Development of a measurement strategy and supervision of wind measurements
Development of a measurement strategy and supervision of wind measurements
Site: Medium size project in Tunisia, mountainous region
Scope: A local company was in charge of the installation and operation of met masts. The equipment had already been procured. aj was to
advise on number of masts
advise on measurement positions
check and document the masts independently
check the measured data continuously
assess the site conditions with respect to turbine specification
prepare wind resource and energy production assessments
Results:
Although the site itself was not very complex, the complex surroundings led to varying and hardly predictable wind flow conditions across the site. Namely, flow detachment was detected on one of the mast positions in an important wind direction.
The placement of the masts was first defined for an initial stage. Care had to be taken to avoid misleading results due to local features.
As some data of the first and second mast had come in, the remaining open questions regarding the wind flow and the most relevant contributions to the uncertainty could be addressed. One of the masts was relocated to cover these best possible.
The choice of the mast location not only addressed the needs of the wind resource assessment, but also of turbine specification.
It was found that some booms had not been mounted as predefined. The wind direction offsets were not correct. The mounting of the anemometers was such that the mast structure influenced the measured data significantly. Together with the installation team, changes of the boom orientations and lengths were agreed. An additional anemometer was mounted to help quantifying all impacts on the measurement and assessing the wind shear with confidence. Finally, sufficient quality and purposefulness of the measured data could be achieved.
It was found that cable ties had been used that were not UV resistant. They were replaced before any measurement cables could have broken.
A measurement documentation was prepared by aj that was able to satisfy the requirements of investors and turbine suppliers.
A wind resource assessment with good confidence and state of the art uncertainty could be prepared by aj based on the data.
In 2019, a wind measurement with a Sodar was completed successfully in the high mountains of Bosnia under winterly conditions. In 2019, a wind measurement with a Sodar was completed successfully in the high mountains of Bosnia under winterly conditions. In 2019, a wind measurement with a Sodar was completed successfully in the high mountains
In September 2019, aj develops a methodology to calibrate the wind flow calculation. This allows for adapting the local wind shear and the horizontal variation of the wind resource simultaneously. Thus, comparison turbines of very different placements and hub heights can be incorporated and uncertainties can be reduced significantly.
aj completes successfully a wind measurement with Sodar to assess the wind shear on a site in Marocco. aj completes successfully a wind measurement with Sodar to assess the wind shear on a site in Marocco.
Oldershausen, 15 May 2018: A new study of aj shows that the wind resource of the years around 1990 cannot be considered as very exceptional any more. Consequently, these years must be included in the long term reference period, if the result should be balanced. Download of the report Wind D NAO-Index E 15.05.2018 aj