Modular servo pitch controls installs easily

The developer has brought power conversion and embedded-system knowledge to pitch controls installed globally since the late 1990’s. The Servo Pitch LRU pitch system uses the latest electronics and is precision manufactured at a world class facility with an AS9100 aerospace quality management.

The company offers a full line of blade-pitch controls for existing and new turbines worldwide. The modular blade pitch platform includes i-Pitch, mini-Pitch (for sub-megawatt turbines), the DC pitch unit which is the original well-established and tested platform, and now the Servo Pitch LRU.

Windurance
http://www.windurance.com

China’s Sewind buys 400 pitch-control systems from Moog

Moog Industrial Group will provide 400 electric pitch-control systems for China-based Sewind Co. Ltd’s 2-MW wind turbines. The controls will go into on-shore and intertidal models. Sewind Co., one of the top five companies in China’s wind-energy industry, specializes in the design, manufacturing, and sale of large units.

Pitch systems control blade positions on wind-turbine rotors to ensure highest possible power capture and to protect the wind turbine. The pitch-control servodrives used in these systems operate under extreme temperature conditions within switch cabinets in the wind turbine rotor hubs, guaranteeing reliable operation. Moog says its pitch systems withstand extremely high mechanical loads in rotating turbines, while improving turbine operating efficiency.

“With worldwide emphasis on renewable energy sources and building a low-carbon economy, wind turbine operators will be searching for ways to increase wind turbine operation time,” says Moog’s general manager for the Asia Pacific Region Sean Gartland.

Sewind is a joint venture of the Shanghai Electric Group Co. Ltd. and China Huadian Engineering Co. Ltd. Sewind headquarters are in Shanghai with production bases in Shanghai and Tianjin.

Moog Industrial Group

moog.com/wind

Poster presentation describes blade pitch controls

Pitch-control systems are crucial to the overall operation of a utility grade turbine. There are two prevalent approaches to the task: Hydraulic and the Electric Pitch Systems. Combining end-user feedback and an internal Eaton assessment, this poster presentation considers each system from a performance, safety, reliability, and maintenance perspective. The poster will analyze these on a system and component level and outline the benefits of the hydraulic approach.

Moog acquires servodrives and backup power company

After taking a 40% ownership stake in privately held LTi REEnergy GmbH last June, Moog Inc, East Aurora, NY, has acquired the remaining 60% of the Germany-based company . The deal lets Moog acquire two manufacturing and testing facilities, one in Unna, Germany and the other in Shanghai, China, along with an electric wind-turbine blade pitch control system that complements Moog’s existing pitch controls, rotor monitoring, and slip-ring products. Blade-pitch systems control rotor speed and, therefore, efficiency of wind turbines.

The LTi REEnergy products acquired by Moog include Pitchmaster servodrives, motors, emergency back-up systems, a control system, and software for remote diagnostics and back-up power. Most blade-pitch controls reside in the wind-turbine hub where temperature and motion can be extreme. If, for example, a wind turbine loses electrical power, then the blade-pitch control taps its battery power to gauge speed, adjusts the turbine’s blades, and puts the rotor into a safe operating mode to protect the entire unit from damage.

Moog Inc. invests in blade-pitch control manufacturer

Moog Inc. has acquired 70% of the stock of Insensys Ltd. for $15.7 million. Insensys supplies pitch control and rotor-blade monitoring equipment for wind turbines. As part of the investment, Moog has an option to purchase the remaining 30% within a year.

Pitch controls position the blade angles, thus controlling loads and efficiency of the turbine. With this acquisition, Moog will have additional functions in pitch control to improve the efficiency and increase a turbine’s lifetime.

“Real-time data improves turbine performance and lowers its total cost of ownership,” says Moog’s International Group Presient Steve Huckvale. “Insensys’ fiber optic sensing systems add advanced measurement capabilities and data intelligence that will be a differentiator for turbine manufacturers, blade manufacturers, and wind-park operators.”

These individual pitch controls let operators reduce the load on each blade, which optimizes efficiency, improves reliability, and saves material and construction costs.

Predictive maintenance is vital to wind-park operators because of the high cost of shutdowns and turbine repairs. The necessity for predictive maintenance is only surpassed by the need to protect multi-million dollar wind turbines from catastrophic failure. Insensys does both with its rotor-blade monitors. With over 1,000 systems and 20,000 sensors delivered to global and regional wind turbine manufacturers, Insensys’ methods for ice detection, lighting strike, rotary imbalance, and damage detection prevent shutdowns, improves safety, and lower maintenance costs. “The company also has a measurement system for design verification and rotor-blade qualification that fits perfectly with Moog’s current methods for static and dynamic blade testing,” says Insensys co-founder and chairman Martin Jones.

