Exposed to difficult climatic and wind conditions, a wind turbine may experience considerable extreme and fatigue loading events. The information obtained from a load measurement campaign supports the optimization of a wind turbine model (low cost, greater life expectancy, safety) and supplements the documentation required for the type approval of prototypes. Specialized measuring campaigns can also help in the

investigation of problems on operating wind turbines.

Load measurements require highly-skilled, competent staff to be involved from the preparation and design of the measurement system up to the analysis and final reporting. A variety of sensors, including, but not limited to, strain gauges, fibre optic sensors, accelerometers and displacement transducers, are installed on the wind turbine blade, shafts and tower.

The Laboratory for Wind Turbine Testing (LWTT) of CRES offers a complete package of

load measurements and data analysis in accordance with IEC 61400-13. The instrumentation used complies with IEC61400-12-1 requirements offering the possibility of a simultaneous power performance testing. Meteorological, load and wind turbine operational sensors are integrated in a compact unit.

The data acquisition system enables continuous or trigger-specific data storage, different sampling rates per channel, real time and off-line review of recorded data and power spectra evaluation. Remote control of the system is an option. LWTT closely cooperates with the customer to ensure fast consideration of the wind turbine performance.

Advances in the grid requirements, related to the safe operation of the wind turbines,

resulted to the need of high frequency load monitoring on wind turbine drive trains during Fault Ride Through Tests (FRTT). CRES has developed a system for wind turbine drive train integrated mechanical load and electrical monitoring, specially designed for FRT tests. The system has been used by wind turbine manufacturers supporting FRT tests.

Within MEASNET, of which LWTT is founding member, LWTT participates in the round robin tests for load measurements. Participating in major EU research projects, LWTT

has acquired valuable experience in monitoring wind turbine loading in complex terrain and was deeply involved in defining recommendations for load measurements and analysis within IEC. Besides load measurements for research purposes, LWTT has

issued many type-certification load measurements reports for European wind turbine

manufacturers.

LWTT is accredited by the ESYD (Hellenic Accreditation System) according to ELOT-EN

ISO/IEC 17025:2005. The accreditation scope includes loads measurements on wind

turbines.