Vertical wind profile characterization and identification of patterns based on a shape clustering algorithm

Wind power plants are becoming a generally accepted resource in the generation mix of many utilities. At the same time, the size and the power rating of individual wind turbines have increased considerably. Under these circumstances, the sector is increasingly demanding an accurate characterization of vertical wind speed profiles to estimate properly the incoming wind speed at the rotor swept area and, consequently, assess the potential for a wind power plant site. The present paper describes a shape-based clustering characterization and visualization of real vertical wind speed data. The proposed solution allows us to identify the most likely vertical wind speed patterns for a specific location based on real wind speed measurements. Moreover, this clustering approach also provides characterization and classification of such vertical wind profiles. This solution is highly suitable for a large amount of data collected by remote sensing equipment, where wind speed values at different heights within the rotor swept area are available for subsequent analysis. The methodology is based on z-normalization, shape-based distance metric solution and the Ward-hierarchical clustering method. Real vertical wind speed profile data corresponding to a Spanish wind power plant and collected by using a commercialWindcube equipment during several months are used to assess the proposed characterization and clustering process, involving more than 100000 wind speed data values. All analyses have been implemented using open-source R-software. From the results, at least four different vertical wind speed patterns are identified to characterize properly over 90% of the collected wind speed data along the day. Therefore, alternative analytical function criteria should be subsequently proposed for vertical wind speed characterization purposes.The authors are grateful for the financial support from the Spanish Ministry of the Economy and Competitiveness and the European Union —ENE2016-78214-C2-2-R—and the Spanish Education, Culture and Sport Ministry —FPU16/042

Remote sensing winds in complex terrain : a review

Ground-based remote sensing is now essential for wind energy purposes. Currently available remote sensing instruments construct a wind vector from wind components measured at several spatially separated volumes, leading to errors on complex terrain where the flow is inhomogeneous. Wind estimation errors are found to be fully described by only two parameters: the flow curvature and flow inclination above the instrument. However, neither parameter is measured directly, nor are they simple products of flow models, so the challenge is to adequately estimate them. Linearized flow models are attractive in being fast and requiring few inputs, but make several limiting assumptions that can lead to their failure to adequately predict corrections for remote sensing. It is found that sophisticated CFD models can also over-correct. The status of such corrections is reviewed here, from a number of diverse measurement campaigns, and it is found that generally remote sensed winds can be corrected to within 1.5% of nearby mast winds. Alternative methods, using multiple receivers sensing several wind components within one volume, are also reviewed. Such systems show promise but are under development and further improvements are likely

Validation of measurements from a ZephIR Lidar

Historically wind speed measurements for wind resource assessment have been made using tall meteorological masts. The development of remote sensing techniques, in particular Doppler lidar (light detection and ranging) now enables these measurements to be made from the ground, without the costs of erecting a met mast. This work compares measurements from a ZephIR 300 continuous wave lidar against measurements from an IEC compliant 91m mast, concluding the lidar data to be at least as good as the mast data and with a higher availability rate

Accurate monitoring and fault detection in wind measuring devices through wireless sensor networks

Many wind energy projects report poor performance as low as 60% of the predicted performance. The reason for this is poor resource assessment and the use of new untested technologies and systems in remote locations. Predictions about the potential of an area for wind energy projects (through simulated models) may vary from the actual potential of the area. Hence, introducing accurate site assessment techniques will lead to accurate predictions of energy production from a particular area. We solve this problem by installing a Wireless Sensor Network (WSN) to periodically analyze the data from anemometers installed in that area. After comparative analysis of the acquired data, the anemometers transmit their readings through a WSN to the sink node for analysis. The sink node uses an iterative algorithm which sequentially detects any faulty anemometer and passes the details of the fault to the central system or main station. We apply the proposed technique in simulation as well as in practical implementation and study its accuracy by comparing the simulation results with experimental results to analyze the variation in the results obtained from both simulation model and implemented model. Simulation results show that the algorithm indicates faulty anemometers with high accuracy and low false alarm rate when as many as 25% of the anemometers become faulty. Experimental analysis shows that anemometers incorporating this solution are better assessed and performance level of implemented projects is increased above 86% of the simulated models

