Reduced Stress - torque limiter reduces drive-train stress
A novel way to handle the drive-train stresses in wind turbines during grid faults is to use the new Zero-Max torque limiter. The multi-operational device can release the entire drive train from mechanical stress during the faults. This cost-effective hardware, available for wind turbines up to 3MW, is self-adjusting and no maintenance is required.
Several grid connection requirements for wind turbines exist in Denmark, the UK, Germany and Ireland. They are under harmonisation in EU. A fault can appear anywhere, from thetransformer’s medium-voltage terminals out to the point of connection, even in the transmission grid. In such an event, a wind turbine must, on most occasions, stay connected throughout the duration of the fault.
A fault in a local network or a transmission grid will be cleared by protective circuit breakers in less than a second. After that, the grid voltage will increase, again within a few seconds, back up to normal level. During this period, transient torque pressures can be imposed on the drive train. The Zero-Max torque limiter has been approved and performed better than expected in full-scale tests, says the company. It is designed for 750kW, 900kW, 1.0MW, 1.3MW, 1.5MW and 2.0MW. Each model has protection levels that can be adjusted as necessary. www.zero-max.dk
Precision wind rotors - projector guides manual cutting process
To guarantee the highest product quality, maximum precision is needed when placing glass-fibre mats, pre-impregnated fibres and carbon decal components in wind rotors, which are usually assembled manually. The Z-Laser Projector shows an image of the contour inside the mould, helping workers place blade components accurately and more quickly than when using templates.
The laser projector guides workers through the manual lay-up process and, according to the company, can increase productivity by up to 30%. The working process is not only optimised but controlled and logged. The software works with common 3D-CAD programs, and databases are available. www.z-laser.com
Balancing benefits. Keep the wind rotor in check
Operations and maintenance employees were considered when the Balancing Box was created. This is a plug-and-use vibration measuring system that will check wind turbines for rotor imbalance. It has been developed by Berlin Wind, a company that provides dynamic rotor balancing and blade-angle measurements. It also allows detection of the causes of accelerated wear or damage to components, identification of problems before major damage is done, and prevention of costly repairs and downtime.
The Balancing Box is used in combination with the company’s Balancing Test and Balancing Viewer software, which take the user step by step through the measuring process, showing the results and providing an assessment of the vibration level.
The results, which can be assessed onsite, are based on vibration limit values and specific measurement conditions for each type and configuration of wind turbine. Measurement results may be documented automatically and can stored in Berlin Wind’s balancing database. www.berlinwind.com
Competitive towers for tall turbinesRuukki has set out to design competitive towers for tall turbines, and has developed a new lattice structure, which the company claims is a cost-effective alternative for tower heights of more than 100 metres.
As wind velocity increases with height, higher turbines are more efficient and able to benefit more easily from inland wind conditions. Ruukki, which supplies pre-fabricated tower plates and other metal-based components to the construction industry, will use a patented design from its collaborator Seeba Technik for its new lattice tower design. It expects that this product will help to meet a growing demand for the taller structures. www.ruukki.com
Dynamic software to simulate turbine operation
Aprogram from MSC Software gives users a single tool for creating an all-in-one model of a whole wind turbine that supports custom levels of detail. Adwimo, the user-friendly and scalable software, provides the complete design process of a turbine. From the conceptual design phase, a simplified turbine can be expanded to include more complex components, such as gears and bearings, and swap from rigid to flexible bodies — all on screen.
Adwimo plugs in to the widely used Adams multi-body dynamics software program, and provides all the features needed to assemble a turbine and to simulate single or multiple wind farms. It includes tower, blades, hub, mainframe, gearbox housing, bearings, transmission, controls (generator, pitch, yaw), aerodynamic and centrifugal forces, coriolis acceleration, gyroscopic moments, point loads, gravity, thermal loads, and wave loads from third parties.www.mscsoftware.com
Maintenance-free coupling for high-speed wind turbine shafts.
A new coupling for the high-speed shaft on wind turbines is being produced by Geislinger, a company that specialises in torsional vibration. The Compowind is a new integrated slip coupling with a unique modular design that can be easily adapted to suit different installation situations.
The coupling is made from high-tech composite materials, making it lightweight and durable. It is a tailor-made solution for wind turbine applications between gearbox and generator, and the company claims that these durable materials ensure that the components maintain their properties for the lifetime of the product.
The Compowind coupling ensures low reaction forces and minimises bearing load, helping to increase system availability. Resistance to ageing and factors like heat, cold and oil is an added benefit.
