Moving the Sun with Rotary Hydraulic Actuators

rotary-hydraulic-actuatorsThose interested in Solar Energy might already be familiar with the 64MW Nevada Solar One – world’s third largest concentrated solar power plant. Located about 25 miles south of Las Vegas, the Plant spans 400 acres and generates approximately 129 million kWh of solar electricity annually, enough to provide power to more than 14000 homes, while emitting near zero carbon dioxide.

Innovatively, Rotary hydraulic actuators enable parabolic solar collectors to rotate and tilt, following the sun. The system uses small, low-speed displacement pumps for solar tracking and high-speed pumps to stow the 760 heat transfer fluid collectors at the 400 acre site at night and during high winds. The rotary actuators are used to rotate and tilt a series of parabolic mirrored troughs, so that they are able to track the sun’s motion for maximum efficiency, and protect the arrays from high winds and dust storms.
The plant is creating a lot of interest in the energy industry because it provides a renewable energy alternative. The hydraulic actuators each drive 12 panels that weigh over 900 kg and have a total of 240 curved mirrors. The actuators enable these panels to track the sun in extremely small increments, with small, low-speed displacement pumps providing two short pulses from the reservoir to the unit’s motor three times per minute. Furthermore, the system is designed to withstand backlash from high winds, by allowing the solar trough to slip and rotate in a controlled fashion, without damage to the motion control mechanics. This designed ‘clutching action’ is inherent in hydraulic systems, with the use of pressure relief valves, and allows the solar collector to realign and begin tracking the sun again when the wind subsides.

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