Mechanical calibration for the load measurement of a 750 kW direct-drive wind turbine generator system (KBP-750D)

• A load measurement was performed for a 750 kW direct-drive wind turbine generator system (KBP-750D).
• Strain gauge bridges were formed at each relevant position to measure the fundamental loads of the wind turbine.
• To measure 40-channel signals, a 4-part measurement system was configured, and a data acquisition program was developed.
• For the strain gauge bridges, zero-point offset measurement and mechanical calibration tests were performed.
• The mechanical calibration could be fulfilled by comparative calibration in spite of many inoperative strain gauge bridges.

A demonstration research through power performance and load measurements was performed for a 750 kW direct-drive wind turbine generator system (KBP-750D) at the Daegwanryeong Wind Turbine Demonstration Complex, Korea. A calibration test of mechanical loads by external force application was conducted as an operation of the load measurement based on the IEC TS 61400-13 standard. Strain gauge bridges were selected and attached to measure the fundamental loads of the wind turbine. A measurement system was then configured to measure total 40 channels of physical quantities, including the strain gauge bridges. Subsequently, a load measurement campaign using a developed data acquisition program lasted for several months. To calibrate the output signals, the zero-point offset of each strain gauge bridge was measured, and the calibration test by external force application was performed. This paper introduces the configuration of the measurement system installed in KBP-750D, reports the detailed processes of the zero-point offset measurement and load calibration tests, and presents the test results.