MAXFARM (MAXimizing wind Farm Aerodynamic Resource via advanced Modelling)
Lead Research Organisation:
University of Surrey
Department Name: Mechanical Engineering Sciences
Abstract
This is a multidisciplinary project that brings together researchers from different academic backgrounds in order to address reliability, lifetime and efficiency in offshore wind farms, and to meet the needs of the UK electricity generation industry. The overarching aim is the reduction of the (levelised) cost of generation of the large offshore wind farms that the UK will need in order to meet national and international objectives in the reduction of CO2 emissions. The multidisciplinary aspect reflects the different but, in context, linked disciplines and brings together the growing discipline of energy meteorology, of aerodynamics and aeroelasticity, of fatigue and structural mechanics, and of systems control. That is, the approach is a holistic one, linking the environmental conditions with their impact on each rotor and the mechanisms to improve farm performance as a whole.
The meteorological contribution is essential because of the range of wind flow conditions that exist, subjecting the turbines and - importantly for large wind farms - the wakes of the turbines to a range of unsteady conditions that are known to reduce wind farm efficiency, and to cause increased structural damage (when compared to small-scale onshore wind farms). Both these contribute to increased capital and operating costs. The energy potential for the UK from offshore wind is huge, but offshore wind energy is still at a relatively early stage in technological terms.
The aerodynamic response of each turbine to a variety of conditions imposed by the wind flow and the wakes of upstream turbines depends on the aeroelastic behaviour of the blades, the load in turn imposed upon the turbine generator, and the response by the turbine control system. In a large wind farm, the behaviour of one turbine - principally how much energy it is extracting from the wind flow - affects the behaviour, efficiency and lifetime of wind turbines in its wake; the turbines are not independent of each other. In fact, all aspects of the performance of wind turbines within large offshore wind farms, whether power output, loads or operations, are affected by their interaction through the wakes. Hence, to improve the cost effectiveness of offshore wind energy requires a better understanding of the flow-field through the wind farm. The project will address this issue and develop models to better represent the flow-field including the wakes and turbulence. Furthermore, capitalising on this, the implication for loads on the individual wind turbines will be investigated and the design of control strategies will be explored that achieve optimal operation of a large wind farm with each turbine controlled to keep operations and maintenance costs to acceptably low levels whilst (subject to this constraint) maximising farm output.
The meteorological contribution is essential because of the range of wind flow conditions that exist, subjecting the turbines and - importantly for large wind farms - the wakes of the turbines to a range of unsteady conditions that are known to reduce wind farm efficiency, and to cause increased structural damage (when compared to small-scale onshore wind farms). Both these contribute to increased capital and operating costs. The energy potential for the UK from offshore wind is huge, but offshore wind energy is still at a relatively early stage in technological terms.
The aerodynamic response of each turbine to a variety of conditions imposed by the wind flow and the wakes of upstream turbines depends on the aeroelastic behaviour of the blades, the load in turn imposed upon the turbine generator, and the response by the turbine control system. In a large wind farm, the behaviour of one turbine - principally how much energy it is extracting from the wind flow - affects the behaviour, efficiency and lifetime of wind turbines in its wake; the turbines are not independent of each other. In fact, all aspects of the performance of wind turbines within large offshore wind farms, whether power output, loads or operations, are affected by their interaction through the wakes. Hence, to improve the cost effectiveness of offshore wind energy requires a better understanding of the flow-field through the wind farm. The project will address this issue and develop models to better represent the flow-field including the wakes and turbulence. Furthermore, capitalising on this, the implication for loads on the individual wind turbines will be investigated and the design of control strategies will be explored that achieve optimal operation of a large wind farm with each turbine controlled to keep operations and maintenance costs to acceptably low levels whilst (subject to this constraint) maximising farm output.
Planned Impact
This project is about improving the efficiency and reliability of wind farms for national electricity generation, in particular the large offshore farms that the UK will need so as to reduce its dependency on fossil fuels. There are two aspects to this reduction. One is simply replacing fossil-fuel plant. The other is with how energy is used, more broadly, in the future. Reduction in demand through, for example, improved housing insulation will likely be more than offset by increased demand. A major increase will come from all-electric vehicles replacing conventional personal and public transport, the latter primarily coming from buses and rail electrification.
The research itself will be beneficial to wind farm developers and operators in achieving best economic performance. These assessments come from the developers and operators themselves, but crucially they also come from independent specialist consultancy companies providing software tools and due-diligence services. For a new wind farm these services - whether from the developer or independent assessor - need to provide accurate assessment of wind resource, how best to use this resource in terms of turbine size, control system type, number and layout of turbines, grid connection requirements etc., and how best to operate the turbines in order to keep maintenance costs acceptably low while obtaining output as high as possible in terms of power supplied to the grid at any one time and the overall energy generated, thereby maximizing return on investment. While tools and knowledge exist to a high level in UK, the knowledge gained from relatively new large (non-UK) offshore wind farms has shown substantial shortcomings in both understanding and capability of the tools. Offshore wind energy is still at a relatively early stage in technological terms.
