Static uncertainty analysis of a wind turbine test bench's load application unit

Modern wind turbine test benches include devices for applying non-torque loads to the driveline of the device under test. The device studied in this paper works by using hydraulic actuators to apply forces to a large disk that is part of and rotates with the driveline. The applied actuator loads result in a net linear force and net moment at the nacelle's control point (point along the driveline that corresponds to what would be the center of the blade hub). Direct measurement of the resulting control point loads is difficult due to their magnitudes (up to 2 million Newtons of linear force and 10 million Newton-meters of bending moment). The current strategy is to use actuator pressure measurements to estimate the loading at the control point. This paper investigates the sources and effects of uncertainty on static, control point load estimation.