Partners from five countries plan to use low cost ultrasound sensors, drones, wireless communications and a sophisticated control system to monitor the structural integrity of offshore wind turbines
They also plan to use the data they collect to flexibly adapt the operation of individual turbines – and entire windfarms – to take account of the condition of structures.
Doing so will enable them to accurately predict the need for operation and maintenance (O&M) and significantly reduce costs, Professor Ainhoa Cortés, the Project Coordinator for the Watereye project at the CEIT research centre told OWJ.
The aim is to develop technology that would form the basis of a monitoring system that would operate 24/7 automatically, in an entirely unattended manner. If the project is successful, they hope the technology could be commercially available from the mid-2020s.
“At CEIT we are experts in ultrasound sensors and wireless communications,” Professor Cortés told OWJ. “Other partners in the project are experts in the use of unmanned aerial vehicles (drones), others in corrosion and others in prognosis and control algorithms.
“We are working together to bring all of these elements together to develop an advanced but cost-effective monitoring system that will make it possible to remotely detect corrosion in offshore wind structures, optimise O&M strategies and adapt the operation of turbines and of windfarms to take account of that corrosion.”
The project got underway in late 2019 and is sponsored by the EU under the Horizon 2020 programme. It has a budget of €4.7M (US$5.1M) and is due to be completed by the end of October 2022.
“Watereye is based on three main pillars,” Professor Cortés explained. “These are a smart sensing and monitoring system, diagnosis and prognosis, and adaptive windfarm O&M control, and there are three key innovation areas in it.
“The first is the use of highly accurate, fast response, low cost ultrasound sensors that will be able to monitor corrosion by detecting wall thickness in foundations.
“Some of the sensors will be mounted in a matrix directly on the structures themselves, such as those in the splash zone. Others will be mounted on a drone.
“The sensors on the drone will be able to monitor wall thickness inside the tower and look at areas where corrosion is often an issue. The drone will wirelessly send the data it collects to a base unit installed in the wind turbine.”
Professor Cortés said it is possible that every turbine might have its own dedicated drone or that a single drone might take measurements from several turbines, being launched and recovered from a drone docking station in the tower of a turbine.
“In addition to measuring corrosion levels, the system will be able to calculate the speed at which corrosion will propagate and determine the structure’s remaining useful life. Areas which are found to be subject to corrosion will be inspected on a more regular basis.
“The data collected by the sensors will be distributed by the wireless communication system and, in this way, we will be able to remotely detect corrosion levels at the most critical points in wind turbine towers, in the splash zone and the above-water area.”
She explained that a wireless system will need to be developed that has sufficient range, data rate and bandwidth for the task, and that demonstrates immunity from noise and electromagnetic interference, that does not need large amounts of power.
“The second innovation is the development of a system that will collect, store and provide access to the data, in order to provide asset owners with an optimised understanding of the structural health of structures,” Professor Cortés told OWJ.
“This will require us to develop accurate mathematical corrosion models for offshore wind turbines, that will enable us to characterise corrosion phenomena in a tower. Condition-based maintenance tools will also be developed, with corrosion prognosis algorithms, a decision support system to support predictive O&M, and fault tolerant control of wind turbine structures.”
She explained that, to do this, Watereye will require significant experimental corrosion testing, analysis and research in a simulated environment like those that offshore structures are exposed to. It will also require the use of samples to extract information the consortium will use to define the sensitivity, accuracy and durability of structural materials in the offshore environment, and a comparability analysis with monitored data in order to define corrosion models that will be used as inputs in Watereye software diagnosis and prognosis tools.
“The third innovation area is the development of control algorithms for adaptive O&M strategies for individual turbines, and for windfarm-level strategies,” Professor Cortés explained. “The Watereye monitoring system will determine the condition of the structures in a windfarm and this information, together with O&M schedules and forecast weather conditions, will be used to adapt power production. In this way, Watereye will enable windfarm operators to optimise execution of O&M, and minimise human intervention, and vessel transfers while also optimising onshore logistics.”
The windfarm controller that the project partners will develop will also receive data from individual windfarm controllers and use this and the corrosion data to optimise overall efficiency, distributing power production between turbines.
“In this way,” Professor Cortés explained, “Watereye will contribute to the development of what we call a ‘virtual power plant’ in which the control algorithms will be flexible, in terms of the trade-offs between foundation load reduction, energy production and blade pitch actuation, so that they can be adapted to a range of O&M strategies.”
In addition to CEIT, the consortium of academic institutions and companies involved in Watereye also includes COBRA, which operates offshore windfarms; Semantic Web, who are experts in data management; and Delft Dynamics, which specialises in developing drones for a wide range of applications. CEIT is the project coordinator.
Also involved in the project are the Oceanic Platform of the Canary Islands (PLOCAN), TU Delft, which will develop weather and operating conditions forecast tool and also develop and simulate load-limiting fault-tolerant control algorithms; SINTEF Industry in Norway, which will undertake corrosion tests and develop advanced corrosion models; and SINTEF Energy Research in Norway, which is responsible for windfarm control and management as well as the integration of turbine control tools into windfarm management. Flanders Make will develop a 3D map of the wall thickness loss features and develop diagnosis and prognosis algorithms for wind turbine structures. At the conclusion of the project, the facilities at PLOCAN will be used to test the technology that has been developed.
“Although the project is still in its early stages, we have already had a lot of interest from industry,” Professor Cortés concluded. “We have interest from asset owners, turbine manufacturers, service providers and companies that specialise in structural health monitoring.
“By the end of the project, we expect to have matured a number of technologies from technology readiness level (TRL) 3-4 to TRL 5. If we can do that, we can demonstrate them at PLOCAN. We hope that if we are successful, it might be possible to put together a pilot project that would help take the concepts developed in WATEREYE to TRL 8/9, which would enable them to be commercialised.”
WATEREYE in brief
WATEREYE will pursue three main lines of enquiry: