Jessica G. Holierhoek

JEHO BV

At JEHO BV we provide different training options in the field of wind turbine aeroelasticity. Seel also our website: www.jeho.nl/service.html

We provide a three day course in which you will learn everything about possible aeroelastic instabilities on a wind turbine as well as resonances that should be avoided. Everything will be treated such that you will become familiar with why these issues can occur and how they can be avoided. An extensive description of the course can be found in th...

Over the years it has become clear that renewable energy is an absolute necessity and wind energy is one alternative source of energy that can replace part of the non-renewable energy generation. Generating the energy from the wind by slowing the wind down must however still be further developed before it becomes economically viable. As the wind ve...

Aeroelasticity concerns the interaction between aerodynamics, dynamics and elasticity. This interaction can result in negatively or badly damped wind turbine blade modes, which can have a significant effect on the turbine lifetime. The first aeroelastic problem that occurred on commercial wind turbines concerned a negatively damped edgewise mode. I...

In this chapter aeroelastic stability for wind turbines is discussed. The complete wind turbine mode shapes, the harmonic modal components, and the main instabilities are explained, possible resonances addressed, and methods to analyze and improve the stability of a wind turbine design are discussed. The main instabilities that current size wind tu...

This paper studies the use of blade tip sensors for load reductions and blade-tower clearance control. Typically, modern blade tip sensors measure flapwise tip deflection distances at a high sampling rate, and such measurements can be utilised as feedback signals for control operations. Thus, this paper proposes a novel blade pitch control design b...

This gives you a very short overview concerning classical flutter for wind turbines

Why is the frequency of a mode on a complete turbine sometimes at a different frequency when you measure it on the tower (stand still frame, but for rotating wind turbine) compared to on the blade root? This mini lecture provides an explanation.

In this paper we report the results of a workshop organised by the Delft University of Technology in 2014, aiming at the comparison between different state-of-the-art numerical models for the simulation of wind turbine wakes. The chosen benchmark case is a wind tunnel measurement, where stereoscopic Particle Image Velocimetry was employed to obtain...

To study wind farm aerodynamics (WFA), the Wind Power industry currently relies on simple Engineering Models (EM) that simulate wind farms using basic principles of physics and empirically established approximations. EMs are fast and accurate for an overview of WFA and gauging mean power production, but cannot resolve phenomena like wake meandering...

ABSTRACTPROcedures for TESTing (PROTEST) and measuring wind energy systems) was a pre‐normative project that ran from 2008 to 2010 in order to improve the reliability of mechanical components of wind turbines. Initiating the project, it was concluded that the procedures concerning these components should be further improved. Within the PROTEST proj...

Aeroelastic instabilities can be disastrous for wind turbines. In the early years of wind turbines, aeroelasticity was not a problem, but once wind turbines became larger than 500 kW, some turbines experienced problems due to aeroelastic instabilities. Therefore it is important to design wind turbines with full knowledge of possible aeroelastic ins...

The dynamic stall phenomenon and its importance for load calculations and aeroelastic simulations is well known. Different models exist to model the effect of dynamic stall; however, a systematic comparison is still lacking. To investigate if one is performing better than another, three models are used to simulate the Ohio State University measurem...

The reliability of mechanical components of wind turbines needs to be improved. In the PROTEST project, a pre-normative project, complementary procedures are developed to improve the specification of the design loads at the interfaces where the mechanical components (pitch and yaw system as well as the drive train) are attached to the wind turbine....

Two different instabilities that might occur in wind turbines are discussed: flap-lag-stall and negative damping of the edgewise mode. The conditions in which these instabilities can come about has been investigated. It can be concluded that the flap-lag-stall instability is not likely to happen. The negative damping of the edgewise mode however, i...

Large wind turbines sometimes suffer from aeroelastic problems, therefore investigating the stability is important. The modeling method used is the first step to be taken in the aeroelastic analysis. Two aspects are looked at in this paper, the stiffness of the springs and the structural pitch. Simulations are run using a fully nonlinear aeroelasti...

In the STAB CON project both passive and active instability suppression of Pitch Regulated Variable Speed (PRVS) and Active-Stall Regulated (ASR) wind turbines have been investigated. The first part of the project concerning passive stability of wind turbines with no active control has lead to a common understanding of turbine instabilities, develo...

One of the instabilities large wind turbines can suffer from is the so-called flap-lag-stall instability. This is caused by the first flap and lead-lag frequencies of the large blade coming closer together as an effect from scaling, combined with the effect of stall. Another instability that can occur in wind turbines operating in or close to stall...