Pieter Gebraad

Pieter Gebraad
Siemens Gamesa Renewable Energy

PhD, dr. ir.

About

33
Publications
12,400
Reads
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2,475
Citations
Additional affiliations
November 2015 - February 2016
National Renewable Energy Laboratory
Position
  • PostDoc Position
November 2010 - October 2014
Delft University of Technology
Position
  • PhD Student

Publications

Publications (33)
Preprint
Full-text available
Wind farm control has been a topic of research for more than two decades. It has been identified as a core component of grand challenges in wind energy science to support accelerated wind energy deployment and transition to a clean and sustainable energy system for the 21st century. The prospect of collective control of wind turbines in an array to...
Article
The FLORIS (FLOw Redirection and Induction in Steady-state) model, a parametric wind turbine wake model that predicts steady-state wake characteristics based on wind turbine position and yaw angle, was developed for optimization of control settings and turbine locations. This article provides details on changes made to the FLORIS model to make the...
Article
Full-text available
In this paper, we present and extend the dynamic medium fidelity control-oriented Wind Farm Simulator (WFSim) model. WFSim resolves flow fields in wind farms in a horizontal, two dimensional plane. It is based on the spatially and temporally discretised two dimensional Navier-Stokes equations and the continuity equation and solves for a predefined...
Chapter
The industry’s primary goal for state-of-the-art wind turbine controllers is to maximise the energy capture while keeping the turbine within its operational limits, such as maximum rotor speed or maximum power, which is limited by the generator capacity. To guarantee a reliable operation over the turbine’s lifetime, the structural loads need to be...
Article
Full-text available
This paper describes a detailed field-test campaign to investigate yaw-based wake steering. In yaw-based wake steering, an upstream turbine intentionally misaligns its yaw with respect to the inflow to deflect its wake away from a downstream turbine, with the goal of increasing total power production. In the first phase, a nacelle-mounted scanning...
Article
Full-text available
Atmospheric stability conditions have an effect on wind turbine wakes. This is an important factor in wind farms in which the wake properties affect the performance of downstream turbines. In the stable atmosphere, wind direction shear has a lateral skewing effect on the wakes. In this paper, we describe changes to the FLOw Redirection and Inductio...
Article
Full-text available
The European Academy of Wind Energy (eawe), representing universities and institutes with a significant wind energy programme in 14 countries, has discussed the long-term research challenges in wind energy. In contrast to research agendas addressing short- to medium-term research activities, this eawe document takes a longer-term perspective, addre...
Article
This paper presents a wind plant modeling and optimization tool that enables the maximization of wind plant annual energy production (AEP) using yaw-based wake steering control and layout changes. The tool is an extension of a wake engineering model describing the steady-state effects of yaw on wake velocity profiles and power productions of wind t...
Article
Wind turbines are typically operated to maximize their performance without considering the impact of wake effects on nearby turbines. Wind plant control concepts aim to increase overall wind plant performance by coordinating the operation of the turbines. This paper focuses on axial-induction-based wind plant control techniques, in which the genera...
Conference Paper
In recent research, cooperative wind turbine control strategies have been proposed to optimize overall performance of wind plants by taking into account the aerodynamic interaction effects that the wind turbines have on each other through their wakes. Wind plant control strategies have different ways of using the control degrees of freedom (DOFs) o...
Article
Recent research has demonstrated exciting potential for wind plant control systems to improve the cost of energy of wind plants. Wind plant controls seek to improve global wind plant performance over control systems in which each turbine optimizes only its individual performance by accounting for the way wind turbines interact through their wakes....
Article
This article presents a wind plant control strategy that optimizes the yaw settings of wind turbines for improved energy production of the whole wind plant by taking into account wake effects. The optimization controller is based on a novel internal parametric model for wake effects called the FLOw Redirection and Induction in Steady-state (FLORIS)...
Article
Full-text available
