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This work is part of a demonstration project where iSpin spinner anemometer uncertainty components were analysed at sites categorized as flat and semi-complex, complex and offshore. The objective of the present work is to identify and quantify the relevant uncertainty components for: ��� Intra-turbine power curve measurements: for a single turbine and its own Spinner Transfer Function (STF); ��� Inter-turbine power curve measurements: when transferring an STF to another WTG in the same site or another site.

This paper exposes a method of modelling and analysis to help verifying design iterations of non-cylindrical shaped floating wind technologies. In order to do so, the Morison based quadratic hydrodynamic drag forcing contribution within the HAWC2-WAMIT coupled model, is modified to account for a panel-based input geometry. The implementation is applied to the P80 platform, and a verification of the hydrodynamic responses is performed. A reduced load case analysis is carried out, in which floating wind technologies can be assessed efficiently during early stage design iterations. The final platform assessment includes the wind and wave coupled effect using three load cases from IEC 61400-3 standards. The results of the simulations show that the chosen cases provide significant information relating to the platform motions and the tower top acceleration, in order to provide feedback for later design iterations of the platform.

The goal of this report is to summarize activities that took place in year 2016 as part of the Cross-Cutting Activity on Wind Turbine Noise, self-financed by DTU Wind Energy. A short description of the background behind this project (in particular Cross-Cutting Activities conducted in year 2015), the main objectives of the various studies and scientific achievements are reported in the introduction. Then, each Work Packages constituting this project are described in more details in the following sections.

The paper studies the applicability of the IEC 61400-1 ed.3, 2005 International Standard of wind turbine minimum design requirements in the case of an onshore Darrieus VAWT and compares the results of basic Design Load Cases (DLCs) with those of a 3-bladed HAWT. The study is based on aeroelastic computations using the HAWC2 aero-servo-elastic code A 2-bladed 5 MW VAWT rotor is used based on a modified version of the DeepWind rotor For the HAWT simulations the NREL 3-bladed 5 MW reference wind turbine model is utilized Various DLCs are examined including normal power production, emergency shut down and parked situations, from cut-in to cut-out and extreme wind conditions. The ultimate and 1 Hz equivalent fatigue loads of the blade root and turbine base bottom are extracted and compared in order to give an insight of the load levels between the two concepts. According to the analysis the IEC 61400-1 ed.3 can be used to a large extent with proper interpretation of the DLCs and choice of parameters such as the hub-height. In addition, the design drivers for the VAWT appear to differ from the ones of the HAWT. Normal operation results in the highest tower bottom and blade root loads for the VAWT, where parked under storm situation (DLC 6.2) and extreme operating gust (DLC 2.3) are more severe for the HAWT. Turbine base bottom and blade root edgewise fatigue loads are much higher for the VAWT compared to the HAWT. The interpretation and simulation of DLC 6.2 for the VAWT lead to blade instabilities, while extreme wind shear and extreme wind direction change are not critical in terms of loading of the VAWT structure. Finally, the extreme operating gust wind condition simulations revealed that the emerging loads depend on the combination of the rotor orientation and the time stamp that the frontal passage of gust goes through the rotor plane.

The EUDP‐2012 proposal, “Improved wind turbine efficiency using synchronizedsensors” is a project which focuses on improving the efficiency of energy production, primarily for wind turbines, but as a spinoff, also traditional powerplants. It builds on the experience and proven technology from three previouswind turbine projects: ‐ A wing mounted inflow sensor for wind turbines. Thissystem has gone through multiple stages of development, and will be greatlyenhanced by the synchronization technology from this project.

DeepWind has been presented as a novel floating offshore wind turbine concept with cost reduction potentials. Twelve international partners developed a Darrieus type floating turbine with new materials and technologies for deep-sea offshore environment. This paper summarizes results of the 5 MW DeepWind conceptual design. The concept was evaluated at the Hywind test site, described on its few components, in particular on the modified Troposkien blade shape and airfoil design. The feasibility of upscaling from 5 MW to 20 MW is discussed, taking into account the results from testing the Deepwind floating 1 kW demonstrator. The 5 MW simulation results, loading and performance are compared to the OC3-NREL 5 MW wind turbine. Finally the paper elaborates the conceptual design on cost modelling.