Pitch controls: electric, hydraulic, or something new?

Dr Sherif El-Henaoui                                                                                                                                              Engineering Director                                                                                                                                                          Moog Inc. East Aurora, NY

Visit YouTube and type in the phrase “wind turbine explodes,” and you will see what could be fodder for an ad about the benefits of pitch-control systems. Beyond those who design and make these systems, the technology does not attract a lot of attention. But it should. A pitch-control system holds the key to maximizing and protecting a multimillion-dollar wind turbine. Pitch controls, mounted in the hub of a wind turbine, make it possible for a turbine operator to control the angle or pitch of a turbine’s blades. The European Wind Energy Association says pitch controls account for about 3% of a wind turbine’s price. But, like an insurance policy, a small investment makes a big difference when the weather turns from good to bad. As of 2007, analysts with Intercedent Asia estimated that 90% of new wind turbines included pitch controls. Although these are almost ubiquitous, knowledge about them is less so. When the wind hits 25 m/sec (50 mph) or higher, a wind turbine must put its blades at an angle that lowers their load and halts the wind turbine. Pitch controls that do the turning generally come in two forms: electric or hydraulic. Pitch control is not limited to failsafe situations. To set the turbine’s blades at an angle for best output, these systems will also adjust pitch (or turn) the blades a few degrees when the wind builds to roughly 12 to 13 m/sec (27 to 29 mph), which is when most turbines reaches peak performance.

The Danish Wind Industry Association recently wrote that “a pitch controlled wind turbine requires some clever engineering to make sure the rotor blades pitch exactly the amount required.” Most wind-turbine manufacturers (exceptions include Enercon and Vestas) tap others to make pitch control systems, so design subtleties may go undetected. For a buyer of wind turbines, it is important to know that most manufacturers are wedded to the use of either hydraulic or electric pitch control systems. Rarely do makers of wind turbines use both types. And, according to research from Intercedent Asia: “The [end users] choice of pitch-control system and design is wholly a function of their choice of manufacturer.”

Nobody would advise a buyer to choose a wind turbine primarily for the type of pitch control it includes. But understanding the differences between these systems will help a buyer’s overall purchasing decision.

Those familiar with pitch controls have varying points of view as to which system is superior and why. Electric pitch control has no risk of leaking hydraulic fluid. As a result, these systems pose no environmental issues, which can arise with a system relying on oil under high pressure. There is also lower consumption, or energy waste. Electric pitch controls tend to consume less power than hydraulic ones because the latter require a pump running at all times. That pump draws energy to keep the system’s oil at high pressure, as well as ready at a moment’s notice when rotor blades must be turned.

In electric pitch control systems, however, failsafe batteries or capacitors are a weakness. A pitch control battery lasts two to three years. When its life is over, it is an undertaking to replace it. Imagine scaling a 2MW turbine tower to swap out a battery in the hub of the prop.

“Supporters for hydraulic and electric systems always claim advantages for each type of technology,” said Peter Baldwin, a researcher with Intercedent Asia. “On the one hand, there’s a strong appeal for electric because of environmental issues. Another advantage to electric is that it’s better for colder climates because hydraulic oil lose viscosity as temperature plummets. But the speed and reliability of hydraulic systems is a clear strength.

“Maintenance and diagnostics are said to be easier with hydraulics because fewer technical components are used,” adds Baldwin. “And, in spite of rising oil costs, the price of hydraulic fluid in pitch controls isn’t significant because it’s a closed system, recycling virtually all of the oil it needs.”

So which type of pitch control system is better? There is no clear winner, yet.

Developments on the horizon, however, may give wind-turbine manufacturers a third option: a hybrid control. With a hybrid control, the wind turbine’s blades are turned electrically while failsafe features, which prevent damage to the blades, runs hydraulically. Proponents of the hybrid design say the risk of leaking oil would be mitigated because the pitch control would rely mostly on electrical power. They contend that energy costs would be lower, too. And because a hybrid pitch control would rely on a hydraulic system for failsafe power, advocates point out that buyers wouldn’t have to worry about a failsafe battery losing charge in a few years.

Along with helping to efficiently produce power from the wind, the pitch controls – no matter what type – play a critical role in protecting and capitalizing on an investment in a wind turbine. Whether a design team selects electric, hydraulic, or hybrid, buyers owe it to themselves to understand this often overlooked system and use that know how when purchasing a wind turbine.

Dr Sherif El-Henaoui is the European marketing manager for Moog, Inc. He also manages activities for core industries, such as plastics machinery, and developing markets, such as wind energy and services.

This article was first published in NACE, Nov/Dec 2008, nacleanenergy.com