Power performance of starting-improved and multi-bladed horizontal-axis small wind turbines

This work numerically compares the mechanical power performance of four horizontal-axis Small Wind Turbines (SWTs) with different design characteristics. One baseline three-bladed turbine designed for optimal Power Coefficient, two three-bladed turbines designed for starting improved, and one five-bladed turbine defined by the addition of two blades on the baseline turbine. The SWTs have a nominal power of 1 kW, a blade length of 1 meter, and are composed by the SD7062 airfoil. In the simulations, a Maximum Power Point Tracking control strategy was implemented as acting on a Permanent Magnet Synchronous Generator. A set of several wind scenarios with specific characteristics was created based on the Markov Chain technique and a Blade Element Momentum theory algorithm was developed and validated for the simulations. The results showed that SWT designed for improved starting performed better in low average wind speeds, conditions correspondent to the common areas of application of SWTs. The five-bladed turbine had a considerable gain in power performance in all wind conditions analyzed, reaching values of 25% for low-speed cases. The relative low-cost of SWT blades combined with the application of modern manufacturing techniques indicates that the five-bladed and starting improved designs to be suitable alternatives for the development of more efficient SWTs.