Large Eddy Simulation of an Onshore Wind Farm with the Actuator Line Model Including Wind Turbine’s Control below and above Rated Wind Speed

Abstract

As the size of wind turbines increases and their hub heights become higher, which partially explains the vertiginous increase of wind power worldwide in the last decade, the interaction of wind turbines with the atmospheric boundary layer (ABL) and between each other is becoming more complex. There are different approaches to model and compute the aerodynamic loads, and hence the power production, on wind turbines subject to ABL inflow conditions ranging from the classical Blade Element Momentum (BEM) method to Computational Fluid Dynamic (CFD) approaches. Also, modern multi-MW wind turbines have a torque controller and a collective pitch controller to manage power output, particularly in maximizing power production or when it is required to down-regulate their production. In this work the results of a validated numerical method, based on a Large Eddy Simulation-Actuator Line Model framework, was applied to simulate a real 7.7 MNW onshore wind farm on Uruguay under different wind conditions, and hence operational situations are shown with the aim to assess the capability of this approach to model actual wind farm dynamics. A description of the implementation of these controllers in the CFD solver Caffa3d, presenting the methodology applied to obtain the controller parameters, is included. For validation, the simulation results were compared with 1 Hz data obtained from the Supervisory Control and Data Acquisition System of the wind farm, focusing on the temporal evolution of the following variables: Wind velocity, rotor angular speed, pitch angle, and electric power. In addition to this, simulations applying active power control at the wind turbine level are presented under different de-rate signals, both constant and time-varying, and were subject to different wind speed profiles and wind directions where there was interaction between wind turbines and their wakes.

Large eddy simulation of an onshore wind farm under different operating regimes including topographic effects

“…LES-ALM simulations are performed with the open source finite volume code caffa3d [23,24], that has been validated for wind energy applications, for both wind tunnel and actual wind farm cases, [4,5,25], including the recently proposed limitation to the projection region of the aerodynamic forces [26]. A brief description of the numerical domain and numerical setup is given below.…”

“…High-fidelity simulations of actual wind farms with the Actuator Line Model (ALM) [1], in a Large Eddy Simulation (LES) framework, have been performed in the past years, for both onshore and offshore sites (see for instance [2,3,4,5]). It has become the state of the art to simulate the wind flow through wind turbines and wind farms and it could be a powerful tool to assess the operation of actual wind farms and potential improvements.…”

Assessment of a heterogeneous computing CFD code in wind farm simulations

“…The representation of wind tubrine generators in the computational domain is done using the Actuator Line Model (ALM) [6]. The implementation of the ALM in caffa3d code and its validation has been described in several works [11][12][13][14].…”

Power and Wind Shear Implications of Large Wind Turbine Scenarios in the US Central Plains

“…However, they are of limited value to characterize long-term wind speed profiles. High-fidelity Large Eddy Simulation models have been used to model the atmosphere and turbine response, but high computational demands limit these to short durations (minutes to hours) and domains of a few kilometers [43]. Thus, this investigation employs output from numerical modeling conducted using the Weather Research and Forecasting (WRF) model.…”