The present proposal addresses wind resource, loads on turbines, in particular fatigue loads, and operating the turbines in an optimal manner so as to keep operations and maintenance cost as low as possible and the energy yield as high as possible, so that the life-time operation is optimized. One of the crucial issues in large farms comes from the wakes of turbines impinging on downwind turbines, but it is not economic to place the turbines far apart. Therefore, the wind farm has to be designed and operated so as to make the adverse consequences acceptably small. Existing wake modelling is known to be seriously deficient. In addition, existing tools do not adequately take into account the types of wind flow that in fact exists most of the time (of stable and convective wind flow). With the replacement of large conventional plant with offshore farms it is highly desirable that wind farms should be able to operate much as conventional plant. The fact that the wind resource is variable makes this not necessarily fully achievable. But, operating the turbines individually - subject to demand from the grid on the one hand and the impinging wind flow conditions on the other - in an overall supervisory control framework, will provide a better strategy than is available at present. This last, is an integrating aspect of this proposal.
The move towards substantial increase in offshore wind power will give the UK a leading role internationally in the design and operation of wind farms at a high technical skill level. Increased UK capability will make the UK a better-informed buyer for its own national needs as well as raising its own export-earnings market for low CO2 energy economies. Greater knowledge and improved capability of modelling tools will improve the economics of large offshore wind power through reducing the uncertainties in design and operation, and will assist policy makers. Increased use of wind power will also reduce dependency on imported (fossil-based) fuels, and the associated uncertainties in the global context in which those fuels are obtained.
The research itself will be beneficial to wind farm developers and operators in achieving best economic performance. These assessments come from the developers and operators themselves, but crucially they also come from independent specialist consultancy companies providing software tools and due-diligence services. For a new wind farm these services - whether from the developer or independent assessor - need to provide accurate assessment of wind resource, how best to use this resource in terms of turbine size, control system type, number and layout of turbines, grid connection requirements etc., and how best to operate the turbines in order to keep maintenance costs acceptably low while obtaining output as high as possible in terms of power supplied to the grid at any one time and the overall energy generated, thereby maximizing return on investment. While tools and knowledge exist to a high level in UK, the knowledge gained from relatively new large (non-UK) offshore wind farms has shown substantial shortcomings in both understanding and capability of the tools. Offshore wind energy is still at a relatively early stage in technological terms.
The present proposal addresses wind resource, loads on turbines, in particular fatigue loads, and operating the turbines in an optimal manner so as to keep operations and maintenance cost as low as possible and the energy yield as high as possible, so that the life-time operation is optimized. One of the crucial issues in large farms comes from the wakes of turbines impinging on downwind turbines, but it is not economic to place the turbines far apart. Therefore, the wind farm has to be designed and operated so as to make the adverse consequences acceptably small. Existing wake modelling is known to be seriously deficient. In addition, existing tools do not adequately take into account the types of wind flow that in fact exists most of the time (of stable and convective wind flow). With the replacement of large conventional plant with offshore farms it is highly desirable that wind farms should be able to operate much as conventional plant. The fact that the wind resource is variable makes this not necessarily fully achievable. But, operating the turbines individually - subject to demand from the grid on the one hand and the impinging wind flow conditions on the other - in an overall supervisory control framework, will provide a better strategy than is available at present. This last, is an integrating aspect of this proposal.
The move towards substantial increase in offshore wind power will give the UK a leading role internationally in the design and operation of wind farms at a high technical skill level. Increased UK capability will make the UK a better-informed buyer for its own national needs as well as raising its own export-earnings market for low CO2 energy economies. Greater knowledge and improved capability of modelling tools will improve the economics of large offshore wind power through reducing the uncertainties in design and operation, and will assist policy makers. Increased use of wind power will also reduce dependency on imported (fossil-based) fuels, and the associated uncertainties in the global context in which those fuels are obtained.