This paper presents the experiences and challenges with concurrently carrying out numerical model development, integrated simulations and design of a novel floating vertical axis wind turbine, the DeepWind concept. The floating VAWT modelling capabilities of the aero-hydro-elastic HAWC2 simulation tool are briefly described and the design approach adopted for such a challenging project was to independently design subsystems in parallel, apart from essential design specifications. Instability issues encountered when integrating all subsystems in the unified numerical model, in particular blade edgewise and controller instabilities, are presented and efforts to alleviate such issues are detailed. A multidisciplinary design and optimization approach is proposed to eliminate these issues and accelerate future design cycles.

The DeepWind concept has been described previously on challenges and potentials, this new offshore floating technology can offer to the wind industry [1]. The paper describes state of the art design improvements, new simulation results of the DeepWind floating vertical axis wind turbine concept, which implies a high potential for cost saving. The most critical aspects of the concept are addressed in proving feasibility, and if it can be scaled up to 20 MW. Applying structural mechanics, generator, floater & mooring system, control system design, and rotor design using detailed integrated models, results have evolved to a 5 MW baseline design. This important outcome will be used as a reference for further improvements. Emphasis in this paper is made on the interplay between different components and some trade-offs. One such example is the rotational speed which largely influences the design of both the generator and the aerodynamic rotor. Another example is aerofoil design affecting energy capture, stall behaviour, structural dynamics and control design. Finally, the potential for up-scaling to 20 MW is discussed.

The work describes is a revised work based on the Report RISOE-2614(EN)[1], which originally was carried out for Statoil. The company showed large interest in the VAWT technology for offshore application and expressed the concept of the creation of ideas within offshore (VAWT). Statoil provided the information as background material to DeepWind, a European funded project under FP7 Future Emerging Technologies 2020, and the material has been revised to take into some considerations of this work.

This paper presents a 1 kW generator and converter applied to a floating Darreius type wind turbine system. The completed system is floated in the sea with the generator 5m below the surface.The present paper sketches the design and presents the laboratory bench test results, as well as the environment where the turbine was placed.

This paper outlines results of a proposed layout of a light 2-bladed rotor, with a driving torque constraint matching the generator design, and shows details of the pultruded blade – and rotor geometry. In comparison with the 1st baseline design of a 5 MW VAWT concept this present development provides during standstill and operation significant less mass with a comparable level of loading strain in the blades and in the junctions between blade and tower. Optimized blade profile having a low weight and high stiffness is obtained according to the design evaluations based on the standstill calculations in ANSYS software. The selected profiles are used in the aero dynamic simulation. Furthermore the simulation code will be demonstrated to show the fully development model, integrating the simulation of turbulent wind inflow, actuator cylinder flow model, power controls, hydraulic floater - and mooring line systems implementation.

A modern wind turbine rotor with a contemporary rotor size would easily with the tips penetrate the air between 116 m and 30 m and herby experience effects of different wind. With current rules on power performance measurements such as IEC 61400-121 the reference wind speed is measured at hub height, an oversimplification of the wind energy power over the rotor disk area is carried out. The project comprised a number of innovative and coordinated measurements on a full scale turbine with remote sensing technology and simulations on a 500 kW wind turbine for the effects of wind field characterization. The objective with the present report is to give a short overview of the different experiments carried out and results obtained within the final phase of this project.

