TY - JOUR
T1 - Modelling turbulence intensity within a large offshore wind farm
AU - Argyle, Peter
AU - Watson, Simon
AU - Montavon, Christiane
AU - Jones, Ian
AU - Smith, Megan
PY - 2018
Y1 - 2018
N2 - The IEC standard 61400-1 edition 3 uses the so-called Frandsen model to assess levels of turbulence intensity (TI) within wind farms, specifically to determine turbine suitability associated with stress and fatigue. Since the Frandsen model was developed, turbines have significantly grown in size and the number of turbines in an individual wind farm has grown in number. It is of interest to test the accuracy of such models, especially when applied to large wind farms offshore. This work presents results from comparing the Frandsen model with measured data from the Greater Gabbard offshore wind farm. Comparisons are also made with a simplified version of the Frandsen model. In general, both models were shown to perform well when predicting values of TI. However, the ambient wind farm turbulence model utilised by the Frandsen model was shown to be less reliable than the use of an individual turbine wake-generated turbulence model, regardless of distance, as demonstrated using a simplified model. The difference between observed mean and 90th percentile (also known as representative TI) values was in general larger than that predicted. It is proposed that this is primarily due to model reliance on variance in the turbulence of the freestream flow rather than actually modelling the variance of the turbulence generated by individual turbines, although this would require further work to confirm this.
AB - The IEC standard 61400-1 edition 3 uses the so-called Frandsen model to assess levels of turbulence intensity (TI) within wind farms, specifically to determine turbine suitability associated with stress and fatigue. Since the Frandsen model was developed, turbines have significantly grown in size and the number of turbines in an individual wind farm has grown in number. It is of interest to test the accuracy of such models, especially when applied to large wind farms offshore. This work presents results from comparing the Frandsen model with measured data from the Greater Gabbard offshore wind farm. Comparisons are also made with a simplified version of the Frandsen model. In general, both models were shown to perform well when predicting values of TI. However, the ambient wind farm turbulence model utilised by the Frandsen model was shown to be less reliable than the use of an individual turbine wake-generated turbulence model, regardless of distance, as demonstrated using a simplified model. The difference between observed mean and 90th percentile (also known as representative TI) values was in general larger than that predicted. It is proposed that this is primarily due to model reliance on variance in the turbulence of the freestream flow rather than actually modelling the variance of the turbulence generated by individual turbines, although this would require further work to confirm this.
KW - Frandsen model
KW - Offshore wind farm
KW - Turbulence intensity
UR - http://www.scopus.com/inward/record.url?scp=85050824081&partnerID=8YFLogxK
UR - http://resolver.tudelft.nl/uuid:3f31bb67-ffe0-43b4-b041-e299bdcaac2d
U2 - 10.1002/we.2257
DO - 10.1002/we.2257
M3 - Article
AN - SCOPUS:85050824081
SN - 1095-4244
VL - 21
SP - 1329
EP - 1343
JO - Wind Energy
JF - Wind Energy
IS - 12
ER -