Structural Monitoring System for Offshore Wind Turbine Foundation Structures

ewec 2006, Athens28 February

J. Wernicke, S. Kuhnt, R. Byars, J. Shadden (WindForce GmbH)

The Idea of WAVEMON™

Knowledge of Foundation Load History of individual Offshore Wind Turbines throughout Lifetime for:

•Predictive Maintenance

•Residual Lifetime Estimation

•Design Verification

•Load Reduction

Targets• Measuring of Height, Direction and Frequency of Ocean Waves• Measuring of Wind- and Tide Currents • Traceability of single Events (extreme Loads, Ship Collisions, etc.)• Traceability of fatigue Loads for residual Lifetime Estimation• Monitoring of Design Parameters• Decreasing of Wave Loads via Turbine Control• Monitoring of the Foundation Structure for early Detection of Damages

and for determining predictive Maintenance• Demonstration of Insurability of Foundation Structures

WAVEMON™Offshore Wind Turbine Foundation Control

WAVEMON Technology

Fibre optical sensors (FOS)– Advantages towards Strain Gauges

• Number of Sensors per Array– Simple Installation, small Sensor Mass

• Increased operational safety – No electrical Conductivity in the Sensor System

• No EMI Problems with Data Acquisition– no Corrosion

• High Quality of Measurement and long term Stability– No moving Parts in Evaluation System– Lifetime >20 years– Simple Field Installation– Simple Calibration in Field– No Movement of zero Point– No Hysteresis

Complete Solution:WAVEMON™ - Offshore Wind Turbine Foundation Control

Performance

• Structural Monitoring Condition Monitoring of the Monopile and its Support Conditions. Single Events can be documented and the Relevance towards Failure can be estimated.

• Adaptive Control Damping of Wave Loads.

• Predictive MaintenanceService Activities based on Event logging and Data Evaluation

• Residual Lifetime EstimationComparison of individual Load History during Operation with Design Load Simulations

Project plan

• Installation and testing of the Measurement System in a Monopile of a Wind Met Mast

• Analysis of Load Data and dynamic Behaviour, Comparison with Simulation

• Development of Methods for controlling and operating, based on Variables

• Development of Methods for assuring the Application Process in serial Production in Offshore Installations

WAVEMON™ Development trend

• Integration in Remote Monitoring• Standard for Performance Supervision and Design Verification• Development of a Wind Park Management System based on Load

Data• Structural monitoring of Concrete Towers

Example of a WAVEMON™ Field Application

Location of the Met Mast

Array Positions

Pictures of the Prototype Installation

Met Mast

Measurement Results

0 10 20 30 40 50 60Time [s]

-70

-60

-50

-40

-30

-20

Senso

r_4 []

Sensor_4Copyright©2005 WindForce GmbH

0 100 200 300 400 500 600Time [s]

-70

-60

-50

-40

-30

-20

Senso

r_4 []

Frequency Analysis

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Frequenz [Hz]0

0.25

0.5

0.75

1

FF

T_S

enso

r_4 []

FFT_Sensor_4

Copyright©2005 WindForce GmbH

www.wind-force.comjens.wernicke@wind-force.com

Die Entwicklung wird teilweise finanziert durch Mittel aus dem PFAU Programm der BIS BremerhavenWindForce GmbH wird unterstützt durch Mittel des GRW Programms des Landes Bremen

Thank you for your Attention!