumption. More than 400 new turbines are installed in 1999 and the total capacity of wind power increases with ca. 20%. The actual energy content of the wind in 1999 was, however, 15% lower than normally which results in a significant reduction of the utilisation of the wind turbine capacity. (ln)

Introduction Of Wavestar Wave Energy Converters At The Danish Offshore Wind Power Plant Horns Rev 2

DEFF Research Database (Denmark)

Marquis, L.; Kramer, Morten; Kringelum, J.

is to be connected to a wind turbine at the DONG Energy owned wind power plant Horns Rev 2 placed off the western coast of Denmark. The plant delivers its energy production to a transformer station owned by Energinet.dk. Energinet.dk has the obligation to ensure that power is transmitted to the Danish consumers...... with this combination. This can increase the value of the produced power from future wind/wave plants. Further potential synergies of combining wind and wave energy in the same area include increased energy production from the available area and sharing of infrastructure costs as well as O&M facilities. In a future....... If Executed the project will be the first one in the world where wind and wave power are combined at full scale. The goal of the project is to evaluate the opportunities of combining wind and wave energy production on a commercial scale and to demonstrate the reduction of energy fluctuations...

Analysis of extreme wind events at Høvsøre and the effect on wind turbine loads

DEFF Research Database (Denmark)

Hannesdóttir, Ásta; Kelly, Mark C.; Mann, Jakob

used to simulate wind turbine response in time domain. The simulations are made for the DTU 10 MW reference wind turbine. Load analysis shows that the maximum tilt moment on the tower yaw bearing correlates well with the wind shear of the measurements. When these loads are compared with the extreme...... wind shear load case of the IEC standards, it is seen that they are of similar magnitude and in one case even higher....

Musculoskeletal extremity pain in Danish school children -how often and for how long?

DEFF Research Database (Denmark)

Fuglkjær, Signe; Hartvigsen, Jan; Wedderkopp, Niels

2017-01-01

need in-depth knowledge about the epidemiology of musculoskeletal extremity problems in this age group, and therefore, the aim of this study was to determine the prevalence, frequency and course of musculoskeletal pain in the upper and lower extremities in a cohort of Danish school children aged 8......-14 years at baseline. METHODS: This was a prospective 3-year school-based cohort study, with information about musculoskeletal pain collected in two ways. Parents answered weekly mobile phone text messages about the presence or absence of musculoskeletal pain in their children, and a clinical consultation...... was performed in a subset of the children. RESULTS: We found that approximately half the children had lower extremity pain every study year. This pain lasted on average for 8 weeks out of a study year, and the children had on average two and a half episodes per study year. Approximately one quarter...

Danish and Norwegian wind industry: The relationship between policy instruments, innovation and diffusion

International Nuclear Information System (INIS)

Buen, Jorund

2006-01-01

This article compares the role of policy instruments in stimulating long-term technological change in Danish and Norwegian wind industry. It concludes that although predictability has periodically been low, Denmark's broad portfolio of policies and measures has been well adapted to the different stages in the development of its wind industry. This has contributed to a high degree of innovation, successful establishment in niche markets, high degree of diffusion and establishment of domestic and international mass markets, and-in recent years-an increasingly successful replacement of senescent technology with new. The motivation of Norway's wind energy policies and measures-at least up until the late 1990s-has been to increase power supply rather than to stimulate industrial development and technological change. Policies and measures have been weaker than in Denmark; have been less stable over time; and stimulated the demand side much less. They have not sufficiently covered the wind industry's perceived needs on different stages in the development of new technology, and have not sufficiently stimulated continuous improvement, learning and new product development (dynamic efficiency) in industry. This has been part of the reason why there has been only a limited extent of innovation and diffusion of wind technology in Norway

Coupling Atmosphere and Waves for Coastal Wind Turbine Design

DEFF Research Database (Denmark)

Bolanos, Rodolfo; Larsén, Xiaoli Guo; Petersen, Ole S.

2014-01-01

model (MIKE 21 SW) are implemented for the North Sea in order to consider wave effects on roughness. The objective is to see the reaction of an atmospheric model to the water surface description through offline coupling. A comparison with three simplified roughness formulations embedded in WRF showed......Offshore wind farms in coastal areas are considered by the Danish government to contribute to the goal of having 50% of the energy consumption from renewable sources by 2025. Therefore, new coastal developments will take place in Danish areas. The impact of waves on atmosphere is most often...... described by roughness length, which is typically determined by the Charnock formulation. This simplification in many atmospheric models has been shown to bring bias in the estimation of the extreme wind. Some wave-dependent formulations have been reported to overestimate the drag coefficient and roughness...

Extreme winds over Europe in the ENSEMBLES regional climate models

Directory of Open Access Journals (Sweden)

S. D. Outten

2013-05-01

Full Text Available Extreme winds cause vast amounts of damage every year and represent a major concern for numerous industries including construction, afforestation, wind energy and many others. Under a changing climate, the intensity and frequency of extreme events are expected to change, and accurate projections of these changes will be invaluable to decision makers and society as a whole. This work examines four regional climate model downscalings over Europe following the SRES A1B scenario from the "ENSEMBLE-based Predictions of Climate Changes and their Impacts" project (ENSEMBLES. It investigates the projected changes in the 50 yr return wind speeds and the associated uncertainties. This is accomplished by employing the peaks-over-threshold method with the use of the generalised Pareto distribution. The models show that, for much of Europe, the 50 yr return wind is projected to change by less than 2 m s−1, while the uncertainties associated with the statistical estimates are larger than this. In keeping with previous works in this field, the largest source of uncertainty is found to be the inter-model spread, with some locations showing differences in the 50 yr return wind of over 20 m s−1 between two different downscalings.

Four wind speed multi-step forecasting models using extreme learning machines and signal decomposing algorithms

International Nuclear Information System (INIS)

Liu, Hui; Tian, Hong-qi; Li, Yan-fei

2015-01-01

Highlights: • A hybrid architecture is proposed for the wind speed forecasting. • Four algorithms are used for the wind speed multi-scale decomposition. • The extreme learning machines are employed for the wind speed forecasting. • All the proposed hybrid models can generate the accurate results. - Abstract: Realization of accurate wind speed forecasting is important to guarantee the safety of wind power utilization. In this paper, a new hybrid forecasting architecture is proposed to realize the wind speed accurate forecasting. In this architecture, four different hybrid models are presented by combining four signal decomposing algorithms (e.g., Wavelet Decomposition/Wavelet Packet Decomposition/Empirical Mode Decomposition/Fast Ensemble Empirical Mode Decomposition) and Extreme Learning Machines. The originality of the study is to investigate the promoted percentages of the Extreme Learning Machines by those mainstream signal decomposing algorithms in the multiple step wind speed forecasting. The results of two forecasting experiments indicate that: (1) the method of Extreme Learning Machines is suitable for the wind speed forecasting; (2) by utilizing the decomposing algorithms, all the proposed hybrid algorithms have better performance than the single Extreme Learning Machines; (3) in the comparisons of the decomposing algorithms in the proposed hybrid architecture, the Fast Ensemble Empirical Mode Decomposition has the best performance in the three-step forecasting results while the Wavelet Packet Decomposition has the best performance in the one and two step forecasting results. At the same time, the Wavelet Packet Decomposition and the Fast Ensemble Empirical Mode Decomposition are better than the Wavelet Decomposition and the Empirical Mode Decomposition in all the step predictions, respectively; and (4) the proposed algorithms are effective in the wind speed accurate predictions

Directional analysis of extreme winds under mixed climate conditions

CSIR Research Space (South Africa)

Kruger, A

2013-07-01

Full Text Available Directional statistics provide design engineers with the opportunity to realise considerable cost savings, but these are not yet provided for in the South African standard for wind loading. The development of the directional statistics of extreme...

Probabilistic forecasting of wind power generation using extreme learning machine

DEFF Research Database (Denmark)

Wan, Can; Xu, Zhao; Pinson, Pierre

2014-01-01

an extreme learning machine (ELM)-based probabilistic forecasting method for wind power generation. To account for the uncertainties in the forecasting results, several bootstrapmethods have been compared for modeling the regression uncertainty, based on which the pairs bootstrap method is identified......Accurate and reliable forecast of wind power is essential to power system operation and control. However, due to the nonstationarity of wind power series, traditional point forecasting can hardly be accurate, leading to increased uncertainties and risks for system operation. This paper proposes...... with the best performance. Consequently, a new method for prediction intervals formulation based on theELMand the pairs bootstrap is developed.Wind power forecasting has been conducted in different seasons using the proposed approach with the historical wind power time series as the inputs alone. The results...

System and market integration of wind power in Denmark

DEFF Research Database (Denmark)

Lund, Henrik; Hvelplund, Frede; Alberg Østergaard, Poul

2013-01-01

Denmark has more than 10 years’ of experience with a wind share of approximately 20 per cent. During these 10 years, electricity markets have been subject to developments with a key focus on integrating wind power as well as trading electricity with neighbouring countries. This article introduces...... a methodology to analyse and understand the current market integration of wind power and concludes that the majority of Danish wind power in the period 2004e2008 was used to meet the domestic demand. Based on a physical analysis, at least 63 per cent of Danish wind power was used domestically in 2008....... To analyse the remaining 37 per cent, we must apply a market model to identify cause-effect relationships. The Danish case does not illustrate any upper limit for wind power integration, as also illustrated by Danish political targets to integrate 50 per cent by 2020. In recent years, Danish wind power has...

Implementing wind forecasting at a utility

Energy Technology Data Exchange (ETDEWEB)

Landberg, L.; Hansen, M.A.; Vesterager, K.; Bergstroem, W.

1997-03-01

This report describes a project - funded by the Danish Ministry of Energy and the Environment - that has as its aim to implement prediction of the power produced by wind farms in the daily planning at the Danish utility ELKRAFT. The predictions are generated from forecasts from HIRLAM (HIgh Resolution Limited Area Model) of the Danish Meteorological Institute. These predictions are then made valid at individual sites (wind farms) by applying either a matrix generated by the sub-models of WA{sup s}P (Wind Atlas Application and Analysis Program) or by use of a Kalman filter. In the project 17 wind farms have been selected for study. The farms are located on the Zealand and Bornholm islands and all belonging to the Danish utility ELKRAFT. (au) 10 tabs., 65 ills., 14 refs.

Mapping Wind Energy Controversies

DEFF Research Database (Denmark)

Munk, Anders Kristian

As part the Wind2050 project funded by the Danish Council for Strategic Research we have mapped controversies on wind energy as they unfold online. Specifically we have collected two purpose built datasets, a web corpus containing information from 758 wind energy websites in 6 different countries......, and a smaller social media corpus containing information from 14 Danish wind energy pages on Facebook. These datasets have been analyzed to answer questions like: How do wind proponents and opponents organize online? Who are the central actors? And what are their matters of concern? The purpose of this report...

Electric vehicles in Danish power system with large penetration of wind power

DEFF Research Database (Denmark)

Yang, Lihui; Xu, Zhao; Østergaard, Jacob

2011-01-01

Electric vehicles (EVs) provide a unique opportunity for reducing the CO2 emissions from the transport sector. At the same time, EVs have the potential to play an important role in the economical and reliable operation of an electricity system with high penetration of renewable energy. An analysi......). The managing structure of V2G adopting virtual power plant (VPP) technology is proposed. © 2011 State Grid Electric Power Research Institute Press....... is made of the potential for using EVs in Denmark, and the benefits of the electric power system with high wind power generation by intelligent charging and discharging of EVs are enumerated. Based on the analysis, important technological gaps are identified, and the corresponding research and development...... initiatives of the recently established EDISON program are described. Moreover, the latest development of the EDISON program is treated, that is, EDISON as a research consortium to design a new model for the Danish power system with high penetration of wind power and EVs with vehicle to grid (V2G...

Estimating return periods of extreme values from relatively short time series of winds

Science.gov (United States)

Jonasson, Kristjan; Agustsson, Halfdan; Rognvaldsson, Olafur; Arfeuille, Gilles

2013-04-01

An important factor for determining the prospect of individual wind farm sites is the frequency of extreme winds at hub height. Here, extreme winds are defined as the value of the highest 10 minutes averaged wind speed with a 50 year return period, i.e. annual exceeding probability of 2% (Rodrigo, 2010). A frequently applied method to estimate winds in the lowest few hundred meters above ground is to extrapolate observed 10-meter winds logarithmically to higher altitudes. Recent study by Drechsel et al. (2012) showed however that this methodology is not as accurate as interpolating simulated results from the global ECMWF numerical weather prediction (NWP) model to the desired height. Observations of persistent low level jets near Colima in SW-Mexico also show that the logarithmic approach can give highly inaccurate results for some regions (Arfeuille et al., 2012). To address these shortcomings of limited, and/or poorly representative, observations and extrapolations of winds one can use NWP models to dynamically scale down relatively coarse resolution atmospheric analysis. In the case of limited computing resources one has typically to make a compromise between spatial resolution and the duration of the simulated period, both of which can limit the quality of the wind farm siting. A common method to estimate maximum winds is to fit an extreme value distribution (e.g. Gumbel, gev or Pareto) to the maximum values of each year of available data, or the tail of these values. If data are only available for a short period, e.g. 10 or 15 years, then this will give a rather inaccurate estimate. It is possible to deal with this problem by utilizing monthly or weekly maxima, but this introduces new problems: seasonal variation, autocorrelation of neighboring values, and increased discrepancy between data and fitted distribution. We introduce a new method to estimate return periods of extreme values of winds at hub height from relatively short time series of winds, simulated

Reliability of offshore wind power production under extreme wind conditions. Deliverable D 9.5. Work Package 9: Electrical grid

DEFF Research Database (Denmark)

Cutululis, Nicolaos Antonio; Zeni, Lorenzo

years, with each year simulated with five random seeds, leading to a total of 25 annual wind power time series for six large offshore wind farms, summing up to a little over 330 wind turbines. Two storm control strategies were used. The analysis involved several aspects inspired from reliability studies....... The aspects investigated are storm events occurrences and durations, storm control strategy impact on the capacity factor (lost production), the loss of production (power produced from wind drops below a certain threshold due to high wind speeds and storm controller) and finally, the wind power production......Reliability of offshore wind production under extreme wind conditions was investigated in this report. The wind power variability from existing and future large offshore wind farms in Western Denmark were simulated using the Correlated Wind model developed at Risø. The analysis was done for five...

Site-optimization of wind turbine generators

Energy Technology Data Exchange (ETDEWEB)

Wolff, T.J. de; Thillerup, J. [Nordtank Energy Group, Richmond, VA (United States)

1997-12-31

The Danish Company Nordtank is one of the pioneers within the wind turbine industry. Since 1981 Nordtank has installed worldwide more than 2500 wind turbine generators with a total name plate capacity that is exceeding 450 MW. The opening up of new and widely divergent markets has demanded an extremely flexible approach towards wind turbine construction. The Nordtank product range has expanded considerable in recent years, with the main objective to develop wind energy conversion machines that can run profitable in any given case. This paper will describe site optimization of Nordtank wind turbines. Nordtank has developed a flexible design concept for its WTGs in the 500/750 kW range, in order to offer the optimal WTG solution for any given site and wind regime. Through this flexible design, the 500/750 turbine line can adjust the rotor diameter, tower height and many other components to optimally fit the turbine to each specific project. This design philosophy will be illustrated with some case histories of recently completed projects.

Bayesian analysis applied to statistical uncertainties of extreme response distributions of offshore wind turbines

NARCIS (Netherlands)

Cheng, P.W.; Kuik, van G.A.M.; Bussel, van G.J.W.; Vrouwenvelder, A.C.W.M.

2002-01-01

Extreme response is an important design variable for wind turbines. The statistical uncertainties concerning the extreme response distribution are simulated here with data concerning physical characteristics obtained from measurements. The extreme responses are the flap moment at the blade root and

Spatio-temporal modelling of wind speed variations and extremes in the Caribbean and the Gulf of Mexico

Science.gov (United States)

Rychlik, Igor; Mao, Wengang

2018-02-01

The wind speed variability in the North Atlantic has been successfully modelled using a spatio-temporal transformed Gaussian field. However, this type of model does not correctly describe the extreme wind speeds attributed to tropical storms and hurricanes. In this study, the transformed Gaussian model is further developed to include the occurrence of severe storms. In this new model, random components are added to the transformed Gaussian field to model rare events with extreme wind speeds. The resulting random field is locally stationary and homogeneous. The localized dependence structure is described by time- and space-dependent parameters. The parameters have a natural physical interpretation. To exemplify its application, the model is fitted to the ECMWF ERA-Interim reanalysis data set. The model is applied to compute long-term wind speed distributions and return values, e.g., 100- or 1000-year extreme wind speeds, and to simulate random wind speed time series at a fixed location or spatio-temporal wind fields around that location.

Extreme Design Loads Calibration of Offshore Wind Turbine Blades through Real Time Measurements

DEFF Research Database (Denmark)

Natarajan, Anand; Vesth, Allan; Lamata, Rebeca Rivera

2014-01-01

Blade Root flap and Edge moments are measured on the blades of a 3.6MW offshore wind turbine in normal operation. Ten minute maxima of the measurements are sampled to determine the extreme blade root flap moment, edge moment and resultant moment over six month duration. A random subset of the mea......Blade Root flap and Edge moments are measured on the blades of a 3.6MW offshore wind turbine in normal operation. Ten minute maxima of the measurements are sampled to determine the extreme blade root flap moment, edge moment and resultant moment over six month duration. A random subset...... of the measurements over a week is taken as input to stochastic load extrapolation whereby the one year extrapolated design extreme is obtained, which are then compared with the maximum extremes obtained from direct measurements over a six month period to validate the magnification in the load levels for the blade...... root flap moment, edge moment obtained by extrapolation. The validation yields valuable information on prescribing the slope of the local extrapolation curve at each mean wind speed. As an alternative to determining the contemporaneous loads for each primary extrapolated load, the blade root resultant...

The potential of wind farms

Energy Technology Data Exchange (ETDEWEB)

1992-01-01

Summaries of papers presented at the European wind energy conference on the potential of wind farms are presented. It is stated that in Denmark today, wind energy provides about 3% to the Danish electricity consumption and the wind power capacity is, according to Danish wind energy policy, expected to increase substantially in the years to come. A number of countries in Europe and elsewhere are making significant progress in this repect. Descriptions of performance are given in relation to some individual wind farms. The subjects covered concern surveys of national planning and policies regarding wind utilization and national and global development of wind turbine arrays. Papers also deal with utility and project planning, wind prediction and certification, wind loads and fatigue, wakes, noise and control. (AB).

Predicting the Extreme Loads on a Wind Turbine Considering Uncertainty in Airfoil Data

DEFF Research Database (Denmark)

Abdallah, Imad; Natarajan, Anand; Sørensen, John Dalsgaard

2014-01-01

The sources contributing to uncertainty in a wind turbine blade static airfoil data include wind tunnel testing, CFD calculations, 3D rotational corrections based on CFD or emprircal models, surface roughness corrections, Reynolds number corrections, expansion to the full 360-degree angle of attack...... range, validation by full scale measurements, and geometric distortions of the blade during manufacturing and under loading. In this paper a stochastic model of the static airfoil data is proposed to supplement the prediction of extreme loads effects for large wind turbines. It is shown...... that the uncertainty in airfoil data can have e significant impact on the prediction of extreme loads effects depending on the component, and the correlation along the span of the blade....

Database on wind characteristics - Analyses of wind turbine design loads

Energy Technology Data Exchange (ETDEWEB)

Larsen, G.C.; Hansen, K.S.

2004-06-01

The main objective of IEA R and D Wind Annex XVII - Database on Wind Characteristics - has been to provide wind energy planners, designers and researchers, as well as the international wind engineering community in general, with a source of actual wind field data (time series and resource data) observed in a wide range of different wind climates and terrain types. Connected to an extension of the initial Annex period, the scope for the continuation was widened to include also support to the international wind turbine standardisation efforts.. The project partners are Sweden, Norway, U.S.A., The Netherlands and Denmark, with Denmark as the Operating Agent. The reporting of the continuation of Annex XVII falls in two separate parts. Part one accounts in details for the available data in the established database bank, and part two describes various data analyses performed with the overall purpose of improving the design load cases with relevance for to wind turbine structures. The present report constitutes the second part of the Annex XVII reporting. Both fatigue and extreme load aspects are dealt with, however, with the main emphasis on the latter. The work has been supported by The Ministry of Environment and Energy, Danish Energy Agency, The Netherlands Agency for Energy and the Environment (NOVEM), The Norwegian Water Resources and Energy Administration (NVE), The Swedish National Energy Administration (STEM) and The Government of the United States of America. (au)

Second wind in the offshore wind industry

International Nuclear Information System (INIS)

Philippe, Edouard; Neyme, Eric; Deboos, Christophe; Villageois, Jean-Remy; Gouverneur, Philippe; Gerard, Bernard; Fournier, Eric; Petrus, Raymond; Lemarquis, David; Dener, Marc; Bivaud, Jean-Pierre; Lemaire, Etienne; Nielsen, Steffen; Lafon, Xavier; Lagandre, Pierre; Nadai, Alain; Pinot de Villechenon, Edouard; Westhues, Markus; Herpers, Frederick; Bisiaux, Christophe; Sperlich, Miriam; Bales, Vincent; Vandenbroeck, Jan; His, Stephane; Derrey, Thierry; Barakat, Georges; Dakyo, Brayima; Carme, Laurent; Petit, Frederic; Ytournel, Sophie; Westhues, Markus; Diller, Armin; Premont, Antoine de; Ruer, Jacques; Lanoe, Frederic; Declercq, Jan; Holmager, Morten; Fidelin, Daniel; Guillet, Jerome; Dudziak, Gregory; Lapierre, Anne; Couturier, Ludovic; Audineau, Jean-Pierre; Rouaix, Eric; De Roeck, Yann-Herve; Quesnel, Louis; Duguet, Benjamin

2011-06-01

After several keynote addresses, this publication contains contributions and Power Point presentations proposed during this conference on the development of offshore wind energy. The successive sessions addressed the following issues: the offshore mass production of electricity (examples of Denmark and Belgium, laying and protecting offshore cables), the space, economic and environmental planning (the Danish experience, the role of the Coastal area integrated management, importance of the public debate, so on), the logistics of port infrastructures (simulation tools, example of Bremerhaven, issues related to project management), innovation at the core of industrial strategies (high power wind turbines, the 6 MW Alstom turbine, chain value and innovation in offshore wind energy, the Vertiwing innovating project of a floating wind turbine, a bench test in Charleston, foundations, gravity base structures, the British experience, the Danish experience), the economic and organisational conditions for development, the validation and certification of technologies

Effects of normal and extreme turbulence spectral parameters on wind turbine loads

DEFF Research Database (Denmark)

Dimitrov, Nikolay Krasimirov; Natarajan, Anand; Mann, Jakob

2017-01-01

the recommended values in the IEC 61400-1 Ed.3 that is used for wind turbine design. The present paper investigates the impact of Mann turbulence model parameter variations on the design loads envelope for 5 MW and 10 MW reference wind turbines. Specific focus is made on the blade root loads, tower top moments...... of design loads is investigated with a focus on the commonly used Mann turbulence model. Quantification of the Mann model parameters is made through wind measurements acquired from the Høvsøre site. The parameters of the Mann model fitted to site specific observations can differ significantly from...... and tower base loads under normal turbulence and extreme turbulence, whereby the change in operating extreme and fatigue design loads obtained through turbulence model parameter variations is compared with corresponding variations obtained from random seeds of turbulence. The investigations quantify...

Drivers and seasonal predictability of extreme wind speeds in the ECMWF System 4 and a statistical model

Science.gov (United States)

Walz, M. A.; Donat, M.; Leckebusch, G. C.

2017-12-01

As extreme wind speeds are responsible for large socio-economic losses in Europe, a skillful prediction would be of great benefit for disaster prevention as well as for the actuarial community. Here we evaluate patterns of large-scale atmospheric variability and the seasonal predictability of extreme wind speeds (e.g. >95th percentile) in the European domain in the dynamical seasonal forecast system ECMWF System 4, and compare to the predictability based on a statistical prediction model. The dominant patterns of atmospheric variability show distinct differences between reanalysis and ECMWF System 4, with most patterns in System 4 extended downstream in comparison to ERA-Interim. The dissimilar manifestations of the patterns within the two models lead to substantially different drivers associated with the occurrence of extreme winds in the respective model. While the ECMWF System 4 is shown to provide some predictive power over Scandinavia and the eastern Atlantic, only very few grid cells in the European domain have significant correlations for extreme wind speeds in System 4 compared to ERA-Interim. In contrast, a statistical model predicts extreme wind speeds during boreal winter in better agreement with the observations. Our results suggest that System 4 does not seem to capture the potential predictability of extreme winds that exists in the real world, and therefore fails to provide reliable seasonal predictions for lead months 2-4. This is likely related to the unrealistic representation of large-scale patterns of atmospheric variability. Hence our study points to potential improvements of dynamical prediction skill by improving the simulation of large-scale atmospheric dynamics.

EcoGrid.dk Phase I. Steps towards a Danish power system with 50 % wind energy. Summary report

Energy Technology Data Exchange (ETDEWEB)

Noerregaard, K. (Teknologisk Institut, AArhus (Denmark)); OEstergaard, J.; Lind, M. (Technical Univ. of Denmark (DTU), CET, Kgs. Lyngby (Denmark)); Bach, P.-F. (Fredericia (Denmark)); Soerensen, P. (Technical Univ. of Denmark, Risoe National Lab. for Sustainable Energy, Roskilde (Denmark)); Tennbakk, B. (Econ Poeyry AS, Copenhagen (Denmark)); Togeby, M. (EA Energy Analyses a/s, Copenhagen (Denmark)); Ackermann, T. (Energynautics GmbH (Denmark))

2009-07-01

In the EcoGrid project phase I a unique combination of scientists, experts and industry stakeholders with different backgrounds and experiences were put together to work towards one common objective: Develop new long-term technologies for the power grid and system that can contribute to realizing the Danish Energy Policy goal of 50% wind energy by 2025. The specific task of the EcoGrid phase I report was to make a general description and analyses of demand and development of the Danish power system with increased volumes of renewable energy. The report describes different solutions with respect to new power system architecture; examine the consequences of future market developments and identify new measures ('building blocks') to support the overall goals and functions of the future power system. The main report includes five work-packages.

Influence of the control system on wind turbine loads during power production in extreme turbulence: Structural reliability

DEFF Research Database (Denmark)

Abdallah, Imad; Natarajan, Anand; Sørensen, John Dalsgaard

2016-01-01

structural reliability are assessed when the extreme turbulence model is uncertain. The structural reliability is assessed for the wind turbine when three configurations of an industrial grade load alleviation control system of increasing complexity and performance are used. The load alleviation features......The wind energy industry is continuously researching better computational models of wind inflow and turbulence to predict extreme loading (the nature of randomness) and their corresponding probability of occurrence. Sophisticated load alleviation control systems are increasingly being designed...... and deployed to specifically reduce the adverse effects of extreme load events resulting in lighter structures. The main objective herein is to show that despite large uncertainty in the extreme turbulence models, advanced load alleviation control systems yield both a reduction in magnitude and scatter...

Extreme fire severity patterns in topographic, convective and wind-driven historical wildfires of Mediterranean pine forests.

Directory of Open Access Journals (Sweden)

Judit Lecina-Diaz

Full Text Available Crown fires associated with extreme fire severity are extremely difficult to control. We have assessed fire severity using differenced Normalized Burn Ratio (dNBR from Landsat imagery in 15 historical wildfires of Pinus halepensis Mill. We have considered a wide range of innovative topographic, fuel and fire behavior variables with the purposes of (1 determining the variables that influence fire severity patterns among fires (considering the 15 wildfires together and (2 ascertaining whether different variables affect extreme fire severity within the three fire types (topographic, convective and wind-driven fires. The among-fires analysis showed that fires in less arid climates and with steeper slopes had more extreme severity. In less arid conditions there was more crown fuel accumulation and closer forest structures, promoting high vertical and horizontal fuel continuity and extreme fire severity. The analyses carried out for each fire separately (within fires showed more extreme fire severity in areas in northern aspects, with steeper slopes, with high crown biomass and in climates with more water availability. In northern aspects solar radiation was lower and fuels had less water limitation to growth which, combined with steeper slopes, produced more extreme severity. In topographic fires there was more extreme severity in northern aspects with steeper slopes and in areas with more water availability and high crown biomass; in convection-dominated fires there was also more extreme fire severity in northern aspects with high biomass; while in wind-driven fires there was only a slight interaction between biomass and water availability. This latter pattern could be related to the fact that wind-driven fires spread with high wind speed, which could have minimized the effect of other variables. In the future, and as a consequence of climate change, new zones with high crown biomass accumulated in non-common drought areas will be available to burn

Extreme fire severity patterns in topographic, convective and wind-driven historical wildfires of Mediterranean pine forests.

Science.gov (United States)

Lecina-Diaz, Judit; Alvarez, Albert; Retana, Javier

2014-01-01

Crown fires associated with extreme fire severity are extremely difficult to control. We have assessed fire severity using differenced Normalized Burn Ratio (dNBR) from Landsat imagery in 15 historical wildfires of Pinus halepensis Mill. We have considered a wide range of innovative topographic, fuel and fire behavior variables with the purposes of (1) determining the variables that influence fire severity patterns among fires (considering the 15 wildfires together) and (2) ascertaining whether different variables affect extreme fire severity within the three fire types (topographic, convective and wind-driven fires). The among-fires analysis showed that fires in less arid climates and with steeper slopes had more extreme severity. In less arid conditions there was more crown fuel accumulation and closer forest structures, promoting high vertical and horizontal fuel continuity and extreme fire severity. The analyses carried out for each fire separately (within fires) showed more extreme fire severity in areas in northern aspects, with steeper slopes, with high crown biomass and in climates with more water availability. In northern aspects solar radiation was lower and fuels had less water limitation to growth which, combined with steeper slopes, produced more extreme severity. In topographic fires there was more extreme severity in northern aspects with steeper slopes and in areas with more water availability and high crown biomass; in convection-dominated fires there was also more extreme fire severity in northern aspects with high biomass; while in wind-driven fires there was only a slight interaction between biomass and water availability. This latter pattern could be related to the fact that wind-driven fires spread with high wind speed, which could have minimized the effect of other variables. In the future, and as a consequence of climate change, new zones with high crown biomass accumulated in non-common drought areas will be available to burn as extreme

Description and evaluation of foreign wind turbine technology

International Nuclear Information System (INIS)

1995-06-01

It is stated that sales of Danish-manufactured wind turbines abroad are decreasing due to an increase in production, marketing and technology research in other countries. The aim was to give an account of this international development which could form the basis for the future strategies of the Danish Wind turbine industry. The study is based on a survey of relevant literature, interviews with experts on the subject and the collection of the latest data. The survey is limited to wind turbines with a larger capacity than 50 kW. Recommendations are given as to how to conserve and develop the market for Danish wind turbines. (AB) 17 refs

The effect of a large Danish offshore wind farm on harbor and grey seal haul-out behaviour

DEFF Research Database (Denmark)

Edrén, Susi Manuela Clermont; Andersen, Signe May; Teilmann, Jonas

2010-01-01

This study investigates the effects of the construction and operation of a large Danish offshore wind farm on harbor and gray seal haul-out behavior within a nearby (4 km) seal sanctuary. Time-lapse photography, visual monitoring, and aerial surveys were used to monitor the number of seals on land...... in daylight hours. Seals were monitored during two preconstruction periods (19 June–31 August 2001 and April–August 2002), a construction period of the wind farm (August 2002–December 2003), and a period of operation of the wind farm (December 2003–December 2004). Monthly aerial surveys were conducted...... to estimate the proportion of seals in the sanctuary relative to neighboring haul-out sites. From preconstruction to construction and through the first year of operation the number of harbor seals in the sanctuary increased at the same rate as the number of seals at the neighboring haul-out sites. No long...

Power System Operation with Large Scale Wind Power Integration

DEFF Research Database (Denmark)

Suwannarat, A.; Bak-Jensen, B.; Chen, Z.

2007-01-01

to the uncertain nature of wind power. In this paper, proposed models of generations and control system are presented which analyze the deviation of power exchange at the western Danish-German border, taking into account the fluctuating nature of wind power. The performance of the secondary control of the thermal......The Danish power system starts to face problems of integrating thousands megawatts of wind power, which produce in a stochastic behavior due to natural wind fluctuations. With wind power capacities increasing, the Danish Transmission System Operator (TSO) is faced with new challenges related...... power plants and the spinning reserves control from the Combined Heat and Power (CHP) units to achieve active power balance with the increased wind power penetration is presented....

Modern wind energy technology for Russian applications. Main report

Energy Technology Data Exchange (ETDEWEB)

Hauge Madsen, P.; Winther-Jensen, M., Bindner, H.W. [and others

1999-05-01

The general objective of the project is to establish a technical foundation for an intensified application of wind energy in Russia with medium to large wind turbines and transfer/adaptation of Danish and European wind turbine technology as a basis for future joint ventures and technology exports. More specifically, the objective is to develop and establish the basic knowledge and design criteria for adaptation and development of Danish wind turbine technology for application under Russian conditions. The research programme is envisaged to be carried out in three phases, the first phase being the project reported herein. The main purpose of phase 1 is to assess the needs for modifications and adaptations of established standard (in casu Danish) wind turbine designs for decentralised energy systems with a limited number of medium sized wind turbines and for grid connected wind turbines in cold climate and in-land sites of Russia. As part of this work it is necessary to clarify the types of operational conditions and requirements that are to be met by wind turbines operating in such conditions, and to outline suitable test procedures and test set-up is for verifications of such adapted and modified wind turbines. The reporting of this project is made in one main report and four topical reports, all of them issued as Risoe reports. This is the Main Report, (Risoe-R-1069), summing up the activities and findings of phase 1 and outlining a strategy for Russian-Danish cooperation in wind energy as agreed upon between the Russian and the Danish parties. (au)

On the synergy between large electric vehicle fleet and high wind penetration – An analysis of the Danish case

DEFF Research Database (Denmark)

Krog Ekman, Claus

2011-01-01

Increasing the level of wind power penetration beyond the present level in the Danish power system implies large challenges when it comes to energy management and system stability. Plug-in electric vehicles promise to contribute to the flexibility of the energy system by creating a link between...... the power system and the transportation sector and provide the possibility to make use of the inherent energy storage of a large electric vehicle (EV) fleet. The present work investigates the effects of different EV charging strategies on the balance between wind power production and consumption in a future...... batteries are used as backup at times with little wind power production) will have very limited effects on the overall energy management and is more likely to be used only for regulation and reserve services, also in the longer perspective....

Uncertainties of the 50-year wind from short time series using generalized extreme value distribution and generalized Pareto distribution

DEFF Research Database (Denmark)

Larsén, Xiaoli Guo; Mann, Jakob; Rathmann, Ole

2015-01-01

This study examines the various sources to the uncertainties in the application of two widely used extreme value distribution functions, the generalized extreme value distribution (GEVD) and the generalized Pareto distribution (GPD). The study is done through the analysis of measurements from...... as a guideline for applying GEVD and GPD to wind time series of limited length. The data analysis shows that, with reasonable choice of relevant parameters, GEVD and GPD give consistent estimates of the return winds. For GEVD, the base period should be chosen in accordance with the occurrence of the extreme wind...

Future steps toward a Danish power system with 50% wind power

DEFF Research Database (Denmark)

Østergaard, Jacob; Ackermann, Thomas; Bach, Poul-Frederik

.dk. The objective of EcoGrid work package 5 is to suggest future research and development activities in EcoGrid.dk. The future activities will consist of related activities of which some should be directed within an EU framework (EcoGridEU). The delivery of phase 1 work package 5 is a packet of proposals to be used......This report is part of the EcoGrid.dk project phase 1 initiated by Energinet.dk and the result of work package 5 dealing with proposals for future steps toward a Danish power system with 50% wind power. The EcoGrid.dk project has the objective to develop new long term technologies and market...... power system with increased volumes of RE. - Phase 2: Specific projects, analyses and recommendations to Energinet.dk with main focus on research activities - Phase 3: Technologies are implemented in real environment and demonstrated with subsequent adoption and implementation in Energinet...

Wind fluctuations over the North Sea

DEFF Research Database (Denmark)

Vincent, Claire Louise; Pinson, Pierre; Giebel, Gregor

2011-01-01

Climatological patterns in wind speed fluctuations with periods of 1 min to 10 h are analysed using data from a meteorological mast in the Danish North Sea. Fluctuations on these time scales are of particular relevance to the effective management of the power supply from large wind farms. The Hil......Climatological patterns in wind speed fluctuations with periods of 1 min to 10 h are analysed using data from a meteorological mast in the Danish North Sea. Fluctuations on these time scales are of particular relevance to the effective management of the power supply from large wind farms...

Extreme wind estimate for Hornsea wind farm

DEFF Research Database (Denmark)

Larsén, Xiaoli Guo

The purpose of this study is to provide estimation of the 50-year winds of 10 min and 1-s gust value at hub height of 100 m, as well as the design parameter shear exponent for the Hornsea offshore wind farm. The turbulence intensity required for estimating the gust value is estimated using two...... approaches. One is through the measurements from the wind Doppler lidar, WindCube, which implies serious uncertainty, and the other one is through similarity theory for the atmospheric surface layer where the hub height is likely to belong to during strong storms. The turbulence intensity for storm wind...... strength is taken as 0.1. The shear exponents at several heights were calculated from the measurements. The values at 100 m are less than the limit given by IEC standard for all sectors. The 50-year winds have been calculated from various global reanalysis and analysis products as well as mesoscale models...

Mesoscale wind fluctuations over Danish waters

Energy Technology Data Exchange (ETDEWEB)

Vincent, C.L.

2010-12-15

Mesoscale wind fluctuations affect the large scale integration of wind power because they undermine the day-ahead predictability of wind speed and power production, and because they can result in large fluctuations in power generation that must be balanced using reserve power. Large fluctuations in generated power are a particular problem for offshore wind farms because the typically high concentration of turbines within a limited geographical area means that fluctuations can be correlated across large numbers of turbines. Furthermore, organised mesoscale structures that often form over water, such as convective rolls and cellular convection, have length scales of tens of kilometers, and can cause large wind fluctuations on a time scale of around an hour. This thesis is an exploration of the predictability of mesoscale wind fluctuations using observations from the world's first two large offshore wind farms - Horns Rev I in the North Sea, and Nysted in the Baltic Sea. The thesis begins with a climatological analysis of wind fluctuations on time scales of 1-10 hours at the two sites. A novel method for calculating conditional climatologies of spectral information is proposed, based on binning and averaging the time axis of the Hilbert spectrum. Results reveal clear patterns between wind fluctuations and locally observed meteorological conditions. The analysis is expanded by classifying wind fluctuations on time scales of 1-3 hours according to synoptic patterns, satellite pictures and wind classes. Results indicate that cold air outbreaks and open cellular convection are a significant contributor to mesoscale wind variability at Horns Rev. The predictability of mesoscale wind fluctuations is tested by implementing standard statistical models that relate local wind variability to parameters based on a large scale weather analysis. The models show some skill, but only achieve a 15% improvement on a persistence forecast. The possibility of explicitly modelling

76 FR 74776 - Forum-Trends in Extreme Winds, Waves, and Extratropical Storms Along the Coasts

Science.gov (United States)

2011-12-01

... Winds, Waves, and Extratropical Storms Along the Coasts AGENCY: National Environmental Satellite, Data...-extratropical-storms/home . FOR FURTHER INFORMATION CONTACT: Brooke Stewart, National Climatic Data Center, 151.../noaa.gov/extreme-winds-waves-extratropical-storms/home . Topics To Be Addressed This forum will address...

