This remote sensoring of offshore wind turbines is made possible by incorporating sensors into the wind turbine blades to discover changes and damage in the blade structure at an early stage before the blade breaks. This could save money as the intervals between inspections can be increased.
Moreover, operation becomes safer and more stable as it is possible to check whether a wind turbine blade has been damaged after a heavy storm remotely.
Risø DTU's part in the project
Risø DTU is helping develop the wind turbine sensor system. Models describing the reaction of composite materials to various load conditions are tested in the laboratory, and classify the various defects and damages that may occur. Efforts are also made to model the reaction of the wind turbine blade to the damage condition, and the loads during operation.
The idea is to develop a model where many small changes in the wind turbine blade material can be monitored one at a time in order to assess the overall impact. In this way one can predict when a particular wind turbine blade should be repaired.
This tool makes it possible to design new types of wind turbine blades, and to predict how damage will develop. The sensors also give the opportunity to develop prognostics calculating the remaining life of the turbine, based on its current condition. Operators of large wind farms could use the tool to decide how best to maintain the blades during operation, Risø DTU says.
Sensors are used in all tests to provide detailed knowledge of the progress of the test. Typical sensors can include fibre optics, piezoelectric materials, strain gauges, etc. They keep an eye on the different types of damage that may occur to the wind turbine blade.
"We want to develop an integrated sensor system which can carry out many tasks simultaneously. It will be needed in a future remote monitoring system for wind turbine blades. No single type of sensor will be able to supply all the necessary information to estimate the condition of the turbine blade because there are many potential sources of errors and damage in blade materials," says Malcolm McGugan and Kaj Borum from the Materials Research Division at Risø DTU.
"The advantage for us is that we can test the blades throughout the entire scale from the microscopic damage of material to tests on the blade at full scale at Risø's Experimental Research Facility for Blade Structure," the two scientists say, continuing: “The intention is to make the new sensors a part of the data flow which is already transmitted from a wind turbine, in accordance with the wind industry IEC standards. Adapting the integrated sensors for these standards, we have created a fine basis for monitoring key components of the wind turbine, including the turbine blades."