Shaun Skilton, Product Sales Manager for the HFDE Condition Monitoring Business Unit of Parker Hannifin, highlights the importance of effective hydraulic system maintenance to ensure long term reliability in installed turbines. As increasing numbers of wind turbines move out of their manufacturers’ warranty period, more and more maintenance contractors will be required to provide independent advice to wind farm operators. In particular, third party technical capacity will be required for component inspections, repairs and refurbishment, especially for critical parts such as gearboxes and blades.
With hydraulic systems representing a substantial part of each turbine, it is important that both operators and potential maintenance providers are aware both of the potential problems that could arise as parts wear, and how to implement an effective preventative maintenance programme.
The latest hydraulics technology can commonly be found in the nacelle of a wind turbine to control the pitch of the blades and the yaw of the nacelle, optimising the turbine’s power generating efficiency and protecting the equipment in high winds. Another use of this equipment is in low maintenance hydraulic gearboxes that are helping wind farm operators to reduce costs considerably.
In pitch control systems, the angle of the rotor blades is altered slowly and precisely to achieve maximum generating output. The blades are either turned into the wind to increase rotational speed if the wind speed falls, or out of the wind if wind speed increases, causing the rotational speed of the blades to decrease in order to protect the turbine from damage. This is typically achieved by installing three pitch control systems in the hub of the turbine, one for each blade. These systems employ hydraulic cylinders that vary the angle of the blades through a cam action.