Organisations
- University of Surrey (Lead Research Organisation)
- Offshore Renewable Energy Catapult (Collaboration, Project Partner)
- DNV GL (United Kingdom) (Project Partner)
- Zenotech (United Kingdom) (Project Partner)
- BMT Group (United Kingdom) (Project Partner)
- Renewable Energy Systems (United Kingdom) (Project Partner)
- Satellite Applications Catapult (United Kingdom) (Project Partner)
- ZX Lidars (Zephir Ltd) (Project Partner)
- SgurrEnergy Ltd (Project Partner)
Publications
Argyle P
(2017)
Offshore Turbine Wake Power Losses: Is Turbine Separation Significant?
in Energy Procedia
Argylex P
(2015)
On the Effects of Directional Bin Size When Simulating Large Offshore Wind Farms with CFD
in Wind Engineering
Artola M
(2021)
Generalized Kelvin-Voigt Damping for Geometrically Nonlinear Beams
in AIAA Journal
Bao J
(2018)
Feedforward Control for Wind Turbine Load Reduction with Pseudo-LIDAR Measurement
in International Journal of Automation and Computing
Bao J
(2015)
Pseudo-LIDAR Data Analysis and Feed-forward Wind Turbine Control Design
in IFAC-PapersOnLine
Bosch J
(2017)
Temporally-explicit and spatially-resolved global onshore wind energy potentials
in Energy
Broughton-Venner J
(2018)
Aeroservoelastic Optimisation of Aerofoils with Compliant Flaps via Reparameterization and Variable Selection
in AIAA Journal
Colone L
(2017)
Optimisation of Data Acquisition in Wind Turbines with Data-Driven Conversion Functions for Sensor Measurements
in Energy Procedia
Del Carre A
(2019)
SHARPy: A dynamic aeroelastic simulation toolbox for very flexible aircraft and wind turbines
in Journal of Open Source Software
Del Carre A
(2019)
Efficient Time-Domain Simulations in Nonlinear Aeroelasticity
Desmond C
(2017)
Modelling the wind energy resource in complex terrain and atmospheres. Numerical simulation and wind tunnel investigation of non-neutral forest canopy flow
in Journal of Wind Engineering and Industrial Aerodynamics
Gonzalez-Salcedo A
(2017)
A Computationally-Efficient Panel Code for Unsteady Airfoil Modelling Including Dynamic Stall
Grams CM
(2017)
Balancing Europe's wind power output through spatial deployment informed by weather regimes.
in Nature climate change
Hancock P
(2020)
Wind-Tunnel Simulation of Stable Atmospheric Boundary Layers with an Overlying Inversion
in Boundary-Layer Meteorology
Hancock P
(2021)
Wind-Tunnel Simulation of Approximately Horizontally Homogeneous Stable Atmospheric Boundary Layers
in Boundary-Layer Meteorology
Hancock P
(2016)
Wind-tunnel simulation of stably stratified atmospheric boundary layers
in Journal of Physics: Conference Series
Hancock P E
(2021)
Wind-Tunnel Simulation of Approximately Horizontally Homogeneous Stable Atmospheric Boundary Layers
in Boundary-Layer Meteorology (Accepted, to appear.)
Hancock PE
(2018)
Wind-Tunnel Simulation of Weakly and Moderately Stable Atmospheric Boundary Layers.
in Boundary-layer meteorology
Hur S
(2015)
Adjustment of wind farm power output through flexible turbine operation using wind farm control
in Wind Energy
Hur S
(2016)
Collective control strategy for a cluster of stall-regulated offshore wind turbines
in Renewable Energy
Hur S
(2017)
Detection and compensation of anomalous conditions in a wind turbine
in Energy
Hur S
(2018)
Control Oriented Modelling of a Wind Turbine and Farm
in Journal of Physics: Conference Series
Hur S
(2016)
Model predictive and linear quadratic Gaussian control of a wind turbine
in Optimal Control Applications and Methods
Hussain R
(2017)
Modelling and Analysis of Aeroelastic Tailoring Blade Wind Turbine Systems
in IFAC-PapersOnLine
James S
(2017)
Using Sentinel-1 SAR satellites to map wind speed variation across offshore wind farm clusters
in Journal of Physics: Conference Series
Kazacoks R
(2019)
Effect of wind flow direction on the loads at wind farm
in Journal of Physics: Conference Series
Kazemi Amiri A
(2019)
Farm-wide assessment of wind turbine lifetime extension using detailed tower model and actual operational history
in Journal of Physics: Conference Series
Konstantelos I
(2017)
Integrated North Sea grids: The costs, the benefits and their distribution between countries
in Energy Policy
Maraniello S
(2019)
State-Space Realizations and Internal Balancing in Potential-Flow Aerodynamics with Arbitrary Kinematics
in AIAA Journal
Maraniello S
(2020)
Parametric Reduced-Order Modeling of the Unsteady Vortex-Lattice Method
in AIAA Journal
Maraniello S
(2018)
State space realisation and model reduction of potential-flow aerodynamics for HAWT applications
in Journal of Physics: Conference Series
Moreira A
(2018)
A Five-Level MILP Model for Flexible Transmission Network Planning Under Uncertainty: A Min-Max Regret Approach
in IEEE Transactions on Power Systems
Ng B
(2015)
Model-based aeroelastic analysis and blade load alleviation of offshore wind turbines
in International Journal of Control
Ng B
(2014)
Aeroservoelastic state-space vortex lattice modeling and load alleviation of wind turbine blades
in Wind Energy
Ng B
(2016)
Effects of leading-edge tubercles on wing flutter speeds
in Bioinspiration & Biomimetics
Ollier S
(2018)
Atmospheric gravity wave impacts on an offshore wind farm
in Journal of Physics: Conference Series
Palacios R
(2017)
Encyclopedia of Continuum Mechanics