Extreme winds in Denmark

DEFF Research Database (Denmark)

Kristensen, L.; Rathmann, Ole; Hansen, S.O.

1999-01-01

Wind-speed data from four sites in Denmark have been analyzed in order to obtain estimates of the basic wind velocity which is defined as the 50-year wind speed under standard conditions, i.e. ten-minute averages at the height 10 m over a uniform terrainwith the roughness length 0.05 m. The sites...... by means of the geostrophic drag law for neutral stratification. The basic wind velocity in 30o sectors are obtainedthrough ranking of the largest values of the ¤friction velocity pressure¤ 1/2 ¤#rho#¤¤u¤"2_x taken both once every two months and once every year. The main conclusion is that the basic wind...

Analysis operating and maintenance cost of Danish wind turbines in 1993

International Nuclear Information System (INIS)

Godtfredsen, F.

1994-10-01

A study of operation and maintenance (O and M) cost of Danish wind turbines has been carried out. The study is based on a questionnaire survey by the wind turbine owners association. The study shows a significant decline in the O and M cost from 55 kW machines installed in 1980-87 to modern machines. In 1993, the average total O and M cost for 55 kW and 150 kW turbines was approximately 0.22 DKK/kWh and 0.07 DKK/kWh, respectively. For 150 kW turbines, insurance and administration costs amounted to 0.04 DKK/kWh while repair and maintenance costs came to 0.03 DKK/kWh. In 1993, repair and maintenance cost were significantly higher for older vintages of 55 kW and 150 kW turbines, but it is not possible based on this study to conclude whether increasing O and M costs generally comes with increasing age. The statistical basis of this study is not large enough to conclude whether there are positive scale effects for ST's from 105 kW. Similarly, because of relatively few large WT are older than 10 years, it is not possible based on this study to predict the size of major future repair costs/reinvestments. To estimate the O and M costs more exactly, a larger empirical basis is needed. (au) (8 tabs., 17 ills., 11 refs.)

Who should own the nearshore wind turbines?

DEFF Research Database (Denmark)

Jensen, Louise Krog; Sperling, Karl

This report examines the possibility for non-profit organisations to participate in tenders for nearshore wind turbines in Denmark under the current frame-work conditions in the area. The point of departure is a case study of the non-profit organisation Wind People’s attempt to participate...... with a popular project in the Danish tender for 350 MW nearshore wind turbines. A series of in-depth interviews have been carried out with Wind People’s staff in order to make an in-depth analysis of their actions and experiences of entering into the market for nearshore wind turbines. The report concludes...... the way for non-profit organisations to be able to enter the market, however, as the study shows that the established actors in the market also have a large influence on who is allowed to enter the market. The results of the report are a number of recommendations to the Danish politicians and the Danish...

Market Prices in a Power Market with more than 50% Wind Power

DEFF Research Database (Denmark)

Skytte, Klaus; Grohnheit, Poul Erik

2018-01-01

Denmark has the highest proportion of wind power in the world. Wind power provided a world record of 39.1% of the total annual Danish electricity consumption in 2014 with as much as 51.7% in Western Denmark. Many would argue that the present power markets are not designed for such high shares...... of wind power production and that it would be hard to get good and stable prices. However, analyses in this chapter show that the Nordic power market works, extreme events have been few, and the current infrastructure and market organization has been able to handle the amount of wind power installed so...... far. It is found that geographical bidding areas for the wholesale electricity market reflect external transmission constraints caused by wind power. The analyses in this chapter use hourly data from West Denmark—which has the highest share of wind energy in Denmark and which is a separate price area...

Market Prices in a Power Market with more than 50% Wind Power

DEFF Research Database (Denmark)

Skytte, Klaus; Grohnheit, Poul Erik

2017-01-01

Denmark has the highest proportion of wind power in the world. Wind power provided a world record of 39.1% of the total annual Danish electricity consumption in 2014 with as much as 51.7% in Western Denmark. Many would argue that the present power markets are not designed for such high shares...... of wind power production and that it would be hard to get good and stable prices. However, analyses in this chapter show that the Nordic power market works, extreme events have been few, and the current infrastructure and market organization has been able to handle the amount of wind power installed so...... far. It is found that geographical bidding areas for the wholesale electricity market reflect external transmission constraints caused by wind power. The analyses in this chapter use hourly data from West Denmark—which has the highest share of wind energy in Denmark and which is a separate price area...

Lightning protection of wind turbines

Energy Technology Data Exchange (ETDEWEB)

Soerensen, T; Brask, M H [DEFU (Denmark); Jensen, F V; Raben, N [SEAS (Denmark); Saxov, J [Nordjyllandsvaerket (Denmark); Nielsen, L [Vestkraft (Denmark); Soerensen, P E [Risoe National Lab. (Denmark)

1999-03-01

Lightning damage to wind turbines is a serious problem for Danish power companies, who have experienced some cases with very costly lightning damage and a large number of cases with minor damage. The most costly cases include one catastrophic damage to an entire wind turbine, and several cases of destruction of blades, main bearings, generators and control systems. Over the years there have been several hundreds of cases with minor damage - typically damage and interruptions of the control and communication systems, or the power systems. The Danish power companies anticipate that the lightning threat will be even bigger for the large off-shore wind turbine installations that are currently being planned in Denmark. Furthermore, it is known from the off-shore wind turbines at Vindeby in Denmark that the costs of inspection and particularly repair work must be expected to be much higher off-shore as compared to wind turbines on land. These considerations was the background for a two year project concerned with investigation of lighting damages and with the formulation of a DEFU Recommendation for lightning protection of wind turbines, which was published in January 1999. The project was funded by the Danish power companies Elsam, Eltra, Elkraft and by DEFU. (au)

On Wind Forces in the Forest-Edge Region During Extreme-Gust Passages and Their Implications for Damage Patterns

Science.gov (United States)

Gromke, Christof; Ruck, Bodo

2018-03-01

A damage pattern that is occasionally found after a period of strong winds shows an area of damaged trees inside a forest stand behind an intact stripe of trees directly at the windward edge. In an effort to understand the mechanism leading to this damage pattern, wind loading in the forest-edge region during passages of extreme gusts with different characteristics are investigated using a scaled forest model in the wind tunnel. The interaction of a transient extreme gust with the stationary atmospheric boundary layer (ABL) as a background flow at the forest edge leads to the formation of a vortex at the top of the canopy. This vortex intensifies when travelling downstream and subsequently deflects high-momentum air from above the canopy downwards resulting in increased wind loading on the tree crowns. Under such conditions, the decrease in wind loading in the streamwise direction can be relatively weak compared to stationary ABL approach flows. The resistance of trees with streamwise distance from the forest edge, however, is the result of adaptive growth to wind loading under stationary flow conditions and shows a rapid decline within two to three tree heights behind the windward edge. For some of the extreme gusts realized, an exceedance of the wind loading over the resistance of the trees is found at approximately three tree heights behind the forest edge, suggesting that the damage pattern described above can be caused by the interaction of a transient extreme gust with the stationary ABL flow.

Fusing Simulation Results From Multifidelity Aero-servo-elastic Simulators - Application To Extreme Loads On Wind Turbine

DEFF Research Database (Denmark)

Abdallah, Imad; Sudret, Bruno; Lataniotis, Christos

2015-01-01

Fusing predictions from multiple simulators in the early stages of the conceptual design of a wind turbine results in reduction in model uncertainty and risk mitigation. Aero-servo-elastic is a term that refers to the coupling of wind inflow, aerodynamics, structural dynamics and controls. Fusing...... the response data from multiple aero-servo-elastic simulators could provide better predictive ability than using any single simulator. The co-Kriging approach to fuse information from multifidelity aero-servo-elastic simulators is presented. We illustrate the co-Kriging approach to fuse the extreme flapwise...... bending moment at the blade root of a large wind turbine as a function of wind speed, turbulence and shear exponent in the presence of model uncertainty and non-stationary noise in the output. The extreme responses are obtained by two widely accepted numerical aero-servo-elastic simulators, FAST...

A Snapshot of the Danish Energy Transition

DEFF Research Database (Denmark)

Ropenus, Stephanie; Klinge Jacobsen, Henrik

a deeper look at Danish energy policy in general and at the electricity sector in particular. What are the major objectives of Danish energy policy? What is the logic behind an integrated approach that encompasses all energy sectors? How has market integration evolved in the Nordic countries? How does...... the offshore wind tendering system work? What are the principles underlying grid expansion within Denmark? What types of consumer participation schemes exist? This paper aims to explore some of the lessons learned from the Danish experience. At the same time, this paper can serve as an introductory overview...

Mesoscale wind fluctuations over Danish waters

DEFF Research Database (Denmark)

Vincent, Claire Louise

in generated power are a particular problem for oshore wind farms because the typically high concentration of turbines within a limited geographical area means that uctuations can be correlated across large numbers of turbines. Furthermore, organised mesoscale structures that often form over water......Mesoscale wind uctuations aect the large scale integration of wind power because they undermine the day-ahead predictability of wind speed and power production, and because they can result in large uctuations in power generation that must be balanced using reserve power. Large uctuations...... that realistic hour-scale wind uctuations and open cellular convection patterns develop in WRF simulations with 2km horizontal grid spacing. The atmospheric conditions during one of the case studies are then used to initialise a simplied version of the model that has no large scale weather forcing, topography...

Contribution of wind power and CHP to exports from Western Denmark during 2000-2004

International Nuclear Information System (INIS)

Mignard, D.; Harrison, G.P.; Pritchard, C.L.

2007-01-01

The experience of Denmark is used by the United Kingdom's anti-wind lobby to demonstrate that intermittency and inaccuracies in wind forecasting make wind power ineffective and expensive. A further assertion is that most of the power is 'unwanted' since up to 80% of it is exported. Here, available data for Danish energy production for 2000-2004 is used to assess the link between wind generation and exports and test the validity of these claims. Net exports in Western Denmark showed good correlation with wind production. However, they were more significantly correlated with the production from local combined heat and power (CHP) plants. In order to test the 80% export claim, a simple technique was devised to correlate and rank hourly net exports and generation from wind and local CHP. In the case where net exports were primarily attributed to (or blamed on) wind, 44-84% of annual wind production was deemed to be exported, with wind 'causing' 57-79% of net annual exports. For this extreme scenario, the percentage values are in line with those of critics. However, under the opposite extreme scenario in which exports are attributed to local CHP, 77-94% of exports were caused by CHP and only 4-32% of wind production was exported. Overall, this study shows that there is some degree of correlation between net exports and wind power, but that the claim that 80% is exported is unwarranted since it ignores the demonstrably stronger influence of local CHP. (author)

SAT-WIND project. Final report

DEFF Research Database (Denmark)

Hasager, Charlotte Bay; Astrup, Poul; Nielsen, Niels Morten

microwave, altimeter, scatterometer and imaging Synthetic Aperture Radar (SAR) technologies for wind energy tools for wind resources and wind-indexing. The study area was the Danish Seas including the North Sea, interior seas and the Baltic Sea. The report describes technical details on the satellite data...

Enhancing Wind Power Integration through Optimal Use of Flexibility in Multi-Carrier Energy Systems from the Danish Perspective

DEFF Research Database (Denmark)

Zong, Yi; Awadelrahman, M. A. Ahmed; Wang, Jiawei

2017-01-01

Denmark’ goal of being independent of fossil energy sources in 2050 puts forward great demands on all energy subsystems (electricity, heat, gas and transport, etc.) to be operated in a holistic manner. The Danish experience and challenges of wind power integration and the development of district...... heating systems are summarized in this paper. How to optimally use the cross-sectoral flexibility by intelligent control (model predictive control-based) of the key coupling components in an integrated heat and power system including electrical heat pumps in the demand side, and thermal storage...

Wind simulation for extreme and fatigue loads

Energy Technology Data Exchange (ETDEWEB)

Nielsen, M.; Larsen, G.C.; Mann, J.; Ott, S.; Hansen, K.S.; Pedersen, B.J.

2004-01-01

Measurements of atmospheric turbulence have been studied and found to deviate from a Gaussian process, in particular regarding the velocity increments over small time steps, where the tails of the pdf are exponential rather than Gaussian. Principles for extreme event counting and the occurrence of cascading events are presented. Empirical extreme statistics agree with Rices exceedence theory, when it is assumed that the velocity and its time derivative are independent. Prediction based on the assumption that the velocity is a Gaussian process underpredicts the rate of occurrence of extreme events by many orders of magnitude, mainly because the measured pdf is non-Gaussian. Methods for simulation of turbulent signals have been developed and their computational efficiency are considered. The methods are applicable for multiple processes with individual spectra and probability distributions. Non-Gaussian processes are simulated by the correlation-distortion method. Non-stationary processes are obtained by Bezier interpolation between a set of stationary simulations with identical random seeds. Simulation of systems with some signals available is enabled by conditional statistics. A versatile method for simulation of extreme events has been developed. This will generate gusts, velocity jumps, extreme velocity shears, and sudden changes of wind direction. Gusts may be prescribed with a specified ensemble average shape, and it is possible to detect the critical gust shape for a given construction. The problem is formulated as the variational problem of finding the most probable adjustment of a standard simulation of a stationary Gaussian process subject to relevant event conditions, which are formulated as linear combination of points in the realization. The method is generalized for multiple correlated series, multiple simultaneous conditions, and 3D fields of all velocity components. Generalization are presented for a single non-Gaussian process subject to relatively

The difficult wind power

International Nuclear Information System (INIS)

Groenaas, Sigbjoern

2005-01-01

The article presents a brief survey of the conditions for wind power production in Norway and points out that several areas should be well suited. A comparison to Danish climate is made. The wind variations, turbulence problems and regional conditions are discussed

Influence of turbulence, orientation, and site configuration on the response of buildings to extreme wind.

Science.gov (United States)

Aly, Aly Mousaad

2014-01-01

Atmospheric turbulence results from the vertical movement of air, together with flow disturbances around surface obstacles which make low- and moderate-level winds extremely irregular. Recent advancements in wind engineering have led to the construction of new facilities for testing residential homes at relatively high Reynolds numbers. However, the generation of a fully developed turbulence in these facilities is challenging. The author proposed techniques for the testing of residential buildings and architectural features in flows that lack fully developed turbulence. While these methods are effective for small structures, the extension of the approach for large and flexible structures is not possible yet. The purpose of this study is to investigate the role of turbulence in the response of tall buildings to extreme winds. In addition, the paper presents a detailed analysis to investigate the influence of upstream terrain conditions, wind direction angle (orientation), and the interference effect from the surrounding on the response of high-rise buildings. The methodology presented can be followed to help decision makers to choose among innovative solutions like aerodynamic mitigation, structural member size adjustment, and/or damping enhancement, with an objective to improve the resiliency and the serviceability of buildings.

Influence of Turbulence, Orientation, and Site Configuration on the Response of Buildings to Extreme Wind

Science.gov (United States)

2014-01-01

Atmospheric turbulence results from the vertical movement of air, together with flow disturbances around surface obstacles which make low- and moderate-level winds extremely irregular. Recent advancements in wind engineering have led to the construction of new facilities for testing residential homes at relatively high Reynolds numbers. However, the generation of a fully developed turbulence in these facilities is challenging. The author proposed techniques for the testing of residential buildings and architectural features in flows that lack fully developed turbulence. While these methods are effective for small structures, the extension of the approach for large and flexible structures is not possible yet. The purpose of this study is to investigate the role of turbulence in the response of tall buildings to extreme winds. In addition, the paper presents a detailed analysis to investigate the influence of upstream terrain conditions, wind direction angle (orientation), and the interference effect from the surrounding on the response of high-rise buildings. The methodology presented can be followed to help decision makers to choose among innovative solutions like aerodynamic mitigation, structural member size adjustment, and/or damping enhancement, with an objective to improve the resiliency and the serviceability of buildings. PMID:24701140

Advanced Offshore Wind Energy - Atlantic Consortium

Energy Technology Data Exchange (ETDEWEB)

Kempton, Willett

2015-11-04

This project developed relationships among the lead institution, U of Delaware, wind industry participants from 11 companies, and two other universities in the region. The participating regional universities were University of Maryland and Old Dominion University. Research was carried out in six major areas: Analysis and documentation of extreme oceanic wind events & their impact on design parameters, calibration of corrosivity estimates measured on a coastal turbine, measurment and modeling of tower structures, measurement and modeling of the tribology of major drive components, and gearbox conditioning monitoring using acoustic sensors. The project also had several educational goals, including establishing a course in wind energy and training graduate students. Going beyond these goals, three new courses were developed, a graduate certificate program in wind power was developed and approved, and an exchange program in wind energy was established with Danish Technical University. Related to the installation of a Gamesa G90 turbine on campus and a Gamesa-UD research program established in part due to this award, several additional research projects have been carried out based on mutual industry-university interests, and funded by turbine revenues. This award and the Gamesa partnership have jointly led to seven graduate students receiving full safety and climb training, to become “research climbers” as part of their wind power training, and contributing to on-turbine research. As a result of the educational program, already six graduate students have taken jobs in the US wind industry.

Economic valuation of the visual externalities of off-shore wind farms

DEFF Research Database (Denmark)

Ladenburg, Jacob; Dubgaard, Alex; Martinsen, Louise

The primary focus of the study presented in this report is visual externalities of off-shore wind farms and the Danish population’s willingness to pay for having these ex-ternalities reduced. The investigation is part of the Danish monitoring programme for off-shore wind farms, comprising several...

An extreme wind erosion event of the fresh Eyjafjallajökull 2010 volcanic ash.

Science.gov (United States)

Arnalds, Olafur; Thorarinsdottir, Elin Fjola; Thorsson, Johann; Waldhauserova, Pavla Dagsson; Agustsdottir, Anna Maria

2013-01-01

Volcanic eruptions can generate widespread deposits of ash that are subsequently subjected to erosive forces which causes detrimental effects on ecosystems. We measured wind erosion of the freshly deposited Eyjafjallajökull ash at a field site the first summer after the 2010 eruption. Over 30 wind erosion events occurred (June-October) at wind speeds > 10 m s(-1) in each storm with gusts up to 38.7 m s(-1). Surface transport over one m wide transect (surface to 150 cm height) reached > 11,800 kg m(-1) during the most intense storm event with a rate of 1,440 kg m(-1) hr(-1) for about 6½ hrs. This storm is among the most extreme wind erosion events recorded on Earth. The Eyjafjallajökull wind erosion storms caused dust emissions extending several hundred km from the volcano affecting both air quality and ecosystems showing how wind erosion of freshly deposited ash prolongs impacts of volcanic eruptions.

The costs of wind power. Socio-economic costs of expansion of wind power; Vindkraftens pris. Samfundsoekonomiske omkostninger ved udbygning af vindkraft

Energy Technology Data Exchange (ETDEWEB)

Busk, R.; Larsen, Anderse; Skovsgaard Nielsen, L.; Nielsen, Uffe; Pade, L.L.; Mulvad Jeppesen, L. [Inst. for Miljoevurdering (Denmark); Munksgaard, J. [Amternes of Kommunernes Forskningsinst. (Denmark)

2007-08-28

This report was prepared in order to inform the basis for making energy policy decisions, particularly in with respect to Denmark's goals for renewable energy and wind power. The report estimates the socio-economic costs of expanding Danish wind power to a share of 30, 40 and 50%, respectively, of the electricity consumption by 2025. The report also analyses barriers to and instruments for the expansion of Danish wind power. The main analysis is a socio-economic cost analysis which includes, among other factors, costs of investments, infrastructure and tax distortion losses. (au)

Turbulence and turbulence-generated structural loading in wind turbine clusters

Energy Technology Data Exchange (ETDEWEB)

Frandsen, Sten

2007-01-15

Turbulence, in terms of standard deviation of wind speed fluctuations, and other flow characteristics are different in the interior of wind farms relative to the free flow and action must be taken to ensure sufficient structural sustainability of the wind turbines exposed to 'wind farm flow'. The standard deviation of wind speed fluctuations is a known key parameter for both extreme- and fatigue loading, and it is argued and found to be justified that a model for change in turbulence intensity alone may account for increased fatigue loading in wind farms. Changes in scale of turbulence and horizontal flow-shear also influence the dynamic response and thus fatigue loading. However, these parameters are typically negatively or positively correlated with the standard deviation of wind speed fluctuations, which therefore can, if need be, represent these other variables. Thus, models for spatially averaged turbulence intensity inside the wind farm and direct-wake turbulence intensity are being devised and a method to combine the different load situations is proposed. The combination of the load cases implies a weighting method involving the slope of the considered material's Woehler curve. In the context, this is novel and necessary to avoid excessive safety for fatigue estimation of the structure's steel components, and non-conservatism for fibreglass components. The proposed model offers significant reductions in computational efforts in the design process. The status for the implementation of the model is that it became part of the Danish standard for wind turbine design DS 472 (2001) in August 2001 and it is part of the corresponding international standard, IEC61400-1 (2005). Also, extreme loading under normal operation for wake conditions and the efficiency of very large wind farms are discussed. (au)

Statistical Modeling of Extreme Values and Evidence of Presence of Dragon King (DK) in Solar Wind

Science.gov (United States)

Gomes, T.; Ramos, F.; Rempel, E. L.; Silva, S.; C-L Chian, A.

2017-12-01

The solar wind constitutes a nonlinear dynamical system, presenting intermittent turbulence, multifractality and chaotic dynamics. One characteristic shared by many such complex systems is the presence of extreme events, that play an important role in several Geophysical phenomena and their statistical characterization is a problem of great practical relevance. This work investigates the presence of extreme events in time series of the modulus of the interplanetary magnetic field measured by Cluster spacecraft on February 2, 2002. One of the main results is that the solar wind near the Earth's bow shock can be modeled by the Generalized Pareto (GP) and Generalized Extreme Values (GEV) distributions. Both models present a statistically significant positive shape parameter which implyies a heavy tail in the probability distribution functions and an unbounded growth in return values as return periods become too long. There is evidence that current sheets are the main responsible for positive values of the shape parameter. It is also shown that magnetic reconnection at the interface between two interplanetary magnetic flux ropes in the solar wind can be considered as Dragon Kings (DK), a class of extreme events whose formation mechanisms are fundamentally different from others. As long as magnetic reconnection can be classified as a Dragon King, there is the possibility of its identification and even its prediction. Dragon kings had previously been identified in time series of financial crashes, nuclear power generation accidents, stock market and so on. It is believed that they are associated with the occurrence of extreme events in dynamical systems at phase transition, bifurcation, crises or tipping points.

Experience with voltage control from large offshore windfarms: The Danish case

DEFF Research Database (Denmark)

Akhmatov, Vladislav

2009-01-01

and frequency control carried out at central, conventional power plants. Moreover, the control of some larger decentralized combined heat and power units is activated for voltage control and system balancing, which is specific for the Danish system. In the years to come, according to the government's goal...... of increasing the share of renewable energy sources in the Danish power system, the share of large offshore windfarms in the Danish power generation mix will increase greatly, replacing central power plants, including their control characteristics during periods of strong winds. Large offshore windfarms must...... and switchable capacitor banks of the offshore wind turbines, which are smaller than those of central power plants measured per unit of the active power rating. Combine this with the use of AC cables, tens of kilometres long, to connect the large offshore windfarms to the on-land transmission system...

Early wind engineering experiments in Denmark

DEFF Research Database (Denmark)

Larose, Guy; Franck, Niels

1997-01-01

A review of works by Danish wind engineers is presented to commemorate the 100th year anniversary of the first wind tunnel experiments. Pioneer tests by Irminger and Nøkkentved in "artificial" wind on scaled models are described. The early experiments aimed at measuring the surface pressure......" that governs today´s wind engineering practice and gave birth to the boundary layer wind tunnel....

South Baltic Wind Atlas

DEFF Research Database (Denmark)

Pena Diaz, Alfredo; Hahmann, Andrea N.; Hasager, Charlotte Bay

A first version of a wind atlas for the South Baltic Sea has been developed using the WRF mesoscale model and verified by data from tall Danish and German masts. Six different boundary-layer parametrization schemes were evaluated by comparing the WRF results to the observed wind profiles at the m...

European Wind Atlas and Wind Resource Research in Denmark

DEFF Research Database (Denmark)

Mortensen, Niels Gylling

to estimate the actual wind climate at any specific site and height within this region. The Danish and European Wind Atlases are examples of how the wind atlas methodology can be employed to estimate the wind resource potential for a country or a sub-continent. Recently, the methodology has also been used...... - from wind measurements at prospective sites to wind tunnel simulations and advanced flow modelling. Among these approaches, the wind atlas methodology - developed at Ris0 National Laboratory over the last 25 years - has gained widespread recognition and is presently considered by many as the industry......-standard tool for wind resource assessment and siting of wind turbines. The PC-implementation of the methodology, the Wind Atlas Analysis and Application Program (WAsP), has been applied in more than 70 countries and territories world-wide. The wind atlas methodology is based on physical descriptions and models...

Automatic Voltage Control (AVC) of Danish Transmission System - Concept design

DEFF Research Database (Denmark)

Qin, Nan; Abildgaard, Hans; Lund, P.

2014-01-01

For more than 20 years it has been a consistent plan by all Danish governments to turn the Danish power production away from fossil fuels towards renewable energy. The result today is that 37% of the total Danish power consumption was covered by mainly wind energy in 2013 aiming at 50% by 2020......, objectives, constraints, algorithms for optimal power flow and some special functions in particular systems, which inspires the concept design of a Danish AVC system to address the future challenges of voltage control. In the concept, the Danish AVC design is based on a centralized control scheme. All...... the substation loses the telecommunications to the control center. RPCs will be integrated to the AVC system as normative regulators in the later stage. Distributed generation units can be organized as virtual power plants and participate in voltage control at transmission level. Energinet.dk as the Danish TSO...

Musculoskeletal extremity pain in Danish school children - how often and for how long? The CHAMPS study-DK.

Science.gov (United States)

Fuglkjær, Signe; Hartvigsen, Jan; Wedderkopp, Niels; Boyle, Eleanor; Jespersen, Eva; Junge, Tina; Larsen, Lisbeth Runge; Hestbæk, Lise

2017-11-25

Musculoskeletal pain is common in childhood and adolescence, and may be long-lasting and recurrent. Musculoskeletal problems tend to follow adolescents into adulthood, and therefore it is important to design better prevention strategies and early effective treatment. To this end, we need in-depth knowledge about the epidemiology of musculoskeletal extremity problems in this age group, and therefore, the aim of this study was to determine the prevalence, frequency and course of musculoskeletal pain in the upper and lower extremities in a cohort of Danish school children aged 8-14 years at baseline. This was a prospective 3-year school-based cohort study, with information about musculoskeletal pain collected in two ways. Parents answered weekly mobile phone text messages about the presence or absence of musculoskeletal pain in their children, and a clinical consultation was performed in a subset of the children. We found that approximately half the children had lower extremity pain every study year. This pain lasted on average for 8 weeks out of a study year, and the children had on average two and a half episodes per study year. Approximately one quarter of the children had upper extremity pain every study year that lasted on average 3 weeks during a study year, with one and a half episodes being the average. In general, there were more non-traumatic pain episodes compared with traumatic episodes in the lower extremities, whereas the opposite was true in the upper extremities. The most common anatomical pain sites were 'knee' and 'ankle/ft'. Lower extremity pain among children and adolescents is common, recurrent and most often of non-traumatic origin. Upper extremity pain is less common, with fewer and shorter episodes, and usually with a traumatic onset. Girls more frequently reported upper extremity pain, whereas there was no sex-related difference in the lower extremities. The most frequently reported locations were 'knee' and 'ankle/ft'.

Sensitivity Analysis of Expected Wind Extremes over the Northwestern Sahara and High Atlas Region.

Science.gov (United States)

Garcia-Bustamante, E.; González-Rouco, F. J.; Navarro, J.

2017-12-01

A robust statistical framework in the scientific literature allows for the estimation of probabilities of occurrence of severe wind speeds and wind gusts, but does not prevent however from large uncertainties associated with the particular numerical estimates. An analysis of such uncertainties is thus required. A large portion of this uncertainty arises from the fact that historical observations are inherently shorter that the timescales of interest for the analysis of return periods. Additional uncertainties stem from the different choices of probability distributions and other aspects related to methodological issues or physical processes involved. The present study is focused on historical observations over the Ouarzazate Valley (Morocco) and in a high-resolution regional simulation of the wind in the area of interest. The aim is to provide extreme wind speed and wind gust return values and confidence ranges based on a systematic sampling of the uncertainty space for return periods up to 120 years.

Market penetration of large wind/diesel systems

International Nuclear Information System (INIS)

Kronborg, T.

1992-01-01

Burmeister ampersand Wain is developing a large size wind/diesel package in collaboration with Micon, the Danish wind turbine manufacturer, and the Danish utility NESA. The package comprises an initial calculation of the technical feasibility and the economic viability of an actual project, installing the optimum number of large wind turbines, and service, operation, and maintenance as needed. The concept should be seen as an addition to existing diesel-based power stations. Wind turbines are especially advantageous in smaller diesel-based electrical systems in the 1-20 MW range because such systems can have high fuel costs and expensive maintenance. Analysis of the market for the wind/diesel concept indicates islands and remote areas with limited population are likely candidates for implementation of wind/diesel systems. An example of an economic analysis of a wind/diesel application on an isolated island is presented, showing the cost savings possible. To obtain practical experience and to demonstrate the wind/diesel concept, a MW-size demonstration plant is being constructed in Denmark

PROBABILISTIC HAZARD ASSESSMENT FOR TORNADOES, STRAIGHT-LINE WIND, AND EXTREME PRECIPITATION AT THE SAVANNAH RIVER SITE

Energy Technology Data Exchange (ETDEWEB)

Werth, D.; (NOEMAIL), A.; Shine, G.

2013-12-04

distribution, and extrapolating the values for any return period from the tail of that function. For the DOE mandated return periods, we expect straight winds of 123 mph every 2500 years, and 132mph every 6250 years at any point within the SRS. These values are similar to those from the W98 report (which also used the Gumbel distribution for wind speeds) which gave wind speeds of 115mph and 122 mph for return periods of 2500 years and 6250 years, respectively. For extreme precipitation accumulation periods, we compared the fits of three different theoretical extreme-value distributions, and in the end decided to maintain the use of the Gumbel distribution for each period. The DOE mandated 6-hr accumulated rainfall for return periods of 2500 years and 6250 years was estimated as 7.8 inches and 8.4 inches, respectively. For the 24- hr rainfall return periods of 10,000 years and 25,000 years, total rainfall estimates were 10.4 inches and 11.1 inches, respectively. These values are substantially lower than comparable values provided in the W98 report. This is largely a consequence of the W98 use of a different extreme value distribution with its corresponding higher extreme probabilities.

Statistical Model of Extreme Shear

DEFF Research Database (Denmark)

Larsen, Gunner Chr.; Hansen, Kurt Schaldemose

2004-01-01

In order to continue cost-optimisation of modern large wind turbines, it is important to continously increase the knowledge on wind field parameters relevant to design loads. This paper presents a general statistical model that offers site-specific prediction of the probability density function...... by a model that, on a statistically consistent basis, describe the most likely spatial shape of an extreme wind shear event. Predictions from the model have been compared with results from an extreme value data analysis, based on a large number of high-sampled full-scale time series measurements...... are consistent, given the inevitabel uncertainties associated with model as well as with the extreme value data analysis. Keywords: Statistical model, extreme wind conditions, statistical analysis, turbulence, wind loading, statistical analysis, turbulence, wind loading, wind shear, wind turbines....

Wind power in the 90's. Pure energy

International Nuclear Information System (INIS)

1994-05-01

The status, historical background and future prospects of wind energy in Denmark are described. Furthermore, the certification system of wind turbines, the electric supply system, wind farms, economy, practical experience, environmental impacts and exports are dealt with. A list of useful addresses within the Danish wind industry is included

Feature selection in wind speed prediction systems based on a hybrid coral reefs optimization – Extreme learning machine approach

International Nuclear Information System (INIS)

Salcedo-Sanz, S.; Pastor-Sánchez, A.; Prieto, L.; Blanco-Aguilera, A.; García-Herrera, R.

2014-01-01

Highlights: • A novel approach for short-term wind speed prediction is presented. • The system is formed by a coral reefs optimization algorithm and an extreme learning machine. • Feature selection is carried out with the CRO to improve the ELM performance. • The method is tested in real wind farm data in USA, for the period 2007–2008. - Abstract: This paper presents a novel approach for short-term wind speed prediction based on a Coral Reefs Optimization algorithm (CRO) and an Extreme Learning Machine (ELM), using meteorological predictive variables from a physical model (the Weather Research and Forecast model, WRF). The approach is based on a Feature Selection Problem (FSP) carried out with the CRO, that must obtain a reduced number of predictive variables out of the total available from the WRF. This set of features will be the input of an ELM, that finally provides the wind speed prediction. The CRO is a novel bio-inspired approach, based on the simulation of reef formation and coral reproduction, able to obtain excellent results in optimization problems. On the other hand, the ELM is a new paradigm in neural networks’ training, that provides a robust and extremely fast training of the network. Together, these algorithms are able to successfully solve this problem of feature selection in short-term wind speed prediction. Experiments in a real wind farm in the USA show the excellent performance of the CRO–ELM approach in this FSP wind speed prediction problem

Reliability-based design methods to determine the extreme response distribution of offshore wind turbines

NARCIS (Netherlands)

Cheng, P.W.; Bussel, van G.J.W.; Kuik, van G.A.M.; Vugts, J.H.

2003-01-01

In this article a reliability-based approach to determine the extreme response distribution of offshore wind turbines is presented. Based on hindcast data, the statistical description of the offshore environment is formulated. The contour lines of different return periods can be determined.

Probing the extreme wind confinement of the most magnetic O star with COS spectroscopy

Science.gov (United States)

Petit, Veronique

2014-10-01

We propose to obtain phase-resolved UV spectroscopy of the recently discovered magnetic O star NGC 1624-2, which has the strongest magnetic field ever detected in a O-star, by an order of magnitude. We will use the strength and variability of the UV resonance line profiles to diagnose the density, velocity, and ionization structure of NGC 1624-2's enormous magnetosphere that results from entrapment of its stellar wind by its strong, nearly dipolar magnetic field. With this gigantic magnetosphere, NGC 1624-2 represents a new regime of extreme wind confinement that will constrain models of magnetized winds and their surface mass flux properties. A detailed understanding of such winds is necessary to study the rotational braking history of magnetic O-stars, which can shed new light on the fundamental origin of magnetism in massive, hot stars.

Wind Energy: A Maturing Power Supply Possibility.

Science.gov (United States)

Petersen, Erik Lundtang; And Others

1987-01-01

Suggests that wind energy for electrification will prove to be an appropriate technology with very positive socioeconomic benefits, especially in developing countries. Provides examples of projects conducted by a Danish wind research laboratory. (TW)

Lexicalisation Patterns in Danish and Spanish

DEFF Research Database (Denmark)

Woldersgaard, Casper A. G

In this dissertation, I investigate the theoretical framework by Leonard Talmy (2000b) on lexicalisation patterns in Motion events. I examine his characterisations of Co-event languages (e.g., Danish) and Path-event languages (e.g., Spanish), and I relate his work to a Danish language setting....... Furthermore, my objective is to determine whether the predictions set forth by Talmy apply to Danish and Spanish from an empirical perspective, i.e., in a Danish monolingual reference corpus, Korpus-DK, and a Spanish monolingual reference corpus, CORPES. I present different methods for testing Talmy’s theory....... As a consequence, to identify Motion events and discard false positives is an extremely time-consuming process. I suggest that a context-free grammar is a way to facilitate the retrieval and analysis of linguistic data that contain Motion events. Thus, I implement a context-free grammar for Spanish. More...

Market for wind turbines in italy

International Nuclear Information System (INIS)

1997-01-01

Wind power utilization in Italy has not been very popular until the privatization of the ENEL and introduction of subsidies for private electricity producers. The greatest interest is concentrated around large wind turbines. Therefore the Danish manufacturers with know-how within large wind turbines can establish themselves on the Italian market. Cooperation with one of the four local wind turbine manufacturers is advisable. (EG)

Database on wind characteristics - contents of database bank

Energy Technology Data Exchange (ETDEWEB)

Larsen, G.C.; Hansen, K.S.

2004-06-01

The main objective of IEA R and D Wind Annex XVII - Database on Wind Characteristics - has been to provide wind energy planners, designers and researchers, as well as the international wind engineering community in general, with a source of actual wind field data (time series and resource data) observed in a wide range of different wind climates and terrain types. Connected to an extension of the initial Annex period, the scope for the continuation was widened to include also support to the international wind turbine standardisation efforts.. The project partners are Sweden, Norway, U.S.A., The Netherlands and Denmark, with Denmark as the Operating Agent. The reporting of the continuation of Annex XVII falls in two separate parts. Part one accounts in details for the available data in the established database bank, and part two describes various data analyses performed with the overall purpose of improving the design load cases with relevance for to wind turbine structures. The present report constitutes the second part of the Annex XVII reporting. Both fatigue and extreme load aspects are dealt with, however, with the main emphasis on the latter. The work has been supported by The Ministry of Environment and Energy, Danish Energy Agency, The Netherlands Agency for Energy and the Environment (NOVEM), The Norwegian Water Resources and Energy Administration (NVE), The Swedish National Energy Administration (STEM) and The Government of the United States of America. (au)

Wind energy in Denmark and within the Elsam utility area

International Nuclear Information System (INIS)

Friis, P.; Grauballe, J.

1995-01-01

At the turn of 1994, 3,700 wind turbines, with a total installed capacity of 540 MW were connected to the Danish utility grid. In 1994 these turbines fed 1,118 GWh wind energy into the grid, corresponding to approximately 3.3% of the total electricity consumption. The ELSAM utility area supplies the electric energy consumed by half the Danish population. The area has a large wind energy potential and approx. 75% of the installed wind energy capacity in Denmark is situated here accounting for 400 MW. In 1994 the ELSAM utilities supplied a total of 18,450 GWh with wind power contributing 850 GWh, i.e. 4.6% of the ELSAM sales to the consumers. (Author)

Offshore Wind Power Production in Critical Weather Conditions

DEFF Research Database (Denmark)

Cutululis, Nicolaos Antonio; Litong-Palima, Marisciel; Sørensen, Poul Ejnar

2012-01-01

control the power balance during offshore storm passages. The demonstration will be done on Horns Rev 2 wind farm. In the same project, the impact of a storm front passage over the system security, for the whole Danish system, and with the expected offshore wind power in 2020 will be investigated....... This paper will present the results of up-scaling the impact that a storm front passage will have on the Danish power system in 2020, given that the existing wind turbine storm controller is not replaced. The simulations are done with CorWind and the analysis is focusing on establishing a reference case...... and quantifying the balancing reserve requirements needed in order to keep the security of the power system....

