Field testing of individual pitch control on the NREL CART-2 wind turbine

A power production controller has been designed for the test turbine, which includes an independent individual pitch control (IPC) algorithm which can easily be switched in and out during operation. The turbine is already instrumented with well-calibrated blade root strain gauges, and by comparing test data with and without the IPC, the load reduction will be quantified. This is a 2bladed teetered turbine, but with the teetering locked by a brake the tests should demonstrate that IPC can be used instead of teeter to reduce the hub moments. It is hoped that the three-bladed CART-3 turbine can subsequently be made available for a similar field test in early 2010. The principles of IPC apply equally to two and three-bladed turbines, since the fundamental control action is calculated after first transforming to the non-rotating reference frame, and it is therefore largely independent of the number of blades. A tower damping algorithm using collective pitch control has also been designed, and will be tested at the same time.