| Description | The MAXFARM project was selected by EPSRC for part of its (case study) strategic review of wind energy research - Powering The Future: https://epsrc.ukri.org/newsevents/casestudies/powering-the-future-of-offshore-wind-farms/ As part of the Surrey contribution we have developed a globally unique capability for laboratory simulations of the lower part of the atmospheric wind - the atmospheric boundary layer (ABL) - suitable for wind turbine and farm studies, using the EnFlo stratified-flow wind tunnel, a NERC/NCAS national facility. Wind turbines operate only in the ABL, where the flow is non-uniform and mostly turbulent. The ABL states are very varied from strongly stable to strongly unstable (also called convective), primarily associated with night-time and daytime conditions, respectively, and have controlling influences on turbine loads and lifetime. In stable conditions, the ABL height can be less than the blade-tip top height, but very much greater (by order 10) in unstable conditions. Moreover, stability is mostly measured near the surface (the surface condition), but the temperature gradient - the inversion - above ABL is of vital significance in simulating the stable layer. (A neutral state is 'between' stable and unstable, and is widely assumed as standard in wind energy studies, but the state is mostly non-neutral. Only in a long-term average is it about neutral.) Prediction of blade loading and hence fatigue life of a machine, and optimised control, require short-period information in order to adequately capture the fluctuating conditions. We first needed to establish how to simulate various stable ABL states before addressing questions associated with turbines themselves; there was no 'off the shelf' prescription. It turned out that we had been lucky in our first study [1]. On the face of it, simulations should be relatively straightforward in that the (potential) temperature should simply increase with height. However, the presence of stability introduces its own difficulties. By contrast, unstable ABLs are much easier [3]. But, through progressing step-by-step, we have found out how to simulate a number of moderately stable states [5, 6, 7, 8, 9]. The difficulty in creating the simulations is connected with the very varied states that the stable ABL naturally exhibits. Also, any 'error' that arose in the initial conditions was very persistent, and complicated the picture. All this also opened up the question 'what is a typical stable ABL?'. In order to make progress, a systematic understanding was required, and developed, but developing the simulations took longer than was originally envisaged. Moreover, our involvement with the InnovateUK SWEPT2 project underlined the practical as well as fundamental importance of our work, with the result of a change of the focus to stable states alone. The simulations have also provided some meteorologically significant results in themselves, such as the degree of independence between surface condition and inversion strength [8], an increase in surface heat flux followed by a decrease as stability increases [6], and the degree to which the flow remains horizontally homogenous [9], horizontally homogeneity representing the relatively constant conditions external to a turbine wake. (More strongly stable cases are likely to be more challenging to simulate and more complex in nature.) The simulations required was guided partly by the work at Loughborough Univ (WP1), particularly the likely surface condition for offshore wind farms. Some progress has been made in the simulation of low-level (or nocturnal) jets. In our work in MAXFARM we concentrated on a single turbine in stable ABLs, in order to understand how the wake develops and interacts with the surrounding flow under a range of moderately stable conditions. Some preliminary results are given in [10, 11]. These experiments set out to understand (i) the effects of stability without and with an overlying inversion. (ii) the effects of change of ABL depth with stability. These have yet to be written up for journal publication. The results have shown that the wakes of wind turbines are both directly and indirectly affected by atmospheric stability. Both have implications for the loading on downwind turbines in a wind farm, in terms of design requirements and life maximization (Loads and Fatigue, WP3), and, in terms of wind farm operations, on short timescales (e.g 10 minute periods) for optimizing power and energy output against machine lifetime and operation and maintenance costs (Farm Control WP4). Towards the end of the project period work was started on developing the techniques in our experiments that will allow the observed effects of stability to be quantified for blade fatigue loading (with Imperial College and RAL, STFC) and farm and turbine control (with Strathclyde) in MAXFARM. This draws on two-point measurement capability developed in the project, together with the statistical method of Veers [12]. As noted in an international industry panel [15], turbine inflow and the influence of wakes from upstream wind turbines are controlling determinants, and the issues are expected to be even more critical as turbines become larger. Two further projects have been funded to take this work further: VESABL (SUPERGEN-Wind Flexible Funding) and VENTI (SUPERGEN ORE, Flexible Fund 1st Call). [1] Hancock, Pascheke Boundary-Layer Met. 151, 3 (2014) [2] Hancock, Pascheke Boundary-Layer Met. 151, 23 (2014) [3] Hancock, Zhang, Hayden Boundary-Layer Met. 149, 355 (2013) [4] Hancock, Zhang Boundary-Layer Met. 156, 395 (2015) [5] Hancock, Hayden, The Science of Making Torque from Wind, doi:10.1088/1742-6596/753/3/032012 (2016) [6] Hancock, Hayden Boundary-Layer Met. 168, 29 (2018) [7] Hancock, Hayden. 