The effect of stability on the coastal gradients at the Anholt wind farm

DEFF Research Database (Denmark)

Volker, Patrick; Hasager, Charlotte Bay; Badger, Merete

We use Synthetic Aperture Radar (SAR) and SCADA measurements and mesoscale model simulations from the Weather Research and Forecast (WRF) model[3] to analyse the flow conditions at the Danish offshore wind farm at Anholt. The first Danish oshore wind farms have been installed in the North Sea of ...

Estimation of Extreme Response and Failure Probability of Wind Turbines under Normal Operation using Probability Density Evolution Method

DEFF Research Database (Denmark)

Sichani, Mahdi Teimouri; Nielsen, Søren R.K.; Liu, W. F.

2013-01-01

Estimation of extreme response and failure probability of structures subjected to ultimate design loads is essential for structural design of wind turbines according to the new standard IEC61400-1. This task is focused on in the present paper in virtue of probability density evolution method (PDEM......), which underlies the schemes of random vibration analysis and structural reliability assessment. The short-term rare failure probability of 5-mega-watt wind turbines, for illustrative purposes, in case of given mean wind speeds and turbulence levels is investigated through the scheme of extreme value...... distribution instead of any other approximate schemes of fitted distribution currently used in statistical extrapolation techniques. Besides, the comparative studies against the classical fitted distributions and the standard Monte Carlo techniques are carried out. Numerical results indicate that PDEM exhibits...

SAT-WIND project. Final report[Winds from satellites for offshore and coastal wind energy mapping and wind-indexing

Energy Technology Data Exchange (ETDEWEB)

Hasager, C.B.; Astrup, P.; Nielsen, M. (and others)

2007-04-15

The SAT-WIND project 'Winds from satellites for offshore and coastal wind energy mapping and wind-indexing' was a research project funded by STVF/DSF in the years 2003 to 2006 (Sagsnr. 2058-03-0006). The goal of the project was to verify the applicability of satellite wind maps derived from passive microwave, altimeter, scatterometer and imaging Synthetic Aperture Radar (SAR) technologies for wind energy tools for wind resources and wind-indexing. The study area was the Danish Seas including the North Sea, interior seas and the Baltic Sea. The report describes technical details on the satellite data sources including: 1) passive microwave (SSM/I, AMSR-E), 2) passive microwave polarimetric (WindSat), 3) scatterometer (ERS, QuikSCAT, Midori-2 and NSCAT), 4) altimeter (ERS, Topex, Poseidon, GFO-1, Jason-1), 5) SAR (ERS, Envisat). The SAR wind maps were treated in S-WAsP developed by Risoe National Laboratory in cooperation with GRAS A/S in the innovative project SAT-WIND-SMV (Sagsnr. 2104-05-0084) in the years 2005 and 2006 in parallel with SAT-WIND. The results from the SAT-WIND project are presented. These include ocean wind statistics, offshore wind resource estimates and comparison results for wind-indexing. (au)

SAT-WIND project. Final report[Winds from satellites for offshore and coastal wind energy mapping and wind-indexing

Energy Technology Data Exchange (ETDEWEB)

Hasager, C B; Astrup, P; Nielsen, M [and others

2007-04-15

The SAT-WIND project 'Winds from satellites for offshore and coastal wind energy mapping and wind-indexing' was a research project funded by STVF/DSF in the years 2003 to 2006 (Sagsnr. 2058-03-0006). The goal of the project was to verify the applicability of satellite wind maps derived from passive microwave, altimeter, scatterometer and imaging Synthetic Aperture Radar (SAR) technologies for wind energy tools for wind resources and wind-indexing. The study area was the Danish Seas including the North Sea, interior seas and the Baltic Sea. The report describes technical details on the satellite data sources including: 1) passive microwave (SSM/I, AMSR-E), 2) passive microwave polarimetric (WindSat), 3) scatterometer (ERS, QuikSCAT, Midori-2 and NSCAT), 4) altimeter (ERS, Topex, Poseidon, GFO-1, Jason-1), 5) SAR (ERS, Envisat). The SAR wind maps were treated in S-WAsP developed by Risoe National Laboratory in cooperation with GRAS A/S in the innovative project SAT-WIND-SMV (Sagsnr. 2104-05-0084) in the years 2005 and 2006 in parallel with SAT-WIND. The results from the SAT-WIND project are presented. These include ocean wind statistics, offshore wind resource estimates and comparison results for wind-indexing. (au)

Assessment of ENSEMBLES regional climate models for the representation of monthly wind characteristics in the Aegean Sea (Greece): Mean and extremes analysis

Science.gov (United States)

Anagnostopoulou, Christina; Tolika, Konstantia; Tegoulias, Ioannis; Velikou, Kondylia; Vagenas, Christos

2013-04-01

The main scope of the present study is the assessment of the ability of three of the most updated regional climate models, developed under the frame of the European research project ENSEMBLES (http://www.ensembles-eu.org/), to simulate the wind characteristics in the Aegean Sea in Greece. The examined models are KNMI-RACMO2, MPI-MREMO, and ICTP - RegCM3. They all have the same spatial resolution (25x25km) and for their future projections they are using the A1B SRES emission scenarios. Their simulated wind data (speed and direction) were compared with observational data from several stations over the domain of study for a time period of 25 years, from 1980 to 2004 on a monthly basis. The primer data were available every three or six hours from which we computed the mean daily wind speed and the prevailing daily wind direction. It should be mentioned, that the comparison was made for the grid point that was the closest to each station over land. Moreover, the extreme speed values were also calculated both for the observational and the simulated data, in order to assess the ability of the models in capturing the most intense wind conditions. The first results of the study showed that the prevailing winds during the winter and spring months have a north - northeastern or a south - south western direction in most parts of the Aegean sea. The models under examination seem to capture quite satisfactorily this pattern as well as the general characteristics of the winds in this area. During summer, winds in the Aegean Sea have mainly north direction and the models have quite good agreement both in simulating this direction and the wind speed. Concerning the extreme wind speed (percentiles) it was found that for the stations in the northern Aegean all the models overestimate the extreme wind indices. For the eastern parts of the Aegean the KNMI and the MPI model underestimate the extreme wind speeds while on the other hand the ICTP model overestimates them. Finally for the

Alteration of course in Danish energy- and environmental policy

International Nuclear Information System (INIS)

Trong, Maj Dang

2002-01-01

A new Danish government has announced great changes in Denmark's energy- and environmental policy. Norwegian hydro power may play a role in the government's consideration of a more efficient energy- and environmental policy. In principle, energy is to be produced where it is cheapest and least harmful to the environment. Green fees will be reorganized and billions will be saved by abolishing the subsidies to wind generators. The goal is to make wind energy self-supported by 2003. Plans for three new windmill parks in Danish waters have been abandoned. However, the environmental ministers of the countries around the North Sea agreed to speed up the development of ''green'' energy, not the least windmill parks at sea. The objective is that these oceanic windmill parks will contribute to reduced emission of carbon dioxide

German offshore wind turbine farms - status and prospective

International Nuclear Information System (INIS)

2004-08-01

As a consequence of Germany's forthcoming phase-out of nuclear power the German government has initiated a number of activities in order to further development of renewable energy in the future. Offshore wind power has been chosen to play a central part. Although the first wind turbine has yet to be erected in German waters there is no doubt that it is a matter of time before the growing German market will gather speed. The objective of this report is to provide Danish business enterprises with interests in wind power with an insight into the German offshore wind power market and the export possibilities of the present and in the near future. As introduction the report lists the general outlines for construction and operation of wind turbine farms in Germany, furthermore, a number of additional conditions that Danish business enterprises should be aware of are listed. The introduction is followed by an up-to-the -minute status account of all ongoing projects. This part of the report has been made on the basis of a questionnaire send out by the Danish Embassy to project leaders in the business enterprises behind the project planning. Finally, the report provides an overview of all partners behind the planned wind farms. The overview contains contact information as well as information about the composition of project companies and consortiums. (BA)

Extreme Response for Wind Turbines

DEFF Research Database (Denmark)

Toft, Henrik Stensgaard; Sørensen, John Dalsgaard

2009-01-01

The characteristic load on wind turbines during operation are among others dependent on the mean wind speed, the turbulence intensity and type and settings of the control system. The characteristic load during operation is normally estimated by statistical extrapolation of a limited number...... of simulated 10min time series of the response according to the wind turbine standard IEC 61400-1. However, this method assumes that the individual 10min time series and the extracted peaks from the time series are independent. In the present paper is this assumption investigated based on field measurements...

Power quality and integration of wind farms in weak grids in India

Energy Technology Data Exchange (ETDEWEB)

Soerensen, P.; Hauge Madsen, P. [Risoe National Lab., Roskilde (Denmark). Wind Energy and Atmospheric Physics Dept.; Vikkelsoe, A.; Koelbaek Jensen, K. [Danske Elvaerkers Forening Udredningsafdelingen (DEFU), Lyngby (Denmark); Fathima, K.A.; Unnikrishnan, A.K.

2000-04-01

This is the final report of a joint Danish and Indian project' Power Quality and Integration of Wind Farms in Weak Grids'. The power quality issues have been studied and analysed with the Indian conditions as a case. On the basis of meetings with Danish wind turbine industry, Indian electricity boards, nodal agencies, wind turbine industry and authorities, the critical power quality as-pects in India have been identified. Measurements on selected wind farms and wind turbines have quantified the power quality, and analyses of power quality issues, especially reactive power compensation, have been performed. Based on measurements and analyses, preliminary recommendations for grid integration of wind turbines in weak grids have been formulated. (au)

Vientos extremos en la provincia de Neuquén Extreme winds in the province of Neuquén

Directory of Open Access Journals (Sweden)

Jorge L. Lassig

2011-12-01

Full Text Available El objetivo de este trabajo es calcular los valores extremos de la velocidad del viento con distintos modelos propuestos en normas internacionales que son utilizadas tanto en el diseño de parques eólicos como en el de obras civiles. Se describen los modelos empleados y se realizan los cálculos en 5 lugares de la Provincia de Neuquén, utilizando datos de vientos medidos cuyas series tienen entre 8 meses y 5 años de longitud. Los valores extremos se obtienen con una recurrencia media de 50 años, y corresponden a la velocidad del viento media en intervalos de 10 minutos y de 3 segundos. Los valores encontrados se analizan y se los compara entre sí, con mediciones y con valores propuestos en la norma argentina de seguridad de obras civiles. Los valores extremos estimados según la European Wind Turbine Standards II no subestiman las mediciones disponibles, y comparados con los obtenidos por los otros modelos, se observa que las menores diferencias corresponden a las estaciones con series de mayor longitud. El parámetro de forma de Weibull y la longitud de los registros serían los factores más importantes en las estimaciones de los valores extremos de la velocidad del viento.The objective of this work is to calculate the extreme values of wind speed with different models proposed in international standards that are utilized so much in the design of wind farms as in civil structures. The employed models are described and the calculations are carried out in 5 places of the Neuquén Province, utilizing data of winds measured whose series have between 8 months and 5 years of length. The extreme values are obtained with a return period of 50 years and they correspond to the extreme of the 10-minute and 3-second average wind speed. The found values are analysed and it are compared among them, with measurements and with values proposed in the standard of security of civil structures of Argentina. The extremes values that were estimated according

Offshore wind turbine risk quantification/evaluation under extreme environmental conditions

International Nuclear Information System (INIS)

Taflanidis, Alexandros A.; Loukogeorgaki, Eva; Angelides, Demos C.

2013-01-01

A simulation-based framework is discussed in this paper for quantification/evaluation of risk and development of automated risk assessment tools, focusing on applications to offshore wind turbines under extreme environmental conditions. The framework is founded on a probabilistic characterization of the uncertainty in the models for the excitation, the turbine and its performance. Risk is then quantified as the expected value of some risk consequence measure over the probability distributions considered for the uncertain model parameters. Stochastic simulation is proposed for the risk assessment, corresponding to the evaluation of some associated probabilistic integral quantifying risk, as it allows for the adoption of comprehensive computational models for describing the dynamic turbine behavior. For improvement of the computational efficiency, a surrogate modeling approach is introduced based on moving least squares response surface approximations. The assessment is also extended to a probabilistic sensitivity analysis that identifies the importance of each of the uncertain model parameters, i.e. risk factors, towards the total risk as well as towards each of the failure modes contributing to this risk. The versatility and computational efficiency of the advocated approaches is finally exploited to support the development of standalone risk assessment applets for automated implementation of the probabilistic risk quantification/assessment. -- Highlights: ► A simulation-based risk quantification/assessment framework is discussed. ► Focus is on offshore wind turbines under extreme environmental conditions. ► Approach is founded on probabilistic description of excitation/system model parameters. ► Surrogate modeling is adopted for improved computational efficiency. ► Standalone risk assessment applets for automated implementation are supported

High Penetrated Wind Farm Impacts on the Electricity Price

DEFF Research Database (Denmark)

Haji Bashi, Mazaher; Yousefi, G. R.; Bak, Claus Leth

2016-01-01

of the high penetrated wind farm integration into electricity markets. Then, stochastic programming approach is employed to compare the volume of trades for a typical wind farm in a high and low wind penetrated market. Although increasing price spikes and volatility was reported in the literature......Energy trading policies, intermittency of wind farm output power, low marginal cost of the production, are the key factors that cause the wind farms to be effective on the electricity price. In this paper, the Danish electricity market is studied as a part of Nord Pool. Considering the completely...... fossil fuel free overview in Danish energy policies, and the currently great share of wind power (more than 100% for some hours) in supplying the load, it is an interesting benchmark for the future electricity markets. Negative prices, price spikes, and price volatility are considered as the main effects...

Wind turbines - facts from 20 years of technological progress

Energy Technology Data Exchange (ETDEWEB)

Hansen, L H; Dannemand Andersen, P [Risoe Ntaional Lab., Roskilde (Denmark)

1999-03-01

The first Danish commercial wind turbines were installed in the late 1970s. Over the last 20 years the Danish wind turbine market has been relatively stable concerning annual installations, and the wind turbine technology has been able to develop continuously. This gives a unique time track for technology analysts. The aim of this paper is to extract reliable information on this time track from existing archives and statistics. Seven generations of wind turbine technology have been identified mainly based on `characteristic` rotor diameters. The technological development of each generation is described using indicators such as: market share in Denmark, generator size, rotor diameter, hub height, electricity production and productivity. Economical indicators comprise: costs of turbine and standard foundation. (au)

Wind turbines - facts from 20 years of technological progress

International Nuclear Information System (INIS)

Hansen, L.H.; Dannemand Andersen, P.

1999-01-01

The first Danish commercial wind turbines were installed in the late 1970s. Over the last 20 years the Danish wind turbine market has been relatively stable concerning annual installations, and the wind turbine technology has been able to develop continuously. This gives a unique time track for technology analysts. The aim of this paper is to extract reliable information on this time track from existing archives and statistics. Seven generations of wind turbine technology have been identified mainly based on 'characteristic' rotor diameters. The technological development of each generation is described using indicators such as: market share in Denmark, generator size, rotor diameter, hub height, electricity production and productivity. Economical indicators comprise: costs of turbine and standard foundation. (au)

Average profiles of the solar wind and outer radiation belt during the extreme flux enhancement of relativistic electrons at geosynchronous orbit

Directory of Open Access Journals (Sweden)

R. Kataoka

2008-06-01

Full Text Available We report average profiles of the solar wind and outer radiation belt during the extreme flux enhancement of relativistic electrons at geosynchronous orbit (GEO. It is found that seven of top ten extreme events at GEO during solar cycle 23 are associated with the magnetosphere inflation during the storm recovery phase as caused by the large-scale solar wind structure of very low dynamic pressure (<1.0 nPa during rapid speed decrease from very high (>650 km/s to typical (400–500 km/s in a few days. For the seven events, the solar wind parameters, geomagnetic activity indices, and relativistic electron flux and geomagnetic field at GEO are superposed at the local noon period of GOES satellites to investigate the physical cause. The average profiles support the "double inflation" mechanism that the rarefaction of the solar wind and subsequent magnetosphere inflation are one of the best conditions to produce the extreme flux enhancement at GEO because of the excellent magnetic confinement of relativistic electrons by reducing the drift loss of trapped electrons at dayside magnetopause.

Recipes for correcting the impact of effective mesoscale resolution on the estimation of extreme winds

DEFF Research Database (Denmark)

Larsén, Xiaoli Guo; Ott, Søren; Badger, Jake

2012-01-01

Extreme winds derived from simulations using mesoscale models are underestimated due to the effective spatial and temporal resolutions. This is reflected in the spectral domain as an energy deficit in the mesoscale range. The energy deficit implies smaller spectral moments and thus underestimatio...

Wind and Wave Setup Contributions to Extreme Sea Levels at a Tropical High Island: A Stochastic Cyclone Simulation Study for Apia, Samoa

Directory of Open Access Journals (Sweden)

Ron Karl Hoeke

2015-09-01

Full Text Available Wind-wave contributions to tropical cyclone (TC-induced extreme sea levels are known to be significant in areas with narrow littoral zones, particularly at oceanic islands. Despite this, little information exists in many of these locations to assess the likelihood of inundation, the relative contribution of wind and wave setup to this inundation, and how it may change with sea level rise (SLR, particularly at scales relevant to coastal infrastructure. In this study, we explore TC-induced extreme sea levels at spatial scales on the order of tens of meters at Apia, the capitol of Samoa, a nation in the tropical South Pacific with typical high-island fringing reef morphology. Ensembles of stochastically generated TCs (based on historical information are combined with numerical simulations of wind waves, storm-surge, and wave setup to develop high-resolution statistical information on extreme sea levels and local contributions of wind setup and wave setup. The results indicate that storm track and local morphological details lead to local differences in extreme sea levels on the order of 1 m at spatial scales of less than 1 km. Wave setup is the overall largest contributor at most locations; however, wind setup may exceed wave setup in some sheltered bays. When an arbitrary SLR scenario (+1 m is introduced, overall extreme sea levels are found to modestly decrease relative to SLR, but wave energy near the shoreline greatly increases, consistent with a number of other recent studies. These differences have implications for coastal adaptation strategies.

Fixed-speed active-stall wind turbines in offshore applications

DEFF Research Database (Denmark)

Akhmatov, Vladislav; Nielsen, Arne Hejde

2005-01-01

A large offshore wind farm in the East Danish power system was commissioned in 2003 at Rodsand. The power capacity of the wind farm is 165 MW divided between 72 wind turbines. For this large offshore application, robust and well-known wind technology has been chosen in the form of fixed-speed, ac...

Research on wind energy

CSIR Research Space (South Africa)

Szewczuk, S

2012-10-01

Full Text Available heights; short-term predictions ? CSIR 2012 Slide 9 Innovation & preliminary wind energy technology tree ? South African Industry?s propensity to innovate is in the same league as their counterparts in Europe. To state this differently, South African...? ? CSIR 2012 Slide 18 Modular form of electrification in rural communities Project funded by the Royal Danish Embassy in Pretoria and carried out by: ? eThekwini (Durban) Municipality ? Ris? DTU (Danish National Laboratory for Sustainable Energy...

Wind power and a liberalised North European electricity exchange

Energy Technology Data Exchange (ETDEWEB)

Nielsen, L H; Morthorst, P E; Skytte, K [and others

1999-03-01

Conditions for wind power on a liberalised North European electrical power market are addressed in the paper. Results are presented from a recently completed study carried out by Risoe National Laboratory in collaboration with the Danish electric utilities Eltra, Elsam and Elkraft. A main result from the study is, that the market will be able to provide the necessary power regulation, that will be required year 2005 as consequence of the expected wind power capacity extension, according to the Danish energy plan, Energy21. The averege sales price on the market for the wind-generated electricity is less than the average spot market price, due to provision of power regulation to balance the unpredictability of the wind power. This reduction in the market value of wind power has been calculated to 10-20 DKK/MWh of 1.3-2.7 EUR/MWh. (au)

When real life wind speed exceeds design wind assumptions

Energy Technology Data Exchange (ETDEWEB)

Winther-Jensen, M; Joergensen, E R [Risoe National Lab., Roskilde (Denmark)

1999-03-01

Most modern wind turbines are designed according to a standard or a set of standards to withstand the design loads with a defined survival probability. Mainly the loads are given by the wind conditions on the site defining the `design wind speeds`, normally including extreme wind speeds given as an average and a peak value. The extreme wind speeds are normally (e.g. in the upcoming IEC standard for wind turbine safety) defined as having a 50-year recurrence period. But what happens when the 100 or 10,000 year wind situation hits a wind turbine? Results on wind turbines of wind speeds higher than the extreme design wind speeds are presented based on experiences especially from the State of Gujarat in India. A description of the normal approach of designing wind turbines in accordance with the standards in briefly given in this paper with special focus on limitations and built-in safety levels. Based on that, other possibilities than just accepting damages on wind turbines exposed for higher than design wind speeds are mentioned and discussed. The presentation does not intend to give the final answer to this problem but is meant as an input to further investigations and discussions. (au)

Electric Vehicles in Power Systems with 50% Wind Power Penetration

DEFF Research Database (Denmark)

Østergaard, Jacob; Foosnæs, Anders; Xu, Zhao

2009-01-01

will be an important balancing measure to enable the Danish government’s energy strategy, which implies 50% wind power penetration in the electric power system. An EV will be a storage device for smoothing power fluctuations from renewable resources especially wind power and provide valuable system services...... for a reliable power system operation. Cost-benefit analysis shows that intelligent bidirectional charging – vehicle to grid (V2G) – provides a socio-economic profit of 150 million Euro/year in the Danish electric power system in 2025 assuming that 15% of the Danish road transport need is supplied by electricity....... This paper analyse the potential for using EVs in Denmark and identify the benefits of the electric power system with high wind power generation by intelligent charging of the EVs. Based on the analysis important technology gabs are identified, and the corresponding research and development initiatives...

Area price and demand response in a market with 25% wind power

International Nuclear Information System (INIS)

Grohnheit, Poul Erik; Andersen, Frits Møller; Larsen, Helge V.

2011-01-01

Denmark, east and west of the Great Belt are bidding areas with separate hourly area prices for the Nord Pool power exchange, covering four Nordic countries and parts of Germany. The share of wind power has now increased to 25% on an annual basis in western Denmark. This has a significant impact not only on the electricity wholesale prices, but also on the development of the market. Hourly market data are available from the website of Danish TSO from 1999. In this paper these data are analysed for the period 2004–2010. Electricity generators and customers may respond to hourly price variations, which can improve market efficiency, and a welfare gain is obtained. An important limitation for demand response is events of several consecutive hours with extreme values. The analysis in this paper is a summary and update of some of the issues covered by the EU RESPOND project. It shows that extreme events were few, and the current infrastructure and market organisation have been able to handle the amount of wind power installed so far. This recommends that geographical bidding area for the wholesale electricity market reflects external transmission constraints caused by wind power. - Highlights: ► More than 10 years of hourly electricity market data are available for western Denmark. ► Current infrastructure and market organisation could handle 25% wind power. ► Demand response to hourly electricity prices leads to limited welfare gain. ► Consecutive hours with high or low price, or high or low wind are relatively few.

Large scale wind power penetration in Denmark

DEFF Research Database (Denmark)

Karnøe, Peter

2013-01-01

he Danish electricity generating system prepared to adopt nuclear power in the 1970s, yet has become the world's front runner in wind power with a national plan for 50% wind power penetration by 2020. This paper deploys a sociotechnical perspective to explain the historical transformation...... of "networks of power" via the interactions of politics, the techno-physics of electrons, and the market setting. The Danish case is about how an assemblage of new agencies has reorganized and reshaped society by building a new sociotechnical network. This has rendered developments highly unpredictable...... and highly experimental. The transformation process can be followed through the way successive technical engineering reports have represented the challenges associated with the penetration of wind power. The iteration shows how novel technical phenomena emerge and are assimilated, and how new engineering...

Sustainable energy planning for 27 small Danish Islands. Summary report

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-06-01

A methodology has been developed and implemented, whereby detailed assessment of a few model or archetype islands may be used as basis for subsequent estimation of possibilities for other islands of similar kind, provided certain key data for present day energy consumption are available. A consistent interaction with the population on the model islands has been important in that process. The technical-economical results of the study show, that a number of measures seem cost-effective with the aim of contributing to a sustainable energy supply for the small Danish islands. Most prominent are energy savings for both heat and electricity, grid connected wind turbines for electricity production and collective heat supply, in decreasing order of cost-effectiveness. It has become clear, that an organisational structure based on the cooperative idea is essential for realising this potential. In Denmark this is a strong tradition, recently manifesting itself in the fact, that a majority of Danish wind turbines have been installed in the fram work of cooperative idea is essential for realising this potential. In Denmark this is a strong tradition, recently manifesting itself in the fact, that a majority of Danish wind turbines have been installed in the framework of cooperatives. This means that it is a well proven concept, in Denmark well established in the legal and financial structure including the tax laws. Consequently such energy cooperatives represent the organisational structure recommended by the project also for other sustainable energy initiatives on the small Danish islands. The implication on a European level is that the methodology developed in the project, as well as the concrete recommendations of the project including organisational structures, seem well suited to be applied on a European level in the context of local communities with a strong identity. (LN)

Annual report of the Certification Secretariat of Wind Turbines for 2009; AArsrapport for Energistyrelsens Godkendelsessekretariat for Vindmoeller 2009

Energy Technology Data Exchange (ETDEWEB)

Lemming, J.

2010-09-15

This report was prepared as documentation for the activities in the Certification Secretariat of Wind Turbines in 2009. The secretariat has performed duties under a contract with the DEA (Danish Energy Agency), where the contents of the tasks are focused on administration of the Danish Certification Scheme for Wind Turbines. The report describes the current state of deployment of wind tur-bines in Denmark and the latest developments in wind turbine industry. Furthermore, the development of test areas is described. The tasks of the Secretariat has included daily administration, including ensuring the secretariat for the Advisory Committee, implementing the system of maintenance and service, development of new licensing rules for small wind turbines, and the approval and reviews of small wind turbines. In addition, the Secretariat and related experts from Risoe participated in Danish and international standards committees. (Author)

An assessment of the wind re-analyses in the modelling of an extreme sea state in the Black Sea

Science.gov (United States)

Akpinar, Adem; Ponce de León, S.

2016-03-01

This study aims at an assessment of wind re-analyses for modelling storms in the Black Sea. A wind-wave modelling system (Simulating WAve Nearshore, SWAN) is applied to the Black Sea basin and calibrated with buoy data for three recent re-analysis wind sources, namely the European Centre for Medium-Range Weather Forecasts Reanalysis-Interim (ERA-Interim), Climate Forecast System Reanalysis (CFSR), and Modern Era Retrospective Analysis for Research and Applications (MERRA) during an extreme wave condition that occurred in the north eastern part of the Black Sea. The SWAN model simulations are carried out for default and tuning settings for deep water source terms, especially whitecapping. Performances of the best model configurations based on calibration with buoy data are discussed using data from the JASON2, TOPEX-Poseidon, ENVISAT and GFO satellites. The SWAN model calibration shows that the best configuration is obtained with Janssen and Komen formulations with whitecapping coefficient (Cds) equal to 1.8e-5 for wave generation by wind and whitecapping dissipation using ERA-Interim. In addition, from the collocated SWAN results against the satellite records, the best configuration is determined to be the SWAN using the CFSR winds. Numerical results, thus show that the accuracy of a wave forecast will depend on the quality of the wind field and the ability of the SWAN model to simulate the waves under extreme wind conditions in fetch limited wave conditions.

Structural analysis of the Danish windmill industry. Strukturanalyse af dansk vindmoelleindustri

Energy Technology Data Exchange (ETDEWEB)

1988-09-15

Most Danish windmill manufacturers have experienced a grave economic crisis during the last three years. In 1987, the total windmill industry in this country ran at a loss of 40 million Danish crowns where the turnover was 550 million crowns. Danish firms are too small and seem to lack professional management. Production costs are too high and there is an urgent need for structural rationalization. Danish windmills cannot at the present time compete with the foreign market, largely because of lack of marketing know-how and financial backing. Yet today, many countries energy policies include the development of renewable energy resources, especially in the case of wind power. This should mean that the world market for windmills will increase, but so will the number of foreign competitors. The authors suggest the merging of Danish windmill manufacturing firms, and these mergers should include corporations that produce electricity. Possibilities for raising financial backing for running costs and export activities are mentioned, and ideas for rationalizing and reconstructing the whole Danish windmill industry are described in detail. (AB).

Energy Comes Together in Denmark: The Key to a Future Fossil-Free Danish Power System

DEFF Research Database (Denmark)

Meibom, Peter; Hilger, Klaus Baggesen; Madsen, Henrik

2013-01-01

The transition of the Danish energy system to a system based only on renewable energy in 2050 carries many challenges. For Denmark to become independent of fossil energy sources, wind power and biomass are expected to become the main sources of energy. Onshore and offshore wind farms are expected...... to provide the majority of electricity, and biomass and electricity are expected to become the major sources of heating. On the way toward the 100% renewable goal in 2050, the Danish government has proposed a 2035 midterm goal to cover the energy consumption for power and heat with renewables....

Assessment of Wind Parameter Sensitivity on Extreme and Fatigue Wind Turbine Loads

Energy Technology Data Exchange (ETDEWEB)

Robertson, Amy N [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Sethuraman, Latha [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Jonkman, Jason [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Quick, Julian [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

2018-01-12

Wind turbines are designed using a set of simulations to ascertain the structural loads that the turbine could encounter. While mean hub-height wind speed is considered to vary, other wind parameters such as turbulence spectra, sheer, veer, spatial coherence, and component correlation are fixed or conditional values that, in reality, could have different characteristics at different sites and have a significant effect on the resulting loads. This paper therefore seeks to assess the sensitivity of different wind parameters on the resulting ultimate and fatigue loads on the turbine during normal operational conditions. Eighteen different wind parameters are screened using an Elementary Effects approach with radial points. As expected, the results show a high sensitivity of the loads to the turbulence standard deviation in the primary wind direction, but the sensitivity to wind shear is often much greater. To a lesser extent, other wind parameters that drive loads include the coherence in the primary wind direction and veer.

Denmark leads in wind energy

International Nuclear Information System (INIS)

Aamand, Rene

1997-01-01

With an engineering background, Danish manufacturers used a ''bottom-up strategy'' to beat the competition. They start with small-scale 55kW wind turbines, and today offer the MW-sized machines. (author)

Effects of the Tunoe Knob offshore wind farm on birdlife

International Nuclear Information System (INIS)

Guillemette, M.; Kyed Larsen, J.; Clausager, I.

1997-01-01

As part of the plans of the Danish government to expand offshore wind energy production, The Ministry of Environment and Energy, in collaboration with the Danish power companies, initiated a three-year study of the effects of the Tunoe Knob offshore wind farm on bird life. The aim of this study was to investigate the potential conflict between offshore wind farms and water birds. Danish coastal waters support very large, internationally important concentrations of moulting, migrating and wintering water birds which depend on shallow water areas as major feeding habitats. The wind farm was established at Tunoe Knob, a shoal in Aarhus Bugt, and consisted of ten 500 kW turbines erected in 3-5 m of water during the late summer of 1995. All studies were carried out during the winter period, and results are reported for eider Somateria mollissima and common scoter Melanitta nigra, which composed the great majority of the bird population. In the part of Tunoe knob where the wind farm was build, eider numbers decreased markedly over the study period. However, this decline was comparable to that observed on other parts of Tunoe Knob. Furthermore, detailed mapping showed a high degree of annual and within season variation in spatial distribution over the area, including occurrence in the immediate vicinity of the wind farm. These results suggest that the observed changes in eider numbers in the wind farm area were due to natural variation. (EG) 21 refs

WindScanner.eu - a new Remote Sensing Research Infrastructure for On- and Offshore Wind Energy

DEFF Research Database (Denmark)

Mikkelsen, Torben; Siggaard Knudsen, Søren; Sjöholm, Mikael

2012-01-01

will be disseminated throughout Europe to pilot European wind energy research centers. The new research infrastructure will become an open source infrastructure that also invites collaboration with wind energy related atmospheric scientists and wind energy industry overseas. Recent achievements with 3D Wind......A new remote sensing based research infrastructure for atmospheric boundary-layer wind and turbulence measurements named WindScanner have during the past three years been in its early phase of development at DTU Wind Energy in Denmark. During the forthcoming three years the technology......Scanners and spin-off innovation activity are described. The Danish WindScanner.dk research facility is build from new and fast-scanning remote sensing equipment spurred from achievements within fiber optics and telecommunication technologies. At the same time the wind energy society has demanded excessive 3D wind...

WindScanner.eu - a new remote sensing research infrastructure for on- and offshore wind energy

Energy Technology Data Exchange (ETDEWEB)

Mikkelsen, Torben; Knudsen, Soeren; Sjoeholm, M.; Angeloua, N.; Tegtmeier, A. [Technical Univ. og Denmark. DTU Wind Energy, DTU Risoe Campus, Roskilde (Denmark)

2012-07-01

A new remote sensing based research infrastructure for atmospheric boundary-layer wind and turbulence measurements named WindScanner have during the past three years been in its early phase of development at DTU Wind Energy in Denmark. During the forthcoming three years the technology will be disseminated throughout Europe to pilot European wind energy research centers. The new research infrastructure will become an open source infrastructure that also invites collaboration with wind energy related atmospheric scientists and wind energy industry overseas. Recent achievements with 3D WindScanners and spin-off innovation activity are described. The Danish WindScanner.dk research facility is build from new and fast-scanning remote sensing equipment spurred from achievements within fiber optics and telecommunication technologies. At the same time the wind energy society has demanded excessive 3D wind flow and ever taller wind profile measurements for the wind energy resource assessment studies on- and off shore of the future. Today, hub heights on +5 MW wind turbines exceed the 100 m mark. At the Danish DTU test site Oesterild testing is ongoing with a Siemens turbine with hub height 120 meters and a rotor diameter of 154 meters; hence its blade tips reaches almost 200 meters into the sky. The wind speed profiles over the rotor planes are consequently no longer representatively measured by a single cup anemometer at hub height from a nearby met-mast; power curve assessment as well as turbine control call for multi-height multi point measurement strategies of wind speed and wind shear within the turbines entire rotor plane. The development of our new remote sensing-based WindScanner.dk facility as well as the first measurement results obtained to date are here presented, including a first wind lidar measurement of turbulence in complex terrain within an internal boundary layer developing behind an escarpment. Also measurements of wind speed and direction profiles

Denmark's future as competence center for wind power; Damarks fremtid som kompetencecentrum for vindkraft

Energy Technology Data Exchange (ETDEWEB)

NONE

2007-09-07

Denmark is a leading centre of competence for wind power, and the Danish wind power industry is very successful. In the latest years significant changes of the technological and market systems have happened, which challenge Denmark's leading position. The partnership Megavind has been established on the initiative of the government to promote sustainable technologies through innovation and research. Megavind represents the Danish wind power sector and is the catalyst and starter of strategies for testing, demonstration, and research within wind power in Denmark. The vision of Megavind is that Denmark shall continue to be the world's leading centre of competence for wind power through efficient integration of wind power in the total power system. Based on an analysis of the Danish competencies, the report presents recommendations to fulfil the vision. Also, the recommendations are based on strengthening the co-operation between the wind power industry's and universities' research and innovation. A coherent strategy for testing and demonstrating wind turbine components, wind turbines and wind farms, and wind power plants in energy systems is recommended. It is also recommended that strategic research initiatives are taken within 1) design and construction of turbines, 2) aerodynamics and materials for winds, 3) wind loads and siting, 4) integration of wind power in the energy system, and 5) offshore technologies. (LN)

Wind and wave extremes over the world oceans from very large ensembles

Science.gov (United States)

Breivik, Øyvind; Aarnes, Ole Johan; Abdalla, Saleh; Bidlot, Jean-Raymond; Janssen, Peter A. E. M.

2014-07-01

Global return values of marine wind speed and significant wave height are estimated from very large aggregates of archived ensemble forecasts at +240 h lead time. Long lead time ensures that the forecasts represent independent draws from the model climate. Compared with ERA-Interim, a reanalysis, the ensemble yields higher return estimates for both wind speed and significant wave height. Confidence intervals are much tighter due to the large size of the data set. The period (9 years) is short enough to be considered stationary even with climate change. Furthermore, the ensemble is large enough for nonparametric 100 year return estimates to be made from order statistics. These direct return estimates compare well with extreme value estimates outside areas with tropical cyclones. Like any method employing modeled fields, it is sensitive to tail biases in the numerical model, but we find that the biases are moderate outside areas with tropical cyclones.

Assessment of extreme design loads for modern wind turbines using the probabilistic approach

DEFF Research Database (Denmark)

Abdallah, Imad

There is a large drive to reduce the cost of energy of wind energy generators. Various tracks are being considered such as enhanced O&M strategies through condition monitoring, increased manufacturing efficiency through higher production volumes and increased automation, improved resource...... and drag coefficients showed (a) a tangible reduction in the load partial safety factor for a blade and (b) generally a larger impact on extreme loads during power production compared to stand-still. Therefore, the way forward is for wind turbine manufactures to further update the stochastic model...... assessment through turbine-mounted real-time site assessment technologies, improved components reliability by increased laboratory testing, increased number of prototype test turbines before serial production, larger rotor and tower concepts for both onshore and offshore installations, advanced drive train...

Strong winds and waves offshore

DEFF Research Database (Denmark)

Larsén, Xiaoli Guo

2016-01-01

is on the meteorologi al and o eani onditions related to storm winds and waves over the North Sea. With regard to the o shore wind energy appli ation, the parameters addressed here in lude: extreme wind and extreme waves, storm wind and waves and turbulen e issues for o shore onditions.......This report is prepared for Statoil, with the intention to introdu e DTU Wind Energy's ongoing resear h a tivities on o shore extreme wind and wave onditions. The purpose is to share our re ent ndings and to establish possible further ollaboration with Statoil. The fo us of this report...

The combined risk of extreme tropical cyclone winds and storm surges along the U.S. Gulf of Mexico Coast

Science.gov (United States)

Trepanier, J. C.; Yuan, J.; Jagger, T. H.

2017-03-01

Tropical cyclones, with their nearshore high wind speeds and deep storm surges, frequently strike the United States Gulf of Mexico coastline influencing millions of people and disrupting offshore economic activities. The combined risk of occurrence of tropical cyclone nearshore wind speeds and storm surges is assessed at 22 coastal cities throughout the United States Gulf of Mexico. The models used are extreme value copulas fitted with margins defined by the generalized Pareto distribution or combinations of Weibull, gamma, lognormal, or normal distributions. The statistical relationships between the nearshore wind speed and storm surge are provided for each coastal city prior to the copula model runs using Spearman's rank correlations. The strongest significant relationship between the nearshore wind speed and storm surge exists at Shell Beach, LA (ρ = 0.67), followed by South Padre Island, TX (ρ = 0.64). The extreme value Archimedean copula models for each city then provide return periods for specific nearshore wind speed and storm surge pairs. Of the 22 cities considered, Bay St. Louis, MS, has the shortest return period for a tropical cyclone with at least a 50 ms-1 nearshore wind speed and a 3 m surge (19.5 years, 17.1-23.5). The 90% confidence intervals are created by recalculating the return periods for a fixed set of wind speeds and surge levels using 100 samples of the model parameters. The results of this study can be utilized by policy managers and government officials concerned with coastal populations and economic activity in the Gulf of Mexico.

