Posters

Abstract

Within RWE, post-construction assessments based on SCADA data are routinely performed on operating wind farms in order to: * Provide a more accurate and precise estimate of the wind farm net P50 than its respective pre-construction assessment[1]. * Inform the accuracy of pre-construction assessments based on meteorological data, through targeted deep dive assessments. * Uncover operational issues which may otherwise remain unnoticed. It is currently advised within the industry to gather two years of operational lifetime prior to performing a post-construction assessment. This is necessary so the operational period wind conditions are reflects the expected long-term wind conditions, as no wind direction correction step is performed in standard long-term correlation processes. To circumvent this wind distribution representativeness constraint, RWE developed a hybrid approach to its post-construction assessment workflow by incorporating a wind direction correction step. This wind direction step component consists in the application of power correction factors (on a wind speed and wind direction basis) based on Patterns of Production (PoP) estimated by turbine-interaction models. To assess the impact of this correction, RWE's in-house post construction assessment tool Clearwind was used with and without the PoP correction step on several RWE offshore wind farms. The sensitivity of several post-construction assessment Key Performance Indicators (KPIs) on the inclusion of the PoP correction step will be analysed, notably: * Correlation factor between the idealised production (e.g. actual production corrected for unavailability and curtailment periods) and estimated mesoscale production (e.g. estimated production from wind farm power curve and magnitude-corrected mesoscale wind speeds). The impact of the correlation factors on the overall estimated uncertainty will also be presented. * The gross* P50 (e.g. the pre-construction gross P50 including losses inherent to the SCADA data such as turbine-interaction losses, sub-optimal performance, performance degradation, inner- and outer-range underperformance). The attendees will observe how the use of the PoP correction step is found to have a beneficial impact on the abovementioned KPIs. Finally, the influence of different turbine-interaction models (EV-DAWM and RWE's proprietary VV model, amongst others) will be shown. [1] L. Vollmer, A. Oldroyd, W. Langreder, H.S. Pedersen, 'WP3 Report : Best Practice Guidelines for comparing pre- and post-construction wind farm yield assessment', dated 12 May 2021.