Estimation of the motion-induced horizontal-wind-speed standard deviation in an offshore doppler lidar

This work presents a new methodology to estimate the motion-induced standard deviation and related turbulence intensity on the retrieved horizontal wind speed by means of the velocity-azimuth-display algorithm applied to the conical scanning pattern of a floating Doppler lidar. The method considers a ZephIR™300 continuous-wave focusable Doppler lidar and does not require access to individual line-of-sight radial-wind information along the scanning pattern. The method combines a software-based velocity-azimuth-display and motion simulator and a statistical recursive procedure to estimate the horizontal wind speed standard deviation—as a well as the turbulence intensity—due to floating lidar buoy motion. The motion-induced error is estimated from the simulator’s side by using basic motional parameters, namely, roll/pitch angular amplitude and period of the floating lidar buoy, as well as reference wind speed and direction measurements at the study height. The impact of buoy motion on the retrieved wind speed and related standard deviation is compared against a reference sonic anemometer and a reference fixed lidar over a 60-day period at the IJmuiden test site (the Netherlands). Individual case examples and an analysis of the overall campaign are presented. After the correction, the mean deviation in the horizontal wind speed standard deviation between the reference and the floating lidar was improved by about 70%, from 0.14 m/s (uncorrected) to -0.04 m/s (corrected), which makes evident the goodness of the method. Equivalently, the error on the estimated turbulence intensity (3–20 m/s range) reduced from 38% (uncorrected) to 4% (corrected).Peer ReviewedPostprint (published version

Studies on cup anemometer performances carried out at IDR/UPM Institute. Past and present research

In the present work, the research derived from a wide experience on cup anemometer calibration works at IDR/UPM Institute (Instituto Universitario de microgravedad “Ignacio Da Riva”)is summarized. This research started in 2008, analyzing large series of calibrations, and is focused on two main aspects: (1) developing a procedure to predict the degradation level of these wind sensors when working on the field and (2) modeling cup anemometer performances. The wear and tear level of this sensor is evaluated studying the output signal and its main frequencies through Fourier analysis. The modeling of the cup anemometer performances is carried out analyzing first the cup aerodynamics. As a result of this process, carried out through several testing and analytical studies since 2010, a new analytical method has been developed. This methodology might represent an alternative to the classic approach used in the present standards of practice such as IEC 64000-12

Wind resource assessment systems: review of new solutions based on laser technology

[SPA] El potencial eólico de una localización geográfica está directamente relacionado con los perfiles de viento existentes en la misma. Su aprovechamiento está determinado por la curva de potencia del aerogenerador, la cual relaciona la velocidad de viento incidente sobre el rotor eólico con la potencia generada por el aerogeneradoro Según la Norma Internacional vigente relativa al cálculo de la curva de potencia de aerogeneradores, la velocidad del viento a la altura del buje es el parámetro principal de entrada para la caracterización de dicha curva, junto al parámetro de densidad del aire como factor secundario. La afirmación anterior supone que la velocidad del viento es constante en toda el área barrida del rotor eólico, Cuando se trata de aerogeneradores de pequeño tamaño, dicha suposición se puede acercar con cierto grado de exactitud a la realidad, pero en los aerogeneradores actuales dotados de grandes diámetros conduce a errores significativos, ya que la velocidad de viento varía considerablemente a lo largo del área barrida por el rotor; además, es importante mencionar que, en breve, se producirá la reforma de la Normativa anterior, en la que se empezará a tener en cuenta mayor número de medidas dentro del rotor. El presente artículo analiza las nuevas técnicas de medición de la velocidad y dirección del viento basadas en tecnología remota: SODAR y LIDAR, Estas soluciones permiten obtener perfiles de viento dentro de un amplio rango de alturas, lo clIal supone clara mejora en comparación con los sistemas convencionales.[ENG] The available wind speed potential strongly depends on the existing wind profi les at different locations. In this way, the exploitation of this resource can be determined by the wind turbine power curve, relating both wind speed at the rotor hub and electric power from the wind turbine. According to the current international Standard for power performance, the wind speed at hub height is the main input parameter for the characterization of the power curve, being considered the air density as a secondary factor. Under this framework, the wind speed is considered as constant over the whole turbine swept rotor area. This assumption can achieve high level of accuracy for small wind turbines. However, current wind turbines are characterized by a large rotor diameter, being exposed to remarkable variations in wind speed with height. Moreover, this Standard will be modifi ed in a short-term, with the aim of taking into account several wind measurements within the swept rotor area. This paper reviews recent solutions to measure wind speed and direction based on remote sensing systems: SODAR and LIDAR technology. These systems are able to collect vertical wind profi les over a wide range of heights, providing a signifi cant advantage in comparison with conventional approaches.Este trabajo ha sido financiado por el Ministerio de Ciencia e Innovación (ENE2009-13106) y por la Junta de Comunidades de Castilla-La Mancha (PEII10-0171-1803), ambos cofinanciados con fondos FEDER