Wind farm acceptance for sale? Evidence from the Danish wind farm co-ownership scheme

DEFF Research Database (Denmark)

Johansen, K.; Emborg, J.

2018-01-01

-investors already support the planned wind farm projects, and many project opponents will not engage themselves in something they are against in principle. Finally, economic benefits potentially gained via OPSS do not appear to compensate for values feared violated by wind farms by many wind farm project...

Research Developments on Power System Integration of Wind Power

DEFF Research Database (Denmark)

Chen, Zhe; Hansen, Jens Carsten; Wu, Qiuwei

2011-01-01

variability and prediction, wind power plant ancillary services, grid connection and operation, Smart grids and demand side management under market functionality. The topics of the first group of PhD program starting 2011 under the wind energy Sino-Danish Centre for Education & Research (SDC) are also......This paper presents an overview on the recent research activities and tendencies regarding grid integration of wind power in Denmark and some related European activities, including power electronics for enhancing wind power controllability, wind turbines and wind farms modeling, wind power...

Statistical uncertainty of extreme wind storms over Europe derived from a probabilistic clustering technique

Science.gov (United States)

Walz, Michael; Leckebusch, Gregor C.

2016-04-01

Extratropical wind storms pose one of the most dangerous and loss intensive natural hazards for Europe. However, due to only 50 years of high quality observational data, it is difficult to assess the statistical uncertainty of these sparse events just based on observations. Over the last decade seasonal ensemble forecasts have become indispensable in quantifying the uncertainty of weather prediction on seasonal timescales. In this study seasonal forecasts are used in a climatological context: By making use of the up to 51 ensemble members, a broad and physically consistent statistical base can be created. This base can then be used to assess the statistical uncertainty of extreme wind storm occurrence more accurately. In order to determine the statistical uncertainty of storms with different paths of progression, a probabilistic clustering approach using regression mixture models is used to objectively assign storm tracks (either based on core pressure or on extreme wind speeds) to different clusters. The advantage of this technique is that the entire lifetime of a storm is considered for the clustering algorithm. Quadratic curves are found to describe the storm tracks most accurately. Three main clusters (diagonal, horizontal or vertical progression of the storm track) can be identified, each of which have their own particulate features. Basic storm features like average velocity and duration are calculated and compared for each cluster. The main benefit of this clustering technique, however, is to evaluate if the clusters show different degrees of uncertainty, e.g. more (less) spread for tracks approaching Europe horizontally (diagonally). This statistical uncertainty is compared for different seasonal forecast products.

Economic viability of transmission capacity expansion at high wind penetrations

DEFF Research Database (Denmark)

Østergaard, Poul Alberg

2005-01-01

investments and analyses of the Nord Pool price variations. The analyses are done for varying degrees of wind power penetrations ranging from 20% of the West Danish electricity demand up to 100% of the demand. The analyses demonstrate, that while there is an economic potential for some expansion in some years......With growing wind power penetrations in many countries, grid and system integration becomes more and more important issues. This is particularly the case in countries or regions with good wind resources as well as substantial installed wind power capacity as found in e.g. Northern Europe. At 20......% penetration in Western Denmark, the issue is pertinent here in relation to future plans of further expansion which is planned in accordance with the Danish Government’s climate change mitigation initiatives. This paper analyses the potential economic benefit of selling excess electricity production...

Wind energy technology developments

DEFF Research Database (Denmark)

Madsen, Peter Hauge; Hansen, Morten Hartvig; Pedersen, Niels Leergaard

2014-01-01

turbine blades and towers are very large series-produced components, which costs and quality are strongly dependent on the manufacturing methods. The industrial wind energy sector is well developed in Denmark, and the competitive advantage of the Danish sector and the potential for job creation...

Analysis of electricity price in Danish competitive electricity market

DEFF Research Database (Denmark)

Hu, Weihao; Chen, Zhe; Bak-Jensen, Birgitte

2012-01-01

electricity markets in some ways, is chosen as the studied power system. 10 year actual data from the Danish competitive electricity market are collected and analyzed. The relationship among the electricity price (both the spot price and the regulation price), the consumption and the wind power generation...... in an electricity market is investigated in this paper. The spot price and the regulation price generally decrease when the wind power penetration in the power system increases or the consumption of the power system decreases. The statistical characteristics of the spot price and the regulation price for different...... consumption periods and wind power penetration are analyzed. Simulation results show that the findings of this paper are useful for wind power generation companies to make the optimal bidding strategy so that the imbalance cost of trading wind power on the electricity market could be reduced....

An effective secondary decomposition approach for wind power forecasting using extreme learning machine trained by crisscross optimization

International Nuclear Information System (INIS)

Yin, Hao; Dong, Zhen; Chen, Yunlong; Ge, Jiafei; Lai, Loi Lei; Vaccaro, Alfredo; Meng, Anbo

2017-01-01

Highlights: • A secondary decomposition approach is applied in the data pre-processing. • The empirical mode decomposition is used to decompose the original time series. • IMF1 continues to be decomposed by applying wavelet packet decomposition. • Crisscross optimization algorithm is applied to train extreme learning machine. • The proposed SHD-CSO-ELM outperforms other pervious methods in the literature. - Abstract: Large-scale integration of wind energy into electric grid is restricted by its inherent intermittence and volatility. So the increased utilization of wind power necessitates its accurate prediction. The contribution of this study is to develop a new hybrid forecasting model for the short-term wind power prediction by using a secondary hybrid decomposition approach. In the data pre-processing phase, the empirical mode decomposition is used to decompose the original time series into several intrinsic mode functions (IMFs). A unique feature is that the generated IMF1 continues to be decomposed into appropriate and detailed components by applying wavelet packet decomposition. In the training phase, all the transformed sub-series are forecasted with extreme learning machine trained by our recently developed crisscross optimization algorithm (CSO). The final predicted values are obtained from aggregation. The results show that: (a) The performance of empirical mode decomposition can be significantly improved with its IMF1 decomposed by wavelet packet decomposition. (b) The CSO algorithm has satisfactory performance in addressing the premature convergence problem when applied to optimize extreme learning machine. (c) The proposed approach has great advantage over other previous hybrid models in terms of prediction accuracy.

Innovation paths in wind power

DEFF Research Database (Denmark)

Lema, Rasmus; Nordensvärd, Johan; Urban, Frauke

Denmark and Germany both make substantial investments in low carbon innovation, not least in the wind power sector. These investments in wind energy are driven by the twin objectives of reducing carbon emissions and building up international competitive advantage. Support for wind power dates back....... The ‘Danish Design’ remains the global standard. The direct drive design, while uncommon in Denmark, dominates the German installation base. Direct drive technology has thus emerged as a distinctly German design and sub-trajectory within the overall technological innovation path. When it comes to organising...... global interconnectedness of wind technology markets and the role of emerging new players, such as China and India....

Development of wind energy in Denmark

Energy Technology Data Exchange (ETDEWEB)

Nielsen, P. [Danske Elvaerkers Forenings Udredningsafdeling (DEFU), Lyngby (Denmark)

1994-12-31

In Denmark, wind energy has for centuries been used for many purposes, among these water pumping, milling of grain, and electricity generation. This paper discusses the development of grid-connected wind turbines on a large-scale sponsored by the national government, the Commission of the European Communities and the Danish electric utilities, and small-scale grid-connected wind turbines both privately and utility owned. Siting investigations have shown that it is possible to find sites of reasonable quality for a potential electricity production of at least 10 percent of the expected electricity consumption in 2005 which corresponds to about 1500 MW of installed capacity. Regulations were introduced in 1991 limiting the owners of wind turbines to noise levels from the wind turbines to the existing levels of 45 dB in rural areas, and 40 dB in residential areas and other noise sensitive areas. Studies of the effects of wind turbines on birds found that compared with other human activities, such as farming and car driving, a wind turbine in a bird sanctuary does not have a particular impact on bird life, although there were some effects such as birds moving away from the turbine to breed, forage etc. The Danish Government`s aim to establish 1500 MW of wind power by the year 2005 has some problems. Funding for research, a combination of agreements with the utilities, and production subsidies to private persons and co-operative societies is contributing to the resolution of these problems. 1 tab., 2 figs.

Social assessment of wind power. Part 3: Employment and balance of payments

International Nuclear Information System (INIS)

Munksgaard, J.; Rahbaek Pedersen, J.; Jensen, T.

1995-12-01

The main object of this report is to investigate the consequences of a wind power development of the Danish electricity system on employment and the balance of payments. The development is carried out as an investment in 1,000 MW wind power compared to a 450 MW coal-based central power plant. The wind power development is consistent with 'Energy 2000 - A Plan of Action for Sustainable Development' from the Danish Ministry of Energy which states that a total capacity of 1,500 MW should be reached by 2005. The effects on the employment and the balance of payments will be quantified as employed per year and million DKK per year respectively. This is due to the opinion that these effects should not have decisive influence on the assessment of long term energy and environmental projects. Based on the assumptions on the cost-efficiency of wind power the capacity of 1,000 MW wind power, supplied by 220 MW backup capacity from natural gas-fired turbines, is equivalent to a 420 MW central power plant base on coal. This forms the basis of two scenarios: a wind power scenario and a coal power scenario. The overall result in this report is that the effects on employment and the balance of payments do not differ very much. Therefore one cannot recommend nor reject wind power in the Danish electricity system compared to a coal-based central power plant. (EG) 13 refs

Comparison of NWP wind speeds and directions to measured wind speeds and directions

DEFF Research Database (Denmark)

Astrup, Poul; Mikkelsen, Torben

Numerical Weather Predictions (NWP) of wind speed and direction has been compared to measurements for seven German sites for nuclear power plants, and for Risø, the site of the Danish nuclear research reactors now being decommissioned . For the German sites the data cover approximately three month...

Towards a generalization procedure for WRF mesoscale wind climatologies

DEFF Research Database (Denmark)

Hahmann, Andrea N.; Casso, P.; Campmany, E.

We present a method for generalizing wind climatologies generated from mesoscale model output (e.g. the Weather, Research and Forecasting (WRF) model.) The generalization procedure is based on Wind Atlas framework of WAsP and KAMM/WAsP, and been extensively in wind resources assessment in DTU Wind...... generalized wind climatologies estimated by the microscale model WAsP and the methodology presented here. For the Danish wind measurements the mean absolute error in the ‘raw’ wind speeds is 9.2%, while the mean absolute error in the generalized wind speeds is 4.1%. The generalization procedure has been...

Analysis of Anholt offshore wind farm SCADA measurements

DEFF Research Database (Denmark)

Hansen, Kurt Schaldemose; Volker, Patrick; Pena Diaz, Alfredo

SCADA measurements from the Danish Anholt offshore wind farm (ANH) for a period of 2½ years have been qualified. ANH covers 12 km × 22 km and is located between Djursland and the island Anholt in Kattegat, Denmark. This qualification encompasses identification of curtailment and idling periods......, start/stop events and a power curve control for each wind turbine in the wind farm. Data also include wind speed measurements from a nearby WindCube lidar and simulations from the WRF model for the same period as the SCADA. An equivalent wind speed (wsi) is derived from the combined power and pitch...

Effects of extreme wind shear on aeroelastic modal damping of wind turbines

DEFF Research Database (Denmark)

Skjoldan, P.F.; Hansen, Morten Hartvig

2013-01-01

Wind shear is an important contributor to fatigue loads on wind turbines. Because it causes an azimuthal variation in angle of attack, it can also affect aerodynamic damping. In this paper, a linearized model of a wind turbine, based on the nonlinear aeroelastic code BHawC, is used to investigate...

Wind power in Arctic regions

International Nuclear Information System (INIS)

Lundsager, P.; Ahm, P.; Madsen, B.; Krogsgaard, P.

1993-07-01

Arctic or semi-arctic regions are often endowed with wind resources adequate for a viable production of electricity from the wind. Only limited efforts have so far been spent to introduce and to demonstrate the obvious synergy of combining wind power technology with the problems and needs of electricity generation in Arctic regions. Several factors have created a gap preventing the wind power technology carrying its full role in this context, including a certain lack of familiarity with the technology on the part of the end-users, the local utilities and communities, and a lack of commonly agreed techniques to adapt the same technology for Arctic applications on the part of the manufacturers. This report is part of a project that intends to contribute to bridging this gap. The preliminary results of a survey conducted by the project are included in this report, which is a working document for an international seminar held on June 3-4, 1993, at Risoe National Laboratory, Denmark. Following the seminar a final report will be published. It is intended that the final report will serve as a basis for a sustained, international effort to develop the wind power potential of the Arctic and semi-arctic regions. The project is carried out by a project group formed by Risoe, PA Energy and BTM Consult. The project is sponsored by the Danish Energy Agency of the Danish Ministry of Energy through grant no. ENS-51171/93-0008. (au)

How wind power landscapes change

DEFF Research Database (Denmark)

Möller, Bernd

2006-01-01

Following 25 years of continuous development, Danish wind energy landscapes are going to face changes. Ceased on-shore construction, unresolved re-powering and stalled regional planning characterize the situation overshadowed by off-shore development. One of the factors inhibiting development...... in general. However, the pattern of visibility will become askew, and the present homogenous distribution of visibility will disappear. This skewness, together with changing ownership and receding local involvement, could eventually lead to lower popular acceptance of wind power....

Area price and demand response in a market with 25% wind power

DEFF Research Database (Denmark)

Grohnheit, Poul Erik; Møller Andersen, Frits; Larsen, Helge V.

2011-01-01

Denmark, east and west of the Great Belt are bidding areas with separate hourly area prices for the Nord Pool power exchange, covering four Nordic countries and parts of Germany. The share of wind power has now increased to 25% on an annual basis in western Denmark. This has a significant impact...... not only on the electricity wholesale prices, but also on the development of the market. Hourly market data are available from the website of Danish TSO from 1999. In this paper these data are analysed for the period 2004–2010. Electricity generators and customers may respond to hourly price variations......, which can improve market efficiency, and a welfare gain is obtained. An important limitation for demand response is events of several consecutive hours with extreme values. The analysis in this paper is a summary and update of some of the issues covered by the EU RESPOND project. It shows that extreme...

Optimal Operation of Plug-In Electric Vehicles in Power Systems with High Wind Power Penetrations

DEFF Research Database (Denmark)

Hu, Weihao; Su, Chi; Chen, Zhe

2013-01-01

in the power systems with high wind power penetrations. In this paper, the integration of plug-in electric vehicles in the power systems with high wind power penetrations is proposed and discussed. Optimal operation strategies of PEV in the spot market are proposed in order to decrease the energy cost for PEV......The Danish power system has a large penetration of wind power. The wind fluctuation causes a high variation in the power generation, which must be balanced by other sources. The battery storage based Plug-In Electric Vehicles (PEV) may be a possible solution to balance the wind power variations...... owners. Furthermore, the application of battery storage based aggregated PEV is analyzed as a regulation services provider in the power system with high wind power penetrations. The western Danish power system where the total share of annual wind power production is more than 27% of the electrical energy...

Dioxin in Danish air

Energy Technology Data Exchange (ETDEWEB)

Vikelsoe, J.; Andersen, H.V. [National Environmental Research Inst., Roskilde (Denmark)

2004-09-15

To gain more knowledge about dioxin levels, sources and emissions in Denmark, the Danish government year 2001 initiated the Danish Dioxin Monitoring Program. The program is a series of investigations, comprising soil, compost, percolate, bio-ash, incineration of municipal and hazardous waste, deposition, air, lake and fjord sediment as well as cows milk and human milk. The present paper describes the preliminary results for the continued investigation of air. Deposition of dioxin over land or sea is of major importance for the human exposure, which takes place mainly from food intake. The dioxin are emitted mainly to the atmosphere, therefore air measurements are well suited for tracking the transport and fate of dioxin from sources to exposure. Whereas measurements from chimneys has been frequently used to estimate the industrial emission from point sources such as incinerators, air measurements also include emission from diffuse sources such as larger urban or industrial regions, residential quarters, and from evaporation. Furthermore, emission measurements must be done on known sources, whereas air measurements include contribution from unknown source. The major drawbacks of air measurements are the long duration required (years), and the results depends on meteorological conditions, such as temperature, rainfall, wind speed and direction. The purpose of the present study has been to measure dioxins in Danish air, emphasizing - background concentrations and annual variation - difference between urban, rural and residential zones - influence from local sources and long range transport - connection between dioxin in air and deposition.

Mobile measurement system for wind turbines

Energy Technology Data Exchange (ETDEWEB)

Kildemoes Moeller, T.

1997-06-01

The aim of this project `Udviklingsafproevning af smaa moellevinger` has been to develop a mobile measurement system for wind turbines. The following report describes the measurement system. The project has been financed by the Danish Ministry of Energy. (au)

4MW per month: the economics and reliability of private wind energy in Denmark

International Nuclear Information System (INIS)

Palmer, C.

1991-01-01

Denmark has an established wind energy industry. For more than 10 years they have had companies which manufacture production wind turbines for sale on the open market. Over the last five years this industry has matured considerably and there are now at least five companies which sell wind turbines as off the shelf products. Many thousands of Danish wind turbines have been sold around the world and the industry has benefitted greatly from this experience. There are no other European manufacturers who have access to such a large bank of experience. Within Denmark itself, wind energy is considered to be an essentially proven technology. As a result it is an accepted part of the investment market. Approximately 1% of the Danish population (50,000 people) have money invested in wind turbines. Borrowing money for this purpose is almost as well established as the house mortgage system in the UK. (Author)

Conditional prediction intervals of wind power generation

DEFF Research Database (Denmark)

Pinson, Pierre; Kariniotakis, Georges

2010-01-01

A generic method for the providing of prediction intervals of wind power generation is described. Prediction intervals complement the more common wind power point forecasts, by giving a range of potential outcomes for a given probability, their so-called nominal coverage rate. Ideally they inform...... on the characteristics of prediction errors for providing conditional interval forecasts. By simultaneously generating prediction intervals with various nominal coverage rates, one obtains full predictive distributions of wind generation. Adapted resampling is applied here to the case of an onshore Danish wind farm...... to the case of a large number of wind farms in Europe and Australia among others is finally discussed....

Wind turbines, is it just wind?

International Nuclear Information System (INIS)

Boiteux, M.

2012-01-01

The author first outlines that wind energy is not only random, but almost absent in extreme situations when it would be needed (for example and notably, very cold weather without wind). He suggests the association of a gas turbine to each wind turbine, so that the gas turbine will replace non operating wind turbines. He notices that wind turbines are not proximity energy as they were said to be, and that profitability in fact requires tens of grouped giant wind turbines. He also outlines the high cost of construction of grids for the connection of these wind turbines. Thus, he states that wind energy is far from being profitable in the present conditions of electricity tariffs in France

Transient Stability Assessment of Power System with Large Amount of Wind Power Penetration

DEFF Research Database (Denmark)

Liu, Leo; Chen, Zhe; Bak, Claus Leth

2012-01-01

Recently, the security and stability of power system with large amount of wind power are the concerned issues, especially the transient stability. In Denmark, the onshore and offshore wind farms are connected to distribution system and transmission system respectively. The control and protection...... methodologies of onshore and offshore wind farms definitely affect the transient stability of power system. In this paper, the onshore and offshore wind farms are modeled in detail in order to assess the transient stability of western Danish power system. Further, the computation of critical clearing time (CCT...... plants, load consumption level and high voltage direct current (HVDC) transmission links are taken into account. The results presented in this paper are able to provide an early awareness of power system security condition of the western Danish power system....

Wind Energy Department. Annual progress report 2001

International Nuclear Information System (INIS)

Skrumsager, B.; Larsen, S.; Hauge Madsen, P.

2002-10-01

The report describes the work of the Wind Energy Department at Risoe National Laboratory in 2001. The research of the department aims to develop new opportunities in the exploitation of wind energy and to map and alleviate atmospheric aspects of environmental problems. The expertise of the department is utilised in commercial activities such as wind turbine testing and certification, training programmes, courses and consultancy services to industry, authorities and Danish and international organisations on wind energy and atmospheric environmental impact. A summary of the department's activities in 2001 is shown, including lists of publications, lectures, committees and staff members. (au)

Wind Energy Department. Annual progress report 2001

Energy Technology Data Exchange (ETDEWEB)

Skrumsager, B.; Larsen, S.; Hauge Madsen, P. (eds.)

2002-10-01

The report describes the work of the Wind Energy Department at Risoe National Laboratory in 2001. The research of the department aims to develop new opportunities in the exploitation of wind energy and to map and alleviate atmospheric aspects of environmental problems. The expertise of the department is utilised in commercial activities such as wind turbine testing and certification, training programmes, courses and consultancy services to industry, authorities and Danish and international organisations on wind energy and atmospheric environmental impact. A summary of the department's activities in 2001 is shown, including lists of publications, lectures, committees and staff members. (au)

Wind power in Denmark technology, policies and results

International Nuclear Information System (INIS)

Dannemand Andersen, Per

1998-11-01

The Association of Danish Electricity Utilities has estimated the total electricity production from wind turbines in 1997 as 1932 GWh: 384 GWh from utility-owned turbines and 1548 GWh from privately owned turbines. This equals 6% of total electricity consumption in Denmark. Corrected to a 'normal wind year' this equals 6.6% of Denmark's annual electricity consumption. The wind energy index in 1997 was 91%. According to the Danish Association of Electricity Utilities, 4784 turbines with a capacity of 1129 MW were connected to the grid at the end of 1997. 534 turbines and 287 MW were added in 1997, the largest figure ever. These are net figures and included dismantled machines. The actual sales of turbines is a bit higher, reflecting the fact that not all machines sold in 1997 were installed that year. New machines are usually 500 kW, 600 kW and 750 kW. No 1500 kW machines have as yet been installed on a commercial basis in Denmark. (au)

Offshore Wind Turbine Design

DEFF Research Database (Denmark)

Frandsen, Sten; Hansen, Erik Asp; Ibsen, Lars Bo

2006-01-01

Current offshore wind turbine design methods have matured to a 1st generation state, manifested in the draft of a possible standard, IEC 61400-3 (2005). It is now time to investigate the possibilities of improving existing methods. To do so in an efficient manner a clear identification of the most...... important uncertainty drivers specific for offshore wind turbine design loads is required. Describing the initial efforts in a Danish research project, the paper points to focal points for research and development. These are mainly: soil-structure interaction, improved modelling of wave loads from deep...

Danish energy-sector exports. Products and consulting services

International Nuclear Information System (INIS)

Wolter, H.C.

2000-06-01

Danish Energy Agency has previously carried out studies of Danish energy-sector exports. The latest results were published in the report, Energisektorens eksport. Produkter og raadgivning. Danish Energy Agency, September 1998. The present survey is an update of the earlier studies, and includes 1998 exports. As previously, the study, carried out in cooperation with the Confederation of Danish Industries and the Danish Council of Consulting Architects and Engineers, is based on questionnaires sent to relevant companies. In addition, information has been obtained from companies that do not belong to these organisations. On the basis of the answers received, 58 Danish companies exported products to a value of approximately DKK 16,000 million, and 22 consulting firms exported consulting services to a value of approximately DKK 370 million. These exports of approximately DKK 16.5 billion accounted for 5% of all Danish exports in 1998. In comparison with 1996, energy-sector exports have risen by more than 40% in a period in which Danish exports in general have risen by an average of 8%. Energy sector exports provide employment for more than 18,000 persons in Denmark - approximately 17,500 employees in companies that export products, and approximately 600 persons in consulting firms. To this must be added a presumably significantly larger number of persons employed by sub-suppliers to the above companies computed by value, 80% of the exports come from relatively few companies, i.e. 13 companies with products, and five offering consulting services. Energy-sector exports fall within the following product areas: 1) Wind turbines (25%). 2) District heating and combined heat and power (CHP) (21%). 3) Energy savings and control (20%). 4) Oil and natural gas (13%). 5) Electricity plants and power supply (13%). 6) Other (8%). 67% of the exports go to Western Europe, 18% to Asia, 7% to Eastern and Central Europe, and 8% to other parts of the world. (EHS)

Integration of wind power in the Danish generation system. EC wind power penetration study, phase 2

Energy Technology Data Exchange (ETDEWEB)

NONE

1989-06-01

The Commission of the European Communities has asked utilities in the member countries to carry out a coordinated study of the wind energy potential. The main objective is to show the consequences for the future electricity system when integrating wind power production covering 5, 10 or 15% of total demand. In addition to the best estimate scenario believed to be operational, some additional calculations have been carried out: wind power production as a negative load only (not operational for the total system); different levels of investment in wind farms. The methodology is based on the following steps: define a reference scenario for year 2000; define an alternative scenario with a certain amount of wind power production; calculate time-series for electrical load and district heating from combined heat/power production; calculate time-series for wind power production; make economic evaluation and sensitivity analysis; show environmental differences. Incorporation of wind power into the ELSAM power system, with the wind energy meeting, about 5% of demand will give rise to additional control capacity, or call for new contracts with neighbouring countries. The study includes estimated network investments. The simulations have been made with the SIM and SLUMP computer programmes. The economic analyses and the sensitivity analyses have been carried out using spreadsheets. The conclusion concerning profitability - based on the best estimate assumptions - is that the studied wind power scenarios are unprofitable. (EG)

Smart Grid Operation and Control – Challenges for Danish Distribution Systems Operators

DEFF Research Database (Denmark)

Iov, Florin

2016-01-01

that Denmark will reach this goal. In order to realise these objectives, the capacity of wind and solar power should be increased and more people should have Electric Vehicles (EVs), along with installing Heat Pumps (HPs) instead of the normal district heating. Penetration of renewable generation is already......, to be produced from sustainable technologies. As part of the total objective, the Danish government aims to 50% of the electricity consumption to be produced by wind power in 2020. In comparison, in 2014, 39% of the electricity consumption was produced by wind power in 2012 this was 30.1%, which indicates...

CWTC business plan; Wind turbine component centre

Energy Technology Data Exchange (ETDEWEB)

Hjuler Jensen, P; Hillestroem, A; Markou, H; Berring, P; Friis, P

2011-04-15

This report presents the Business Plan for the establishment of the Wind Turbine Component Centre (CWTC) to meet the objectives of performing theoretical research and experimental testing. The core idea of a CWTC is to support the Danish wind energy industry and research activities at the component level improving the competitive advantage of that industry. The CWTC will in itself operate its activities, including access to test and experimental facilities, on a semi commercial basis. The business model for the CWTC presented is based on revenues coming from component manufacturers as well as research grants, and will include membership fees as well as hourly payment and larger projects where payment is a limited project sum. The presented roadmap model clarifies the development path towards a fully developed CWTC, which will cover test of all important components along the drive-train as well as offering a comprehensive systematic understanding of the entire drive-train. The CWTC will over time market and sell its products and services on a global scale, but first and foremost the CWTC is established to support and strengthen the Danish wind energy industry and specifically the Danish sub suppliers to the Danish wind turbine industry and also the Danish research establishments. The presented organizational structure reflects that there are certain functions that are separated from the operations and it also reflects that scientific staffing are hired in on a project basis. Machine operators will be hired in on a permanent basis. The breakdown of the cost for running the rig, both for R and D and commercial projects is presented. The income from the other activities is calculated based on the cost for the research staff, both for R and D activities and commercial. In the first year the income will be 100% from R and D activities, which is the cost for the staff to set-up the test-rig, the guidelines and test procedures, and partly for running the rig. Within 3

Rational Calibration of Four IEC 61400-1 Extreme External Conditions

DEFF Research Database (Denmark)

Larsen, Gunner Chr.; Hansen, Kurt Schaldemose

2008-01-01

Based on a set of asymptotic statistical models on closed form this paper presents a rational and consistent calibration of four extreme external conditions defined in the International Electrotechnical Commission (IEC) 61400-1 standard: extreme operating gust, extreme wind shear, extreme coheren...... and proposed specifications of the magnitudes of the extreme external wind conditions are highlighted and discussed using an illustrative example based on two selected terrain types. Copyright © 2008 John Wiley & Sons, Ltd....... gust with direction change and extreme wind direction change. These four extreme external conditions are used in the definition of six of the IEC 61400-1 ultimate load cases. The statistical models are based on simple and easily accessible mean wind speed and turbulence characteristics...

Annual report 1997. Wind Energy and Atmospheric Physics Department

Energy Technology Data Exchange (ETDEWEB)

Madsen, P.H.; Dannemand Andersen, P.; Skrumsager, B. [eds.

1998-08-01

The report describes the work of the Wind Energy and Atmospheric Physics Department at Risoe National Laboratory during 1997. The research of the department aims to develop new opportunities in the exploitation of wind energy and to map and alleviate atmospheric aspects of environmental problems. The expertise of the department is utilised in commercial activities such as wind turbine testing and certification, training programmes, courses and consultancy services to industry, authorities and Danish and international organisations on wind energy and atmospheric environmental impact. (au)

Quantifying uncertainties in wind energy assessment

Science.gov (United States)

Patlakas, Platon; Galanis, George; Kallos, George

2015-04-01

The constant rise of wind energy production and the subsequent penetration in global energy markets during the last decades resulted in new sites selection with various types of problems. Such problems arise due to the variability and the uncertainty of wind speed. The study of the wind speed distribution lower and upper tail may support the quantification of these uncertainties. Such approaches focused on extreme wind conditions or periods below the energy production threshold are necessary for a better management of operations. Towards this direction, different methodologies are presented for the credible evaluation of potential non-frequent/extreme values for these environmental conditions. The approaches used, take into consideration the structural design of the wind turbines according to their lifespan, the turbine failures, the time needed for repairing as well as the energy production distribution. In this work, a multi-parametric approach for studying extreme wind speed values will be discussed based on tools of Extreme Value Theory. In particular, the study is focused on extreme wind speed return periods and the persistence of no energy production based on a weather modeling system/hind cast/10-year dataset. More specifically, two methods (Annual Maxima and Peaks Over Threshold) were used for the estimation of extreme wind speeds and their recurrence intervals. Additionally, two different methodologies (intensity given duration and duration given intensity, both based on Annual Maxima method) were implied to calculate the extreme events duration, combined with their intensity as well as the event frequency. The obtained results prove that the proposed approaches converge, at least on the main findings, for each case. It is also remarkable that, despite the moderate wind speed climate of the area, several consequent days of no energy production are observed.

Framing Failures in Wood-Frame Hip Roofs under Extreme Wind Loads

Directory of Open Access Journals (Sweden)

Sarah A. Stevenson

2018-02-01

Full Text Available Wood-frame residential roof failures are among the most common and expensive types of wind damage. Hip roofs are commonly understood to be more resilient during extreme wind in relation to gable roofs. However, inspection of damage survey data from recent tornadoes has revealed a previously unstudied failure mode in which hip roofs suffer partial failure of the framing structure. In the current study, evidence of partial framing failures and statistics of their occurrence are explored and discussed, while the common roof design and construction practice are reviewed. Two-dimensional finite element models are developed to estimate the element-level load effects on hip roof trusses and stick-frame components. The likelihood of failure in each member is defined based on relative demand-to-capacity ratios. Trussed and stick-frame structures are compared to assess the relative performance of the two types of construction. The present analyses verify the common understanding that toenailed roof-to-wall connections are likely to be the most vulnerable elements in the structure of a wood-frame hip roof. However, the results also indicate that certain framing members and connections display significant vulnerability under the same wind uplift, and the possibility of framing failure is not to be discounted. Furthermore, in the case where the roof-to-wall connection uses hurricane straps, certain framing members and joints become the likely points of failure initiation. The analysis results and damage survey observations are used to expand the understanding of wood-frame residential roof failures, as they relate to the Enhanced Fujita Scale and provide assessment of potential gaps in residential design codes.

Wind energy planning in Denmark

International Nuclear Information System (INIS)

Godtfredsen, F.; Lemming, J.; Nielsen, S.R.; Jessien, S.

1992-01-01

The total capacity of the about 3300 Danish wind turbines is approximately 450 MW. Most of the wind turbines have been erected detached or in small clusters by private citizens - especially by joint ownership. 100 MW of the capacity have been installed by the power companies, mainly in wind farms. Up till now the privately owned wind turbines have been erected without a previous planning process. Increased expansion of wind energy makes demands on physical planning, since access to suitable locations in Denmark is limited. Hence more coordination is called for between the interested parties to ensure optimal utilization of the sites allocated by the physical planning authorities. A siting committee appointed by the Government has recommended locations for additional 100 MW power company wind farms as well as a more detailed planning in each local community. The detailed planning in the municipality of Thisted is described. (au)

Intraday Trading of Wind Energy

DEFF Research Database (Denmark)

Skajaa, Anders; Edlund, Kristian; Morales González, Juan Miguel

2015-01-01

In this paper, we tackle the problem of a wind power producer participating in a short-term electricity market that allows for the continuous, but potentially illiquid, intraday trading of energy. Considering the realistic case of a wind farm operating in the western Danish price area of Nord Pool......, we build a simple but effective algorithm for the wind power producer to fully benefit from the Elbas intraday market. We then investigate the sensitivity of the obtained benefits to the maximum volume of energy the wind power producer is willing to trade in the intraday market, the ultimate aim...... of the trade (either to decrease energy imbalances or to increase profits) and to the installed capacity of the wind farm. Our numerical results reveal that the wind power producer can substantially increase his revenues by partaking in the intraday market but with diminishing returns to scale—a result that we...

Policy instruments for regulating the development of wind power in a liberated electricity market

Energy Technology Data Exchange (ETDEWEB)

Morthorst, P E [Risoe National Lab., Roskilde (Denmark)

1999-03-01

Wind power is facing the dual challenge of entering a liberated electricity market and at the same time being one of the main contributors to the reduction of greenhouse gas emissions. The paper analyses the importance of the existing standard payment schemes in the development of wind power, and how this might be affected by the introduction of a liberated electricity market. The existing Danish standard payment scheme has strongly encouraged investments in wind turbines. It has been and still is very effective in promoting a high wind power capacity development, but at a high economic cost to the Danish Government. Different models of conditions for wind power at an electricity exchange do exist, but all seem to introduce a higher risk to the individual wind turbine owner than seen with the present payment scheme. In short it might be stated that going from the existing standard payment system to a market based system, the political uncertainty is converted to a market risk for the individual wind turbine owner. (au)

Policy instruments for regulating the development of wind power in a liberated electricity market

International Nuclear Information System (INIS)

Morthorst, P.E.

1999-01-01

Wind power is facing the dual challenge of entering a liberated electricity market and at the same time being one of the main contributors to the reduction of greenhouse gas emissions. The paper analyses the importance of the existing standard payment schemes in the development of wind power, and how this might be affected by the introduction of a liberated electricity market. The existing Danish standard payment scheme has strongly encouraged investments in wind turbines. It has been and still is very effective in promoting a high wind power capacity development, but at a high economic cost to the Danish Government. Different models of conditions for wind power at an electricity exchange do exist, but all seem to introduce a higher risk to the individual wind turbine owner than seen with the present payment scheme. In short it might be stated that going from the existing standard payment system to a market based system, the political uncertainty is converted to a market risk for the individual wind turbine owner. (au)

Policy instruments for regulating the development of wind power in a liberated electricity market

International Nuclear Information System (INIS)

Morthorst, P.E.

1999-01-01

Wind power is facing the dual challenge of entering a liberated electricity market and at the same time being one of the main contributors to the reduction of greenhouse gas emissions. The paper analyses the importance of the existing standard payment schemes in the development of wind power, and how this might be affected by the introduction of a liberated electricity market. The existing Danish standard payment scheme has strongly encouraged investments in wind turbines. It has been and still is very effective in promoting a high wind power capacity development, but at a high economic cost to the Danish Government. Different models of conditions for wind power at an electricity exchange do exist, but all seem to introduce a higher risk to the individual wind turbine owner than seen with the present payment scheme. In short it might be stated that going from the existing standard payment system to a market based system, the political uncertainty is converted to a market risk for the individual wind turbine owner. (author)

Annual report of the Certification Secretariat of Wind Turbines for 2010; AArsrapport: Energistyrelsens Godkendelsessekretariat for Vindmoeller 2010

Energy Technology Data Exchange (ETDEWEB)

Lemming, J.K.; Friis, P.

2011-12-15

This report was prepared as documentation for the activities in the Certification Secretariat of Wind Turbines in 2010. The secretariat has performed duties under a contract with the DEA, where the contents of the tasks are focused on administration of the Danish Certification Scheme for Wind Turbines. The report describes the current state of deployment of wind turbines in Denmark and the latest developments in wind turbine industry. Furthermore, the development of test areas is described. The tasks of the Secretariat has included daily administration, including ensuring the secretariat for the Advisory Committee, implementing the system of maintenance and service, development of new licensing rules for small wind turbines, and the approval and reviews of small wind turbines. In addition, the Secretariat and related experts from Risoe DTU participated in Danish and international standards committees. (Author)

Statistical Model of Extreme Shear

DEFF Research Database (Denmark)

Hansen, Kurt Schaldemose; Larsen, Gunner Chr.

2005-01-01

In order to continue cost-optimisation of modern large wind turbines, it is important to continuously increase the knowledge of wind field parameters relevant to design loads. This paper presents a general statistical model that offers site-specific prediction of the probability density function...... by a model that, on a statistically consistent basis, describes the most likely spatial shape of an extreme wind shear event. Predictions from the model have been compared with results from an extreme value data analysis, based on a large number of full-scale measurements recorded with a high sampling rate...

South Baltic wind atlas. South Baltic offshore wind energy regions project

Energy Technology Data Exchange (ETDEWEB)

Pena, A.; Hahmann, A.; Hasager, C.B.; Bingoel, F.; Karagali, I.; Badger, J.; Badger, M.; Clausen, Niels-Erik

2011-05-15

A first version of a wind atlas for the South Baltic Sea has been developed using the WRF mesoscale model and verified by data from tall Danish and German masts. Six different boundary-layer parametrization schemes were evaluated by comparing the WRF results to the observed wind profiles at the masts. The WRF modeling was done in a nested domain of high spatial resolution for 4 years. In addition the long-term wind statistics using the NCAR-NCEP reanalysis data were performed during 30 years to provide basis for a long-term adjustment of the results and the final WRF results include a weighting for the long-term trends variability in the South Baltic Sea. Observations from Earth observing satellites were used to evaluate the spatial resolution of the WRF model results near the surface. The QuikSCAT and the WRF results compared well whereas the Envisat ASAR mean wind map showed some variation to the others. The long-term analysis revealed that the South Baltic Sea has a spatially highly variable wind climate during the 30-years. (Author)

Vehicle-to-Grid Systems for Frequency Regulation in an Islanded Danish Distribution Network

DEFF Research Database (Denmark)

Pillai, Jayakrishnan Radhakrishna; Bak-Jensen, Birgitte

2010-01-01

vehicles could provide power system ancillary services in the form of power balancing reserves to support the large-scale integration of variable renewable energy sources like wind power. This paper investigates the dynamic frequency response of an islanded Danish distribution system operation with large...

