The American-made Sky Farm 50 kW vertical axis wind turbine can mount in groups of 10 to 12 turbines on a roof surface creating a “Sky Farm” to maximize energy output. The turbine starts at the low speed of 4.2 m/sec (9.4 mph), and shut downs at 40m/sec (90 mph). The relatively small rotor, with three 6-m blades, has a 4.5-m diameter.

A electrical component manufacturer has launched a partnership with Boston-based Eastern Wind Power to test new power equipment for decentralized power generation in the small-to-mid range. The Drive Technologies Div. of Siemens will provide drive trains for small-scale or micro-power generation projects between 30 to 900 kW. “This is a fast moving business segment for OEMs targeting decentralized power generation,” says Razvan Panaitescu, business development manager of the distributed power generation and microgrids sector for Siemens Drive Technologies Division.

“Cooperation with Eastern Wind Power will provide data to support what we feel is the next generation of green initiatives, or what we call the 4C’s of the tomorrow’s energy landscape – Create, Convert, Control, and Conserve. The aim is to provide the basic building blocks for system integrators or OEM’s that would like to build equipment for localized power generation, distribution and storage and install them into commercial buildings, neighborhoods, farms and micro or smart grids.”

The partnership, a proposed six-month pilot program, will let the two parties work on a Siemens 55 kW permanent magnet generator and Energy Conversion System within the first prototype of Eastern Wind Power’s vertical axis wind turbine (VAWT).

The project is being conducted at Martha’s Vineyard Airport in Edgartown, Massachusetts where the airport manager and staff have lent their support. Eastern Wind Power believes its Sky Farm concept of mounting between 10 to 20, 50kW VAWT’s on the roofs of commercial or residential high-rise buildings is the most efficient way to produce on-site distributed green energy in urban areas which are land-poor but building-rich.

“Working with Siemens’ engineers we have now commissioned one turbine and are producing power for the airport,” says Jonathan Haar, President of Eastern Wind Power. He adds that the company’s 50kW turbine on a high-rise can generate about 45,000 kWh annually.

“Our 50kW VAWT can handle turbulent urban winds, runs quietly, does not harm avian life, and easily mounts and connects to a power grid. Its small scale is aesthetically acceptable to community standards. A 10 unit Sky Farm 50kW unit will generate enough electrical energy to supply about 10% of a typical 500,000 ft² high-rise building’s electrical power needs,” he says.

The turbine is connected to the NSTAR grid, the largest Massachusetts-based investor-owned electric and gas utility. The companies are logging real-time data including kilowatt output credited to the airport, temperature, wind speed, and wind direction. Upon completion of small wind safety certification this winter, the companies expect to build an install a second unit atop a high-rise building in Boston for further testing. The Siemens Drive Technologies Division serves all vertical markets in the production and process industries as well as the infrastructure and energy segment.

Siemens
www.usa.siemens.com/drivetechnologies

Eastern Wind Power
Easternwindpower.us

Windpower Engineering & Development

The SPS-Pavan 25 features minimum harmonic point tracking to reduce harmonic distortion, and a unity power factor operation while drawing or supplying power to a single-phase grid.

Small and community-wind farms (25 to 100 kW) are fast growing markets in North America for wind-energy applications. But this great opportunity has drawbacks. For instance, farms are mostly supplied with split single phase power. Though single phase inverters are available for small wind turbines, such products are not practically usable at such power levels. Larger wind turbines at such power levels typically work on three-phase power which is not readily available in rural areas, so products that need it go unused.

Though the available wind inverters have many useful features, they can only supply power into a grid. Power can’t be taken from the grid for critical functions such as electrical breaking of a turbine during high winds or starting a turbine and overcoming its inertia under light winds. This issue forces turbine manufactures to design around the drawback by adding larger resistor and mechanical brakes which drives costs up.

A third issue is safety. To their knowledge, says a company spokesman, there are no UL 1741 certified bi-directional single phase 25 to 100-kW systems commercially available to the small and community-wind-turbine manufactures at this time.

Smart Power Systems Inc says it has developed a solution to the problems with the introduction of a 25 kW single phase bi-directional inverter. The SPS-Pavan 25 features minimum harmonic point tracking to reduce harmonic distortion, and a unity power factor operation while drawing or supplying power to a single-phase grid.

The inverter has passed UL 1741 certification tests at Metlabs Inc and is certified for production. The 25-kW model can be paralleled to produce 50 or 100 kW systems. Three such inverters can also be used to make 3 phase, high-power systems. The SPS Pavan-25 inverter is said to be a versatile unit that with minor modifications can be used for solar farms as well. Additional inverter features include

• Single phase grid tie in for generated power
• Bi-directional power conversion
• Net metering made possible for single-phase farm lines and small businesses.
• Useful where three-phase power is unavailable or prohibitively expensive
• Helps energy production under light wind conditions by starting a wind turbine from rest
• Provides assistance in shutting down the wind turbine under high wind conditions.
• Low harmonic distortions, less than 5 %
• Possible to add power generation capacity through modular approach. (up to 100 kW)

Smart Power Systems Inc.
www.smartpowerusa.com

Windpower Engineering & Development

The wind and solar power combination captures more energy than either could alone. A solar tracker from ATR keeps the solar panels pointed at the sun for a 30% improvement over stationary panels.

The first commercially available solar-wind hybrid system in Maryland can be sized for a home or small business. One has just begun generating power on Maryland’s Eastern Shore.  Under suitable conditions, this grid-tied device, which features a residential-size wind turbine with six solar panels attached to the turbine’s post, can produce one-third to one-half the power used by the average Maryland home. The device uses two clean-energy sources at once along with a sun tracker designed by Advanced Technology & Research, Columbia, Md. that lets the solar arrays produce up to 30% more power than fixed panels. “Some days it’s windy and some days it’s not,” says ATR VP Rob Lundahl. “Many days it’s sunny and sometimes it’s not. The combination of the two provides more power more often,” says Lundahl.

