Development of a Pitch Controller via Multiple-step Experiments of Scale Models of a Horizontal Axis Tidal Current Turbine

Abstract

Up to now, a pitch controller has been used as a typical solution for adapting the variation of flow speed in horizontal axis tidal current turbines. This study was mainly about the development procedure of a pitch controller for a horizontal axis tidal current turbine throughout analyzing thrust, torque, and rotational speed which measured from multiple-step experiments. First, we conducted indoor experiments using a scale turbine model with a pitch-change module to explorethe effect of pitch variation at the beginning of the development. In the next step, the different extracted powers by the pitch angle variation is measured from the indoor experiments of a scaled-up model. In the last step, a re-scaled-upturbine model with a pitch controller was fabricated based on the results of the indoor experiments and used for consecutive outdoor experiments. In a broad range of the flow speed from 1 to 4 m/s, the developed pitch controller successfully regulated the rotational speed within 80±8 rev/min hence, the extracted power was maintained within 6.73±0.55 kW. Moreover, the thrust, which is a big burden to the tidal current turbine and its supporting structure, was stayed from 10.5 to 7.1 kN. Namely, it was recognized from the outdoor experiments that the developed pitch controller could well regulate the power as well as the thrust of the tidal turbine model in the unpredictable flow speed variation of an offshoreal axis tidal current turbine throughout analyzing thrust, torque, and rotational speed which measured from multiple-step experiments. First, we conducted indoor experiments using a scale turbine model with a pitch-change module to explorethe effect of pitch variation at the beginning of the development. In the next step, the different extracted powers by the pitch angle variation is measured from the indoor experiments of a scaled-up model. In the last step, a re-scaled-upturbine model with a pitch controller was fabricated based on the results of the indoor experiments and used for consecutive outdoor experiments. In a broad range of the flow speed from 1 to 4 m/s, the developed pitch controller successfully regulated the rotational speed within 80±8 rev/min hence, the extracted power was maintained within 6.73±0.55 kW. Moreover, the thrust, which is a big burden to the tidal current turbine and its supporting structure, was stayed from 10.5 to 7.1 kN. Namely, it was recognized from the outdoor experiments that the developed pitch controller could well regulate the power as well as the thrust of the tidal turbine model in the unpredictable flow speed variation of an offshore