Development and Installation of a Robust and Reliable Research Structural Health Monitoring System for Grouted Joints of Offshore Wind Turbines

Abstract

Offshore wind turbines are highly exposed to operating loads and extreme environmental conditions. To ensure technically reliable and economically worthwhile operation, high plant availability must be provided. Structural health monitoring (SHM) respectively condition monitoring (CM) makes a valuable contribution to this. The grout connection used in offshore foundations is usually monitored in compliance with regulatory requirements, e. g. VDI 4551 or insurance conditions. In the project "In-Situ-WIND" an extended hard, - and software concept adapted to the SHM-application, based on vibration-based methods, acoustic emission analysis and radar measurement technology was developed. The overall objective of the project is to find a suitable system configuration and appropriate methods to monitor the grout connection. The challenges are that the measurement system needs to operate reliable under extreme environmental conditions in the grout area, must be accessible remotely due to extremely limited accessibility and the offshore installation should be carried out timeefficiently under very difficult installation conditions. Due to this, a decentralized measurement system has been set up. A central server cabinet in the entrance area of the wind turbine contains the essential components for power supply, data storage and data processing. A redundant, diagnosable, and remotely maintainable design of many of these central components increases the reliability of the overall measuring system. One measurement system is placed directly in the grout area in a rugged offshore-ready control cabinet and receives signals from 50 channels of different sensors. Due to limited installation options, a hybrid cable for power supply and data transmission was used to connect the system with the control cabinet in the entrance area. Another measuring system records the vibrations of the tower by several acceleration sensors.