Submitted to: Windpower
Publication Type: Proceedings
Publication Acceptance Date: 7/1/2007
Publication Date: 8/1/2007
Citation: Neal, B., Clark, R.N. 2007. Speed control of a small turbine using electrical loading. In: Proceedings of the AWEA Windpower 2007 Conference, June 3-6, 2007, Los Angeles, California. 2007 CD-ROM.
Interpretive Summary: Laboratory testing of a 900 watt wind electric pumping system has shown that in high winds the pumping system operates at reduced power. During high winds the turbine stays turned out of the wind (furled). When the turbine is furled, little or no water is pumped. An additional electrical load was connected to the pumping system. The electrical load was controlled based on turbine rotational. Results from this test have shown that the turbine was not staying furled in winds up to 15 meters per second. It has been shown that by implementing this controlled electrical loading, almost 1 million additional liters of water could be pumped per year. Results also show that an additional 669 kilowatt hours of energy would be produced that could be used in a beneficial way.
Technical Abstract: Small wind turbines with permanent magnet alternators (PMA) seldom have active speed control systems. The turbines rely on passive mechanisms such as furling and/or blade flutter to control the rotational speed. These passive methods cause high mechanical stresses and undesirable noise. One method to reduce the stresses and noise is to control the rotational speed of the rotor using electrical loading of the PMA. This method is known as 'soft stall.' The 'soft stall' method was used to control the speed of a 900 watt wind turbine in wind speeds up to 15 meters per second.