13th Conf on Wind Engineering, Univ of Leeds, 3-4th Sept 2018 [8] Hancock, Hayden. Wind-tunnel simulation of stable atmospheric boundary layers with an overlying inversion. Boundary-Layer Met.doi.org/10.1007/s10546-019-00496-7 (2020) [9] Hancock, Hayden. (2021) Wind-Tunnel Simulation of Approximately Horizontally-Homogeneous Stable Atmospheric Boundary Layers. Accepted, to appear. [10] Hancock, Hayden. Offshore Wind 2018, Bremerhaven, Germany, http://www.rave-offshore.de/en/conference.html [11] Placidia, Hancock and Farr. Blockage effects as inferred from measurements in the EnFlo stratified-flow wind tunnel. WESC 2019, 17th-20th June 2019, Cork https://doi.org/10.5281/zenodo.3360292 [12] Veers (1988). Three-Dimensional Wind Simulation (No. SAND88-0152/UC-261). Sandia Report. [13] Industry panel discussion, Offshore Wind 2018, Bremerhaven, Germany. [14] Marucci, Carpentieri, Hayden P 2018On the simulation of thick non-neutral boundary layers for urban studies in a wind tunnel. Int Jnl Heat and Fluid Flow. 72, 37-51 10.1016/j.ijheatfluidflow.2018.05.012 [15] Marucci, Carpentieri 2020 Dispersion in an array of buildings in stable and convective atmospheric conditions. Atmos Env 222, 117100 10.1016/j.atmosenv.2019.117100 Overviews of MAXFARM can be seen at the following sites. These are from the Wind Europe 2019 Supergen-Wind Showcase Side Event, Bilbao, and at the April 2017 General Assembly, Univ of Durham. https://www.supergen-wind.org.uk/files/WE/MAXFARM%20Bilbao%20Apr%202019.pdf (in https://www.supergen-wind.org.uk/research/windeurope) https://www.supergen-wind.org.uk/files/GA%20April2017/MAXFARM%20General%20Assembly%20Apr%202017%20-%20PH.pdf (in https://www.supergen-wind.org.uk/research/april-2017-general-assembly) An example of a presentation on the work at Surrey can be seen at https://www.rave-offshore.de/files/downloads/konferenz/konferenz-2018/Finale_Praesentationen/16316-min.pdf The work at Loughborough broadly comprised four parts: offshore wind resource; behaviour of typical current wind farms; investigation of improved farm configuration; the influence of short-time scale passing fronts or atmospheric gravity waves. Offshore wind measurements are scarce and expensive, and as part of the MAXFARM project, an evaluation has been made of the wind-flow parameters that most affect wind turbine performance and lifetime in the context of large offshore wind farms with specific emphasis is placed on the mean and distribution of wind speed and turbulence. Unlike most offshore resource assessment campaigns which use measurements from one point location to represent the conditions across a large farm, this work uses multiple data sources around the UK to provide insight into the variability of conditions around the UK. Multiple datasets were made available by The Crown Estate via the Marine Data Exchange from 12 meteorological masts and 3 Lidar instruments located offshore in UK waters, covering a wide range of dates from 1999 to 2015, varying in length and availability: Blyth, Celtic Array, Docking Shoal, Greater Gabbard (IGMMZ), Gunfleet Sands, Gwynt Y Mor, Humber Gateway, Inner Dowsing, Kentish Flats, London Array, Navitus Bay, Race Bank, Rampion, Shell Flats. Atmospheric stability has been calculated at 11 locations where temperature measurements were available at multiple heights, though due to the variations in instrumentation layouts between sites, multiple calculation methods are required and displaying some inherent discrepancies. Some datasets such as from Humber Gateway did not encompass an entire year and so caution needed to be applied to any time-based statistic as the wind resource varies with the seasons. Since there was no common time frame from which all locations report data, it was assumed that inter-annual variation was minimal for the purposes of comparison between sites. In addition, not all the same parameters were available for each dataset due to varying mast instrumentation or various amounts of filtering performed by the data owners before submitting it to The Marine Exchange. An example of this is the Navitus Bay Lidar dataset which for a short period contains values of 10 minute mean wind speed and direction up to 190m above sea level but supplies no data about the 10 minute standard deviation values, making the calculation of turbulence intensity impossible. The UK offshore wind resource is heavily affected by its global location both in terms of latitude due to the polar jet stream resulting in a south-westerly prevailing wind, and by the North Atlantic Ocean Gulf Stream which maintains warmer waters than usual for that latitude. The prevailing south-westerly wind is clearly seen across the collection of wind roses