PREVIENTO meets HORNS REV Short-Term Wind-Power Prediction - as well for Offshore Sites

摘要

Excellent offshore conditions with mean windspeeds of more than 9 m/s in 62m height as well as shortage of onshore-sites motivate the current wind farm intentions in the North Sea. It will become vitally important to know the offshore electricity production two days in advance: Liberalised electricity markets call for reliable wind power predictions because balancing power is expensive. Previento is a wind power prediction system providing the expected power output of wind farms up to 72 hours in advance and is in operational use for German onshore sites. It includes advanced regional upscaling and in addition to the prediction an estimate of the uncertainty of the actual forecast. For offshore sites, wind power prediction tools have to deal with the special meteorological conditions over the sea. Important effects are in particular thermal air-sea interaction, a dynamic roughness length of the sea surface and the influence of the land-sea-discontinuity. How good is the wind speed forecast offshore? We present first promising results of short term wind speed predictions for potential offshore sites in the North Sea. For verification, we used recent measurements from Horns Rev and synoptic met-masts. Because of the presented high accuracy of the offshore wind speed forecast, Previento will allow for an economic grid integration of future offshore wind farms. Surprisingly, measured westerly winds from the sea show a larger wind shear compared to the logarithmic profile, in all thermal conditions. This fact might be due to a decreased thickness of the atmospheric Prandtl Layer over the sea. Further analysis is required and in progress.