Pitch control in wind turbines is essential not only to harness the maximum energy-generation potential, but also to protect the blades and turbine in extreme environmental conditions.
Wind turbines are designed to operate 24-hours a day in large installations with minimal human intervention. To maximise efficiency and ensure longevity of the equipment, precise motion control is required to balance the pitch of the three rotating blades.
This process of pitch control is further complicated as each blade has different and changing reaction forces depending on their up or down position. Ensuring safety and reliability is also critical due to the large size, height and cost of the units.
MADE provided US-based Moog with a list of technical challenges specific to pitch control in wind turbines: dynamic pitch control for changing reaction forces; returning blades to "home position" in the event of a fault; rugged motion control and data transmission able to perform reliably in extreme vibration and temperature situations.
MADE also wanted the solution to be capable of remote self-monitoring to reduce down-time and avoid operators climbing the wind turbine towers to detect faults.
Moog's intelligent servovalve uses embedded motion control and digital communications to close the position loop entirely within the valve.
Effectively, the servovalve is able to provide axis control functionality, remote diagnostics and process control in one device.
Moog says the use of embedded motion control also removes the need for an external PLC.
The servovalve used in the MADE solution is based on Moog's proven hydraulic valve platform, providing axis control with CAN-bus interface. Moog built flexible configuration software for its axis control technology that was able to meet MADE's dynamic pitch control requirements.
Moog is also supplying prototypes of its Radial Piston Pump (RKP), arranged as a dual pump on the same shaft thereby reducing costs.
Implementation of digital valve technology enabled Moog to meet the remote diagnostics requirements and provide the "on the fly" control critical to optimal performance.
Moog says digital valves also offer a "plug and play" benefit, with each new valve identical to its predecessor, reducing installation and calibration requirements.