with variation due site location around the UK being minimal. The rose for the Blyth, though, appears offset by about 30 degrees. This is occurs throughout the dataset at all heights, and is perhaps because the proximity to shore (less than 2km) affecs the flow -also suggested by higher turbulence level. Pararametric studies of wind-turbine wake effects were made in a hypothetical offshore wind farm with varying turbine separation using a Computational Fluid Dynamics (CFD) model. Results were analyzed from a simulated 40 turbine farm with 60 layout options, 4 wind speeds and 10° directional bins. Results show that increasing turbine separation in one or both directions leads to greater power generation, though this effect diminishes for separations above 8 diameters. Similarly, turbulence intensity is shown to decrease with increases in turbine separation but with little variation beyond 8 diameters. For 3 out of 4 wind speeds when combined with a representative UK offshore wind rose the farm was shown to have an optimal layout orientation along an axis 350°-170°, though the difference in power produced between orientation angles was less than between changes in turbine separation. Atmospheric Gravity Waves (AGWs) frequently occur around near coastal offshore wind farms. They often result from displacement of flow by topographical obstacles in neutral or stable surface atmospheric conditions with a strong temperature inversion above the atmospheric boundary layer. They also form via jet stream turbulence, weather fronts, cold air outbreaks, polar lows and various other sources. AGWs are frequent in the offshore environment and influence the wind fields over large areas of the ocean. Stability effects can lead to an oscillation of this displaced flow, creating waves. Several studies have shown that wind farms can also cause AGWs. I work at Loughborough we have investigated the influence of pre-existing AGWs on individual turbines and whole wind farms, on or offshore. We have used a typical offshore wind farm downstream of a topographical obstacle, a coastal edge, to simulate the time-dependent impact of AGWs on the wind energy output. All the wind farms assessed in this research have frequent AGW events. Preliminary results based on a theoretical CFD model of Greater Gabbard [2] show that when the wind farm extent was contained within one wavelength of an AGW (about 5km), there was substantial variation in wind speed across the farm and associated power output (76% change) compared to control cases (29%). Further, unpublished results based on SCADA from UK wind farms and CFD support the preliminary theoretical findings; the impact of AGW on wind fields and subsequent power output is substantial and results in variation in wind speed and power between individual turbines within operational European wind farms. [1] DTU-WE, "ENVISAT and Sentinel 1 surface wind field processing." Danish Technical University (DTU) Department of Wind Energy, 2016. [2] S. J. Ollier, S. J. Watson, and C. Montavon, "Atmospheric gravity wave impacts on an offshore wind farm," IOP Conf. Ser. J. Phys., vol. 1037, 2018. Other features that have been investigated include roll-vortices and meso-scale gust fronts. Roll vortices are rotating motions where the axis of rotation is in the (broad) direction of the wind. They arise particularly downstream of a coastal edge. Meso-scale gust are gusts that are driven by large-scale motions in the atmosphere, but can be quite sharp in that they involve sharp changes over relatively small distances - comparable with the scale of a wind farm, and so lead to rapid variation of conditions across a farm. |
| Exploitation Route | It is expected the work will feed into industry standards such as DNV-GL's Bladed and WindFarmer software tools (e.g. through the SWEPT2 project), with implications of both improved design and improved operation of wind turbines and wind farms. Three database sets (A-C) have been created based on previous (Supergen) and new work at Surrey, and released to the SWEPT2 project. A forth set (D) will be developed in due course. These are as follows: A Stable ABL, and baseline neutral [1, 2] B Unstable ABL, and baseline neutral [3, 4] C Stable ABL, no overlying inversion, and baseline neutral [see 10, 11] D Stable ABL, with an overlying inversion, and baseline no inversion [see 10, 11] Some datasets have also been provided to TUDelft and Enercon, for example. The wind simulations techniques have been used as a basis for studies on the effect of atmospheric stability on the urban environment, and the movement of pollutants or hazardous substances [14, 15]. |
| Sectors | Energy,Environment |
| URL | https://www.supergen-wind.org.uk/ |