The classic Geislinger Coupling uses steel leaf springs and hydrodynamic damping, providing elasticity and damping to the drive train and reducing peak torques. www.geislinger.com
Producing high torque capacityThese gearboxes are quite different from the standard conventional planetary designs, says Czech manufacturer Wikov. The company uses flexible pins in all of its gearboxes and multi-planetary epicyclic trains, mostly in a differential arrangement that splits the torque transmission, significantly increasing torque capacity while reducing size and weight. There is equal load distribution across the tooth face and among the planet wheels, which compensates for deflections caused by enormous rotor loads. This, says Wikov, produces outstanding reliability and long service life.
The company produces generator drive gearboxes for wind turbines of 1.5MW, 2MW, 3MW, 3.6MW and 5MW for onshore and offshore use, and supplies the largest 5MW offshore wind turbines with a rotor diameter of over 140 metres.
The 5MW gearbox is very compact, weighing only 57 tonnes, while facing an input torque of over 5,000kNm. Wikov also produces a variable gear ratio system that enables standard synchronous generators to operate at constant speed. This simplifies the drive train and reduces the need for power electronics. www.wikov.com
Low-power ground based radar detection
Until an aircraft is detected, the warning lights of the OCAS audio visual warning system remains passive. And only if the aircraft is known to be tracking an unsafe route does the system light up the nighttime sky. OCAS operates in the US, Canada and Norway already, and claims to be the only obstacle-marking system approved by the International Dark Sky Association.
New offshore jack-up platform
The biggest barrier to offshore wind growth, some experts claim, is the shortage of capacity to install turbines at sea. A new jack-up platform, Thor, built by Hochtief Construction, will equip the company more widely for the task of developing and building new offshore wind farms.
Thor is one of the largest jack-up platforms for the installation of wind turbines at sea. Its 82-metre-long legs allow it to work in depths of up to 50 metres. The permanently installed 500-tonne crane is designed for safe and efficient working, and its rapid lifting speed makes it more comfortable in rough seas.
Environmental edge to this high-tech solution
Repair Versus Replace is a new service from Dex, a supply-chain solutions provider for high-tech industries. The company’s unique engineering solutions, together with its world-class repair services, form the backbone of this new initiative.
As the name suggests, this new service emphasises repairing defective turbine components rather than purchasing replacements. With teams of skilled electrical and mechanical engineers, Dex uses reliable, repeatable tests to develop and document repairs for a growing range of wind turbines.
Dex aims to provide customers with quick, efficient and competitively priced repairs for electronic and electromechanical turbine components, to maximise output while saving customers up to 70% in replacement costs. It also offers quick turnaround times, averaging seven to ten days.
"The cost of repair is approximately one-third of buying new," says Duncan Kellet of ScottishPower Renewables, Dex’s biggest wind power client, which now keeps a contingency stock of repaired units to be swapped out if necessary. "This makes us less reliant on the original equipment manufacturer to have parts transported to site," Kellet says.
To ensure highest quality standards and reliable repairs, all Dex locations maintain rigorous international standards. www.dex.com
Extending an old idea to aid major construction
To improve the reliability of multi-megawatt turbines, engineering firm Timken has created a series of massive, tapered roller bearings based on those invented by the company in 1898.
The fundamental engineering of the Ultrawind series is similar to the original, with the addition of integrated seals, lubrication and condition monitoring to enable it to operate in a turbine high on a wind tower in extreme conditions.
These new bearings provide a simplified drive train for main-shaft wind turbine designs — both geared and gearless. The bearing raceway profiles are designed to control maximum stress levels for enhanced durability. www.timken.com
Protect and restore surface metal structures
To prevent wear and tear in gearboxes and bearings of wind turbines, German technology company Rewitec has developed a technologically advanced coating that restores worn surface metal structures and permanently protects them from abrasion, even under extreme conditions.
Rewitec Nanocoating can offer protection for engines, gearboxes, compressors and bearings.
The technology is not based on modification of the oil film, but on modification of the surface texture of frictional metal parts and the creation of a new, smooth metal-silicate coating.
The soft silicate particles remove dirt from rubbing metal surfaces and react with the metal to form a smooth protective layer on the surface. Metal no longer rubs on metal, but between two metal-silicate surfaces with low friction and improved friction-related properties, increasing the lifetime of the parts.
The coating reduces fuel, lubricant and energy consumption. And the low cost means that if a wind turbine’s life is prolonged by six days, the product costs are paid, says the company. Furthermore, a targeted exchange and maintenance of the gearbox and bearings is also possible. www.rewitec.com