Autonomous Aerial Sensors, i.e. meteorological sensors mountedon Unmanned Aerial Systems UAS, can characterise theatmospheric flow in and around wind farms. We instrumented threeplanes, a helicopter and a lighter-than-air LTA system to fly oneweek together in a well-instrumented wind farm, partly with nanosynchronisedsensors (time stamped with about 100 ns globalaccuracy). Between bankruptcy of a partner, denied overflightrights at the main test location, denied Civil Aviation Authoritiespermits at the alternative location, stolen planes, and crashed UASwe managed to collect data at a wind farm in Lolland and on anatmospheric campaign in France. Planning of an offshore campaignusing the developed techniques is underway. Autonomous Aerial Sensors, i.e. meteorological sensors mounted on Unmanned Aerial Systems UAS, can characterise the atmospheric flow in and around wind farms. We instrumented three planes, a helicopter and a lighter-than-air LTA system to fly one week together in a well-instrumented wind farm, partly with nano-synchronised sensors (time stamped with about 100 ns global accuracy). Between bankruptcy of a partner, denied overflight rights at the main test location, denied Civil Aviation Authorities permits at the alternative location, stolen planes, and crashed UAS we managed to collect data at a wind farm in Lolland and on an atmospheric campaign in France. Planning of an offshore campaign using the developed techniques is underway.

The present report is the final effort of tasks carried out under UPWIND WP1B2 transmission and conversion, which describes: 1) results and recommendations developed in the course of developing the long-term load measurement technique 2) the hardware details, type of sensors and location, data storage and 3) data analysis technique to verify design load assumptions. The work is carried out under Contract no 019945 (SES6) "UPWIND" within the European Commission The interaction between the mechanical and electrical generator subsystems is described rudimentarily, based primarily on HAWC2 simulations below stall of the mechanical system with simple generator and gearbox systems. The electrical system simulations were not carried out as intended in DOW[2], but indications of the conditions for establishing the interaction have been described by measurements and by argument, that this might have an effect as indicated. The hypothesis stating, that the power signal can be utilized as a basic signal for extended analysis of mechanical as well as electrical power signal with static and dynamic features, has been demonstrated on performance and dynamic bandwidth capability. It is however from present analysis obvious that improved signal conditions could be achieved with other mechanical joint solutions than with the present torque signal as measured with the cardan joint. For the reasons mentioned, the comparison with a signal showing the mechanical properties could be improved, with a likely gain on the accuracy as a result.

An overview of wind related metrology research made at Risø DTU over the period of the UPWIND project is given. A main part of the overview is devoted to development of the Lidar technology with several sub-chapters considering different topics of the research. Technical problems are not rare for this new technology, and testing against a traditional met mast have shown to be efficient for gaining confidence with the ground based Lidar technology and for trust in accuracy of measurements. In principle, Lidar measurements could be traceable through the fundamental measurement principles, but at this stage of development it is not found feasible. Instead, traceability is secured through comparison with met masts that are traceable through wind tunnel calibrations of cup anemometers. The ground based Lidar measurement principle works almost acceptable in flat terrain. In complex terrain and close to woods the measurement volume is disturbed because the flow is no longer horizontally homogeneous. These conditions require special attention and correction methods. Due to the large measurement volume, ground based Lidars perform a spatial averaging which has the effect of a low pass filter on turbulence measurements. Theory and measurements seem to be in good agreement. Lidar measurements from a rotating spinner have been performed. The analysis show good perspectives for scanning the incoming wind, which may lead to better controlled wind turbines. Lidars have also been used to scan the wake of wind turbines. These measurements document the meandering wake pattern. The second part of the overview considers power performance measurements. A new investigation on the influence of wind shear points to a revision of the definition of a power curve. A new measurement method has been developed which has a good chance of being implemented in the present revision of the IEC performance standard. Also, a turbulence normalization method has been tested but not found efficient enough for inclusion in the IEC standard. In relation to the coming IEC standard on performance verification with the use of nacelle anemometry, IEC61400- 12-2-CD, nacelle anemometry has been studied, both with experiments and in theory. An alternative to nacelle anemometry has been developed, the socalled spinner anemometer. This type of sensor measures yaw-error with high absolute accuracy, and avoids the draw-backs of nacelle anemometry because the spinner anemometer is positioned in front of the rotor. Advances in classic mast measurement technologies have also been made. A mast flow distortion correction method has been developed to improve classical state of the art mast measurements. Finally, an optical method for measurements of turbine vibrations is considered.

