Direct ice sensing and localized closed-loop heating for active de-icing of wind turbine blades

Experimental results of closed-loop de-icing are presented using distributed optical ice sensors, temperature sensors, and resistive heaters on a stationary turbine blade part at a fixed pitch angle inside a custom icing chamber. Optical frequency domain reflectometry (OFDR) is used for direct detection of ice on the blade. Distributed temperature sensors mounted at the leading edge of the blade are used for input to the closed-loop controller. Each resistive heater is surrounded by optical ice sensors which are used to inform a heater on/off decision. Scaling up, the experiments show that using combined OFDR with temperature sensing and distributed PID control uses a total power expenditure of less than 0.5% of the rated power under light/medium icing conditions; de-icing could yield a larger percentage of power improvement and a longer turbine up-time in cold regions. The power consumption for this localized heating is only about 10% of uniformly heating the blade. Furthermore, de-icing performance of high-intensity pulsed actuation versus continuous low intensity actuation is investigated. The results show that using high intensity pulse amplitude modulation (PAM) actuation achieves better de-icing performance than continuous PID control.