A control-oriented dynamic wind farm model: WFSim

Abstract

Wind turbines are often sited together in wind
farms as it is economically advantageous. Controlling the flow within
wind farms to reduce the fatigue loads, maximize energy production and
provide ancillary services is a challenging control problem due to the
underlying time-varying non-linear wake dynamics. In this paper, we
present a control-oriented dynamical wind farm model called the
WindFarmSimulator (WFSim) that can be used in closed-loop wind farm
control algorithms. The three-dimensional Navier–Stokes equations were
the starting point for deriving the control-oriented dynamic wind farm
model. Then, in order to reduce computational complexity, terms
involving the vertical dimension were either neglected or estimated in
order to partially compensate for neglecting the vertical dimension.
Sparsity of and structure in the system matrices make this model
relatively computationally inexpensive. We showed that by taking the
vertical dimension partially into account, the estimation of flow data
generated with a high-fidelity wind farm model is improved relative to
when the vertical dimension is completely neglected in WFSim. Moreover,
we showed that, for the study cases considered in this work, WFSim is
potentially fast enough to be used in an online closed-loop control
framework including model parameter updates. Finally we showed that the
proposed wind farm model is able to estimate flow and power signals
generated by two different 3-D high-fidelity wind farm models.