Integrated Wind Power Planning Tool

DEFF Research Database (Denmark)

Rosgaard, M. H.; Giebel, Gregor; Nielsen, T. S.

2012-01-01

model to be developed in collaboration with ENFOR A/S; a danish company that specialises in forecasting and optimisation for the energy sector. This integrated prediction model will allow for the description of the expected variability in wind power production in the coming hours to days, accounting......This poster presents the current state of the public service obligation (PSO) funded project PSO 10464, with the working title "Integrated Wind Power Planning Tool". The project commenced October 1, 2011, and the goal is to integrate a numerical weather prediction (NWP) model with purely...

Properties of Extreme Point Rainfall I

DEFF Research Database (Denmark)

Harremoës, Poul; Mikkelsen, Peter Steen

1995-01-01

Extreme rainfall has been recorded by the larger municipalities in Denmark since 1933. National intensity-duration-frequency curves were produced on this basis for engineering application in the whole of Denmark. In 1979, on the initiative of The Danish Water Pollution Control Committee under...

Operation and control of large wind turbines and wind farms

Energy Technology Data Exchange (ETDEWEB)

Soerensen, Poul; Hansen, Anca D.; Thomsen, Kenneth (and others)

2005-09-01

This report is the final report of a Danish research project 'Operation and control of large wind turbines and wind farms'. The objective of the project has been to analyse and assess operational strategies and possibilities for control of different types of wind turbines and different wind farm concepts. The potentials of optimising the lifetime/energy production ratio by means of using revised operational strategies for the individual wind turbines are investigated. Different strategies have been simulated, where the power production is decreased to an optimum when taking loads and actual price of produced electricity into account. Dynamic models and control strategies for the wind farms have also been developed, with the aim to optimise the operation of the wind farms considering participation in power system control of power (frequency) and reactive power (voltage), maximise power production, keep good power quality and limit mechanical loads and life time consumption. The project developed models for 3 different concepts for wind farms. Two of the concepts use active stall controlled wind turbines, one with AC connection and one with modern HVDC/VSC connection of the wind farm. The third concept is based on pitch controlled wind turbines using doubly fed induction generators. The models were applied to simulate the behaviour of the wind farm control when they were connected to a strong grid, and some initial simulations were performed to study the behaviour of the wind farms when it was isolated from the main grid on a local grid. Also the possibility to use the available information from the wind turbine controllers to predict the wind speed has been investigated. The main idea has been to predict the wind speed at a wind turbine using up-wind measurements of the wind speed in another wind turbine. (au)

Wind power in Denmark technology, policies and results

Energy Technology Data Exchange (ETDEWEB)

Dannemand Andersen, Per [ed.] [Risoe National Lab. (Denmark)

1998-11-01

The Association of Danish Electricity Utilities has estimated the total electricity production from wind turbines in 1997 as 1932 GWh: 384 GWh from utility-owned turbines and 1548 GWh from privately owned turbines. This equals 6% of total electricity consumption in Denmark. Corrected to a `normal wind year` this equals 6.6% of Denmark`s annual electricity con-sumption. The wind energy index in 1997 was 91%. According to the Danish Association of Electricity Utilities, 4784 turbines with a capacity of 1129 MW were connected to the grid at the end of 1997. 534 turbines and 287 MW were added in 1997, the largest figure ever. These are net figures and included dismantled machines. The actual sales of turbines is a bit higher, reflecting the fact that not all machines sold in 1997 were installed that year. New machines are usually 500 kW, 600 kW and 750 kW. No 1500 kW machines have as yet been installed on a commercial basis in Denmark. (au)

Wind energy in the Mediterranean countries

International Nuclear Information System (INIS)

Gaudiosi, G.

1992-01-01

This paper reviews the main findings relative to the European Communities OPET (Organization for the Promotion of Energy Technology) June 1992 conference on the potential for small and medium size wind energy applications in the Mediterranean countries and gives a panoramic look at progress being made by these countries in the development and use of wind energy turbines. One system which appears to be promising is the Danish 100 kW 'Bonus' wind turbine (23 m rotor, 30 m tower height) which has seen successful applications at a seaside resort and at a remote radio station in terms of performance, environmental compatibility and public acceptance

Evaluation of power control with different electrical and control concept of wind farm

DEFF Research Database (Denmark)

Hansen, Anca Daniela

This report investigates the impact of wind power in large power systems. The motivation for this investigation is the ever-increasing wind energy penetration into the power systems throughout the world. A generic large power system model delivered by the Danish Transmission System Operator Energi...

The establishment of the Danish windmill industry - was it worthwhile?

International Nuclear Information System (INIS)

Drud Hansen, J.; Jensen, C.; Stroejer Madsen, E.

2002-01-01

The renewed interest for using wind energy commercially is not more than twenty-five years old. From an experimental stage of turning wind energy into electricity in the 1970s, a new industry for producing standardised windmills gained foothold in the beginning of the 1980s and since then it has developed rapidly through the 1980s and the 1990s. The Danish innovators of the new windmill technology have been the pioneers behind this development, and Denmark has succeeded in acquiring a first mover advantage on the world market. This position has been maintained and at present Denmark satisfies more than half of the world market's demand for windmills. There are at least two reasons for this pioneering position of the Danish windmill industry. First, Denmark is by nature very 'abundant' in wind energy due to its geographical position at the nexus between the Gulf Stream and the European continent. The windy climate makes given technologies of windmills more productive. Secondly, the production of electricity from wind power has been subsidised by state aid schemes among which the most important one has been a price guarantee per produced kWh (kilowatt-hours) to the owners of windmill. These subsidies have made production of electricity from windmills profitable for private investors and hence competitive on the market for electricity produced by fossil fuel. Although the public subsidies to produced electricity from wind power in Denmark have been motivated by environmental concerns over the emission of carbon dioxide (CO 2 ) from power plants using fossil fuels, the subsidies have resulted in the development of a new industry with a strong export performance. The development of the windmill industry thus illustrates an infant industry strategy where state aid in the upstart phase results in a build up of an internationally competitive industry in the long run. This is the Mill's test of an infant industry strategy. However, a precondition for a successful outcome of

Modern wind energy technology for Russian applications. Main report

DEFF Research Database (Denmark)

Madsen, Peter Hauge; Winther-Jensen, Martin; Bindner, Henrik W.

1999-01-01

The general objective of the project is to establish a technical foundation for an intensified application of wind energy in Russia with medium to large wind turbines and transfer/adaptation of Danish and European wind turbine technology as a basis forfuture joint ventures and technology exports...... climate and in-land sites of Russia. As part of this work it is necessary to clarify the types of operationalconditions and requirements that are to be met by wind turbines operating in such conditions, and to outline suitable test procedures and test set-up’s for verifications of such adapted...

Charging Schedule for Electric Vehicles in Danish Residential Distribution Grids

DEFF Research Database (Denmark)

Pillai, Jayakrishnan Radhakrishna; Huang, Shaojun; Bak-Jensen, Birgitte

2015-01-01

energy sources like wind in power systems. The EV batteries could be used to charge during periods of excess electricity production from wind power and reduce the charging rate or discharge on deficit of power in the grid, supporting system stability and reliability. By providing such grid services......The prospects of Electric Vehicles (EVs) in providing clean transportation and supporting renewable electricity is widely discussed in sustainable energy forums worldwide. The battery storage of EVs could be used to address the variability and unpredictability of electricity produced from renewable......, the vehicle owner, vehicle fleet operator and other parties involved in the process could economically benefit from the process. This paper investigates an optimal EV charging plan in Danish residential distribution grids in view of supporting high volumes of wind power in electricity grids. The results...

Denmark - supplier of competitive offshore wind solutions. Megavind's strategy for offshore wind research, development and demonstration

Energy Technology Data Exchange (ETDEWEB)

2010-12-15

In May 2006, the Danish Government presented a report on promoting environmentally effective technology and established a number of innovative partnerships. The partnerships intend to strengthen public-private cooperation between the state, industry, universities and venture capital to accelerate innovation for a number of green technologies. The partnership for wind energy is called Megavind. Megavind's strategy for offshore wind describes the offshore challenges and suggests research, development and demonstration (RD and D) priorities to enable offshore wind power become to competitive with other energy technologies. The strategy lists key recommendations as well as key thematic priorities and for each of these a number of RD and D priorities. Under each thematic priority references are made to the European Strategic Energy Technology plan (SET-plan), which prioritises offshore wind RD and D in Europe. (LN)

Wind power policy in Norway

International Nuclear Information System (INIS)

2002-01-01

The Norwegian government's ambition of developing 3 TWh wind power by 2010 seems hard to fulfill. Recently Norway's first wind park was officially opened on the island of Smoela, just off Kristiansund. The 20 large windmills are Danish-made and described in some detail in this article. Fulfillment of the government's ambition requires that 20 similar power stations are put into operation the coming eight years, and so far it has not been decided to build the next one. Statkraft have great ambitions for wind power. However, environmental considerations present difficulties. For instance, for Smoela, Statkraft spent an extra 4 million NOK on ground cables the last 1.5 km to land in order to minimize the disturbance of bird populations. Considerations for the white-tailed eagle may be a decisive factor in the development of wind power plants in Norway

Automatic Voltage Control System with Market Price Employing Large Wind Farms

DEFF Research Database (Denmark)

Qin, Nan; Bak, Claus Leth; Abildgaard, Hans

2018-01-01

of the voltage control service provided by the power plant owners. The benefit of employing the large offshore wind farms in this AVC system is investigated. The simulation based on the measurement data from the Danish electricity control center demonstrates the superiority of the proposed approach in terms...... of the cost minimization. The gained profit by employing the wind farms can be an argument to purchase the voltage control service provided by these wind farms....

Characteristics of offshore extreme wind-waves detected by surface drifters with a low-cost GPS wave sensor

Science.gov (United States)

Komatsu, Kosei

Wind-generated waves have been recognized as one of the most important factors of the sea surface roughness which plays crucial roles in various air-sea interactions such as energy, mo-mentum, heat and gas exchanges. At the same time, wind waves with extreme wave heights representatively called as freak or rogue waves have been a matter of great concern for many people involved in shipping, fishing, constracting, surfing and other marine activities, because such extreme waves frequently affect on the marine activities and sometimes cause serious dis-asters. Nevertheless, investigations of actual conditions for the evolution of wind waves in the offshore region are less and sparse in contrast to dense monitoring networks in the coastal re-gions because of difficulty of offshore observation with high accuracy. Recently accurate in situ observation of offshore wind waves is getting possible at low cost owing to a wave height and di-rection sensor developed by Harigae et al. (2004) by installing a point-positioning GPS receiver on a surface drifting buoy. The point-positioning GPS sensor can extract three dimensional movements of the buoy excited by ocean waves with minimizing effects of GPS point-positioning errors through the use of a high-pass filter. Two drifting buoys equipped with the GPS-based wave sensor charged by solar cells were drifted in the western North Pacific and one of them continued to observe wind waves during 16 months from Sep. 2007. The RMSE of the GPS-based wave sensor was less than 10cm in significant wave height and about 1s in significant wave period in comparison with other sensors, i.e. accelerometers installed on drifting buoys of Japan Meteorological Agency, ultrasonic sensors placed at the Hiratsuka observation station of the University of Tokyo and altimeter of the JASON-1. The GPS-based wave buoys enabled us to detect freak waves defined as waves whose height is more than twice the significant wave height. The observation conducted by

Noise from wind turbines

International Nuclear Information System (INIS)

Andersen, B.; Larsen, P.

1993-01-01

Denmark has 3200 wind turbines with an installed maximum capacity of 418MW. The most important Danish research projects into wind turbine noise and the main results are listed. These date from 1983. Two comprehensive studies are currently in progress. The first is an analytical and empirical investigation of aerodynamic noise from wind turbine rotors and has so far dealt mainly with tip noise. The measurement method, using a hard board mounted microphone on the ground near the turbine, is described. Four different tip designs have been tested. Some examples of reference sound power level spectra for three of the designs are presented. During the past two years a computerbased data acquisition system has been used for real-time determination of sound power levels. The second study, which has just commenced, is on annoyance from wind turbine noise. It will include noise measurements, masking calculations and a social survey on the perceived nuisance. (UK)

Reliability Analysis of Wind Turbines

DEFF Research Database (Denmark)

Toft, Henrik Stensgaard; Sørensen, John Dalsgaard

2008-01-01

In order to minimise the total expected life-cycle costs of a wind turbine it is important to estimate the reliability level for all components in the wind turbine. This paper deals with reliability analysis for the tower and blades of onshore wind turbines placed in a wind farm. The limit states...... consideres are in the ultimate limit state (ULS) extreme conditions in the standstill position and extreme conditions during operating. For wind turbines, where the magnitude of the loads is influenced by the control system, the ultimate limit state can occur in both cases. In the fatigue limit state (FLS......) the reliability level for a wind turbine placed in a wind farm is considered, and wake effects from neighbouring wind turbines is taken into account. An illustrative example with calculation of the reliability for mudline bending of the tower is considered. In the example the design is determined according...

Statistical Analysis of the Impact of Wind Power on Market Quantities and Power Flows

DEFF Research Database (Denmark)

Pinson, Pierre; Jónsson, Tryggvi; Zugno, Marco

2012-01-01

In view of the increasing penetration of wind power in a number of power systems and markets worldwide, we discuss some of the impacts that wind energy may have on market quantities and cross-border power flows. These impacts are uncovered through statistical analyses of actual market and flow data...... of load and wind power forecasts on Danish and German electricity markets....

Green energy - the road to a Danish energy system without fossil fuels. Summary of the work, results and recommendations of the Danish Commission on Climate Change Policy

Energy Technology Data Exchange (ETDEWEB)

2010-09-15

This summary report describes the main outcomes of the deliberations of the Danish Commission on Climate Change Policy. It includes a proposal for how Denmark can become independent of fossil fuels and, at the same time, meet the target of reducing greenhouse gases by 80%-95% compared with 1990. In addition, 40 specific recommendations for initiatives which will contribute to the realisation of the vision are presented. The documentation section of the overall report, which is only available in Danish, presents the Climate Commission's work in more detail, as well as a description of the comprehensive analyses on which the Climate Commission has based its recommendations. Finally, the background documents, which have been prepared at the request of the Climate Commission are available (in Danish) at the Commission's website, www.klimakommissionen.dk. We can both reduce Danish emissions of greenhouse gasses significantly, and make Denmark independent of fossil fuels. This will require a total conversion of the Danish energy system; conversion away from oil, coal and gas, which today account for more than 80% of our energy consumption, and to green energy with wind turbines and bioenergy as the most important elements. The cost of conversion may seem surprisingly low. The low cost means that not only can we maintain our present living standards, we can also have considerable economic growth, so that energy expenditures will constitute less of our budgets in the future than today. The reason the cost is not higher is primarily because we will not have to pay for overpriced fossil fuels and CO{sub 2} reductions, and we will be able to limit our energy consumption through efficiency improvements in all areas in the future. It is difficult to make predictions about the exact design of the green energy system of the future. However, in overall terms it could look like this: 1) Energy will be used far more efficiently, so that we can, for example, heat our houses

Public acceptance of wind farm development: Developer practices and review of scientific literature

DEFF Research Database (Denmark)

Cronin, Tom; Ram, Bonnie; Gannon, Jim

This report is the first deliverable of Work Package 3 of the Wind2050 project. The Wind2050 project is about the public perception of wind power in Denmark, its role in the planning and development of wind farms and, ultimately, the meaning it has for reaching the Danish government’s targets...... for wind power in 2050. Work Package 3 looks specifically at how private developers handle the public’s perception of wind power and what it means for their projects. This report firstly outlines the common stages found in wind farm development and then discusses what manner of interaction the developer...

A turn for the better? Innovative concepts for wind turbines

International Nuclear Information System (INIS)

De Vries, Eize

2001-01-01

This paper focuses on successful innovation in wind technology and describes the approach of Danish developers using a rigid, non-integrated, gear-driven transmission layout with 3 blades which is often viewed as the basis of the modern wind industry. Recent developments reviewed cover multi-rotor designs, hybrid designs, direct drive technology, variable speed operation, modular systems, high voltage systems, discoidal technology, and the diffuser augmented turbine

Ten year review og the international wind power industry 1995-2004. Forecast for 2015. Long term scenario to 2025

International Nuclear Information System (INIS)

2005-09-01

Since 1995 BTM-Consult has published a World Market Report on International Wind Energy Development. Ten years on we are marking the anniversary with this special publication. That very first report was funded by the Danish Ministry of Energy under a dedicated programme for supporting new renewable energy sources. The primary target group was the emerging Danish wind power industry, represented by FDV, the Danish Wind Turbine Manufacturers Association. The aim of the report was to 'map the international wind power industry and evaluate the strengths and weaknesses of Danish manufacturers in this business environment. Although published in Danish, an English summary including the main factual data was distributed to all foreign companies which had contributed information to the survey. This summary was the starting point for publishing the annual publication World Market Update. During the process of conducting this initial survey, a global network was established alongside other information sources which BTM-C had already developed since its formation in 1986. In 1997 the first issue of World Market Update in the format and concept used now was published. A mountain of data has been collected since then, and in this report a selection of the findings over the period from 1995 to 2004 is presented and evaluated with the benefit of hindsight. Over the years, a continuing dialogue with our customers has been the most inspiring input to the ongoing process of improving the report's content. We are proud to have achieved the status of being 'the reference', the most cited report in the industry in terms of progress and future perspectives on wind power. Neither BTM Consult nor other analysts in the industry could imagine in 1995 that the wind power industry would progress as successfully as it has actually performed. The aggregate installed capacity has grown from 3,531 MW in 1994 to almost 48,000 MW by the end of 2004. This represents an average annual growth rate of

Wind energy. Energy technologies in national, European and global perspective

International Nuclear Information System (INIS)

Hauge Madsen, P.; Bjerregaard, E.T.D.

2002-01-01

According to a recent study, global wind generating capacity increased by some 6800 MW in 2001, an annual growth of just over half the corresponding figure for 2000. 2001 was the third consecutive year in which new wind power capacity exceeded new nuclear power capacity, showing the maturity of wind power technology. Total installed wind power worldwide by the end of 2001 was close to 25.000 MW. Germany, Spain and Denmark are the main players, accounting for 56% of the world's capacity increase in 2001 and a total cumulative installed capacity of 14.750 MW, or 59% of the global total. The USA and India are also significant users of wind power; in 2001 the USA added 1700 MW of new installed capacity to become the world's second-largest market for wind power. The report Wind Force 10 outlines a scenario in which wind power provides 10% of the world's electricity by 2020, corresponding to a total installed capacity of 1200 GW. Risoe's System Analysis Department has looked at the possible future costs of electricity produced by wind turbines compared to conventional power. A learning curve analysis of historical data results in a progress ratio of 0,85. This means that for every doubling of the installed capacity, the cost of wind-generated electricity is reduced by 15%. Until recently the main driver for wind power has been a concern for greenhouse gases. Security of energy supply has now become an important issue, however, especially in Europe and the USA. Wind power plants can be erected at short notice and in a modular fashion that allows capacity to be added as required. The European Commission has supported wind power by sponsoring international research co-operation between institutes, universities and equipment manufacturers. The IEA supports worldwide co-operation, and has recently issued a report on the longterm R and D needs of wind energy. Denmark has, mainly financed by the Danish Energy Agency, taken part in the IEA's R and D Wind international co

Comparative analysis of methods for modelling the short-term probability distribution of extreme wind turbine loads

DEFF Research Database (Denmark)

Dimitrov, Nikolay Krasimirov

2016-01-01

We have tested the performance of statistical extrapolation methods in predicting the extreme response of a multi-megawatt wind turbine generator. We have applied the peaks-over-threshold, block maxima and average conditional exceedance rates (ACER) methods for peaks extraction, combined with four...... levels, based on the assumption that the response tail is asymptotically Gumbel distributed. Example analyses were carried out, aimed at comparing the different methods, analysing the statistical uncertainties and identifying the factors, which are critical to the accuracy and reliability...

Annual progress report 2000. Wind Energy and Atmospheric Physics Department

International Nuclear Information System (INIS)

Larsen, S.E.; Skrumsager, B.

2001-05-01

The report describes the work of the Wind Energy and Atmospheric Physics Department at Risoe National Laboratory in 2000. The research of the department aims to develop new opportunities in the exploitation of wind energy and to map and alleviate atmospheric aspects of environmental problems. The expertise of the department is utilised in commercial activities such as wind turbine testing and certification, training programmes, courses and consultancy services to industry, authorities and Danish and international organisations on wind energy and atmospheric environmental impact. A summary of the department's activities in 2000 is shown, including lists of publications, lectures, committees and staff members. (au)

Wind data for wind driven plant. [site selection for optimal performance

Science.gov (United States)

Stodhart, A. H.

1973-01-01

Simple, averaged wind velocity data provide information on energy availability, facilitate generator site selection and enable appropriate operating ranges to be established for windpowered plants. They also provide a basis for the prediction of extreme wind speeds.

Comparative assessment of hydrogen storage and international electricity trade for a Danish energy system with wind power and hydrogen/fuel cell technologies. Final project report

Energy Technology Data Exchange (ETDEWEB)

Soerensen, Bent (Roskilde University, Energy, Environment and Climate Group, Dept. of Environmental, Social and Spatial Change (ENSPAC) (DK)); Meibom, P.; Nielsen, Lars Henrik; Karlsson, K. (Technical Univ. of Denmark, Risoe National Laboratory for Sustainable Energy, Systems Analysis Dept., Roskilde (DK)); Hauge Pedersen, A. (DONG Energy, Copenhagen (DK)); Lindboe, H.H.; Bregnebaek, L. (ea Energy Analysis, Copenhagen (DK))

2008-02-15

This report is the final outcome of a project carried out under the Danish Energy Agency's Energy Research Programme. The aims of the project can be summarized as follows: 1) Simulation of an energy system with a large share of wind power and possibly hydrogen, including economic optimization through trade at the Nordic power pool (exchange market) and/or use of hydrogen storage. The time horizon is 50 years. 2) Formulating new scenarios for situations with and without development of viable fuel cell technologies. 3) Updating software to solve the abovementioned problems. The project has identified a range of scenarios for all parts of the energy system, including most visions of possible future developments. (BA)

Cost-efficient foundation structures for large offshore wind farms

International Nuclear Information System (INIS)

Birch, C.; Gormsen, C.; Lyngesen, S.; Rasmussen, J. L.; Juhl, H.

1997-01-01

This paper presents the results of the development of a cost-efficient foundation for large (1.5 MW) offshore wind farms at water depth of 5 to 11 m. Previously, medium sized wind turbines (500 kW) in Denmark have been installed offshore at water depths of approximately 5 m on concrete gravity foundations. The installation of larger turbines at greater depth does, however, hold great promise in terms of wind environment and environmental considerations. The costs of a traditional gravity foundation at these increased water depths is expected to be prohibitive, and the aim of the project has been to reduce the foundations costs in general. This paper describes the theoretical basis for the geotechnical and structural design of three alternative concepts and presents an optimised layout of each based on a research and development project. The basis has been a wind farm consisting of 100 turbines. The R and D project has been undertaken by the consulting engineers Nellemann, Nielsen and Rauschenberger A/S (Gravity foundation), LICengineering A/S (Mono pile) and Ramboell (Tripod) in co-operation with the Danish utility engineering companies Elkraft and Elsamprojekt A/S. The project was partly financed by the participants and by the Danish Energy Agency through their 1996 Energy Research Programme (EFP-96). (au) 18 refs

Dynamic Security Assessment of Danish Power System Based on Decision Trees: Today and Tomorrow

DEFF Research Database (Denmark)

Rather, Zakir Hussain; Liu, Leo; Chen, Zhe

2013-01-01

The research work presented in this paper analyzes the impact of wind energy, phasing out of central power plants and cross border power exchange on dynamic security of Danish Power System. Contingency based decision tree (DT) approach is used to assess the dynamic security of present and future...

The socio-economic costs of the planned development of wind power energy

International Nuclear Information System (INIS)

Bentzen, J.

1992-01-01

The socio-economic consequences of the Danish government's planned further development of wind power energy are discussed in detail. It is claimed that, currently, electricity produced by wind turbines is more expensive than that produced by power stations, if the relative environmental effects are not taken into consideration. It is expected that technological development will contribute to cost reduction by the year 2010 so that electricity produced by wind turbines will be competitive, but until then costs of wind power energy will be high and it is reckoned that losses will be in the range of 5-6 billion Danish crowns, minus 2.5 billion saved by lack of CO 2 emission. The socio-economic factors regarding windmills of various sizes (150 kW and 225 kW) are calculated and the planned development of wind power until 2010 is explained. The socio-economic costs of the development programme under various conditions, including the calculation of the saved emissions of carbon dioxide, are discussed. The author states that, in the light of these arguments, he is not in agreement with the governmental plan for the development of wind-turbine produced electricity. It is suggested that this plan could be postponed until such time as wind-power produced electricity should be more competitive in price, and that it should not be pursued during a period of economic recession. (AB)

Identifying shared and contested elements in climate plans as part of shaping transitions towards a Danish low carbon society

DEFF Research Database (Denmark)

Jørgensen, Michael Søgaard

2011-01-01

The Danish government's vision about Denmark as a society independent of fossil energy has initiated several Danish energy and climate action plans during 2009-2010 with visions and measures for a 30-40 year time perspective. The paper analyses differences and similarities in action plans from....... The analyses are conducted as part of a project about sustainable transitions towards a low carbon society. The plan from the renewable energy NGO is an energy plan, while the other plans are climate plans, which include non-energy related greenhouse gasses from land use changes and use of fertilizers...... in agriculture. The plans differ with respect to whether and how agricultural production and Danish food consumption should change as part of transitions towards a low carbon society. All four plans agree about a significant increase in Danish wind turbine capacity and stronger energy saving efforts in Danish...

Industrial initiatives in the wind industry

International Nuclear Information System (INIS)

Edworthy, J.

1992-01-01

Industrial initiatives are methods of lobbying and marketing to increase the activity, revenues, profits, and commercial viability of an industry. They may be undertaken by industry individuals or firms, industry groups, government agencies, or combinations of all these. In Canada, one example of an industrial initiative is the Canadian Wind Energy Association. Other initiatives relevant to the wind power industry include Technology Inflow Programs sponsored by External Affairs Canada, used for visiting foreign firms with the view to licensing foreign technology, and Industrial Research Assistance Programs to develop or adapt new technologies in partnership with government. The Conservation/Renewable Energy Council, Small Power Producers of Alberta, and Independent Power Producers Society of Ontario are also active in supporting wind energy initiatives. In other countries, notable initiatives for wind energy include the Danish wind turbine warranty guarantee program. The Western Wind Industry Network of Canada conducts regional lobbying. It is suggested that in Canada, more such networks are needed, as well as joint ventures with utilities and governments, and more work with the regulatory agencies, to promote wind energy

Status and perspectives for wind energy within the programme for the development of renewable energy. Background report for the document entitled 'Handlingsplan for Vedvarende Energi 1995-97' produced by the Committee for Renewable Energy

International Nuclear Information System (INIS)

1995-08-01

The report, which is intended to comprise the basis for the document 'Plan of Management for Renewable Energy 1995-97' produced by the (Danish) Committee for Renewable Energy, updates information on wind technology and its implementation and describes the status of wind energy as found in the relevant section contained in the Danish development programme for renewable energy. An evaluation is presented of the future perspectives for wind energy with regard to technological developments, market potential and overall costs. A detailed list is given of approved, rejected and concluded Danish projects relevant to wind energy under the Programme for the Development of Wind Energy during the period 1991-1994 and a global status for wind power status and estimates in MW ranging under the headings: New capacity in 1994, Estimated capacity in 1994 and Estimated capacity in 2000. (AB)

The 1.5 MW wind turbine of tomorrow

Energy Technology Data Exchange (ETDEWEB)

De Wolff, T.J.; Sondergaard, H. [Nordtank Energy Group, Richmond, VA (United States)

1996-12-31

The Danish company Nordtank is one of the pioneers within the wind turbine industry. Since 1981 Nordtank has installed worldwide more than 2300 wind turbine generators with a total name plate capacity that is exceeding 350 MW. This paper will describe two major wind turbine technology developments that Nordtank has accomplished during the last year: Site Optimization of Nordtank wind turbines: Nordtank has developed a flexible design concept for its WTGs in the 500/600 kW range, in order to offer the optimal WTG solution for any given site and wind regime. Nordtank`s 1.5 MW wind turbine: In September 1995, Nordtank was the first company to install a commercial 1.5 NM WTG. This paper will document the development process, the design as well as operations of the Nordtank 1.5 MW WTG.

Wind Power Meteorology

DEFF Research Database (Denmark)

Lundtang Petersen, Erik; Mortensen, Niels Gylling; Landberg, Lars

Wind power meteorology has evolved as an applied science, firmly founded on boundary-layer meteorology, but with strong links to climatology and geography. It concerns itself with three main areas: siting of wind turbines, regional wind resource assessment, and short-term prediction of the wind...... resource. The history, status and perspectives of wind power meteorology are presented, with emphasis on physical considerations and on its practical application. Following a global view of the wind resource, the elements of boundary layer meteorology which are most important for wind energy are reviewed......: wind profiles and shear, turbulence and gust, and extreme winds. The data used in wind power meteorology stem mainly from three sources: onsite wind measurements, the synoptic networks, and the re-analysis projects. Wind climate analysis, wind resource estimation and siting further require a detailed...

Ultimate loading of wind turbines

DEFF Research Database (Denmark)

Larsen, Gunner Chr.; Ronold, K.; Ejsing Jørgensen, Hans

1999-01-01

An extreme loading study has been conducted comprising a general wind climate analysis as well as a wind turbine reliability study. In the wind climate analysis, the distribution of the (horizontal) turbulence standard deviation, conditioned on the meanwind speed, has been approximated by fitting......, a design turbulence intensity for off-shore application is proposed which, in the IEC code framework, is applicable for extreme as well as for fatigue loaddetermination. In order to establish a rational method to analyse wind turbine components with respect to failure in ultimate loading, and in addition...... a three parameter Weibull distribution to the measured on-shore and off-shore data for wind speed variations. Specific recommendations on off-shore design turbulence intensities are lacking in the presentIEC-code. Based on the present analysis of the off-shore wind climate on two shallow water sites...

Hospitalizations among employees in the Danish hotel and restaurant industry.

Science.gov (United States)

Hannerz, Harald; Tüchsen, Finn; Kristensen, Tage S

2002-09-01

The aim of the present study was to provide a broad picture of the morbidity among employees in the Danish hotel and restaurant industry. Cohorts of all 20-59-year-old employees in the Danish hotel and restaurant industry in the years 1981, 1986, 1991 and 1994 were formed to calculate age-standardized hospitalization ratios (SHR) and time trends (1981-1997) for many different diagnoses. Both for women and men, significantly higher SHRs were found for infectious and parasitic diseases, neoplasms, diseases in the nervous system and sense organs, diseases of the circulatory system, diseases of the respiratory system, diseases of the digestive system and diseases of the musculoskeletal system among employees in hotels and restaurants than in the digestive system and diseases of the musculoskeletal system among employees in hotels and restaurants than in the working population at large. Furthermore, among women a significantly elevated risk was found for injuries in the lower extremities, injuries in the upper extremities and head injuries, and among men a high risk was found for head injuries and a low risk for ruptures in ligaments and muscles. The trend assessments did not detect any significant changes in SHRs over time. Employment in the Danish hotel and restaurant industry is associated with an elevated hospitalization risk due to many diseases, which may be related to occupation and lifestyle. In line with the official policy of reducing inequality in health, focus should be placed on the health problems in this group.

Modelling of extreme gusts for design calculations (NewGust)

Energy Technology Data Exchange (ETDEWEB)

Bierbooms, W; Cheng, Po-Wen [Delft Univ. of Technology, Inst. for Wind Energy, Delft (Netherlands); Larsen, G [Risoe National Lab., Roskilde (Denmark); Juul Pedersen, B [Vestas Wind Systems A/S, Lem (Denmark); Hansen, K [Tecnical Univ. of Denmark (Denmark)

1999-03-01

The main objective of the NewGust project is to come to a realistic and verified description of extreme gusts based on the stochastic properties of wind. In this paper the first results of the project are presented. Theoretical considerations indicate that the shape of extreme gusts is very sharp. Based on simulated wind time series, mean gust shapes (for several amplitudes and mean wind speeds) are determined and compared with the theoretical curves. The resemblance turned out to be very good. Furthermore, the influence of the sampling rate and the dynamics of a cup anemometer on the empirical mean gust shape are examined. The promising results are confirmed by a (preliminary) verification based on measured wind time series, available from the database on wind characteristics. The mean shape of gusts, of certain amplitude, together with their probability of occurrence can be used to obtain the distribution of the extreme response of wind turbines to gust loading. (au)

A Two-Bladed Concept Wind Turbine

DEFF Research Database (Denmark)

Kim, Taeseong

2012-01-01

This article shows the potential for reducing extreme loads with an innovative design of wind turbine, a partial pitch two-bladed concept turbine. The most extreme conditions to test a turbine are considered to be stand-still combined with a grid failure in which the wind comes from all directions...

Stochastic Evaluation of Maximum Wind Installation in a Radial Distribution Network

DEFF Research Database (Denmark)

Chen, Peiyuan; Bak-Jensen, Birgitte; Chen, Zhe

2011-01-01

This paper proposes an optimization algorithm to find the maximum wind installation in a radial distribution network. The algorithm imposes a limit on the amount of wind energy that can be curtailed annually. The algorithm implements the wind turbine reactive power control and wind energy...... curtailment using sensitivity factors. The optimization is integrated with Monte Carlo simulation to account for the stochastic behavior of load demand and wind power generation. The proposed algorithm is tested on a real 20 kV Danish distribution system in Støvring. It is demonstrated that the algorithm...... executes reactive compensation and energy curtailment sequentially in an effective and efficient manner....

Characterization of wind velocities in the upstream induction zone of a wind turbine using scanning continuous-wave lidars

DEFF Research Database (Denmark)

Simley, Eric; Angelou, Nikolas; Mikkelsen, Torben Krogh

2016-01-01

As a wind turbine generates power, induced velocities, lower than the freestream velocity, will be present upstream of the turbine due to perturbation of the flow by the rotor. In this study, the upstream induction zone of a 225kW horizontal axis Vestas V27 wind turbine located at the Danish...... Technical University’s Risø campus is investigated using a scanning Light Detection and Ranging (lidar) system. Three short-range continuous-wave “WindScanner” lidars are positioned in the field around the V27 turbine allowing detection of all three components of the wind velocity vectors within...... the induction zone. The time-averaged mean wind speeds at different locations in the upstream induction zone are measured by scanning a horizontal plane at hub height and a vertical plane centered at the middle of the rotor extending roughly 1.5 rotor diameters (D) upstream of the rotor. Turbulence statistics...

International wind energy development. World market update 1996. Forecast 1997-2001

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-03-01

It is intended topublish and update this report `International Wind Power Development - Market Update 1996` every year in March. The latest issue was published in December of 1995 by BTM Consult ApS. Market data for demand side does normally, where it has been possible, only include installed wind turbines which has been connected to the grid during 1996. Supply side data is based on collected information (reference lists) from the 12-15 largest wind turbine manufacturers in the world. Due to these circumstances there are some conflicts between demand side and supply side data. Another important factor is that all wind turbine manufacturers do not use the same methodology when they are making their reference lists. Some manufacturers include only installed and operating wind turbines, while others include all units shipped from the factory. This is another conflict that might cause some differences in the data. Lately another new issue has been added to the list of uncertain factors, which is: is a Nordex Balcke-Duerr wind turbine Danish or German? And is a Gamesa Eolica wind turbine Danish or Spanish? etc. To minimize annual variations, this report includes the last 3 years data for the largest markets and wind turbine manufacturers. The prognosis includes data for the next 5 years until the year 2001, and an estimate has also been included for development until the year 2005. This version of the report can be found on internet web-pages: http://home4.inet.tele.dk/btmcwind/index.html. (EG)

International wind energy development. World market update 1996. Forecast 1997-2001

International Nuclear Information System (INIS)

1997-03-01

It is intended topublish and update this report 'International Wind Power Development - Market Update 1996' every year in March. The latest issue was published in December of 1995 by BTM Consult ApS. Market data for demand side does normally, where it has been possible, only include installed wind turbines which has been connected to the grid during 1996. Supply side data is based on collected information (reference lists) from the 12-15 largest wind turbine manufacturers in the world. Due to these circumstances there are some conflicts between demand side and supply side data. Another important factor is that all wind turbine manufacturers do not use the same methodology when they are making their reference lists. Some manufacturers include only installed and operating wind turbines, while others include all units shipped from the factory. This is another conflict that might cause some differences in the data. Lately another new issue has been added to the list of uncertain factors, which is: is a Nordex Balcke-Duerr wind turbine Danish or German? And is a Gamesa Eolica wind turbine Danish or Spanish? etc. To minimize annual variations, this report includes the last 3 years data for the largest markets and wind turbine manufacturers. The prognosis includes data for the next 5 years until the year 2001, and an estimate has also been included for development until the year 2005. This version of the report can be found on internet web-pages: http://home4.inet.tele.dk/btmcwind/index.html. (EG)

Impact of wind turbines on birds

International Nuclear Information System (INIS)

Clausager, I.; Nohr, H.

1996-01-01

The paper is a review of the present knowledge on impacts of wind turbines on birds, requested by the Danish Ministry of the Environment and Energy. The main conclusions of the review are, that in nearly all the studies so far the numbers of birds recorded colliding with wind turbines have been limited. Some studies indicate that stationary (breeding) birds inside the wind turbine area in the short run habituate to wind turbines, especially the noise and visual impacts, and that the risk for collision becomes low. However, some of the few more long term studies indicate that a negative impact may occur in later generations of breeding birds. In some studies a disturbance effect on bird species, which temporarily stay inside a wind turbine area in order to forage or rest, is observed. The degree of impact is species-specific. An effect is typically recorded inside a zone of up to 250-800 m, with geese and waders as the most sensitive groups of birds. (author)

Wind Tunnel Assessment of Ship Manoeuvrability using a PMM Technique

DEFF Research Database (Denmark)

Agdrup, Kristian; Jensen, Andreas G.; Aage, Christian

1999-01-01

Tests have been performed at the Danish Maritime Institute (DMI) to investigate the applicability of a new wind tunnel Planar Motion Mechanism (PMM) for the determination of hydrodynamic coefficients of ships. The method has been tested on a tanker with known towing tank data. The wind tunnel model...... data giving reasonable results. The dependency of amplitude and frequency is evaluated, and sources of inaccuracy are discussed. It is concluded that the wind tunnel method is a promising method to achieve a fast and cost-effective estimate of the hydrodynamic coefficients of a ship hull...

