Control co-design of a large offshore wind farm considering the effect of wind extractability

Abstract

Abstract We present a prototype of a novel control co-design (CCD) method for large offshore wind farms. A traditional wind farm internal flow model using a Gaussian wake model and a Boolean yaw optimisation method is coupled, via the two-scale momentum theory, with an analytical model of ‘wind extractability’, to account for the farm-scale blockage effect that depends on the farm size and atmospheric boundary layer height. We also introduce a ‘gridded’ turbine layout optimisation into the CCD, which allows us to quickly find optimal angles of the primary axes of a regular turbine array to maximise the annual energy production (AEP) of a given number of turbines at a given offshore farm site. The developed CCD method is used to demonstrate an important trade-off between the minimum number of turbines and minimum farm area required to achieve a certain AEP at the Seagreen offshore farm site as an example. Our results also suggest that the yaw optimisation could help reduce the number of turbines required, but only when we aim to achieve a high AEP with a small farm area. The developed model could be further coupled with a financial model of wind farms in future studies.