Wind Energy Consultancies in Finland

This research paper studies the consulting market for the Finnish wind energy industry and the consulting services available for wind project developers in Finland. Since there were no previous studies conducted on the subject, there was a need for a research where the Finnish consulting services are mapped out. The theoretical framework for this study discusses the current state of the Finnish wind energy industry in general and in comparison to the rest of the European Union, production of wind power and the key players in the market. The process of planning and implementing a wind project is explained throughout, and issues that often require expertise from external consultancies are pointed out. The theory also explains briefly what consultancies are, what they do and what guidelines they follow in their operations. The study was conducted using a questionnaire that was sent to eight consultancy companies operating in Finland. The survey contained questions about the services that the companies provide, wind energy assessment methods as well as the competitive situation in the Finnish consulting market. The views of the respondents are reported and discussed in the analysis section of the research paper. The results of the study show that although foreign consultancies entering the Finnish wind energy market are generally more experienced, Finnish consultancies are catching up with their foreign counterparts in terms of expertise and experience. The main strengths of the Finnish consultancies are knowledge of the local weather conditions, regulations and processes. Although the new national wind targets have not yet been set, the respondents believe that the demand for wind consulting will continue to grow.Tämä opinnäytetyö tutkii Suomen tuulivoimakonsultointimarkkinoita ja tuulivoimahankkeiden kehittäjille tarjolla olevia konsulttipalveluita. Aiheesta ei ole tehty aikaisempaa tutkimusta ja tavoitteena oli tutkimus, jossa Suomen tuulivoimakonsultointipalvelut ovat kartoitettu. Opinnäytetyön teoria käsittelee Suomen tuulivoimasektorin nykytilaa yleisellä tasolla sekä verrattuna Euroopan unioniin, kuinka tuulivoimaa tuotetaan sekä tuulivoimaprojektien tyypillisiä osapuolia. Teoria selittää tuulivoimahankkeiden läpiviennin eri vaiheet sekä osiot, jotka tyypillisesti teetetään konsulttiyrityksillä. Konsulttitoiminnan yleiset sopimusehdot sekä suomalaisen konsulttitoiminnan nykytila käydään läpi lyhyesti. Tutkimus toteutettiin elektronisen kyselylomakkeen avulla. Kysely lähetettiin kahdeksalle Suomessa toimivalle konsultointiyritykselle.. Kysymykset jaoteltiin kolmeen osa-alueeseen; yritysten taustatietoihin ja palveluihin, tuulimittausten toteutukseen sekä yritysten arvioihin tuulivoimakonsultoinnin kilpailutilanteesta Suomessa. Tulokset osoittavat, että vaikka ulkomaiset konsulttiyritykset ovat suurilta osin suomalaisia konsulttiyrityksiä kokeneempia, on suomalaisten yritysten toiminta laadultaan pääosin samalla tasolla. Kotimaisten konsulttiyritysten vahvuuksia ovat paikallisten tuuliolosuhteiden, lakien ja toimintatapojen tuntemus. Vaikka Suomen tulevaisuuden tuulivoimatavoitteet ovat yhä epäselviä, uskovat vastaajat tuulivoimakonsultoinnin kysynnän jatkavan kasvuaan