Wind direction error in the Lillgrund offshore wind farm

The reduction of wake effects and maximisation of wind farm power output are always of interest to wind researchers [2][3]. However, one of the research challenges is to distinguish sensor errors from wake losses and losses due to poor yaw alignment. SCADA data from Lillgrund, the Swedish offshore wind farm, shows significant differences between the wind direction as measured at the met mast and as indicated by the nacelle directions measured at the individual wind turbines. Various possibilities might explain this data, the most likely being poor yaw control at particular wind turbines and/or sensor error. Both of these make power performance assessment and wake analysis problematic. In this paper, animations presented have been proved useful in the initial identification of turbines with potential problems. These anomalous turbines are then subject to a range of analyses designed to distinguish the different potential issues.