The research focused on the effects of changes in the number of rotor blades; the size of the blades; and the electrical design of the generator.

This potential to increase efficiency comes at a critical time for the small scale renewable energy sector; from the beginning of April UK owners of small wind turbines are able to generate income from producing their own renewable electricity. The British Government has also recently announced support for new testing infrastructure and related equipment to be based at East Kilbride.

Gaia-Wind MD Jonnie Andringa said, “more and more of our customers are seeing small wind turbines as part of the solution to the moral and ethical issues around energy consumption. And, whether they are farms, businesses or private citizens, we believe they are entitled to a good return on their investment”.

About the research

• The investigation was carried out by means of the blade element momentum theory and several electrical models to estimate the electrical performance of induction generators and permanent magnet generators coupled to inverters. Additionally, part of the findings of the analyses is supported by comparisons with real power curves associated to operational turbines;
• It was found that the geometric parameter having the strongest impact on the extracted power is the rotor diameter. Both performed computer simulations and examination of the power curves of installed turbines show that the effect of this parameter on the collected power is particularly strong at low wind speeds, where most small wind turbines work with a power coefficient close to the maximum. The radial chord distribution (one of the parameters that define the rotor solidity) also has a smaller but still significant effect on the power curve;
• Other design parameters affecting the aerodynamic performance of SWT are the number of blades (another parameter appearing in the definition of the rotor solidity) and the choice of the rotational speed control, based on which constant- or variable-speed turbines can be designed. Theoretical analyses highlight that a smaller number of blades is preferable when using constant-speed turbines.