Dynamic fault simulation of wind turbines using commercial simulation tools

DEFF Research Database (Denmark)

Lund, Torsten; Eek, Jarle; Uski, Sanna

2005-01-01

This paper compares the commercial simulation tools: PSCAD/EMTDC, PowerFactory, SIMPOW and PSS/E for analysing fault sequences defined in the Danish grid code requirements for wind turbines connected to a voltage level below 100 kV. Both symmetrical and unsymmetrical faults are analysed. The devi......This paper compares the commercial simulation tools: PSCAD/EMTDC, PowerFactory, SIMPOW and PSS/E for analysing fault sequences defined in the Danish grid code requirements for wind turbines connected to a voltage level below 100 kV. Both symmetrical and unsymmetrical faults are analysed....... The deviations and the reasons for the deviations between the tools are stated. The simulation models are imple-mented using the built-in library components of the simulation tools with exception of the mechanical drive-train model, which had to be user-modeled in PowerFactory and PSS/E....

Residential heat pumps in the future Danish energy system

DEFF Research Database (Denmark)

Petrovic, Stefan; Karlsson, Kenneth Bernard

2016-01-01

for politically agreed targets which include: at least 50% of electricity consumption from wind power starting from 2020, fossil fuel free heat and power sector from 2035 and 100% renewable energy system starting from 2050. Residential heat pumps supply around 25% of total residential heating demand after 2035......Denmark is striving towards 100% renewable energy system in 2050. Residential heat pumps are expected to be a part of that system.We propose two novel approaches to improve the representation of residential heat pumps: Coefficients of performance (COPs) are modelled as dependent on air and ground...... temperature while installation of ground-source heat pumps is constrained by available ground area. In this study, TIMES-DK model is utilised to test the effects of improved modelling of residential heat pumps on the Danish energy system until 2050.The analysis of the Danish energy system was done...

Probabilistic Design of Wind Turbines

DEFF Research Database (Denmark)

Toft, Henrik Stensgaard

During the last decades, wind turbines have been continuously developed with the aim of maximizing the life cycle benefits (production of electricity) minus the costs of planning, materials, installation, operation & maintenance as well as possible failure. In order to continue this development...... turbines and the central topics considered are statistical load extrapolation of extreme loads during operation and reliability assessment of wind turbine blades. Wind turbines differ from most civil engineering structures by having a control system which highly influences the loading. In the literature......, methods for estimating the extreme load-effects on a wind turbine during operation, where the control system is active, have been proposed. But these methods and thereby the estimated loads are often subjected to a significant uncertainty which influences the reliability of the wind turbine...

Annual progress report for 1999. Wind Energy and Atmospheric Physics Department

International Nuclear Information System (INIS)

Larsen, S.E.; Skrumsager, B.

2000-06-01

The report describes the work of the Wind Energy and Atmospheric Physics Department at Risoe National Laboratory in 1999. The research of the department aims to develop new opportunities in the exploitation of wind energy and to map and alleviate atmospheric aspects of environmental problems. The expertise of the departments is utilised in commercial activities such as wind turbine testing and certification, training programmes, courses and consultancy services to industry, authorities and Danish and international organisations on wind energy and atmospheric environmental impact. A summary of the department's activities in 1999 is presented, including lists of publications, lectures, committees and staff members. (au)

Dynamic behavior of parked wind turbine at extreme wind speed

DEFF Research Database (Denmark)

Totsuka, Yoshitaka; Imamura, Hiroshi; Yde, Anders

2016-01-01

of standstill and idling is analyzed by time domain simulations using two different coupled aero-hydro-servo-elastic codes. Trend in modern wind turbines is development of bigger, lighter and more flexible rotors where vibration issues may cause aero-elastic instabilities which have a serious impact...

National flood risk mapping of the Danish coastline

DEFF Research Database (Denmark)

Jumppanen Andersen, Kaija; Earnshaw, Matthew; Sørensen, Carlo

2015-01-01

Ocean flooding related to extreme storm surges poses a large damage potential for society. With future climate changes such as sea level rise and increased storminess, ocean flooding becomes one of the largest challenges for Denmark, due to its many islands and long low-lying coastline....... At The Danish Coastal Authority under the Ministry of the Environment we are carrying out a rapid screening of the areas vulnerable to ocean flooding throughout the whole of Denmark; today, in 2065 and in 2100, respectively, to determine hazard areas and vulnerabilities towards floods. With this information we...... can estimate the future requirement for sea defences along the Danish coastline now and into the future. While carrying out this screening we have to assess the factors influencing the flood level. This includes changes in the topography from glacial isostasy and subsidence along with future mean sea...

Wind energy. Energy technologies in national, European and global perspective

Energy Technology Data Exchange (ETDEWEB)

Hauge Madsen, P.; Bjerregaard, E.T.D. [Risoe National Lab., Wind Energy Dept., Roskilde (Denmark)

2002-10-01

According to a recent study, global wind generating capacity increased by some 6800 MW in 2001, an annual growth of just over half the corresponding figure for 2000. 2001 was the third consecutive year in which new wind power capacity exceeded new nuclear power capacity, showing the maturity of wind power technology. Total installed wind power worldwide by the end of 2001 was close to 25.000 MW. Germany, Spain and Denmark are the main players, accounting for 56% of the world's capacity increase in 2001 and a total cumulative installed capacity of 14.750 MW, or 59% of the global total. The USA and India are also significant users of wind power; in 2001 the USA added 1700 MW of new installed capacity to become the world's second-largest market for wind power. The report Wind Force 10 outlines a scenario in which wind power provides 10% of the world's electricity by 2020, corresponding to a total installed capacity of 1200 GW. Risoe's System Analysis Department has looked at the possible future costs of electricity produced by wind turbines compared to conventional power. A learning curve analysis of historical data results in a progress ratio of 0,85. This means that for every doubling of the installed capacity, the cost of wind-generated electricity is reduced by 15%. Until recently the main driver for wind power has been a concern for greenhouse gases. Security of energy supply has now become an important issue, however, especially in Europe and the USA. Wind power plants can be erected at short notice and in a modular fashion that allows capacity to be added as required. The European Commission has supported wind power by sponsoring international research co-operation between institutes, universities and equipment manufacturers. The IEA supports worldwide co-operation, and has recently issued a report on the longterm R and D needs of wind energy. Denmark has, mainly financed by the Danish Energy Agency, taken part in the IEA's R and D Wind

Annual progress report 2000. Wind Energy and Atmospheric Physics Department

Energy Technology Data Exchange (ETDEWEB)

Larsen, S.E.; Skrumsager, B. (eds.)

2001-05-01

The report describes the work of the Wind Energy and Atmospheric Physics Department at Risoe National Laboratory in 2000. The research of the department aims to develop new opportunities in the exploitation of wind energy and to map and alleviate atmospheric aspects of environmental problems. The expertise of the department is utilised in commercial activities such as wind turbine testing and certification, training programmes, courses and consultancy services to industry, authorities and Danish and international organisations on wind energy and atmospheric environmental impact. A summary of the department's activities in 2000 is shown, including lists of publications, lectures, committees and staff members. (au)

Annual progress report 2000. Wind Energy and Atmospheric Physics Dept.

Energy Technology Data Exchange (ETDEWEB)

Larsen, S.E.; Skrumsager, B. [eds.

2001-05-01

The report describes the work of the Wind Energy and Atmospheric Physics Department at Risoe National Laboratory in 2000. The research of the department aims to develop new opportunities in the exploitation of wind energy and to map and alleviate atmospheric aspects of environmental problems. The expertise of the department is utilised in commercial activities such as wind turbine testing and certification, training programmes, courses and consultancy services to industry, authorities and Danish and international organisations on wind energy and atmospheric environmental impact. A summary of the department's activities in 2000 is shown, including lists of publications, lectures, committees and staff members. (au)

Political extremism and violence in Denmark 1917-1940

DEFF Research Database (Denmark)

Larsen, Chris Holmsted

. Regarding the interwar years, the Danish political parties and conditions had many structural and ideological similarities with the neighboring German Weimar Republic. But more important, the situation also differed significantly in terms of particular historical and actor-based conditions– e.g. in terms...... of generalization, but since the research-subject of political violence, in a Danish context, is largely absent and at best minimal, I have concluded that for the sake of the wider perspective, it is imperative to focus on the framework as a prerequisite for a more detailed study of political violence in Denmark....... Therefore, a crucial question is why did the political extremism and violence of the interwar years not manage to scuttle the Danish democracy? And second, why were both fascist and communist protagonists unsuccessful in subverting parliamentarism through a strategy of political violence? To gain...

Wind Speed Perception and Risk

Science.gov (United States)

Agdas, Duzgun; Webster, Gregory D.; Masters, Forrest J.

2012-01-01

Background How accurately do people perceive extreme wind speeds and how does that perception affect the perceived risk? Prior research on human–wind interaction has focused on comfort levels in urban settings or knock-down thresholds. No systematic experimental research has attempted to assess people's ability to estimate extreme wind speeds and perceptions of their associated risks. Method We exposed 76 people to 10, 20, 30, 40, 50, and 60 mph (4.5, 8.9, 13.4, 17.9, 22.3, and 26.8 m/s) winds in randomized orders and asked them to estimate wind speed and the corresponding risk they felt. Results Multilevel modeling showed that people were accurate at lower wind speeds but overestimated wind speeds at higher levels. Wind speed perceptions mediated the direct relationship between actual wind speeds and perceptions of risk (i.e., the greater the perceived wind speed, the greater the perceived risk). The number of tropical cyclones people had experienced moderated the strength of the actual–perceived wind speed relationship; consequently, mediation was stronger for people who had experienced fewer storms. Conclusion These findings provide a clearer understanding of wind and risk perception, which can aid development of public policy solutions toward communicating the severity and risks associated with natural disasters. PMID:23226230

Wind speed perception and risk.

Directory of Open Access Journals (Sweden)

Duzgun Agdas

Full Text Available BACKGROUND: How accurately do people perceive extreme wind speeds and how does that perception affect the perceived risk? Prior research on human-wind interaction has focused on comfort levels in urban settings or knock-down thresholds. No systematic experimental research has attempted to assess people's ability to estimate extreme wind speeds and perceptions of their associated risks. METHOD: We exposed 76 people to 10, 20, 30, 40, 50, and 60 mph (4.5, 8.9, 13.4, 17.9, 22.3, and 26.8 m/s winds in randomized orders and asked them to estimate wind speed and the corresponding risk they felt. RESULTS: Multilevel modeling showed that people were accurate at lower wind speeds but overestimated wind speeds at higher levels. Wind speed perceptions mediated the direct relationship between actual wind speeds and perceptions of risk (i.e., the greater the perceived wind speed, the greater the perceived risk. The number of tropical cyclones people had experienced moderated the strength of the actual-perceived wind speed relationship; consequently, mediation was stronger for people who had experienced fewer storms. CONCLUSION: These findings provide a clearer understanding of wind and risk perception, which can aid development of public policy solutions toward communicating the severity and risks associated with natural disasters.

Wind speed perception and risk.

Science.gov (United States)

Agdas, Duzgun; Webster, Gregory D; Masters, Forrest J

2012-01-01

How accurately do people perceive extreme wind speeds and how does that perception affect the perceived risk? Prior research on human-wind interaction has focused on comfort levels in urban settings or knock-down thresholds. No systematic experimental research has attempted to assess people's ability to estimate extreme wind speeds and perceptions of their associated risks. We exposed 76 people to 10, 20, 30, 40, 50, and 60 mph (4.5, 8.9, 13.4, 17.9, 22.3, and 26.8 m/s) winds in randomized orders and asked them to estimate wind speed and the corresponding risk they felt. Multilevel modeling showed that people were accurate at lower wind speeds but overestimated wind speeds at higher levels. Wind speed perceptions mediated the direct relationship between actual wind speeds and perceptions of risk (i.e., the greater the perceived wind speed, the greater the perceived risk). The number of tropical cyclones people had experienced moderated the strength of the actual-perceived wind speed relationship; consequently, mediation was stronger for people who had experienced fewer storms. These findings provide a clearer understanding of wind and risk perception, which can aid development of public policy solutions toward communicating the severity and risks associated with natural disasters.

Wind and waves in extreme hurricanes

NARCIS (Netherlands)

Holthuijsen, L.H.; Powell, M.D.; Pietrzak, J.D.

2012-01-01

Waves breaking at the ocean surface are important to the dynamical, chemical and biological processes at the air-sea interface. The traditional view is that the white capping and aero-dynamical surface roughness increase with wind speed up to a limiting value. This view is fundamental to hurricane

Denmark - supplier of competitive offshore wind solutions. Megavind's strategy for offshore wind research, development and demonstration

Energy Technology Data Exchange (ETDEWEB)

2010-12-15

In May 2006, the Danish Government presented a report on promoting environmentally effective technology and established a number of innovative partnerships. The partnerships intend to strengthen public-private cooperation between the state, industry, universities and venture capital to accelerate innovation for a number of green technologies. The partnership for wind energy is called Megavind. Megavind's strategy for offshore wind describes the offshore challenges and suggests research, development and demonstration (RD and D) priorities to enable offshore wind power become to competitive with other energy technologies. The strategy lists key recommendations as well as key thematic priorities and for each of these a number of RD and D priorities. Under each thematic priority references are made to the European Strategic Energy Technology plan (SET-plan), which prioritises offshore wind RD and D in Europe. (LN)

Skill forecasting from ensemble predictions of wind power

DEFF Research Database (Denmark)

Pinson, Pierre; Nielsen, Henrik Aalborg; Madsen, Henrik

2009-01-01

Optimal management and trading of wind generation calls for the providing of uncertainty estimates along with the commonly provided short-term wind power point predictions. Alternative approaches for the use of probabilistic forecasting are introduced. More precisely, focus is given to prediction...... risk indices aiming to give a comprehensive signal on the expected level of forecast uncertainty. Ensemble predictions of wind generation are used as input. A proposal for the definition of prediction risk indices is given. Such skill forecasts are based on the spread of ensemble forecasts (i.e. a set...... of alternative scenarios for the coming period) for a single prediction horizon or over a took-ahead period. It is shown on the test case of a Danish offshore wind farm how these prediction risk indices may be related to several levels of forecast uncertainty (and potential energy imbalances). Wind power...

Optimal electricity market for wind power

International Nuclear Information System (INIS)

Holttinen, H.

2005-01-01

This paper is about electricity market operation when looking from the wind power producers' point of view. The focus in on market time horizons: how many hours there is between the closing and delivering the bids. The case is for the Nordic countries, the Nordpool electricity market and the Danish wind power production. Real data from year 2001 was used to study the benefits of a more flexible market to wind power producer. As a result of reduced regulating market costs from better hourly predictions to the market, wind power producer would gain up to 8% more if the time between market bids and delivery was shortened from the day ahead Elspot market (hourly bids by noon for 12-36 h ahead). An after sales market where surplus or deficit production could be traded 2 h before delivery could benefit the producer almost as much, gaining 7%

Danish dental education:

DEFF Research Database (Denmark)

Moore, Rod

1985-01-01

The effects of Danish cultural traditions on dental education in Denmark are described, as well as the system's current structure and developing issues. Some Danish ideas for future exports of dental education programs and dental personnel are also discussed.......The effects of Danish cultural traditions on dental education in Denmark are described, as well as the system's current structure and developing issues. Some Danish ideas for future exports of dental education programs and dental personnel are also discussed....

Excess wind power

DEFF Research Database (Denmark)

Østergaard, Poul Alberg

2005-01-01

Expansion of wind power is an important element in Danish climate change abatement policy. Starting from a high penetration of approx 20% however, momentary excess production will become an important issue in the future. Through energy systems analyses using the EnergyPLAN model and economic...... analyses it is analysed how excess productions are better utilised; through conversion into hydrogen of through expansion of export connections thereby enabling sales. The results demonstrate that particularly hydrogen production is unviable under current costs but transmission expansion could...

Wind energy and spatial planning procedures; La programmation spatiale des projects eoliens

Energy Technology Data Exchange (ETDEWEB)

NONE

2002-07-01

Wind turbines projects have been increasing, but some are very conflicted. May be it is a reason why some local authorities have to deal with different point of view, above the only energy question and including local specificity. To give local authorities the possibility to be implicated and to be in control of wind projects in their territory, wind spatial planning should permit to choose suitable areas and to optimize wind power development. In this context this synthesis presents the wind spatial planning in Finistere (France), the french regulation, some international experiences (Danish, Flemish, Walloon region, Dutch) and the different approaches of spatial planning. (A.L.B.)

The Danish East India Company

DEFF Research Database (Denmark)

Sørensen, Karsten Engsig

2005-01-01

The article analysis the first Danish East India Company incorporated in 1616, which was the first Danish Stock Company and which has impacts even on modern Danish company la......The article analysis the first Danish East India Company incorporated in 1616, which was the first Danish Stock Company and which has impacts even on modern Danish company la...

Ancillary services and the integration of substantial quantities of wind power

DEFF Research Database (Denmark)

Østergaard, Poul Alberg

2006-01-01

. Ballerup: Elkraft System; 2004]. At the same time, Denmark has other forms of distributed generation, e.g., extensive cogeneration of heat and power (CHP) plants for district heating or for covering industrial heat demands. This results in a high fuel-efficiency but also in a technically complex energy......Denmark has the World’s highest penetration of grid connected wind power in electricity generation with a share of 15.0% of total domestic demand in 2002 [Danish Energy Authority. Rapport fra arbejdsgruppen om kraftvarme- og VE-elektricitet. Bilagsrapport. Copenhagen: Danish Energy Authority; 2001...... as the potential impact of heat pumps used for district heating and installed for integration purposes. The analyses are made with particular focus on grid stability and delivery of ancillary services (required to control voltage and frequency) and demonstrate that it is possible to accommodate 50% or more wind...

Benchmarking Danish Industries

DEFF Research Database (Denmark)

Gammelgaard, Britta; Bentzen, Eric; Aagaard Andreassen, Mette

2003-01-01

compatible survey. The International Manufacturing Strategy Survey (IMSS) doesbring up the question of supply chain management, but unfortunately, we did not have access to thedatabase. Data from the members of the SCOR-model, in the form of benchmarked performance data,may exist, but are nonetheless...... not public. The survey is a cooperative project "Benchmarking DanishIndustries" with CIP/Aalborg University, the Danish Technological University, the DanishTechnological Institute and Copenhagen Business School as consortia partners. The project has beenfunded by the Danish Agency for Trade and Industry...

Offshore wind farm Bockstigen - installation and operation experience

Energy Technology Data Exchange (ETDEWEB)

Lange, B [Risoe National Lab., Wind Energy and Atmospheric Physics Dept., Roskilde (Denmark); Aagaard, E; Andersen, P E; Moeller, A [Wind World af 1997 A/S, Noerresundby (Denmark); Niklasson, S; Wickman, A [Vindkompaniet, Degerhamn (Sweden)

1999-03-01

The first Swedish offshore wind farm Bockstigen is operating since March 1998 near the coast of Gotland. It was built as a demonstration project by the Swedish wind farm developer Vindkompaniet, the Danish wind turbine manufacturer Wind World and the British offshore construction company Seacore and partly funded under the EU-THERMIE program. Bockstigen is the fourth offshore wind farm world-wide. While at previous wind farms the main emphasis laid on the demonstration of the technical feasibility of offshore wind energy utilisation, Bockstigen was aimed at demonstrating its economic viability. A number of innovative concepts have been employed: Drilled monopile foundations were used to save costs. A new construction method has been applied making use of a jack-up barge. A new control system for the turbines and the whole wind farm was developed, which controls the maximum power output, the flicker and the reactive power consumption depending on online measurements of the actual grid state. These new developments have been implemented successfully. A substantial cost reduction compared to previous offshore projects could be achieved. (au)

Optimizing investments in coupled offshore wind -electrolytic hydrogen storage systems in Denmark

DEFF Research Database (Denmark)

Hou, Peng; Enevoldsen, Peter; Eichman, Joshua

2017-01-01

, electrolyzers, and hydrogen fuel cells is explored. This research reveals the investment potential of coupling offshore wind farms with different hydrogen systems. The benefits in terms of a return on investment are demonstrated with data from the Danish electricity markets. This research also investigates......In response to electricity markets with growing levels of wind energy production and varying electricity prices, this research examines incentives for investments in integrated renewable energy power systems. A strategy for using optimization methods for a power system consisting of wind turbines...

Annual progress report for 1999. Wind Energy and Atmospheric Physics Department

Energy Technology Data Exchange (ETDEWEB)

Larsen, S.E.; Skrumsager, B. [eds.

2000-06-01

The report describes the work of the Wind Energy and Atmospheric Physics Department at Risoe National Laboratory in 1999. The research of the department aims to develop new opportunities in the exploitation of wind energy and to map and alleviate atmospheric aspects of environmental problems. The expertise of the departments is utilised in commercial activities such as wind turbine testing and certification, training programmes, courses and consultancy services to industry, authorities and Danish and international organisations on wind energy and atmospheric environmental impact. A summary of the department's activities in 1999 is presented, including lists of publications, lectures, committees and staff members. (au)

Conference on 'How to finance wind energy?'

International Nuclear Information System (INIS)

Metzler, Vincent; Weiler, Sibylle; Mous, Dirk; Hodges, Charlie; Talagrand, Romain; Soerensen, Hans Chr.; Feddersen, Hans; Dosdall, Bjoern; Jourdain, Pierre; Duval, Jocelyn

2010-01-01

The French-German office for Renewable energies (OFAEnR) organised a conference on wind energy financing. In the framework of this French-German exchange of experience, more than 150 participants exchanged views on the existing financing solutions for wind energy projects in France, Germany, UK and Denmark. This document brings together the available presentations (slides) made during this event: 1 - How to go on with wind energy projects financing? What evolution of the senior wind energy debt? (Vincent Metzler); 2 - Financing of wind energy projects - Legal aspects (Sibylle Weiler); 3 - Current and future trends in offshore wind financing in Germany (Dirk Mous); 4 - Financing offshore wind: a UK perspective (Charlie Hodges); 5 - Financing the UK Offshore Wind Sector - Transverse analysis of French and European Offshore Wind energy financing (Romain Talagrand); 6 - Cooperative ownership of Danish Wind Turbines (Hans Chr. Soerensen); 7 - Development and financing of a citizen's wind farm - Buergerwindpark (Hans Feddersen); 8 - Citizens' wind farms in Germany - as seen by a project developer (Bjoern Dosdall); 9 - Wind turbines in Vilaine region - A cooperative and pedagogical wind farm: a unique experience in France (Pierre Jourdain); 10 - Status of French participative models (Jocelyn Duval)

Evaluating Maximum Wind Energy Exploitation in Active Distribution Networks

DEFF Research Database (Denmark)

Siano, Pierluigi; Chen, Peiyuan; Chen, Zhe

2010-01-01

The increased spreading of distributed and renewable generation requires moving towards active management of distribution networks. In this paper, in order to evaluate maximum wind energy exploitation in active distribution networks, a method based on a multi-period optimal power flow (OPF......) analysis is proposed. Active network management schemes such as coordinated voltage control, energy curtailment and power factor control are integrated in the method in order to investigate their impacts on the maximization of wind energy exploitation. Some case studies, using real data from a Danish...... distribution system, confirmed the effectiveness of the proposed method in evaluating the optimal applications of active management schemes to increase wind energy harvesting without costly network reinforcement for the connection of wind generation....

A Reduced Wind Power Grid Model for Research and Education

Energy Technology Data Exchange (ETDEWEB)

Akhmatov, V. [Energinet.dk, Fjordvejen 1-11, DK-7000 Fredericia (Denmark); Lund, T.; Hansen, A.D.; Sorensen, P.E. [Risoe National Laboratory, DK-4000 Roskilde (Denmark); Nielsen, A.H. [Centre for Electric Technology, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark)

2006-07-01

A reduced grid model of a transmission system with a number of central power plants, consumption centers, local wind turbines and a large offshore wind farm is developed and implemented in the simulation tool PowerFactory (DIgSILENT). The reduced grid model is given by Energinet.dk, Transmission System Operator of Denmark (TSO) for Natural Gas and Electricity, to the Danish Universities and the Risoe National Laboratory. Its intended usage is education and studying of interaction between electricity-producing wind turbines and a realistic transmission system. Focus in these studies is on voltage stability issues and on the ride-through capability of different wind turbine concepts, equipped with advanced controllers, developed by the Risoe National Laboratory.

Stochastic Optimal Regulation Service Strategy for a Wind Farm Participating in the Electricity Market

DEFF Research Database (Denmark)

Zhang, Baohua; Hu, Weihao; Chen, Zhe

2015-01-01

in the stochastic optimization to deal with the uncertainty of the up regulation price and the up regulation activation of the power system.The Danish short-term electricity market and a wind farm in western Denmark are chosen to evaluate the effect of the proposed strategy. Simulation results showthe proposed......As modern wind farmshave the ability to provideregulation service for the power system, wind power plant operators may be motivated to participate in the regulating market to maximize their profit.In this paper, anoptimal regulation servicestrategy for a wind farm to participate...... strategy can increase the revenue of wind farms by leavinga certain amount of wind powerfor regulation service....

Milk production and composition in Danish Holstein, Danish Red, and Danish Jersey cows supplemented with saturated or unsaturated fat

DEFF Research Database (Denmark)

Weisbjerg, Martin Riis; Larsen, Mette Krogh; Hymøller, Lone

2013-01-01

The aim of the experiment was to study the response in milk production and composition of substituting barley with either saturated or unsaturated fat in mixed rations (MR) for dairy cows. The experiment included 35 Danish Holstein (DH), 39 Danish Red (DR), and 31 Danish Jersey (DJ) cows from...

Stochastic Optimal Wind Power Bidding Strategy in Short-Term Electricity Market

DEFF Research Database (Denmark)

Hu, Weihao; Chen, Zhe; Bak-Jensen, Birgitte

2012-01-01

Due to the fluctuating nature and non-perfect forecast of the wind power, the wind power owners are penalized for the imbalance costs of the regulation, when they trade wind power in the short-term liberalized electricity market. Therefore, in this paper a formulation of an imbalance cost...... minimization problem for trading wind power in the short-term electricity market is described, to help the wind power owners optimize their bidding strategy. Stochastic optimization and a Monte Carlo method are adopted to find the optimal bidding strategy for trading wind power in the short-term electricity...... market in order to deal with the uncertainty of the regulation price, the activated regulation of the power system and the forecasted wind power generation. The Danish short-term electricity market and a wind farm in western Denmark are chosen as study cases due to the high wind power penetration here...

Wind power integration into the automatic generation control of power systems with large-scale wind power

DEFF Research Database (Denmark)

Basit, Abdul; Hansen, Anca Daniela; Altin, Müfit

2014-01-01

Transmission system operators have an increased interest in the active participation of wind power plants (WPP) in the power balance control of power systems with large wind power penetration. The emphasis in this study is on the integration of WPPs into the automatic generation control (AGC......) of the power system. The present paper proposes a coordinated control strategy for the AGC between combined heat and power plants (CHPs) and WPPs to enhance the security and the reliability of a power system operation in the case of a large wind power penetration. The proposed strategy, described...... and exemplified for the future Danish power system, takes the hour-ahead regulating power plan for generation and power exchange with neighbouring power systems into account. The performance of the proposed strategy for coordinated secondary control is assessed and discussed by means of simulations for different...

Extreme Wind, Rain, Storm Surge, and Flooding: Why Hurricane Impacts are Difficult to Forecast?

Science.gov (United States)

Chen, S. S.

2017-12-01

The 2017 hurricane season is estimated as one of the costliest in the U.S. history. The damage and devastation caused by Hurricane Harvey in Houston, Irma in Florida, and Maria in Puerto Rico are distinctly different in nature. The complexity of hurricane impacts from extreme wind, rain, storm surge, and flooding presents a major challenge in hurricane forecasting. A detailed comparison of the storm impacts from Harvey, Irma, and Maria will be presented using observations and state-of-the-art new generation coupled atmosphere-wave-ocean hurricane forecast model. The author will also provide an overview on what we can expect in terms of advancement in science and technology that can help improve hurricane impact forecast in the near future.

The Relationship Between Electricity Price and Wind Power Generation in Danish Electricity Markets

DEFF Research Database (Denmark)

Hu, Weihao; Chen, Zhe; Bak-Jensen, Birgitte

2010-01-01

of competitive electricity markets in some ways, is chosen as the studied power system. The relationship between the electricity price (both the spot price and the regulation price) and the wind power generation in an electricity market is investigated in this paper. The spot price, the down regulation price...... and the up regulation price generally decreases when the wind power penetration in the power system increases. The statistical characteristics of the spot price for different wind power penetration are analyzed. The findings of this paper may be useful for wind power generation companies to make the optimal...... bidding strategy and may be also useful for the optimal operation of modern power systems with high wind power penetrations....

Optimal application of climate data to the development of design wind speeds

DEFF Research Database (Denmark)

Kruger, Andries C.; Retief, Johan V.; Goliger, Adam M.

2014-01-01

Africa (WASA project) focuses, amongst others, on the development of a Regional Extreme Wind Climate (REWC) for South Africa. Wind farms are planned for areas with relatively strong and sustained winds, with wind turbines classed according to their suitability for different wind conditions. The REWC...... statistics are used during the construction and design phase to make assumptions about the local strong wind climate that the wind turbines will be exposed to, with the local environment and topography as additional input. The simultaneous development of the REWC and revision of the extreme wind statistics...... of South Africa created an opportunity to bring together a range of expertise that could contribute to the optimal development of design wind speed information. These include the knowledge of the statistical extraction of extreme wind observations from reanalysis and model data, the quality control...

The Danish Hymnbook

DEFF Research Database (Denmark)

Nielsen, Kirsten

2010-01-01

After an introduction to the use of the word artifact as it is defined by Brian Malley in his work on the Bible as artifact, follows a section on The Danish Hymnbook as Artifac, a section on The Danish Hymnbook between Artifact and Text, and a section on The Danish Hymnbook as Text. The article e...

Extreme climate, not extreme weather: the summer of 1816 in Geneva, Switzerland

Directory of Open Access Journals (Sweden)

R. Auchmann

2012-02-01

Full Text Available We analyze weather and climate during the "Year without Summer" 1816 using sub-daily data from Geneva, Switzerland, representing one of the climatically most severely affected regions. The record includes twice daily measurements and observations of air temperature, pressure, cloud cover, wind speed, and wind direction as well as daily measurements of precipitation. Comparing 1816 to a contemporary reference period (1799–1821 reveals that the coldness of the summer of 1816 was most prominent in the afternoon, with a shift of the entire distribution function of temperature anomalies by 3–4 °C. Early morning temperature anomalies show a smaller change for the mean, a significant decrease in the variability, and no changes in negative extremes. Analyzing cloudy and cloud-free conditions separately suggests that an increase in the number of cloudy days was to a significant extent responsible for these features. A daily weather type classification based on pressure, pressure tendency, and wind direction shows extremely anomalous frequencies in summer 1816, with only one day (compared to 20 in an average summer classified as high-pressure situation but a tripling of low-pressure situations. The afternoon temperature anomalies expected from only a change in weather types was much stronger negative in summer 1816 than in any other year. For precipitation, our analysis shows that the 80% increase in summer precipitation compared to the reference period can be explained by 80% increase in the frequency of precipitation, while no change could be found neither in the average intensity of precipitation nor in the frequency distribution of extreme precipitation. In all, the analysis shows that the regional circulation and local cloud cover played a dominant role. It also shows that the summer of 1816 was an example of extreme climate, not extreme weather.

Low-frequency noise from large wind turbines – additional data and assessment of new Danish regulations

DEFF Research Database (Denmark)

Pedersen, Christian Sejer; Møller, Henrik; Pedersen, Steffen

2012-01-01

turbines in Denmark. In this study, the data material has been increased to include more data on noise from modern production turbines up to 5 MW. In addition, the new Danish regulations are assessed. The previous result that the relative amount of low-frequency noise is higher for large turbines (> 2 MW...... frequencies, and for several of the investigated large turbines, the one-third-octave band with the highest level is at or below 250 Hz. It is thus beyond any doubt that the low-frequency part of the spectrum plays an important role in the noise at the neighbors. The new Danish regulation is based...

National flood risk mapping of the Danish coastline

OpenAIRE

Jumppanen Andersen, Kaija; Earnshaw, Matthew; Sørensen, Carlo

2015-01-01

Ocean flooding related to extreme storm surges poses a large damage potential for society. With future climate changes such as sea level rise and increased storminess, ocean flooding becomes one of the largest challenges for Denmark, due to its many islands and long low-lying coastline. At The Danish Coastal Authority under the Ministry of the Environment we are carrying out a rapid screening of the areas vulnerable to ocean flooding throughout the whole of Denmark; today, in 2065 and in 2100...

Impact Assessment of an Off-Shore Wind Park on Sea Ducks

DEFF Research Database (Denmark)

Guillemette, M.; Larsen, J. K.; Clausager, I.

of the study with a marked difference between Tunø Knob and Ringebjerg Sand in the size available. This was associated with a general impoverishment of the whole benthic community. This suggests that the decrease observed in sea duck abundance over the three years was caused by the availability of food supply......As part of the plan of the Danish government to expand off-shore wind energy production, The Ministry of Environment and Energy, in collaboration with ELSAM (an energy consortium), initiated a three-year study of the potential conflict between the Tunø Knob off-shore wind park and aquatic birds...... in 1994-97. Danish coastal waters support very large, internationally important concentrations of moulting, migrating and wintering sea ducks which depend on shallow water areas as major feeding habitats. Denmark is committed, in relation to international conventions and EU directives, to protect...

Wind climate modeling using Weibull and extreme value distribution ...

African Journals Online (AJOL)

It is very much important to fit wind speed data into some suitable statistical model for two aspects. One is fatigue failure due to periodic vortex shedding and the other is to estimate the wind energy potential of a particular location. For the fatigue failure due to periodic vortex shedding, it is important to analyse the load cycle.

Computational micromechanics of wind blade materials: recent activities at the Materials Research Division, Risoe DTU

Energy Technology Data Exchange (ETDEWEB)

Mishnaevsky Jr., L.; Broendsted, P.; Qing, H.; Wang, H.; Soerensen, Bent F. (Technical Univ. of Denmark, Riso National Lab. for Sustainable Energy. Materials Research Div., Roskilde (Denmark)); OEstergaard, R.C. (LM Wind Power Blades, Composite Mechanics, Roskilde (Denmark))

2010-10-22

Recent research works in the area of 3D computational microstructural modelling, virtual testing and numerical optimization of wind blade materials, carried out at the Materials Research Division, Rise DTU (Programme Composites and Materials Mechanics) are summarized. The works presented here have been carried out in the framework of several research projects: EU FP6 Upwind, Danida project 'Development of wind energy technologies in Nepal' and SinoDanish project '3D Virtual Testing of composites for wind energy applications' as well as the Framework Program 'Interface design of composite materials' and recently established Danish Centre for Composite Structures and Materials for Wind Turbines. Different groups of materials, which are used or have a potential for use for the wind turbine blades, are modelled with the use of the methods of the computational micromechanics, in particular: (1) glass and carbon fiber reinforced polymer composites used in the large wind turbine blades, (2) different sorts of timber, used in small wind turbines (first of all, in developing countries) and (3) nanoparticle reinforced polymer matrix composites (which have a potential to be used as components for future high strength wind blades). On the basis of the developed 3D microstructural finite element models of these materials, we analyzed the effect of their microstructures on damage resistance, strength and stiffness. The methods of the 3D model design and results of the simulations are discussed in this paper. (Author)

Danish Women in the Trades

DEFF Research Database (Denmark)

Pedersen, Elsebet Frydendal

1997-01-01

A review on the Danish situation on womens entry and participation as tradeswomen in the Danish Construction Industry.......A review on the Danish situation on womens entry and participation as tradeswomen in the Danish Construction Industry....

Fundamentally Danish?

DEFF Research Database (Denmark)

Henkel, Heiko

2010-01-01

A closer look at the Muhammad cartoon crisis illuminates some of the key issues that were, and continue to be, at stake for the various actors in the public contestations over the legitimate place of Muslims (and the Islamic tradition) in Danish society. Using a conceptual framework developed...... by Axel Honneth, I suggest in this article that the cartoon crisis is part of an ongoing struggle for recognition in Denmark, through which the terms by which Muslims residing in Denmark are recognized as legitimate citizens/residents of Danish society are negotiated—and on which Muslims may recognize...... the demands of Danish majority society as legitimate. As much as the cartoon affair was an event that, as Palle Weis (2006) writes, “suddenly” ruptured Danish society in 2005, it was therefore also part of a process that continues to shape social actors and their relationships....

Danish Vernacular

DEFF Research Database (Denmark)

Hyams, Inger Louise Berling

2014-01-01

Despite the number of internationally successful Danish architects like Jacobsen, Utzon and in recent years Ingels just to name a few, Danish architecture has always leaned greatly on international architectural history and theory. This is only natural for a small nation. However, since the begin...

Elements of extreme wind modeling for hurricanes

DEFF Research Database (Denmark)

Larsen, Søren Ejling; Ejsing Jørgensen, Hans; Kelly, Mark C.

The report summarizes characteristics of the winds associated with Tropical Cyclones (Hurricanes, Typhoons). It has been conducted by the authors across several years, from 2012-2015, to identify the processes and aspects that one should consider when building at useful computer support system...

Technological learning in offshore wind energy: Different roles of the government

International Nuclear Information System (INIS)

Smit, Thijs; Junginger, Martin; Smits, Ruud

2007-01-01

Offshore wind energy is a promising source of renewable electricity, even though its current costs prevent large-scale implementation. Technological learning has improved the technology and its economic performance already, and could result in significant further improvements. This study investigates how technological learning takes place in offshore wind energy and how technological learning is related to different policy regimes. Offshore wind energy developments in Denmark and the United Kingdom have been analysed with a technology-specific innovation systems approach. The results reveal that the dominant forms of learning are learning by doing and learning by using. At the same time, learning by interacting is crucial to achieve the necessary binding elements in the technology-specific innovation system. Generally, most learning processes were performed by self-organizing entities. However, sometimes cultural and technical barriers occurred, excluding component suppliers and knowledge institutes from the innovation system. Danish policies successfully anticipated these barriers and removed them; therefore, the Danish policies can be characterized as pro-active. British policies shaped stable conditions for learning only; therefore, they can be characterized as active. In the future, barriers could hinder learning by interacting between the oil and gas industry, the offshore wind industry and academia. Based on this study, we suggest national and international policy makers to design long-term policies to anticipate these barriers, in order to contribute to technological learning

A Cyber-Based Data-Enabled Virtual Organization for Wind Load Effects on Civil Infrastructures: VORTEX-Winds

Directory of Open Access Journals (Sweden)

Ahsan Kareem

2017-08-01

Full Text Available Despite many advances in the area of wind effects on structures in recent decades, research has been traditionally conducted within limited resources scattered geographically. With the trend toward increasingly complex designs of civil infrastructure combined with the escalating potential for losses by extreme wind events, a new culture of research needs to be established based on innovative and collaborative solutions for better management of the impact of extreme wind events. To address this change, this paper presents a new paradigm of a multiscale cyber-based laboratory framework for the analysis/design, modeling, and simulation of wind load effects based on an ongoing collaborative cyberinfrastructure-based platform, Virtual Organization for Reducing the Toll of EXtreme Winds (VORTEX-Winds, https://vortex-winds.org, and discusses its current status since its inception in 2007 and ongoing developments. This collaborative framework as it evolves would enable a paradigm shift by offering advanced cyber-enabled modules (e-modules for accelerating advances in research and education to achieve improved understanding and better modeling of wind effects on structures. Accordingly, it will enhance wind community’s analysis and design capabilities to address next-generation challenges posed by wind. Through empowering those without computational or experimental resources, the e-modules will encompass a large set of subject areas and topics categorized as Database-enabled design, Full-scale/Field site data repository, Statistical/Stochastic toolboxes, Tele-experimentation, Uncertainty modeling, Damage assessment, and Computational platforms. This prototype will allow access to the individual e-module, while it is envisaged that next level of development in VORTEX-Winds will have the capability for an automated and integrated analysis/design through a nexus of e-modules. A highlight of the e-modules currently completed or in development is presented

Two anthrax cases with soft tissue infection, severe oedema and sepsis in Danish heroin users

DEFF Research Database (Denmark)

Russell, Lene; Pedersen, Michael; Jensen, Andreas V

2013-01-01

Anthrax had become extremely rare in Europe, but in 2010 an outbreak of anthrax among heroin users in Scotland increased awareness of contaminated heroin as a source of anthrax. We present the first two Danish cases of injectional anthrax and discuss the clinical presentations, which included both...