| Description | A major part of the activity during this project has been developing and improving techniques for the simulation of various atmospheric wind states that are relevant to wind power. (For example, night time winds are structurally mostly very different from daytime winds.) For the Surrey contribution, this turned out to be a substantially larger task than was originally envisaged based on our earlier work within earlier phases of Supergen, as there was an element of 'good luck' in the very few cases that we had investigated by that point. In addressing these issues we have made a substantial contribution to academic understanding, enhancing our globally leading capability of the Surrey EnFlo laboratory, both in regard to wind power, and spin-off into other areas, principally urban environment studies. (See for example, Marucci et al. 2018.) Our link with the industry-led (by DNV-GL) Innovate SWEPT2 project was particularly valuable in that the difficulties we were finding with the simulation of stable atmospheric winds reflected the difficulties they were having with modelling stable wind conditions. This meant that there was strong interaction between the two projects, and that there was a change of emphasis in the MAXFARM work at Surrey. The group at Imperial College was also involved with SWEPT2, concerned with the aeroelastic response to wind conditions and consequences for fatigue degradation of turbines. In due course this work, through knowing how turbine inflows can be more accurately modelled for a variety of wind conditions and the associated structural responses represented, will feed into a) improved turbine and wind farm design methods, b) improved wind farm operating procedures combined with short-period weather forecasting. All this will contribute to reduced capital and revenue costs, through increased reliability, of large-scale wind energy, and will come about through improved industrial tools and methods, such as the industry standards of DNV-GL. The meteorological data used in the Loughborough contribution to the project from The Marine Data Exchange was freely available without charge, though it is unsurprising that the quality of raw data available and the number of parameters varied significantly between individual datasets. Caution is highly recommended when processing the data. However, once the cleaned, the data shows surprisingly little variation exists between locations in UK waters. Most of the variation seen can in part be attributed to temporal variation and length in the datasets rather than location. More effort is needed to compare temporal/seasonal variation within the longer datasets than possibly between individual shorter datasets. With enough datasets from around the UK/North Sea region, it may be possible to build up an "expected" wind profile to test against current atmospheric boundary layer theory and provide a measure of confidence to developers about their future offshore wind resource before measurement campaigns begin. Atmospheric Gravity Waves (AGWs) often result from displacement of flow by topographical features in neutral or stable surface atmospheric conditions with a strong temperature inversion above the atmospheric boundary layer. AGW are frequent at European offshore wind farms, especially during winter. Considering their influence on offshore wind fields, AGW are likely to be important for offshore wind power, thus, this research investigates the influence of AGW on offshore wind farm power output. Preliminary results demonstrate that AGWs can have a substantial impact on the variation in wind speeds experienced across an offshore wind farm and the resulting power output potential of individual wind turbines within a farm. In an example, the AGW generation was 20km upstream of a supposed wind farm site. Despite this distance the influence was detected at the turbines and, moreover, enhanced by the effect of an upper-layer inversion to force strong AGWs. These results demonstrate that with the same apparent wind conditions, local conditions favouring AGW formation may lead to large deviations between the predicted and actual wind speed. Thus, power output from individual turbines and whole farms will vary significantly from predicted if these conditions are not accounted for. What is more, the structural fatigue loads would also be increased. This ongoing research combines the detection of real AGW events detected in Synthetic Aperture Radar (SAR) images processed for 10m wind fields [1] with SCADA data from European wind farms and Computational Fluid Dynamics(CFD) modelling of theoretical AGW events at Greater Gabbard [2], Anholt and Westermost Rough Wind Farms. |
| First Year Of Impact | 2017 |
| Sector | Energy,Environment |
| Impact Types | Societal,Economic |
| Description | (ConFlex) - Control of flexible structures and fluid-structure interactions |
| Amount | € 3,932,721 (EUR) |
| Funding ID | 765579 |
| Organisation | European Commission |
| Sector | Public |
| Country | European Union (EU) |
| Start | 10/2017 |
| End | 09/2021 |
| Description | EC ETN |
| Amount | € 273,000 (EUR) |
| Funding ID | EC H2020-MSCA-ITN-2017 |
| Organisation | European Commission H2020 |
| Sector | Public |
| Country | Belgium |
| Start | 10/2017 |
| End | 03/2021 |
| Description | EPSRC UK-China ORE |
| Amount | £812,415 (GBP) |
| Funding ID | EP/R007470/1 |
| Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
| Sector | Public |
| Country | United Kingdom |
| Start | 07/2017 |
| End | 06/2020 |
| Description | High-Performance Computing for Wind Energy (HPCWE) |
| Amount | € 1,995,651 (EUR) |
| Funding ID | 828799 1 995 651 |
| Organisation | European Commission H2020 |
| Sector | Public |
| Country | Belgium |
| Start | 06/2019 |
| End | 05/2021 |
