Acceptance criteria for the tracking error of wind turbine drivetrain test bench when replicating dynamic loads

A 7.5-MW wind turbine drivetrain test bench has been used to apply dynamic loads from IEC 61400-1 design load cases to a multi-MW wind turbine drivetrain. A total of 15 test profiles were tested with each test profile demanding the simultaneous application of vertical, lateral, and longitudinal forces, yawing and nodding bending moments, and rotational speed. These inputs to the test bench were compared with the forces, bending moments, and speed that were applied to the wind turbine drivetrain to quantify the tracking error of the test bench and cross-coupling between forces and bending moments. The effect of the tracking error and cross-coupling on the dynamic response of the test article was quantified using multibody simulation. The tracking error was found not to significantly change the dynamic response of the drivetrain. The experimental and simulation results are used to recommend acceptance criteria for the tracking error when replicating dynamic loads.