Proportional directional valves for wind turbines

The global push towards sustainability has led to increased interest in alternative power sources other than coal and fossil fuels. One of these sustainable sources is to exploit energy from the wind through wind turbines, by converting wind movement into electrical current thanks to the rotor blades and a power generator.
As the wind energy source is not constant, wind turbines are modulating the angle on the blades (“pitch angle”) to optimize their power generation in response to changing wind conditions. The hydraulic pitch system, located within the turbine hub, rotates the three variable-pitch turbine blades to precisely control the generator speed based on a feedback signal.
This ensures that the electrical power required by the consumer is produced regardless of varying wind speed, optimizing the energy yield as well as reducing the mechanical load, thereby extending the wind turbine service life.

Hydraulic pitch system provides an efficient and reliable way to control the pitch angle of a wind turbine as it meets requirements with long-term operative life, allowing also for accurate and high-performance control of the pitch angle.
With hydraulic pitch system the angle of the rotor blades is changed via hydraulic cylinders: the supply source is in the fixed zone of the nacelle, while the actuator of each blade rotates with the hub.
The proportional directional valves are the key component of the system, designed to ensure accurate and high dynamic control of the actuator position. Reliability is another key factor as proportional directional valves operate in presence of high mechanical stress: being in the rotating turbine hub, it is exposed to heavy vibrations, shocks, and rotational forces, as well as subjected to lightning strikes. Also, proportional directional valves must be designed to operate in critical environmental conditions like in northern regions or marine areas characterized by low temperatures and high humidity.

Atos has developed a range of proportional directional valves specifically designed for the demanding requirements of onshore and offshore wind turbines. Atos digital proportional valves with on-board electronic offers superior performances, high reliability as well as advanced tuning and diagnostic functions.
Features:

• high dynamic response with excellent spool position accuracy & repeatability
• rugged execution according to mechanical stress tests for sine/random vibrations EN 60068-2-6 and shocks EN 60068-2-27
• EMC compliance according to EN 61000-6-2, -3, -4 standards
• enhanced protection against lighting according to EN 61000-4-9 and disturbances related to medium and high voltage substations according to EN 61000-4-10
• IP66 / IP67 classification against dirt, grease and moisture
• extended ambient temperature range down to -40°C
• remote advanced diagnostic functions thanks to built-in oscilloscope and permanent alarm history
• fieldbus communication CANopen, PROFIBUS, EtherCAT, POWERLINK, EtherNet/IP and PROFINET

Thanks to the digital electronics, valve flow output and performances can be customized to match different turbine requirements, ensuring compatibility with the existing control parameters.
Atos digital proportional valve are the preferred choice for hydraulic pitch system of several wind turbine manufacturers worldwide, who appreciate its superior performances and reliability, results of years of R&D and successful field experiences