Wind turbines arranged in a wind plant impact each other through their wakes. Wind plant control is an active research field that attempts to improve wind plant performance by coordinating control of individual turbines to take into account these turbine–wake interactions.In this paper, high-fidelity simulations of a two-turbine fully waked scenari...
Article
Full-text available
In this paper, we present a novel control-oriented model for predicting wake effects in wind plants, called the FLOw Redirection and Induction Dynamics (FLORIDYN) model. The model predicts the wake locations and the effective flow velocities at each turbine, and the resulting turbine electrical energy productions, as a function of the control degre...
Article
Full-text available
Several sources of error exist in lidar measurements for feedforward control of wind turbines including the ability to detect only radial velocities, spatial averaging, and wind evolution. This paper investigates another potential source of error: the upstream induction zone. The induction zone can directly affect lidar measurements and presents an...
Conference Paper
This paper presents a novel parametric model that will be used to optimize the yaw settings of wind turbines in a wind plant for improved electrical energy production of the whole wind plant. The model predicts the effective steady-state flow velocities at each turbine, as well as the resulting electrical energy productions, as a function of the ax...
Conference Paper
Recently there has been interest in the design of wind farm control systems that can coordinate individual turbine controllers to improve global plant performance. This improvement comes from accounting for the way in which turbines interact through wakes. Often however, controllers are designed assuming steady and known environmental conditions, w...
Conference Paper
Wind turbines are typically operated to maximize their own performance without considering the impact of wake effects on nearby turbines. There is the potential to increase total power and reduce structural loads by properly coordinating the individual turbines in a wind farm. The effective design and analysis of such coordinated controllers requir...
Article
This paper presents a data-driven adaptive scheme to adjust the control settings of each wind turbine in a wind farm such that an increase in the total power production of the wind farm is achieved. This is carried out by taking into account the interaction between the turbines through wake effects. The optimization scheme is designed in such a way...
Article
This brief presents an identification experiment performed on the coupled dynamics of the edgewise bending vibrations of the rotor blades and the in-plane motion of the drivetrain of three-bladed wind turbines. These dynamics vary with rotor speed, and are subject to periodic wind flow disturbances. This brief demonstrates that this time-varying be...
Conference Paper
By extracting kinetic energy from the wind flow, a wind turbine reduces the wind speed in the wake downstream of the wind turbine rotor. In a wind power plant, this wake effect reduces the power production of downstream turbines. This paper presents a control scheme for optimizing the total power output of a wind power plant by taking into account...
Article
This paper presents a new tool for testing wind plant controllers in the Simulator for Offshore Wind Farm Applications (SOWFA). SOWFA is a high-fidelity simulator for the interaction between wind turbine dynamics and the fluid flow in a wind plant. The new super-controller testing environment in SOWFA allows for the implementation of the majority o...
Conference Paper
This paper presents a Basis Pursuit DeNoising (BPDN) sparse estimation approach as a regularization technique in a predictor-based subspace method for the identification of Linear Parameter-Varying (LPV) state-space systems. It is known that in this identification method, the choice of the past window of a state predictor factorization will influen...
Conference Paper
In this paper we apply a state-of-the-art algorithm for subspace identification of linear parameter-varying (LPV) systems to identify the coupled dynamics of the drive-train and the edgewise bending motion of the rotor blades of three- bladed wind turbines. These dynamics are varying with the rotor speed. The identification algorithm uses a factori...
Conference Paper
It is well-known that recently proposed Linear Parameter-Varying (LPV) subspace identification techniques suffer from a curse of dimensionality leading to an ill-posed parameter estimation problem. In this paper we will focus on regularization methods to solve the parameter estimation problem. Tikhonov and TSVD regularization are conventional gener...
Conference Paper
In this paper we exploit a novel identification algorithm to identify a linear parameter-varying (LPV) aeroelastic system equipped with trailing edge flaps. In the identification algorithm we use a recently introduced factorization which makes it possible to form predictors which are based on past inputs, outputs, and known aeroelastic data. The pr...

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