Advanced Wind Turbine Program Next Generation Turbine ... - NREL

Development of the concept required more time, however, than would permit incorporation into
the POC machine. Therefore, it has been incorporated at the EMD stage.
As Phase 2 of the development, a wide variety of tower top accelerometers were subjected to exhaustive
testing. Accelerometers from several different vendors were evaluated with respect to
the performance, reliability, and quality of the manufacturer. GE selected a modified version of
the unit that was already being employed for diagnostic monitoring in the GE1.5 turbines.
Figure 39 illustrates this unit and its location on the EMD turbine.
Figure 39. EMD Tower-Top Accelerometer Package
Fore-aft acceleration is measured from the unit via an output that is wired directly to the controller
analog input. The control algorithm is PI from the filtered signal to collective pitch increment,
as illustrated in Figure 40. Error traps are programmed for mean value drift, mean value
significantly different from zero, non-changing signal, and large change in signal in one time
step. The system was tested in emulation with serial communication to the controller before being
implemented on the operating turbine.
PCH Filters PI
Error Traps
Pitch ∆
Figure 40. Flowchart of the EMD Tower Top Accelerometer Feedback
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