Submitted to: American Society of Mechanical Engineers
Publication Type: Proceedings
Publication Acceptance Date: 1/13/2000
Publication Date: 6/30/2000
Citation: Ling, S., Nelson, V., Clark, R.N., Vick, B.D. 2000. Field testing of a smart controller for wind-electric water pumping systems. American Society of Mechanical Engineers. AIAA Paper No. 2000-0055. pp 339-345. Interpretive Summary: Electrical water pumps can be powered directly by electricity generated from wind turbines. The water pumping system consists of an electrical motor and pump connected through a controller to a wind turbine with a permanent magnet generator. The purpose of the controller is to engage the motor with electricity from the wind turbine generator after it has started dproducing power. If the motor is engaged too quickly before the wind turbine has reached sufficient speed to keep turning with a load on it, the wind turbine will be stopped by the sudden current load. This is easily overcome by not engaging the motor until a frequency of approximately 35 Hz is reached and by adding the right size of compensating capacitance. However, keeping the electric motor synchronized with the generator at high wind speeds is more difficult because the winds are often gusty and change rapidly. A smart controller was designed and tested with three different size wind turbines to perform this function at high wind speeds. The controller connects and disconnects dynamically a relatively large amount of capacitance and/or resistance load to the system. The volume of water pumped was increased significantly using this smart controller.
Technical Abstract: The wind-electric water pumping system consists of a wind turbine with a permanent magnet generator that produces 3-phase variable-voltage, variable-frequency electricity. The system performs efficiently at low winds if the right size compensating capacitance is used. At high winds, when the frequency reaches a certain level (60-85 Hz), the system tends to lose synchronization especially under the gusty wind condition. Most smal wind turbines have mechanical furling mechanism to turn the rotor out of the wind and slow down the rotor speed. However, furling generally does not occur until synchronization has been lost, so system efficiency is quite low at high wind speeds. By dynamically connecting a relatively large capacitance and/or resistance in the system, the system will stay synchronized over an extended wind speed range and system efficiency will be increased. Based on this principle, smart controllers for three different sized wind-electric water pumping system were designed, built an tested by USDA-Agricultural Research Service (ARS) and West Texas A&M University, Alternative Energy Institute (AEI). The systems with this controller stayed on line more time at high winds and pumped more water.