| Description | Robust- and sustainable-by-design ultra-high aspect ratio wing and airframe (RHEA) |
| Amount | € 2,000,000 (EUR) |
| Funding ID | 883670 |
| Organisation | European Commission H2020 |
| Sector | Public |
| Country | Belgium |
| Start | 06/2020 |
| End | 05/2022 |
| Description | Veers' Extension to Non-neutral Incoming Winds (VENTI) |
| Amount | £93,865 (GBP) |
| Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
| Department | Supergen ORE Hub |
| Sector | Charity/Non Profit |
| Country | United Kingdom |
| Start | 01/2020 |
| End | 12/2020 |
| Description | Veers' method Extension to Stable Atmospheric Boundary Layers (VESABL) |
| Amount | £26,971 (GBP) |
| Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
| Sector | Public |
| Country | United Kingdom |
| Start | 04/2019 |
| End | 09/2019 |
| Description | Collaboration with ORE Catapult - offshore wind energy costs |
| Organisation | Offshore Renewable Energy Catapult |
| Country | United Kingdom |
| Sector | Charity/Non Profit |
| PI Contribution | Creation of a GIS software tool to estimate costs of offshore wind energy |
| Collaborator Contribution | Provision of cost data |
| Impact | Work in progress |
| Start Year | 2018 |
| Title | SHARPy: Simulation of High-Aspect-Ratio aircraft and wind turbines in Python |
| Description | Nonlinear and dynamically linearized models of very flexible aircraft dynamics for design, analysis, and control law synthesis. |
| Type Of Technology | Software |
| Year Produced | 2014 |
| Open Source License? | Yes |
| Impact | It has been used in the aerodynamic and structural design of Facebook's Aquila, Airbus's Zephyr and Astigan Ltd's solar-powered aircraft. |
| URL | http://www.imperial.ac.uk/aeroelastics/sharpy |
| Description | Mini-Symposium meeting at Wind Energy Science Conference, Cork, 2019 |
| Form Of Engagement Activity | A formal working group, expert panel or dialogue |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Industry/Business |
| Results and Impact | Industry invitation to Surrey team from special-interest group Mini Symposium at Wind Energy Science Conference (2019) to address the question of aerodynamic blockage in wind farms, arising from atmospheric stability and other influences. |
| Year(s) Of Engagement Activity | 2018,2019 |
| Description | SWEPT2 InnovateUK project |
| Form Of Engagement Activity | A formal working group, expert panel or dialogue |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Industry/Business |
| Results and Impact | DNVGL (formally Garrad Hassan and Partners Ltd) is the major internationally-recognised wind-energy consultancy company, and was an industry partner to the MAXFARM project (and also to the SUPETGEN-Wind HUB). MAXFARM was funded under the 2015 Grand Challenges call. The involvement with DNVGL through the SWEPT2 project very usefully added to the shaping of the MAXFARM project as it progressed, and led us to focus entirely on simulating stable winds (and reference neutral winds). Stable winds are particularly complex - and were found to be complex to simulate in the laboratory - and modelling of them has become of major interest to the industry. It is appropriate, therefore, to record this here. |
| Year(s) Of Engagement Activity | 2015,2016,2017,2018 |
| URL | https://gtr.ukri.org/projects?ref=102239 |
| Description | Wind Europe Side Event: Supergen Wind Hub. Wed 3rd April |
| Form Of Engagement Activity | Participation in an activity, workshop or similar |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Industry/Business |
| Results and Impact | Wind Europe is the major Europe-wide conference for the WInd Energy Sector. A Side Event programme was given by members of the SUPERGEN-Wind project, covering Theme 1 Planning & Consenting, "Wind energy: economic, social and environmental analysis" (Strathclyde) "MAXFARM (MAXimizing wind Farm Aerodynamic Resource via advanced Modelling)" (Surrey) Theme 2 Design, Manufacturing & Installation, "Servo-aeroelastic tailoring of wind turbines using new active-to-passive control systems" (Bristol) "Integrated Structural and Foundation Monitoring for Offshore Wind Turbines" (Oxford) Theme 3 Operation, Maintenance & Decommissioning, "Optical, Contactless Torque Measurement System /Turbine Generator Condition Monitoring/UK Wind Farm Operational Performance Analysis /Directory of UK based test and demonstration facilities for wind technologies" (Durham) "Offshore Renewables ACcess, Loss Estimation & Safety (ORACLES)" Strathclyde together with Overview of projects and linkages arising from Supergen Wind, Presentations on other projects and linkages (UK/China Joint Projects, AURA/Properity Partnerships). The purpose was to 'showcase' the results of the SUPERGEN-Wind project to this point. An outcome for the MAXFARM project was a new engagement with Enercon specifically focused on the atmospheric boundary layer simulation and the effect of atmospheric conditions on wind turbine wakes. A more detailed presentation was given to meteorology group at Enercon (Bremen) and further exchanges are taking place. |
| Year(s) Of Engagement Activity | 2019 |
| URL | https://www.supergen-wind.org.uk/news/2019/supergen-wind-side-event-at-windeurope-3-april-2019-bilba... |