Wind Turbine Reliability – The Importance of Highly Reliable Pitch Control and Blade Sensing Systems

In this 40 minute webinar, learn how two common hazards can hamper a wind turbine’s production. Wind-turbine owners and operators may experience a significant reduction of generated power, reducing overall turbine efficiency, if they don’t take into account:

• Blade Icing

• Failed Slip Rings Issues
• Increased Reliability

In this free webinar, we explore how Moog Blade Sensing Ice Detection Systems can monitor the load of each blade, providing real-time data indicating presence and level of ice build-up. We also examine key challenges with transmitting power and data signals from the nacelle through slip rings to the pitch-control system. Costly downtime can be eliminated by using fiber-brush technology and rugged mechanical components in the slip ring. Moog representatives show how they designed a slip ring that addresses these requirements for reliability and maintainability and thereby reduces a wind turbine’s overall operating cost.

Electric blade pitch control

A state-of-the art servodrive for electric pitch systems was on display at WINDPOWER 2010 in the Moog booth. The PITCHmaster II was developed for the harsh conditions prevailing in rotor hubs. It operates reliably at constant internal switch gear cabinet temperatures ranging from -22°F to 158°F.

The design features several advantages, such as a capability to withstand high mechanical loads in the rotating hub. An external connection is facilitated by means of an integrated diode for EPU and dc link circuit decoupling. No need for shielded cables for the EPU because its connection is included in the EMC concept. Accurate EPU voltage measurements reduce the number of additional components in the switchgear cabinet, thus reducing installation time and increasing reliability. An integrated acceleration sensor supplies information on rotor speed, rotor position, and vibrations. This data can be used for condition monitoring equipment. An inherently earth-fault proof brake driver allows regulating holding brakes to EPU voltage level, thus reducing the number of relevant switching devices in the switchgear cabinet. The motor software also supports control of synchronous, asynchronous, or dc motors.

Lastly, the PITCHmaster II was optimized to increase its reliable operation in harsh environments. This reduces the number of maintenance intervals which leads to higher wind turbine availability.

Electromechanical device for blade pitch control

In addition to hydraulically controlled and actuated blade pitch control systems, Parker can provide components and systems for dynamic performances with electromechanical technology. Parker’s electromechanical solutions, on display in Booth 10443, include dc drives with rugged designs and flexible connectivity, brushless servomotors in a full power range with flexible connection options, multi-axis motion controllers providing high speed coordinated multi-axis motion, and servo drives with compact power. Full programmability and electric cylinders offer compact power in a rugged package.

Think proportional flow for blade-pitch control

To provide smooth and consistent power outputs, wind-turbine manufacturers use hydraulics to set the “pitch” of the rotor blade. The Eaton Vickers KB range of proportional flow control valves from Eaton’s Hydraulics Operations, Eden Prairie, Minn., has been the frequently selected valve to control blade pitch. It is globally installed in over 20,000 turbines. KB proportional valves, along with power control electronics, allow accurate, high dynamic control of the blade pitch.

An amplifier is housed in a durable metal enclosure, sealed against environmental contaminates. The valves are reliable, rugged, and provide easy access for test equipment. The company says a few valve features include:

• An integrated amplifier for “plug and play” installation

• IP 65 & 67 environmental protection rating (best-in-class) for reliability to handle harsh environments

• Resistance to vibration and shock

• CanOpen bus communication option for easy diagnostics

• A complete size range, and

• Three performance levels: standard, high, and servo screw-in cartridge valves