Wind up with continuous intra-day electricity markets? The integration of large-share wind power generation in Denmark

International Nuclear Information System (INIS)

Karanfil, Fatih; Li, Yuanjing

2015-01-01

This paper suggests an innovative idea to examine the functionality of an electricity intra-day market by testing causality among its fundamental components. As fluctuations of poorly predicted wind power generation are challenging the stability of the current electricity system, an intra-day market design can play an important role in managing wind forecast errors. Using Danish and Nordic data, it investigates the main drivers of the price difference between the intra-day and day-ahead markets, and causality between wind forecast errors and their counterparts. Our results show that the wind and conventional generation forecast errors significantly cause the intra-day price to differ from the day-ahead price, and that the relative intra-day price decreases with the unexpected amount of wind generation. Cross-border electricity exchanges are found to be important to handle wind forecast errors. Additionally, some zonal differences with respect to both causality and impulse responses are detected. This paper provides the first evidence on the persuasive functioning of the intra-day market in the case of Denmark, whereby intermittent production deviations are effectively reduced, and wind forecast errors are jointly handled through the responses from demand, conventional generation, and intra-day international electricity trade. (authors)

Measurement and Analysis of Extreme Wave and Ice Actions in the Great Lakes for Offshore Wind Platform Design

Energy Technology Data Exchange (ETDEWEB)

England, Tony [Univ. of Michigan, Ann Arbor, MI (United States). College of Engineering; van Nieuwstadt, Lin [Univ. of Michigan, Ann Arbor, MI (United States). College of Engineering; De Roo, Roger [Univ. of Michigan, Ann Arbor, MI (United States). College of Engineering; Karr, Dale [Univ. of Michigan, Ann Arbor, MI (United States). College of Engineering; Lozenge, David [Univ. of Michigan, Ann Arbor, MI (United States). College of Engineering; Meadows, Guy [Univ. of Michigan, Ann Arbor, MI (United States). College of Engineering

2016-05-30

This project, funded by the Department of Energy as DE-EE0005376, successfully measured wind-driven lake ice forces on an offshore structure in Lake Superior through one of the coldest winters in recent history. While offshore regions of the Great Lakes offer promising opportunities for harvesting wind energy, these massive bodies of freshwater also offer extreme and unique challenges. Among these challenges is the need to anticipate forces exerted on offshore structures by lake ice. The parameters of interest include the frequency, extent, and movement of lake ice, parameters that are routinely monitored via satellite, and ice thickness, a parameter that has been monitored at discrete locations over many years and is routinely modeled. Essential relationships for these data to be of use in the design of offshore structures and the primary objective of this project are measurements of maximum forces that lake ice of known thicknesses might exert on an offshore structure.

The Danish Retail Market

DEFF Research Database (Denmark)

Aastrup, Jesper; Bjerre, Mogens; Kornum, Niels

2010-01-01

This paper presents an overview of the Danish retail market. A detailed picture of the Danish grocery sector is provided, and we highlight issues from the specialty sectors of fashion and DIY as well as patterns of internationalisation among Danish retailers. We further profile the Danish consumer...... in terms of consumption patterns and demographic changes as well as some specific consumer tendencies with a special emphasis on sustainability issues. E-commerce is taken up as a special theme, both profiling the consumer side and the retailer side. This part is exemplified with books and groceries...

Extending wind turbine operational conditions; a comparison of set point adaptation and LQG individual pitch control for highly turbulent wind

International Nuclear Information System (INIS)

Engels, W P; Subhani, S; Zafar, H; Savenije, F

2014-01-01

Extreme wind conditions can cause excessive loading on the turbine. This not only results in higher design loads, but when these conditions occur in practice, will also result in higher maintenance cost. Although there are already effective methods of dealing with gusts, other extreme conditions should also be examined. More specifically, extreme turbulence conditions (e.g. those specified by design load case 1.3 in IEC61400-1 ed. 3) require special attention as they can lead to design-driving extreme loads on blades, tower and other wind turbine components. This paper examines two methods to deal with extreme loads in a case of extreme turbulent wind. One method is derating the turbine, the other method is an individual pitch control (IPC) algorithm. Derating of the turbine can be achieved in two ways, one is changing the rated torque, the other is changing the rated rotor speed. The effect of these methods on fatigue loads and extreme loads is examined. Non-linear aero-elastic simulations using Phatas, show that reducing the rated rotor speed is far more effective at reducing the loads than reducing torque. Then, the IPC algorithm is proposed. This algorithm is a linear quadratic Gaussian (LQG) controller based on a time invariant model, defined in the fixed reference frame that includes the first tower and blade modes. Because this method takes the dynamics of the system into account more than conventional IPC control, it is expected that these loads dealt with more effectively, when they are particularly relevant. It is expected that in extreme turbulent the blade and tower dynamics are indeed more relevant. The effect of this algorithm on fatigue loads and pitch effort is examined and compared with the fatigue loads and pitch effort of reference IPC. Finally, the methods are compared in non-linear aero-elastic simulations with extreme turbulent wind

The Danish letters

DEFF Research Database (Denmark)

Beier, Sofie; Ejlers, Steen

2011-01-01

The talk will focus on Danish type designers and their work on Æ (AE), Ø (Oslash) and Å (Aring). These 'anomalies' found in the Danish written language, often causes difficulties for type designers. The counters of Ø/ø sometimes appear overcrowded, the uppercase Æ can result in an uncomfortably o......' attempt to create the optimal variation of these letters, we will give a brief introduction to the Danish typography tradition ranging from the early 20th Century and up until today....

More Danish, More English

DEFF Research Database (Denmark)

Chopin, Kimberly Renée

-up approachto determining language use. This research has implications for other institutions which are affected by similar language issues. It adds to existing work on English-medium instruction in higher education, and adds to discussions on domain loss and the language of education inuniversities.......Universities in Denmark are becoming increasingly internationalized, and areincreasingly using English as a language of research, teaching, and administration. At the same time, the Danish language is seen by some as being under threat, and Danish public discourse has focused on what role...... the Danish language may play in higher education in Denmark. This study investigates both trends through a focus on recently implemented language policies at one Danish university faculty which mandate that graduate instruction becarried out only in English, and undergraduate instruction only in Danish...

Danish Pancreatic Cancer Database

DEFF Research Database (Denmark)

Fristrup, Claus; Detlefsen, Sönke; Palnæs Hansen, Carsten

2016-01-01

: Death is monitored using data from the Danish Civil Registry. This registry monitors the survival status of the Danish population, and the registration is virtually complete. All data in the database are audited by all participating institutions, with respect to baseline characteristics, key indicators......AIM OF DATABASE: The Danish Pancreatic Cancer Database aims to prospectively register the epidemiology, diagnostic workup, diagnosis, treatment, and outcome of patients with pancreatic cancer in Denmark at an institutional and national level. STUDY POPULATION: Since May 1, 2011, all patients...... with microscopically verified ductal adenocarcinoma of the pancreas have been registered in the database. As of June 30, 2014, the total number of patients registered was 2,217. All data are cross-referenced with the Danish Pathology Registry and the Danish Patient Registry to ensure the completeness of registrations...

The 2011 Danish Election - Summary of the 2011 Danish election campaign

Directory of Open Access Journals (Sweden)

David Nicolas Hopmann

2011-01-01

Full Text Available On September 15, 2011 a record-high turn-out of 88 percent of the approx. 4 million Danes eligible to vote for the Danish parliament, the Folketing, was reached. This paper gives a short descriptive summary of the 2011 Danish election campaign. Irrespective of which side would win the position as primeminister, one thing was given: an exceptional era in Danish politics was coming to an end. After ten years of a Right Liberal-Conservative minority government supported by the Danish People's Party, Danish poli-tics would return to its classic modus operandi of centrist parties determining the prime-minister. By a margin of a few thousand votes, the red block won the elections and the new prime minister of Denmark is the Social Democrat Helle Thorning-Schmidt. This article describes the political context prior to the election campaign, the course of the election campaign, furthermore it presents the election results in a historical perspective and shortly discusses the challenges the new government is facing.

Incentives and barriers for wind power expansion and system integration in Denmark

DEFF Research Database (Denmark)

Hvelplund, Frede; Ostergaard, Poul Alberg; Meyer, Niels I

2017-01-01

In Denmark expansion of on-shore, near-shore and off-shore wind power is planned to increase the wind power share to 50% of electricity consumption by 2020. In this situation a continuation of past policies will not suffice, and a dual-track incentive system that both establishes incentives...... for investing in wind power and integration infrastructure with integration between the electricity, heating and transportation sectors, is required. The current Danish taxation system discourages electricity use and works against this integration. Likewise, the current day-ahead electricity spot market...... is not appropriate for a high-wind future as wind reduces price levels, but integration across sectors can partly assist in increasing demand and prices. The European Emission Trading System does not suffice in providing a level playing field for wind power and thus needs a revision. Another barrier for on...

Coastal wind study based on Sentinel-1 and ground-based scanning lidar

DEFF Research Database (Denmark)

Hasager, Charlotte Bay; Badger, Merete; Pena Diaz, Alfredo

Winds in the coastal zone have importance for near-shore wind farm planning. Recently the Danish Energy Agency gave new options for placing offshore wind farms much closer to the coastlines than previously. The new tender areas are located from 3 to 8 km from the coast. Ground-based scanning lidar...... located on land can partly cover this area out to around 15 km. In order to improve wind farm planning for near-shore coastal areas, the project‘Reducing the Uncertainty of Near-shore Energy estimates from meso- and micro-scale wind models’ (RUNE) is established. The measurement campaign starts October....... The various observation types have advantages and limitations; one advantage of both the Sentinel-1 and the scanning lidar is that they both observe wind fields covering a large area and so can be combined for studying the spatial variability of winds. Sentinel-1 are being processed near-real-time at DTU Wind...

A risk analysis for natural-draught cooling towers under wind load

International Nuclear Information System (INIS)

Niemann, H.J.

1977-01-01

A satisfactory safety level of natural-draught cooling towers is usually reached by assuming an extreme wind load, for which the probability of being exceeded is very low. Taking into account the dispersion of strength, the relevant extreme wind velocity for the limiting carrying capacity is calculated for a desired probability of failure. Compared with the method of partial safety coefficients, the reliability can be calculated more exactly in this way, even though the probability distribution of the extreme wind velocity must be extrapolated from limited observations. (orig.) [de

Wind conditions and resource assessment

DEFF Research Database (Denmark)

Lundtang Petersen, Erik; Troen, Ib

2012-01-01

The development of wind power as a competitive energy source requires resource assessment of increasing accuracy and detail (including not only the long-term ‘raw’ wind resource, but also turbulence, shear, and extremes), and in areas of increasing complexity. This in turn requires the use of the...

Integrity of reinforced concrete cooling towers under extreme loads: Wind and earthquake

International Nuclear Information System (INIS)

Louhi, Amine

2015-01-01

The authorities have planned to increase the lifetime of currently operating nuclear power plants. The ageing of reinforced concrete structures such as cooling towers should be evaluated and its impact on the bearing capacity calculated. In the case of significant damage, the strengthening must be considered to ensure the sustainability of these towers facing the risk of storms and earthquakes becoming more and more frequent. This work aims to quantify the adverse effects that can generate concrete cracks and rebar section loss induced by corrosion, especially on the bearing capacity of nuclear power plant cooling towers under monotonic or cyclic extreme load conditions (wind and earthquake). These loads are certainly the most severe, since they take the structure into the nonlinear domain and can induce or amplify cracking damage. Numerical simulations are proposed to determine the quasi-static or dynamic response of the structure, taking into account appearance of concrete cracks and their evolution via an appropriate material concrete law and rebar's yielding. In the case of a seismic load, the responses are evaluated by three different methods; the nonlinear response history analysis (NLRHA), the response spectrum analysis and the modal response history analysis (MRHA) in order to compare the earthquake modeling approaches and to evaluate the robustness of the results. Parametric studies on damping, load combinations and structural configurations, are also performed. In the case of a wind load, the strengthening technique using composite materials, such as carbon fiber reinforced plastic (CFRP) is modeled. The behavior of the damaged structure with an advanced corrosion rate is estimated in the pre- and post-cracking regime, compared to the undamaged structure. The drop of bearing capacity is quantified, a reinforcement designed is proposed to restore the integrity and thus increase the lifetime of the structure. (author)

Variable Speed (DFIG) Wind Turbines: Rapid Frequency Response to Power System Disturbances

DEFF Research Database (Denmark)

Chandrashekhara, Divya K; Hansen, Anca Daniela; Sørensen, Poul Ejnar

2009-01-01

This paper examines the effect of integrating large number of wind turbines particularly the double fed induction generator (DFIG) on the virtual inertia of the Danish power system network. The virtual inertia refers to the kinetic energy stored in the rotating masses which can be released...... initially to counter act the frequency change during a power system disturbance. Simulation studies have been carried out on a generic reduced model of a transmission power grid of the Danish TSO Energinet.dk to assess the impact of loss of generation on system frequency. Further, simulation study has been...

Analysis of measurements on wind turbine arrays. Vol. 1

International Nuclear Information System (INIS)

Hoeg, E.

1990-12-01

In 1989 a Danish electric power company initiated an analysis of eight wind turbine arrays. Data from this project is presented together with the explained results of the analyses and the output variations for individual arrays and for systems within the arrays. The models for prognosis are compared and evaluated in order to find that which is most effective. (AB)

Wind Tunnel Tests for Wind Pressure Distribution on Gable Roof Buildings

Science.gov (United States)

2013-01-01

Gable roof buildings are widely used in industrial buildings. Based on wind tunnel tests with rigid models, wind pressure distributions on gable roof buildings with different aspect ratios were measured simultaneously. Some characteristics of the measured wind pressure field on the surfaces of the models were analyzed, including mean wind pressure, fluctuating wind pressure, peak negative wind pressure, and characteristics of proper orthogonal decomposition results of the measured wind pressure field. The results show that extremely high local suctions often occur in the leading edges of longitudinal wall and windward roof, roof corner, and roof ridge which are the severe damaged locations under strong wind. The aspect ratio of building has a certain effect on the mean wind pressure coefficients, and the effect relates to wind attack angle. Compared with experimental results, the region division of roof corner and roof ridge from AIJ2004 is more reasonable than those from CECS102:2002 and MBMA2006.The contributions of the first several eigenvectors to the overall wind pressure distributions become much bigger. The investigation can offer some basic understanding for estimating wind load distribution on gable roof buildings and facilitate wind-resistant design of cladding components and their connections considering wind load path. PMID:24082851

Recruited into Danishness?

DEFF Research Database (Denmark)

Lapina, Linda

2017-01-01

This article critically examines emergence of Danishness via an autoethnography of passing as Danish. Drawing on feminist scholarship, the author conceptualizes passing as an embodied, affective and discursive relation; simultaneously spontaneous and laboured, fleeting and solid, emergent and con...

Advances in the Assessment of Wind Turbine Operating Extreme Loads via More Efficient Calculation Approaches

Energy Technology Data Exchange (ETDEWEB)

Graf, Peter; Damiani, Rick R.; Dykes, Katherine; Jonkman, Jason M.

2017-01-09

A new adaptive stratified importance sampling (ASIS) method is proposed as an alternative approach for the calculation of the 50 year extreme load under operational conditions, as in design load case 1.1 of the the International Electrotechnical Commission design standard. ASIS combines elements of the binning and extrapolation technique, currently described by the standard, and of the importance sampling (IS) method to estimate load probability of exceedances (POEs). Whereas a Monte Carlo (MC) approach would lead to the sought level of POE with a daunting number of simulations, IS-based techniques are promising as they target the sampling of the input parameters on the parts of the distributions that are most responsible for the extreme loads, thus reducing the number of runs required. We compared the various methods on select load channels as output from FAST, an aero-hydro-servo-elastic tool for the design and analysis of wind turbines developed by the National Renewable Energy Laboratory (NREL). Our newly devised method, although still in its infancy in terms of tuning of the subparameters, is comparable to the others in terms of load estimation and its variance versus computational cost, and offers great promise going forward due to the incorporation of adaptivity into the already powerful importance sampling concept.

Danish Technology Framework

DEFF Research Database (Denmark)

Bonke, Sten; Jørgensen, Tom Rydahl

This report investigates the occurrence of foundation failures within the context of the Danish construction technology framework. The report comprises a definition/typology section on the basis of which Danish regulatory and administrative procedures in relation to foundation failures are reviewed....

Two wind power prognosis criteria and regulating power costs

DEFF Research Database (Denmark)

Nielsen, Claus S.; Ravn, Hans F.; Schaumburg-Müller, Camilla

2003-01-01

. Basically, the choice is between focusing on predicting the energy content of the wind and focusing on the cost of buying regulating power to compensate for the prognosis errors. It will be shown that it can be expected that the two power curves thus estimated will differ, and that therefore also the hourly......The objective of the present work is to investigate the consequences of the choice of criterion in short-term wind power prognosis. This is done by investigating the consequences of choice of objective function in relation to the estimation of the power curve that is applied in the prognoses...... wind power production predicted will differ. In turn this will influence the operation and economics of the system. The consequences of this are illustrated by application to the integration of wind power in the Danish parts of the Nordpool area, using recent data. Using a regression analysis...

The Beginnings of Danish Speech Perception

DEFF Research Database (Denmark)

Østerbye, Torkil

, in the light of the rich and complex Danish sound system. The first two studies report on native adults’ perception of Danish speech sounds in quiet and noise. The third study examined the development of language-specific perception in native Danish infants at 6, 9 and 12 months of age. The book points......Little is known about the perception of speech sounds by native Danish listeners. However, the Danish sound system differs in several interesting ways from the sound systems of other languages. For instance, Danish is characterized, among other features, by a rich vowel inventory and by different...... reductions of speech sounds evident in the pronunciation of the language. This book (originally a PhD thesis) consists of three studies based on the results of two experiments. The experiments were designed to provide knowledge of the perception of Danish speech sounds by Danish adults and infants...

Comparison of Danish dichotomous and BI-RADS classifications of mammographic density.

Science.gov (United States)

Hodge, Rebecca; Hellmann, Sophie Sell; von Euler-Chelpin, My; Vejborg, Ilse; Andersen, Zorana Jovanovic

2014-06-01

In the Copenhagen mammography screening program from 1991 to 2001, mammographic density was classified either as fatty or mixed/dense. This dichotomous mammographic density classification system is unique internationally, and has not been validated before. To compare the Danish dichotomous mammographic density classification system from 1991 to 2001 with the density BI-RADS classifications, in an attempt to validate the Danish classification system. The study sample consisted of 120 mammograms taken in Copenhagen in 1991-2001, which tested false positive, and which were in 2012 re-assessed and classified according to the BI-RADS classification system. We calculated inter-rater agreement between the Danish dichotomous mammographic classification as fatty or mixed/dense and the four-level BI-RADS classification by the linear weighted Kappa statistic. Of the 120 women, 32 (26.7%) were classified as having fatty and 88 (73.3%) as mixed/dense mammographic density, according to Danish dichotomous classification. According to BI-RADS density classification, 12 (10.0%) women were classified as having predominantly fatty (BI-RADS code 1), 46 (38.3%) as having scattered fibroglandular (BI-RADS code 2), 57 (47.5%) as having heterogeneously dense (BI-RADS 3), and five (4.2%) as having extremely dense (BI-RADS code 4) mammographic density. The inter-rater variability assessed by weighted kappa statistic showed a substantial agreement (0.75). The dichotomous mammographic density classification system utilized in early years of Copenhagen's mammographic screening program (1991-2001) agreed well with the BI-RADS density classification system.

A Sustainability Index of potential co-location of offshore wind farms and open water aquaculture

DEFF Research Database (Denmark)

Bennassai, G.; Mariani, Patrizio; Stenberg, Claus

2014-01-01

This paper presents the definition of a Sustainability Index for the co-location in marine areas of offshore wind farms and aquaculture plans. The development of the index is focused on the application of MCE technique based on physical constraints and biological parameters that are directly linked...... to the primary production. The relevant physical factors considered are wind velocity and depth range (which directly governs the choice of the site for energy production and for offshore technology), the relevant biological parameters are SST, SST anomaly and CHL-a concentration (as a measurement...... the computation of the Sustainability Index (SI) was identified in the Danish portion of the Baltic Sea and in the western part of the Danish North Sea. Results on the spatial distribution of the SI underline different responses as a function of the physical and biological main influencing parameters...

Calculation of individual and population doses on Danish territory resulting from hypothetical core-melt accidents at the Barsebaeck reactor

International Nuclear Information System (INIS)

1977-01-01

Individual and population doses within Danish territory are calculated from hypothetical, severe core-melt accidents at the Swedish nuclear plant at Barsebaeck. The fission product inventory of the Barsebaeck reactor is calculated. The release fractions for the accidents are taken from WASH-1400. Based on parametric studies, doses are calculated for very unfavourable, but not incredible weather conditions. The probability of such conditions in combination with wind direction towards Danish territory is estimated. Doses to bone marrow, lungs, GI-tract and thyroid are calculated based on dose models developed at Risoe. These doses are found to be consistent with doses calculated with the models used in WASH-1400. (author)

Wind turbine optimal control during storms

International Nuclear Information System (INIS)

Petrović, V; Bottasso, C L

2014-01-01

This paper proposes a control algorithm that enables wind turbine operation in high winds. With this objective, an online optimization procedure is formulated that, based on the wind turbine state, estimates those extremal wind speed variations that would produce maximal allowable wind turbine loads. Optimization results are compared to the actual wind speed and, if there is a danger of excessive loading, the wind turbine power reference is adjusted to ensure that loads stay within allowed limits. This way, the machine can operate safely even above the cut-out wind speed, thereby realizing a soft envelope-protecting cut-out. The proposed control strategy is tested and verified using a high-fidelity aeroservoelastic simulation model

Variations of extreme rainfall in space and time

DEFF Research Database (Denmark)

Gregersen, Ida Bülow; Madsen, H.; Rosbjerg, Dan

2012-01-01

variation, whereas annual variations are related to changes in the average Danish summer precipitation, the average Danish summer temperature and the East Atlantic pattern. The spatio-temporal Poisson regression model was found to be a helpful tool when comparing the internal importance of these variables......In the ongoing climate change discussion, methods for identification of variability governed by climate change are important tools. The magnitude of variables that can describe this variability should be compared with magnitudes of variables describing variability in a stationary setting....... This study focuses on variations of extreme rainfall events, observed at 70 different locations in Denmark over a period of 31 years. The aim is to identify and compare variables, both spatially and temporally, which can explain different parts of the variability in this data set. Assuming that the number...

Hazard analysis of typhoon-related external events using extreme value theory

Energy Technology Data Exchange (ETDEWEB)

Kim, Yo Chan; Jang, Seung Cheol [Integrated Safety Assessment Division, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Lim, Tae Jin [Dept. of Industrial Information Systems Engineering, Soongsil University, Seoul (Korea, Republic of)

2015-02-15

After the Fukushima accident, the importance of hazard analysis for extreme external events was raised. To analyze typhoon-induced hazards, which are one of the significant disasters of East Asian countries, a statistical analysis using the extreme value theory, which is a method for estimating the annual exceedance frequency of a rare event, was conducted for an estimation of the occurrence intervals or hazard levels. For the four meteorological variables, maximum wind speed, instantaneous wind speed, hourly precipitation, and daily precipitation, the parameters of the predictive extreme value theory models were estimated. The 100-year return levels for each variable were predicted using the developed models and compared with previously reported values. It was also found that there exist significant long-term climate changes of wind speed and precipitation. A fragility analysis should be conducted to ensure the safety levels of a nuclear power plant for high levels of wind speed and precipitation, which exceed the results of a previous analysis.

Danish SDHW Technology

DEFF Research Database (Denmark)

Furbo, Simon

1996-01-01

The status of Danish technology for solar heating systems for hot water supply as well as R&D work in the field is presented.......The status of Danish technology for solar heating systems for hot water supply as well as R&D work in the field is presented....

The statistical prediction of offshore winds from land-based data for wind-energy applications

DEFF Research Database (Denmark)

Walmsley, J.L.; Barthelmie, R.J.; Burrows, W.R.

2001-01-01

Land-based meteorological measurements at two locations on the Danish coast are used to predict offshore wind speeds. Offshore wind-speed data are used only for developing the statistical prediction algorithms and for verification. As a first step, the two datasets were separated into nine...... percentile-based bins, with a minimum of 30 data records in each bin. Next, the records were randomly selected with approximately 70% of the data in each bin being used as a training set for development of the prediction algorithms, and the remaining 30% being reserved as a test set for evaluation purposes....... The binning procedure ensured that both training and test sets fairly represented the overall data distribution. To base the conclusions on firmer ground, five permutations of these training and test sets were created. Thus, all calculations were based on five cases, each one representing a different random...

A short Introduction to Danish Hymnody

DEFF Research Database (Denmark)

Balslev-Clausen, Peter

1988-01-01

After a general introduction of Danish Hymnody an analysis of 4 Danish Hymns from Thomas Kingo to K.L. Aastrup, followed by a presentation of "Songs from Denmark"......After a general introduction of Danish Hymnody an analysis of 4 Danish Hymns from Thomas Kingo to K.L. Aastrup, followed by a presentation of "Songs from Denmark"...

Full-load converter connected asynchronous generators for MW class wind turbines

Energy Technology Data Exchange (ETDEWEB)

Akhmatov, Vladislav

2005-06-15

Wind turbines equipped with full-load converter-connected asynchronous generators are a known concept. These have rating up to hundreds of kW and are a feasible concept for MW class wind turbines and may have advantages when compared to conventional wind turbines with directly connected generators. The concept requires the use of full-scale frequency converters, but the mechanical gearbox is smaller than in conventional wind turbines of the same rating. Application of smaller gearbox may reduce the no-load losses in the wind turbines, which is why such wind turbines with converter connected generators may start operation at a smaller wind speed. Wind turbines equipped with such converted connected asynchronous generators are pitch-controlled and variable-speed. This allows better performance and control. The converter control may be applied to support the grid voltage at short-circuit faults and to improve the fault-ride-through capability of the wind turbines, which makes the concepts relevant for large wind farms. The Danish transmission system operator Energinet-DK has implemented the general model of wind turbines equipped with converter connected asynchronous generators with the simulation tool Powerfactory (DlgSilent). The article presents Energinet-DK's experience of modeling this feasible wind turbine concept. (Author)

Analysis of Danish Media setting and framing of Muslims, Islam and racism

DEFF Research Database (Denmark)

Jacobsen, Sara Jul; Jensen, Tina Gudrun; Vitus, Kathrine

This paper presents the results of two case studies exploring the role which the Danish newspaper Media play in the reproduction of racial and ethnic inequalities. One case study analyses representations of Muslims and Islam in Danish newspapers, the other the presence and absence of discussions...... framed and restricted to certain topics such as extremism, terror and sharia, whereas positive actions and critical topics like racism and discrimination against Muslims were more or less nonexistent in the Media coverage. Constructed through an antagonistic and hierarchical relationship between ‘Danes......, the lives and opinions of the less visible majority of Muslims more or less vanished in the Media coverage. In this way, the newspapers constructed a distorted and negative picture of Muslims and their religion, and thereby contributed to a general climate of intolerance and discrimination against Muslim...

Integrated energy systems and local energy markets

International Nuclear Information System (INIS)

Lund, Henrik; Muenster, Ebbe

2006-01-01

Significant benefits are connected with an increase in the flexibility of the Danish energy system. On the one hand, it is possible to benefit from trading electricity with neighbouring countries, and on the other, Denmark will be able to make better use of wind power and other types of renewable energy in the future. This paper presents the analysis of different ways of increasing flexibility in the Danish energy system by the use of local regulation mechanisms. This strategy is compared with the opposite extreme, i.e. trying to solve all balancing problems via electricity trade on the international market. The conclusion is that it is feasible for the Danish society to include the CHP plants in the balancing of fluctuating wind power. There are major advantages in equipping small CHP plants as well as the large CHP plants with heat pumps. By doing so, it will be possible to increase the share of wind power from the present 20 to 40% without causing significant problems of imbalance between electricity consumption and production. Investment in increased flexibility is in itself profitable. Furthermore, the feasibility of wind power is improved

Fault ride-through capability of DFIG wind turbines

Energy Technology Data Exchange (ETDEWEB)

Hansen, Anca D. [Risoe National Laboratory, Wind Energy Department, P.O. Box 49, DK-4000 Roskilde (Denmark); Michalke, Gabriele [Darmstadt University, Institute for Electrical Power Systems, Landgraf-Georg-Strasse 4, 64283 Darmstadt (Germany)

2007-07-15

This paper concentrates on the fault ride-through capability of doubly fed induction generator (DFIG) wind turbines. The main attention in the paper is, therefore, drawn to the control of the DFIG wind turbine and of its power converter and to the ability to protect itself without disconnection during grid faults. The paper provides also an overview on the interaction between variable-speed DFIG wind turbines and the power system subjected to disturbances, such as short circuit faults. The dynamic model of DFIG wind turbine includes models for both mechanical components as well as for all electrical components, controllers and for the protection device of DFIG necessary during grid faults. The viewpoint of the paper is to carry out different simulations to provide insight and understanding of the grid fault impact on both DFIG wind turbines and on the power system itself. The dynamic behaviour of DFIG wind turbines during grid faults is simulated and assessed by using a transmission power system generic model developed and delivered by the Danish Transmission System Operator Energinet.dk in the power system simulation toolbox PowerFactory DIgSILENT. The data for the wind turbines are not linked to a specific manufacturer, but are representative for the turbine and generator type used in variable-speed DFIG wind turbines with pitch control. (author)

Warm-season severe wind events in Germany

Science.gov (United States)

Gatzen, Christoph

2013-04-01

A 15-year data set of wind measurements was analyzed with regard to warm season severe wind gusts in Germany. For April to September of the years 1997 to 2011, 1035 wind measurements of 26 m/s or greater were found. These wind reports were associated with 268 wind events. In total, 252 convective wind events contributed to 837 (81%) of the wind reports, 16 non-convective synoptic-scale wind events contributed to 198 reports (19%). Severe wind events were found with synoptic situations characterized by rather strong mid-level flow and advancing mid-level troughs. Severe convective wind events were analyzed using radar images and classified with respect to the observed radar structure. The most important convective mode was squall lines that were associated with one third of all severe wind gusts, followed by groups, bow echo complexes, and bow echoes. Supercells and cells were not associated with many wind reports. The low contribution of isolated cells indicates that rather large-scale forcing by synoptic-scale features like fronts is important for German severe wind events. Bow echoes were found to be present for 58% of all wind reports. The movement speed of bow echoes indicated a large variation with a maximum speed of 33 m/s. Extreme wind events as well as events with more than 15 wind reports were found to be related to higher movement speeds. Concentrating on the most intense events, derechos seem to be very important to the warm season wind threat in Germany. Convective events with a path length of more than 400 km contributed to 36% of all warm-season wind gusts in this data set. Furthermore, eight of nine extreme gusts exceeding 40 m/s were recorded with derecho events.

An inplementation strategy for the utilization of wind energy in Estonia. Phase 1: Pre-feasibility study and project identification. Final report

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-12-01

This report presents the results of a pre-feasibility and project identification study with the purpose of investigating the possibilities for wind energy in Estonia and to recommend on possible actions, as outlined in Letters of Interest from the Estonian Ministries of Economy and Environment in 1995. Wind as source of energy in Estonia appears not yet to have been analyzed in detail. Available data indicates that wind can constitute a viable domestic source of energy, as average wind speeds of about 6 m/s (at 10 m) are reported at many coastal regions of Estonia. With state-of-the-art wind energy technology this means cost of wind produced electricity about 0.7-0.8 EEK/kWh - comparable to the cost of electricity from a modern coal-fired power plant. Two types of grids exist in these regions: On the mainland and on islands with sea cable grid connected wind turbines can be implemented. On islands without sea cable wind turbines can be connected to the diesel powered local grids. As a first step it is proposed to undertake the detailed planning and feasibility study of grid connected wind energy demonstrations in the framework of the Danish-Estonian country collaboration agreement. If the decision is made to implement this wind energy demonstration project, a certain proportion of grant money should be allocated for the demonstration. Subsequent steps in the Danish-Estonian country collaboration agreement should include the detailed planning and feasibility studies of autonomous wind energy demonstration and the associated capacity building. (EG)

Legal method in danish law

DEFF Research Database (Denmark)

Blume, Peter Erik

and furthermore a brief account of Danish legal history is provided. The following chapters concern: • Legal institutions, • Statute and Statutory Law • Legal Decisions • Legal Literature and Legal Knowledge • Other National Legal Sources • External Influences on Danish Law......This book describes how legal method is used within the Danish legal system. Its target group is foreign lawyers and law students who have an interest in knowing how Danish law commonly is determined and applied. In the first chapters legal method and legal sources in general are defined...

Managing Danish pupils’ well-being

DEFF Research Database (Denmark)

Ratner, Helene Gad; Gad, Christopher

The concept of well-being has become a key category of social and political imagination, cultivating new understandings of 'what it means to be a capable person' (Corsín Jiménez, 2008, 2). In 2015, the Danish Ministry of Education began conducting national, annual measurements of Danish pupils...... national objectives for pupils' well-being; 2) the Danish newspaper A4's interactive, online mapping of pupils' well-being at all Danish schools, developed from the same numbers (accessed through their juridical right to access government files) but using different calculative techniques and aimed...

Facing the challenges of distribution systems operation with high wind power penetration

DEFF Research Database (Denmark)

Das, Kaushik; Altin, Müfit; Hansen, Anca Daniela

2017-01-01

power flow in 60kV distribution networks through controlling the ability of wind power plants (WPPs) to generate or absorb reactive power. This paper aims to understand the characteristics of a distribution network with high penetration of distributed generation. A detailed analysis of the active...... and reactive power flows in a real distribution network under different wind and load conditions based on actual measurements is performed in order to understand the correlation between the consumption, wind power production, and the network losses. Conclusive remarks are presented, briefly expressing......This paper addresses the challenges associated with the operation of a distribution system with high penetration of wind power. The paper presents some preliminary investigations of an ongoing Danish research work, which has as main objective to reduce the network losses by optimizing the reactive...

Large-scale integration of wind power into different energy systems

DEFF Research Database (Denmark)

Lund, Henrik

2005-01-01

The paper presents the ability of different energy systems and regulation strategies to integrate wind power. The ability is expressed by the following three factors: the degree of electricity excess production caused by fluctuations in wind and Combined Heat and Power (CHP) heat demands......, the ability to utilise wind power to reduce CO2 emission in the system, and the ability to benefit from exchange of electricity on the market. Energy systems and regulation strategies are analysed in the range of a wind power input from 0 to 100% of the electricity demand. Based on the Danish energy system...... and such potential future energy systems different regulation strategies have been analysed, i.e. the inclusion of small CHP plants into the regulation task of electricity balancing and ancillary grid stability services and investments in electric heating, heat pumps and heat storage capacity. The results...

Grid fault and design-basis for wind turbines - Final report

DEFF Research Database (Denmark)

Hansen, Anca Daniela; Cutululis, Nicolaos Antonio; Markou, Helen

, have been performed and compared for two cases, i.e. one when the turbine is immediately disconnected from the grid when a grid fault occurs and one when the turbine is equipped with a fault ride-through controller and therefore it is able to remain connected to the grid during the grid fault......This is the final report of a Danish research project “Grid fault and design-basis for wind turbines”. The objective of this project has been to assess and analyze the consequences of the new grid connection requirements for the fatigue and ultimate structural loads of wind turbines....... The fulfillment of the grid connection requirements poses challenges for the design of both the electrical system and the mechanical structure of wind turbines. The development of wind turbine models and novel control strategies to fulfill the TSO’s requirements are of vital importance in this design. Dynamic...

The Danish Press during the German Occupation

DEFF Research Database (Denmark)

Roslyng-Jensen, Palle

2010-01-01

Censorship, self-censorship in Danish newspapers and Danish Radio during the German occupation of Denmark 1940-45......Censorship, self-censorship in Danish newspapers and Danish Radio during the German occupation of Denmark 1940-45...