In this report we investigate on wind direction dependent errors in the measurement of the horizontal wind speed by boom mounted cup anemometers. The boom mounting on the studied lattice tower is performed according to IEC standard design rules, yet, larger deviations than predicted by flow models are observed. The errors on the measurements are likely caused by an underestimation of the flow distortions around the tower. In this paper an experimental method for deriving a correction formula and an in-field calibration is suggested. The method is based on measurements with two cup anemometers mounted with booms at the same height but pointing in 60° different directions. In the examined case of a 1.9 m wide equilateral triangular lattice tower with booms protruding 4.1 m at 80 m height the measurement errors are observed to reach up to ± 2 %. Errors of this magnitude are severely problematic in the measurement of wind turbine power performance, wind resource assessment and for providing purposeful in-field comparisons between different sensors, e.g. lidar anemometers. With the proposed method, direction dependent errors can be extracted and the mast flow distortion effect on the wind measurements corrected to an uncertainty estimated to better than 0.5%. This level of uncertainty is probably acceptable for the above mentioned applications.

Aerodynamic simulations (HAWC2Aero) were used to investigate the influence of the speed shear, the direction shear and the turbulence intensity on the power output of a multi-megawatt turbine. First simulation cases with laminar flow and power law wind speed profiles were compared to the case of a uniform inflow. Secondly, a similar analysis was done for cases with direction shear. In each case, we derived a standard power curve (function of the wind speed at hub height) and power curves obtained with various definitions of equivalent wind speed in order to reduce the scatter due to shear. Thirdly, the variations of the power output and the power curve were analysed for various turbulence intensities. Furthermore, the equivalent speed method was successfully tested on a power curve resulting from simulations cases combining shear and turbulence. Finally, we roughly simulated the wind speed measurements we may get from a LIDAR mounted on the nacelle of the turbine (measuring upwind) and we investigated different ways of deriving an equivalent wind speed from such measurements.

This report describes the DAN-AERO MW experiments carried out within a collaborative, three years research project between Risø DTU and the industrial partners LM Glasfiber, Siemens Wind Power, Vestas Wind Systems A/S and the utility company DONG Energy. The main objective of the project was to establish an experimental data base which can provide new insight into a number of fundamental aerodynamic and aero-acoustic issues, important for the design and operation of MW size turbines. The most important issue is the difference between airfoil characteristics measured under 2D, steady conditions in a wind tunnel and the unsteady 3D flow conditions on a rotor. The different transition characteristics might explain some of the differences between the 2D and 3D airfoil data and the experiments have been set up to provide data on this subject. The overall experimental approach has been to carry out a number of coordinated, innovative measurements on full scale MW size rotors as well as on airfoils for MW size turbines in wind tunnels. Shear and turbulence inflow characteristics were measured on a Siemens 3.6 MW turbine with a five hole pitot tube. Pressure and turbulent inflow characteristics were measured on a 2MW NM80 turbine with an 80 m rotor. One of the LM38.8 m blades on the rotor was replaced with a new LM38.8 m blade where instruments for surface pressure measurements at four radial sections were build into the blade during the blade production process. Additionally, the outmost section on the blade was further instrumented with around 50 microphones for high frequency surface pressure measurements. The surface pressure measurements have been correlated with inflow measurements from four five hole pitot tubes and two sensors for measuring the high frequency (50 Hz to10 kHz) contents of the inflow turbulence. In parallel, 2D wind tunnel measurements on common airfoils for wind turbine applications have been conducted in three different wind tunnels at Delft University (NL), at LM Glasfiber (DK) and at VELUX (DK). Initial results from the different measurement set-ups are presented in order to show the application areas for the total data set.

The present report is the 12 month intermediate report of the UPWIND WP1B2 transmission and conversion describes the developed measurement technique for long-term load measurement technique, presents the hardware details, type of sensors and location, data storage and data analysis technique to verify design load assumptions.