European wind power integration study. Periodic report 1

Energy Technology Data Exchange (ETDEWEB)

NONE

1992-12-31

This periodic report no. 1 describes the work done in the Danish part of the European Wind Power Integration Study in the period until 1.4.1991. The R and D project was initiated January 1, 1989 upon prior establishment of registration equipment at 7 wind farms and at the Tjaereborg turbine. ELSAM and the meteorological service centre in Karup (VTC-Karup) have supplied data for the task. Wind Predictability, Potential and Benefits, Wind Farm - Grid Interface, Distribution System Strength, Wind Farm Cost and Operation, and Co-generation Wind Turbines/Other renewables were measured and modelled. The statistical distribution of the wind speed variations (changes in wind speed from one period of time to another) has been established with great certainty in the report. The wind speed variations follow a Weibull distribution, irrespective of the time intervals with which the data are considered. Duration curves and power distributions for the 7 wind farms have been estimated. Registration equipment for one-minute measurements was chosen in order to clarify the short-term variations in the wind power production. The possibility of working out production forecasts, to be applied in the daily load dispatching, were to be assessed for the total amount of wind power production in Jutland and Funen. The report has examined whether it would be possible to have only one wind measurement and then let it be `guiding` for the total wind farm production. Some simulations are to be carried out in the attempt to set up guidelines for the connection between the strength of distribution systems and the requirements which must be made to the wind farms which are to be places in the system. (EG)

Rationality of the subsidy regime for wind power in Sweden and Denmark

Energy Technology Data Exchange (ETDEWEB)

Helby, P [Lund Univ. (Sweden). Dept. of Environmental and Energy System Studies

1996-12-31

This study comprise analysis and discussion of incentives inherent in the Swedish and Danish subsidy regimes for household owned wind power. New results include an evaluation of the subsidy value of income and VAT tax breaks available to investors, and a demonstration of the importance of the choice of ownership arrangements for the profitability of wind power projects. The study outlines the complex restrictions associated with different forms of wind power ownership. These cause the investment market to be highly segmented. The discussion includes several irrational system effects of the subsidy regimes. Among these are collision with energy saving goals, excessive capital costs, dubious siting decisions, and distorted competition among technologies. In conclusion, come policy recommendations are suggested. (author)

Rationality of the subsidy regime for wind power in Sweden and Denmark

Energy Technology Data Exchange (ETDEWEB)

Helby, P. [Lund Univ. (Sweden). Dept. of Environmental and Energy System Studies

1995-12-31

This study comprise analysis and discussion of incentives inherent in the Swedish and Danish subsidy regimes for household owned wind power. New results include an evaluation of the subsidy value of income and VAT tax breaks available to investors, and a demonstration of the importance of the choice of ownership arrangements for the profitability of wind power projects. The study outlines the complex restrictions associated with different forms of wind power ownership. These cause the investment market to be highly segmented. The discussion includes several irrational system effects of the subsidy regimes. Among these are collision with energy saving goals, excessive capital costs, dubious siting decisions, and distorted competition among technologies. In conclusion, come policy recommendations are suggested. (author)

Rationality of the subsidy regime for wind power in Sweden and Denmark

International Nuclear Information System (INIS)

Helby, P.

1995-01-01

This study comprise analysis and discussion of incentives inherent in the Swedish and Danish subsidy regimes for household owned wind power. New results include an evaluation of the subsidy value of income and VAT tax breaks available to investors, and a demonstration of the importance of the choice of ownership arrangements for the profitability of wind power projects. The study outlines the complex restrictions associated with different forms of wind power ownership. These cause the investment market to be highly segmented. The discussion includes several irrational system effects of the subsidy regimes. Among these are collision with energy saving goals, excessive capital costs, dubious siting decisions, and distorted competition among technologies. In conclusion, come policy recommendations are suggested. (author)

Quality development of Danish strawberries

DEFF Research Database (Denmark)

Østergaard, Peder; Stacey, Julia

1999-01-01

The quality of fruit and berries has often been the topic of debate and Danish strawberries have been both praised and criticized. Therefore the Danish Institute of Agricultural Sciences, Danish Fruit Growers' Association, the Danish Veterinary and Food Administration and MAPP have joined together...... in a project about quality assurance of strawberries. One purpose of the project has been to provide systematic knowledge about Danish consumers' attitudes towards strawberries, knowledge, buying behaviour and consumption of strawberries. Another purpose has been to take an active part in the development...... of new strawberry varieties and growing methods and also to support better distribution and sale of strawberries. During 1999, focus group interviews and a representative study with 1174 householdswere carried out. In-home tests of existing and new varieties of strawberries will be carried out during...

Selecting optimum locations for co-located wave and wind energy farms. Part II: A case study

International Nuclear Information System (INIS)

Astariz, S.; Iglesias, G.

2016-01-01

Highlights: • The benefits of wave and wind combined systems relative to independent farms are analysed. • This purpose is carried out through a case study off the Danish coast. • The power production, power smoothing and shadow effect are analysed. • Hindcast and measured wave and wind data from 2005 to 2015 are used. • Third-generation models of winds and waves (WAsP and SWAN) are used. - Abstract: Combined energy systems present an opportunity to enhance the competitiveness of renewables and overcome other challenges of these novel renewables by realising the synergies between them. Among the different possibilities for combined systems, this work focuses on wave and wind co-located farms with the aim of assessing their benefits relative to standalone wind farms. To this end we estimate the energy production, investigate the power smoothing and shadow effect, and quantify the reduction in downtime achieved by the co-located farm through a case study off the Danish coast – a promising area for co-located farms based on the available resource and other considerations including technical constraints. The analysis is carried out based on hindcast data and observations extending from 2005 to 2015, and by means of state-of-the-art numerical models of the wind and wave fields – WAsP and SWAN, respectively. It is found that the energy yield per unit area with the combined wave-wind farm increases by 3.4% relative to a standalone wind farm, the downtime periods decrease by 58% and the power output variability reduces by 12.5%. Moreover, the capital and operational expenditures (CAPEX and OPEX, respectively) would also be significantly reduced thanks to the synergies realised through the combination of wind and wave power.

Energy System Analysis of Large-Scale Integration of Wind Power

International Nuclear Information System (INIS)

Lund, Henrik

2003-11-01

The paper presents the results of two research projects conducted by Aalborg University and financed by the Danish Energy Research Programme. Both projects include the development of models and system analysis with focus on large-scale integration of wind power into different energy systems. Market reactions and ability to exploit exchange on the international market for electricity by locating exports in hours of high prices are included in the analyses. This paper focuses on results which are valid for energy systems in general. The paper presents the ability of different energy systems and regulation strategies to integrate wind power, The ability is expressed by three factors: One factor is the degree of electricity excess production caused by fluctuations in wind and CHP heat demands. The other factor is the ability to utilise wind power to reduce CO 2 emission in the system. And the third factor is the ability to benefit from exchange of electricity on the market. Energy systems and regulation strategies are analysed in the range of a wind power input from 0 to 100% of the electricity demand. Based on the Danish energy system, in which 50 per cent of the electricity demand is produced in CHP, a number of future energy systems with CO 2 reduction potentials are analysed, i.e. systems with more CHP, systems using electricity for transportation (battery or hydrogen vehicles) and systems with fuel-cell technologies. For the present and such potential future energy systems different regulation strategies have been analysed, i.e. the inclusion of small CHP plants into the regulation task of electricity balancing and grid stability and investments in electric heating, heat pumps and heat storage capacity. Also the potential of energy management has been analysed. The results of the analyses make it possible to compare short-term and long-term potentials of different strategies of large-scale integration of wind power

Danish Gynecological Cancer Database

DEFF Research Database (Denmark)

Sørensen, Sarah Mejer; Bjørn, Signe Frahm; Jochumsen, Kirsten Marie

2016-01-01

AIM OF DATABASE: The Danish Gynecological Cancer Database (DGCD) is a nationwide clinical cancer database and its aim is to monitor the treatment quality of Danish gynecological cancer patients, and to generate data for scientific purposes. DGCD also records detailed data on the diagnostic measures...... data forms as follows: clinical data, surgery, pathology, pre- and postoperative care, complications, follow-up visits, and final quality check. DGCD is linked with additional data from the Danish "Pathology Registry", the "National Patient Registry", and the "Cause of Death Registry" using the unique...... Danish personal identification number (CPR number). DESCRIPTIVE DATA: Data from DGCD and registers are available online in the Statistical Analysis Software portal. The DGCD forms cover almost all possible clinical variables used to describe gynecological cancer courses. The only limitation...

Review of wind power tariff policies in China

International Nuclear Information System (INIS)

Hu, Zheng; Wang, Jianhui; Byrne, John; Kurdgelashvili, Lado

2013-01-01

In the past 20 years, China has paid significant attention to wind power. Onshore wind power in China has experienced tremendous growth since 2005, and offshore wind power development has been on-going since 2009. In 2010, with a total installed wind power capacity of 41.8 GW, China surpassed the U.S. as the country with the biggest wind power capacity in the world. By comparing the wind power situations of three typical countries, Germany, Spain, and Denmark, this paper provides a comprehensive evaluation and insights into the prospects of China’s wind power development. The analysis is carried out in four aspects including technology, wind resources, administration and time/space frame. We conclude that both German and Spanish have been growing rapidly in onshore capacity since policy improvements were made. In Denmark, large financial subsidies flow to foreign markets with power exports, creating inverse cost-benefit ratios. Incentives are in place for German and Danish offshore wind power, while China will have to remove institutional barriers to enable a leap in wind power development. In China, cross-subsidies are provided from thermal power (coal-fired power generation) in order to limit thermal power while encouraging wind power. However, the mass installation of wind power capacity completely relies on power subsidies. Furthermore, our study illustrates that capacity growth should not be the only consideration for wind power development. It is more important to do a comprehensive evaluation of multi-sectorial efforts in order to achieve long-term development. - Highlights: ► Key components to exam China’s wind power. ► Evaluation of Europe could be helpful. ► China has to remove institutional barrier.

Review report 2004. The Danish offshore wind farm demonstration project: Horns Rev and Nysted offshore wind farms. Environmental impact assessment and monitoring

Energy Technology Data Exchange (ETDEWEB)

NONE

2005-10-15

The present review report presents the two wind farms Horns Rev and Nysted with regard to environmental characteristics and the results of the environmental studies carried out in connection with the Environmental Impact Assessment (EIA) and the baseline and monitoring programmes at the two sites. The descriptions of the programmes are based on extracts from the individual annual reports. Detailed information on method, programmes and conclusions can be found in these reports (see Appendix 1). This review report is divided into two parts. The first part contains a description of the potential environmental impacts of offshore wind farms and the potentially affected part of the environment. The second part includes a description of Horns Rev and Nysted Offshore Wind Farm and the environmental studies carried out here until the end of 2003. Appendix I is a list of the literature published on the studies carried out at Horns Rev and Nysted Offshore Wind Farm. Appendix II is a list of some of the literature relevant to the demonstration projects but not directly related to the projects. The offshore wind farm situated in the Roedsand area is officially denoted Nysted Offshore Wind Farm, and in the present report the denotation 'Nysted' will be used as well when referring to Nysted Offshore Wind Farm. The denotation Roedsand will be used when referring to the actual area Roedsand. (au)

Review report 2003. The Danish offshore wind farm demonstration project: Horns Rev and Nysted offshore wind farms. Environmental impact assessment and monitoring

Energy Technology Data Exchange (ETDEWEB)

NONE

2004-09-15

The present review report presents the two wind farms Homs Rev and Nysted, with regard to environmental characteristics and the results of the environmental studies carried out in connection with the Environmental Impact Assessment (EIA) and the baseline and monitoring programmes at the two sites. The descriptions of the programmes are based on extracts from the individual annual reports. Detailed information on methods, programmes and conclusions can be found in these reports. This review report is divided into two parts. The first part contains a description of the potential environmentally impacts of offshore wind farms and the potentially affected part of the environment. The second part includes a description of Horns Rev and Nysted Offshore Wind Farm and the environmental studies carried out here until the end of 2003. Appendix I is a list of the literature published on the studies carried out at Hors Rev and Nysted Offshore Wind Farm. Appendix II is a list of some of the literature relevant to the demonstration projects but not directly related to the projects. The offshore wind farm situated at the bdsand area is officially denoted Nysted Offshore Wind Farm, and in the present report the denotation 'Nysted' will be used as well when referring to Nysted Offshore Wind Farm. The denotation Roedsand will be used when referring to the actual area Roedsand. (au)

Review report 2004. The Danish offshore wind farm demonstration project: Horns Rev and Nysted offshore wind farms. Environmental impact assessment and monitoring

Energy Technology Data Exchange (ETDEWEB)

NONE

2005-10-15

The present review report presents the two wind farms Horns Rev and Nysted with regard to environmental characteristics and the results of the environmental studies carried out in connection with the Environmental Impact Assessment (EIA) and the baseline and monitoring programmes at the two sites. The descriptions of the programmes are based on extracts from the individual annual reports. Detailed information on method, programmes and conclusions can be found in these reports (see Appendix 1). This review report is divided into two parts. The first part contains a description of the potential environmental impacts of offshore wind farms and the potentially affected part of the environment. The second part includes a description of Horns Rev and Nysted Offshore Wind Farm and the environmental studies carried out here until the end of 2003. Appendix I is a list of the literature published on the studies carried out at Horns Rev and Nysted Offshore Wind Farm. Appendix II is a list of some of the literature relevant to the demonstration projects but not directly related to the projects. The offshore wind farm situated in the Roedsand area is officially denoted Nysted Offshore Wind Farm, and in the present report the denotation 'Nysted' will be used as well when referring to Nysted Offshore Wind Farm. The denotation Roedsand will be used when referring to the actual area Roedsand. (au)

Response Analysis and Comparison of a Spar-Type Floating Offshore Wind Turbine and an Onshore Wind Turbine under Blade Pitch Controller Faults

DEFF Research Database (Denmark)

Etemaddar, M.; Blanke, Mogens; Gao, Z.

2016-01-01

in the controller dynamic link library and a short-term extreme response analysis is performed using the HAWC2 simulation tool.The main objectives of this paper are to investigate how different faults affect the performance of wind turbines for condition monitoring purposes and which differences exist...... in the structural responses between onshore and offshore floating wind turbines. Statistical analysis of the selected response parameters are conducted using the six1-hour stochastic samples for each load case.For condition monitoring purpose,the effects of faults on the responses at different wind speeds and fault...... amplitudes are investigated by comparing the same response under normal operation.The severities of the individual faults are categorized by the extreme values of structural loads and the structural components are sorted based on the magnitude of the fault effects on the extreme values.The pitch sensor fixed...

A Review of Methodological Approaches for the Design and Optimization of Wind Farms

DEFF Research Database (Denmark)

Herbert-Acero, José F.; Probst, Oliver; Réthoré, Pierre-Elouan

2014-01-01

This article presents a review of the state of the art of the Wind Farm Design and Optimization (WFDO) problem. The WFDO problem refers to a set of advanced planning actions needed to extremize the performance of wind farms, which may be composed of a few individual Wind Turbines (WTs) up to thou...... and offshore wind farms; and (3) to propose a comprehensive agenda for future research.......This article presents a review of the state of the art of the Wind Farm Design and Optimization (WFDO) problem. The WFDO problem refers to a set of advanced planning actions needed to extremize the performance of wind farms, which may be composed of a few individual Wind Turbines (WTs) up...

WindPACT Reference Wind Turbines

Energy Technology Data Exchange (ETDEWEB)

Dykes, Katherine L [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Rinker, Jennifer [Former National Renewable Energy Laboratory (NREL) employee

2018-04-02

To fully understand how loads and turbine cost scale with turbine size, it is necessary to have identical turbine models that have been scaled to different rated powers. The report presents the WindPACT baseline models, which are a series of four baseline models that were designed to facilitate investigations into the scalings of loads and turbine cost with size. The models have four different rated powers (750 kW, 1.5 MW, 3.0 MW, and 5.0 MW), and each model was designed to its specified rated power using the same design methodology. The models were originally implemented in FAST_AD, the predecessor to NREL's open-source wind turbine simulator FAST, but have yet to be implemented in FAST. This report contains the specifications for all four WindPACT baseline models - including structural, aerodynamic, and control specifications - along with the inherent assumptions and equations that were used to calculate the model parameters. It is hoped that these baseline models will serve as extremely useful resources for investigations into the scalings of costs, loads, or optimization routines.

The Danish Air Quality Monitoring Programme

DEFF Research Database (Denmark)

Ellermann, Thomas; Nøjgaard, Jacob Klenø; Nordstrøm, Claus

Aarhus University, DCE – Danish Centre for Environment and Energy, 64 pp. Scientific Report from DCE – Danish Centre for Environment and Energy No. 162. http://dce2.au.dk/pub/SR162.pdf......Aarhus University, DCE – Danish Centre for Environment and Energy, 64 pp. Scientific Report from DCE – Danish Centre for Environment and Energy No. 162. http://dce2.au.dk/pub/SR162.pdf...

Representational Learning for Fault Diagnosis of Wind Turbine Equipment: A Multi-Layered Extreme Learning Machines Approach

Directory of Open Access Journals (Sweden)

Zhi-Xin Yang

2016-05-01

Full Text Available Reliable and quick response fault diagnosis is crucial for the wind turbine generator system (WTGS to avoid unplanned interruption and to reduce the maintenance cost. However, the conditional data generated from WTGS operating in a tough environment is always dynamical and high-dimensional. To address these challenges, we propose a new fault diagnosis scheme which is composed of multiple extreme learning machines (ELM in a hierarchical structure, where a forwarding list of ELM layers is concatenated and each of them is processed independently for its corresponding role. The framework enables both representational feature learning and fault classification. The multi-layered ELM based representational learning covers functions including data preprocessing, feature extraction and dimension reduction. An ELM based autoencoder is trained to generate a hidden layer output weight matrix, which is then used to transform the input dataset into a new feature representation. Compared with the traditional feature extraction methods which may empirically wipe off some “insignificant’ feature information that in fact conveys certain undiscovered important knowledge, the introduced representational learning method could overcome the loss of information content. The computed output weight matrix projects the high dimensional input vector into a compressed and orthogonally weighted distribution. The last single layer of ELM is applied for fault classification. Unlike the greedy layer wise learning method adopted in back propagation based deep learning (DL, the proposed framework does not need iterative fine-tuning of parameters. To evaluate its experimental performance, comparison tests are carried out on a wind turbine generator simulator. The results show that the proposed diagnostic framework achieves the best performance among the compared approaches in terms of accuracy and efficiency in multiple faults detection of wind turbines.

Energy researchers - 8. Wind power production: Wind power, the energy of the future; A mature sector; The ecological attraction of wind

International Nuclear Information System (INIS)

Minster, Jean-Francois; Appert, Olivier; Moisan, Francois; Salha, Bernard; Tardieu, Bernard; Florette, Marc; Ghidaglia, Jean-Michel; Viterbo, Jerome

2012-01-01

A first article comments the development in the design of wind turbines which become more powerful, with higher performance. Researchers are also working on blade shape, on alternator technology, on the use of multiplier to enable the reduction of the alternator weight, on better control and command systems to increase the load factor. The development of offshore wind farms is also a challenge in terms of maintenance, in wind turbine design in order to withstand sea corrosion, and in terms of connection to the grid. A second article comments the evolution of the wind energy sector in terms of installed capacity, costs and competitiveness. In an interview, three researchers outline the extremely positive carbon footprint and other benefits of wind power, and also discuss its disadvantages: they mainly concern the impact on landscape, but also birds and marine fauna

Wind power integration into the automatic generation control of power systems with large-scale wind power

Directory of Open Access Journals (Sweden)

Abdul Basit

2014-10-01

Full Text Available Transmission system operators have an increased interest in the active participation of wind power plants (WPP in the power balance control of power systems with large wind power penetration. The emphasis in this study is on the integration of WPPs into the automatic generation control (AGC of the power system. The present paper proposes a coordinated control strategy for the AGC between combined heat and power plants (CHPs and WPPs to enhance the security and the reliability of a power system operation in the case of a large wind power penetration. The proposed strategy, described and exemplified for the future Danish power system, takes the hour-ahead regulating power plan for generation and power exchange with neighbouring power systems into account. The performance of the proposed strategy for coordinated secondary control is assessed and discussed by means of simulations for different possible future scenarios, when wind power production in the power system is high and conventional production from CHPs is at a minimum level. The investigation results of the proposed control strategy have shown that the WPPs can actively help the AGC, and reduce the real-time power imbalance in the power system, by down regulating their production when CHPs are unable to provide the required response.

The transport sectors potential contribution to the flexibility in the power sector required by large-scale wind power integration

DEFF Research Database (Denmark)

Nørgård, Per Bromand; Lund, H.; Mathiesen, B.V.

2007-01-01

-scale integration of renewable energy in the power system – in specific wind power. In the plan, 20 % of the road transport is based on electricity and 20 % on bio- fuels. This, together with other initiatives allows for up to 55-60 % wind power penetration in the power system. A fleet of 0.5 mio electrical...... vehicles in Denmark in 2030 connected to the grid 50 % of the time represents an aggregated flexible power capacity of 1- 1.5 GW and an energy capacity of 10-150 GWh.......In 2006, the Danish Society of Engineers developed a visionary plan for the Danish energy system in 2030. The paper presents and qualifies selected part of the analyses, illustrating the transport sectors potential to contribute to the flexibility in the power sector, necessary for large...

An extensive evaluation of wind resource using new methods and strategies for development and utilizing wind power in Mah-shahr station in Iran

International Nuclear Information System (INIS)

Nedaei, Mojtaba; Assareh, Ehsanolah; Biglari, Mojtaba

2014-01-01

Highlights: • In this research, results suggest that the Weibull distribution is the best function to model the wind data in Mah-shahr. • The compatibility of the wind data with three methods of estimating Weibull parameters was assessed. • An extreme analysis of wind in Mah-shahr was done to determine the maximum gust wind speeds over a 50-year return period. • An extensive economic evaluation of installing a wind park was performed on RETScreen® software. - Abstract: In this study, the 10-min period measured short-term wind speed data at 10 m and 40 m heights for Mah-shahr station in Iran was statistically analyzed to determine the potential of wind power generation. In addition in this paper different distribution functions are compared to each other in order to find the best distribution in Mah-shahr which is compatible with the wind data. It is found that the Weibull distribution is the best function to model the wind data in Mah-shahr. It should also be mentioned that the different methods for calculating Weibull parameters were used and compared to each other. Moreover an extreme analysis of wind data in Mah-shahr was carried out to determine the maximum gust wind speed over a 50-year return period (Ve50). Using the method of “periodic maxima” for analysis of extreme winds, it was revealed that the 50-year wind speed at 80 m in Mah-shahr which is 39.5 m/s is lower than usual values of Ve50 limits for different wind turbines. This means that the risk of extreme wind gusts in Mah-shahr might not be a problem for installation of wind turbines. From the primary evaluation of wind data in Mah-shahr it is found the studied site has an acceptable potential of wind power for electricity generation. Energy production of different wind turbines at different heights is determined. Then a simple economic evaluation carried out to determine whether studied site is suitable for development of commercial or small and residential wind turbines. It became clear

Global impact of Danish drama series

DEFF Research Database (Denmark)

Jensen, Pia Majbritt

2016-01-01

In recent years Danish TV series have experienced a global export boom. This article maps the regional and global export patterns over the last fifteen years in order to assess the international impact of Danish TV drama.......In recent years Danish TV series have experienced a global export boom. This article maps the regional and global export patterns over the last fifteen years in order to assess the international impact of Danish TV drama....

Impact assessment of an off-shore wind park on sea ducks

International Nuclear Information System (INIS)

Guillemette, M.; Kyed Larsen, J.; Clausager, I.

1998-03-01

As part of the plan of the Danish government to expand off-shore wind energy production, The Ministry of Environment and Energy, in collaboration with ELSAM (an energy consortium), initiated a three-year study of the potential conflict between the Tunoe Knob off-shore wind park and aquatic birds in 1994-97. Danish coastal waters support very large, internationally important concentrations of moulting, migrating and wintering sea ducks which depend on shallow water areas as major feeding habitats. Denmark is committed, in relation to international conventions and EU directives, to protect and maintain these populations of aquatic birds and such shallow coastal areas are precisely the type of areas in which future wind parks are planned. Two general approaches were adopted for the investigation: the before-after-control-impact design (BACI) and After studies conducted around the wind park. The aim of the BACI studies was to compare bird abundance and distribution before and after the construction of the wind park and between the area presumably affected by the development and a control area. This was carried out on three spatial scales: (i) conducting aerial surveys in two large zones (about 5,000 ha), Tunoe Knob and Ringebjerg Sand, while controlling the total number of birds in Aarhus Bay (88,000 ha), (ii) conducting ground surveys of two areas of about 700-800 ha coverage at Tunoe Knob and Ringebjerg Sand, using the latter as a control area and (iii) within Tunoe using three sub areas (160-250 ha) as controls compared to the construction area. The after experiments were conducted around the wind park with the aim of controlling the confounding effect of food supply and to establish (a) the short-term possible effects of noise and rotor movements generated by the turbines on the distribution and abundance of sea ducks and (b) the long-term scaring effect of the wind park (the impact of revolving rotors and the presence of the standing towers). Finally, an

The economic value of accurate wind power forecasting to utilities

Energy Technology Data Exchange (ETDEWEB)

Watson, S J [Rutherford Appleton Lab., Oxfordshire (United Kingdom); Giebel, G; Joensen, A [Risoe National Lab., Dept. of Wind Energy and Atmospheric Physics, Roskilde (Denmark)

1999-03-01

With increasing penetrations of wind power, the need for accurate forecasting is becoming ever more important. Wind power is by its very nature intermittent. For utility schedulers this presents its own problems particularly when the penetration of wind power capacity in a grid reaches a significant level (>20%). However, using accurate forecasts of wind power at wind farm sites, schedulers are able to plan the operation of conventional power capacity to accommodate the fluctuating demands of consumers and wind farm output. The results of a study to assess the value of forecasting at several potential wind farm sites in the UK and in the US state of Iowa using the Reading University/Rutherford Appleton Laboratory National Grid Model (NGM) are presented. The results are assessed for different types of wind power forecasting, namely: persistence, optimised numerical weather prediction or perfect forecasting. In particular, it will shown how the NGM has been used to assess the value of numerical weather prediction forecasts from the Danish Meteorological Institute model, HIRLAM, and the US Nested Grid Model, which have been `site tailored` by the use of the linearized flow model WA{sup s}P and by various Model output Statistics (MOS) and autoregressive techniques. (au)

Danish Slaves in Barbary

DEFF Research Database (Denmark)

Madsen, Peter

2010-01-01

On a number of Danish (including Icelandic) 17th and 18th century autobiographical accounts of slavery in the Maghreb.......On a number of Danish (including Icelandic) 17th and 18th century autobiographical accounts of slavery in the Maghreb....

Aerodynamics of Wind Turbines

DEFF Research Database (Denmark)

Hansen, Martin Otto Laver

Aerodynamics of Wind Turbines is the established essential text for the fundamental solutions to efficient wind turbine design. Now in its second edition, it has been entirely updated and substantially extended to reflect advances in technology, research into rotor aerodynamics and the structural...... response of the wind turbine structure. Topics covered include increasing mass flow through the turbine, performance at low and high wind speeds, assessment of the extreme conditions under which the turbine will perform and the theory for calculating the lifetime of the turbine. The classical Blade Element...... Momentum method is also covered, as are eigenmodes and the dynamic behavior of a turbine. The new material includes a description of the effects of the dynamics and how this can be modeled in an aeroelastic code, which is widely used in the design and verification of modern wind turbines. Further...

Estimation of the high-spatial-resolution variability in extreme wind speeds for forestry applications

Directory of Open Access Journals (Sweden)

A. Venäläinen

2017-07-01

Full Text Available The bioeconomy has an increasing role to play in climate change mitigation and the sustainable development of national economies. In Finland, a forested country, over 50 % of the current bioeconomy relies on the sustainable management and utilization of forest resources. Wind storms are a major risk that forests are exposed to and high-spatial-resolution analysis of the most vulnerable locations can produce risk assessment of forest management planning. In this paper, we examine the feasibility of the wind multiplier approach for downscaling of maximum wind speed, using 20 m spatial resolution CORINE land-use dataset and high-resolution digital elevation data. A coarse spatial resolution estimate of the 10-year return level of maximum wind speed was obtained from the ERA-Interim reanalyzed data. Using a geospatial re-mapping technique the data were downscaled to 26 meteorological station locations to represent very diverse environments. Applying a comparison, we find that the downscaled 10-year return levels represent 66 % of the observed variation among the stations examined. In addition, the spatial variation in wind-multiplier-downscaled 10-year return level wind was compared with the WAsP model-simulated wind. The heterogeneous test area was situated in northern Finland, and it was found that the major features of the spatial variation were similar, but in some locations, there were relatively large differences. The results indicate that the wind multiplier method offers a pragmatic and computationally feasible tool for identifying at a high spatial resolution those locations with the highest forest wind damage risks. It can also be used to provide the necessary wind climate information for wind damage risk model calculations, thus making it possible to estimate the probability of predicted threshold wind speeds for wind damage and consequently the probability (and amount of wind damage for certain forest stand configurations.

Optimizing investments in coupled offshore wind -electrolytic hydrogen storage systems in Denmark

Science.gov (United States)

Hou, Peng; Enevoldsen, Peter; Eichman, Joshua; Hu, Weihao; Jacobson, Mark Z.; Chen, Zhe

2017-08-01

In response to electricity markets with growing levels of wind energy production and varying electricity prices, this research examines incentives for investments in integrated renewable energy power systems. A strategy for using optimization methods for a power system consisting of wind turbines, electrolyzers, and hydrogen fuel cells is explored. This research reveals the investment potential of coupling offshore wind farms with different hydrogen systems. The benefits in terms of a return on investment are demonstrated with data from the Danish electricity markets. This research also investigates the tradeoffs between selling the hydrogen directly to customers or using it as a storage medium to re-generate electricity at a time when it is more valuable. This research finds that the most beneficial configuration is to produce hydrogen at a time that complements the wind farm and sell the hydrogen directly to end users.

Improving genomic prediction for Danish Jersey using a joint Danish-US reference population

DEFF Research Database (Denmark)

Su, Guosheng; Nielsen, Ulrik Sander; Wiggans, G

Accuracy of genomic prediction depends on the information in the reference population. Achieving an adequate sized reference population is a challenge for genomic prediction in small cattle populations. One way to increase the size of reference population is to combine reference data from different...... populations. The objective of this study was to assess the gain of genomic prediction accuracy when including US Jersey bulls in the Danish Jersey reference population. The data included 1,262 Danish progeny-tested bulls and 1,157 US progeny-tested bulls. Genomic breeding values (GEBV) were predicted using...... a GBLUP model from the Danish reference population and the joint Danish-US reference population. The traits in the analysis were milk yield, fat yield, protein yield, fertility, mastitis, longevity, body conformation, feet & legs, and longevity. Eight of the nine traits benefitted from the inclusion of US...

When did the Danish nation emerge

DEFF Research Database (Denmark)

Brincker, Benedikte

2009-01-01

This article provides a review of the debate among Danish historians on the emergence of the Danish nation. It places this debate in the context of the distinction between patriotism and nationalism, much discussed by many scholars of nationalism.......This article provides a review of the debate among Danish historians on the emergence of the Danish nation. It places this debate in the context of the distinction between patriotism and nationalism, much discussed by many scholars of nationalism....

Wind Data Analysis and Wind Flow Simulation Over Large Areas

Directory of Open Access Journals (Sweden)

Terziev Angel

2014-03-01

Full Text Available Increasing the share of renewable energy sources is one of the core policies of the European Union. This is because of the fact that this energy is essential in reducing the greenhouse gas emissions and securing energy supplies. Currently, the share of wind energy from all renewable energy sources is relatively low. The choice of location for a certain wind farm installation strongly depends on the wind potential. Therefore the accurate assessment of wind potential is extremely important. In the present paper an analysis is made on the impact of significant possible parameters on the determination of wind energy potential for relatively large areas. In the analysis the type of measurements (short- and long-term on-site measurements, the type of instrumentation and the terrain roughness factor are considered. The study on the impact of turbulence on the wind flow distribution over complex terrain is presented, and it is based on the real on-site data collected by the meteorological tall towers installed in the northern part of Bulgaria. By means of CFD based software a wind map is developed for relatively large areas. Different turbulent models in numerical calculations were tested and recommendations for the usage of the specific models in flows modeling over complex terrains are presented. The role of each parameter in wind map development is made. Different approaches for determination of wind energy potential based on the preliminary developed wind map are presented.

The Danish Adoption Register

DEFF Research Database (Denmark)

Petersen, Liselotte; Sørensen, Thorkild I A

2011-01-01

The Danish Adoption Register was established in 1963-1964 to explore the genetic and environmental contribution to familial aggregation of schizophrenia.......The Danish Adoption Register was established in 1963-1964 to explore the genetic and environmental contribution to familial aggregation of schizophrenia....

Employees' perception on risk and risk management: evidence from Danish offshore wind industry

DEFF Research Database (Denmark)

Ahsan, Dewan

in a mismatch between the experiences acquired by the supporting companies and the expectations the clients. It has been perceived that complicated project manuals (because of special and increased requirements from the clients) sometimes create more risk exposures. The employees identified that demand from......Production of electricity from offshore wind energy is receiving much priority in several develop and developing countries. Nevertheless, this industry is becoming more expensive and challenging due to various operational and policy related risks factors. Therefore, the aim of this paper...... is to provide empirical insight into risks in offshore wind industry as perceived by the workers and managers. The survey has been conducted with the employees who are working in several offshore wind industries in Denmark. It has been revealed that there is a lack of common standard which is resulting...

近海风电机结构动力响应极值预报%Prediction of Structural Dynamic Response Extreme Values of Offshore Wind Turbine

Institute of Scientific and Technical Information of China (English)

王立夫

2017-01-01

鉴于国内外在预报风浪共同作用下近海风电机的极限结构动力响应方面仍然面临挑战的现状,提出用最小二乘法高效精确地求解广义柏拉图分布中的待定参数,预报某5 MW漂浮式风电机塔筒平台接合处的前后向弯矩极值,并用蒙特卡罗仿真和诊断图证明了最小二乘法与传统的矩方法相比的优越性.可为浮式海上风电机的结构设计提供参考.%Due to the fact that it is still a challenge at both home and abroad on how to predict the extreme structural dynamic responses of an offshore wind turbine under the con current action of wind and waves,the method of least squares is used to more efficiently and accurately estimate the unknown parameters in the Generalized Pareto distribution so that the extreme values of the fore-aft bending moments at the tower-Spar interface of a 5 MW floating wind turbine are predicted.Monte Carlo simulation and diagnostic plots are used to test the advantages of the method of least squares over the traditional method of moments.The new method proposed will become a powerful tool for the people in their structural design of a floating offshore wind turbine.

Prospects of the French offshore wind power market

International Nuclear Information System (INIS)

Anon.

2011-12-01

This market study about the French offshore wind power industry presents: 1 - the bases of the offshore wind power market: wind turbine operation principle, foundations and scale change; 2 - business model of offshore wind power projects: logistical, technical and financial challenges, cost structure and profitability of projects (investment, power generation costs, incentive mechanisms), project development time; 3 - European and French regulatory framework: the energy/climate package, the French 'Grenelle de l'Environnement' commitments for the development of renewable energies; 4 - start up of the French offshore wind power market: the onshore wind power market looking for growth relaying, the lateness of the offshore market, outlines of the call for bids and of the first phase launching (schedule, selected sites and candidates), market development stakes and opportunities; 5 - offshore wind power overview in Europe - lessons for the French market prospects: status of the European market (installed power/country, projects in progress), European leaders of the market (analysis of the British, Danish and German markets successful takeoff), specificities of the French market (are all favourable conditions present?); 6 - takeoff of the French market - what opportunities on the overall value chain?: front-end of the industry (manufacturers and component suppliers: industry structure, competition, R and D, subcontractors in France), back-end of the industry (developers/operators: sector analysis, ambitions, alliances, competences), specific French know-how in offshore installation and connection of wind turbines (reconversion of harbour areas, re-positioning of shipbuilding industry). (J.S.)

The Danish National Database for Asthma

DEFF Research Database (Denmark)

Hansen, Susanne; Hoffmann-Petersen, Benjamin; Sverrild, Asger

2016-01-01

in death only in extreme cases, the disease is associated with significant morbidity, reduced quality of life, increased absenteeism, and large costs for society. Asthma can be diagnosed based on report of characteristic symptoms and/or the use of several different diagnostic tests. However......, there is currently no gold standard for making a diagnosis, and some degree of misclassification and inter-observer variation can be expected. This may lead to local and regional differences in the treatment, monitoring, and follow-up of the patients. The Danish National Database for Asthma (DNDA) is slated...... control visits, appropriate pharmacological treatment, measurement of lung function, and asthma challenge testing; second, tools used for diagnosis in new cases; and third, annual assessment of smoking status, height, and weight measurements, and the proportion of patients with acute hospital treatment...

Analysis on the furthering of competition in relation to the establishment of large off-shore wind farms in Denmark. Main report; Analyse vedroerende fremme af konkurrence ved etablering af store havmoelleparker i Danmark. Hovedrapport

Energy Technology Data Exchange (ETDEWEB)

Joergensen, Carsten; Enevoldsen, M [Deloitte, Copenhagen (Denmark)

2011-04-15

The report, based on the 2010 tender for Anholt Offshore Wind Farm, is an analysis of how competition in the offshore wind power area can be increased, and a lower consumer price achieved. The study concludes that there is broad support for the Danish tender model among relevant parties, just as the process of working with Danish authorities and connecting to the power grid were viewed positively by potential investors in Danish offshore wind farms. But the report also found that inflexible guidelines in the Anholt Offshore Wind Farm tender contributed to a higher settlement price. One example singled out by the report was the threat of drastic fines and short deadlines. Moreover, the tender also occurred at a time when the production of wind turbines and foundations could not keep pace with increasing demand, particularly in Germany and the United Kingdom. Deloitte forecasts that the price for building and operating offshore wind farms, despite the increasing demand for offshore wind turbines, can be cut by between 25% and 30% by 2020, given the right framework guidelines and tender conditions. Applied to the planned Kriegers Flak Offshore Wind Farm, this calculation would result in a settlement price of between DKK 0.781 and DKK 0.979/kWh. The settlement price for Anholt Offshore Wind farm is currently DKK 1.051/kWh. The report recommends that the tender be altered to permit a greater dialogue with potential bidders, and to allow for information about the tenders to be spread internationally. Deloitte's report is based on interviews with individuals from a number of energy companies, investors, and public agencies, and takes into account other countries' experiences building offshore wind farms, as well as an evaluation of the competitive conditions within the offshore wind sector. (ENS)

Analysis on the furthering of competition in relation to the establishment of large off-shore wind farms in Denmark. Main report; Analyse vedroerende fremme af konkurrence ved etablering af store havmoelleparker i Danmark. Hovedrapport

Energy Technology Data Exchange (ETDEWEB)

Joergensen, Carsten; Enevoldsen, M. (Deloitte, Copenhagen (Denmark))

2011-04-15

The report, based on the 2010 tender for Anholt Offshore Wind Farm, is an analysis of how competition in the offshore wind power area can be increased, and a lower consumer price achieved. The study concludes that there is broad support for the Danish tender model among relevant parties, just as the process of working with Danish authorities and connecting to the power grid were viewed positively by potential investors in Danish offshore wind farms. But the report also found that inflexible guidelines in the Anholt Offshore Wind Farm tender contributed to a higher settlement price. One example singled out by the report was the threat of drastic fines and short deadlines. Moreover, the tender also occurred at a time when the production of wind turbines and foundations could not keep pace with increasing demand, particularly in Germany and the United Kingdom. Deloitte forecasts that the price for building and operating offshore wind farms, despite the increasing demand for offshore wind turbines, can be cut by between 25% and 30% by 2020, given the right framework guidelines and tender conditions. Applied to the planned Kriegers Flak Offshore Wind Farm, this calculation would result in a settlement price of between DKK 0.781 and DKK 0.979/kWh. The settlement price for Anholt Offshore Wind farm is currently DKK 1.051/kWh. The report recommends that the tender be altered to permit a greater dialogue with potential bidders, and to allow for information about the tenders to be spread internationally. Deloitte's report is based on interviews with individuals from a number of energy companies, investors, and public agencies, and takes into account other countries' experiences building offshore wind farms, as well as an evaluation of the competitive conditions within the offshore wind sector. (ENS)