This hybrid sits at the home of Dewayne and Dawn Stewart. The unit, a Southwest Windpower Skystream, was installed by Fluharty’s Electric, Tilghman, Md., where Dewayne works, about four years ago while the tracking solar panels were just added.

“Our use of green power is saving on our electric bill and more importantly, setting a good example for our children and the children in her day care,” he added.  Fluharty’s began installing wind turbines about five years ago and is a Southwest Wind dealer and installer, said owner Tim Fluharty. The idea of combining wind and solar power intrigued the company. Fluharty says for the average buyer, the solar part of the system should pay for itself in about six years with the availability of solar renewable energy credits, while the wind component should take 10 to 15 years because the wind credits aren’t as strong.

Talbot County Engineer Ray Clark says the Department of Public Works is also interested in the idea of combining wind and solar power. The agency is finalizing the design of a 50-kW wind turbine for Tilghman Island’s wastewater treatment plant, and is looking at incorporating a solar array producing up to 50 kW more for the plant.  And now that he knows about ATR’s sun tracker, the department may consider using trackers for the treatment plant as well as other county projects.

In addition to helping consumers and small businesses cut energy costs, the hybrid’s solar module—along with three other ATR tracking solar products—can benefit Maryland by helping generate jobs because nearly all of the trackers’ components are made and assembled in the state, says Lundahl. “This tracking technology is exportable to all counties in Maryland, the entire U.S., and beyond,” Lundahl added.

Advanced Technology and Research
www.ATRsolartech.com

Windpower Engineering & Development

Wind-turbine towers appear to be rising to new heights–literally. As blade lengths increase to capture more wind energy, towers must also reach higher to accommodate the longer blades.

Increased tower dimensions also translate into elevated levels of vibration and stress on tower fasteners, which can lead to loosening and bolted-joint failure. However, fastener failure can be eliminated with a locking washer.

Locking washers come in pairs with cam faces glued together.

The working principle behind the device is simple: It consists of two washer-shaped pieces that are preassembled (glued pairs), and have inclined cams on one side with a series of radial ridges on the other. On installation, the two cam sides are mated together and placed between the nut and joint material. Under vibration, the nut attempts to rotate loose. But because the cam angle is greater than the bolt-thread-pitch angle, the interlocking cams and non-slip ridges of the washer work together. The resulting jamming effect prevents loosening and further locks the assembly, thereby maintaining joint integrity. The result: a vibration proof fastening system.

Locking washers from DISC-LOCK have a steeper cam angle than the angle on bolt threads. Hence, vibration cannot turn them loose.

The locking washers also offer a fastening system that combines a heavy hex nut and tension-control bolt. Tension-control bolts are replacing conventional high-strength, friction-grip bolts and swaged-collar rivets because they are quick and easy to install with a lightweight electric shear wrench. Guaranteed tension and a visual inspection eliminates the likelihood of operator error and ensures engineers that connections are tightened in accordance with specifications. This bolting system is easily removed and can be reused. Other types of secure bolts are not reusable because they must be burned or cut off for removal, thus destroying the bolt.

The bolt spline works with the electric shear wrench.

The electrically powered shear wrench is lighter than hydraulic wrenches, a distinct advantage when considering tower height and precarious installations. This translates to a one-man operation that trims installation cost. The DISC-LOCK shear wrench uses an outer socket to engage the nut, while an inner socket engages the bolt. The two sockets rotate in opposite directions allowing the nut to turn while the bolt remains stationary. This counter-force operation transfers no torque to the operator, thereby reducing fatigue that can cause carpal tunnel syndrome.

Other interlocking cam fasteners from the company can help maintain bolted-joint integrity on wind farms. These include hex-head bolts for use in blind-hole applications and locking nuts that can be installed with standard tools. Forces that induce other lock nuts to loosen cause locking cam nuts to tighten.

Two sockets on the electric shear wrench work in opposite directions, turning the nut to turn while holding the bolt stationary. Zero torque to the crew member means less stress and fatigue on him.

WPE

Windpower Engineering & Development

Scott Merrick (with glasses) talks to an attendee at the Bergey Windpower booth at Wind and Solar Expo. The company’s XL.1, a 1kW battery-charger turbine sits to the right. He says the turbine will be available as a direct grid-tied version within a year.

Small wind was a highlight of the Solar and Wind Expo (www.thesolarandwindexpo.com) a consumer-oriented renewable energy event recently held in Baltimore. Several small-wind companies exhibiting were enthusiastic about the event and its attendees. “They came to see and learn about the latest in renewable energy equipment,” said Gary K. Sorrelle, a wind specialist with Atech Energy in Oxford, Pa. Atech displayed an Endurance S-250 residential sized wind turbine blade, a unit with an 18-ft dia. rotor.

“This was the most successful show we have participated in this year,” said Susan Fausnaught, operations specialist at Groundloop/A+ Solar, Darlington, Md. The company sells and services solar, wind, and geothermal equipment. “A significant numbers of attendees had researched different products and knew exactly what they were seeking.” A+ Solar showed a Swift turbine, manufactured by Cascade Engineering, Grand Rapids, Mich.

Also important, added Atech’s Sorrelle, is that the event is a great opportunity to introduce the Mid-Atlantic region to the benefits of ‘small wind’ turbines. It has been assumed the Mid-Atlantic region is unsuitable for wind turbines. But with ever-rising energy costs and advances in technology, wind is a viable option for the region. The next Solar and Wind Expo is slated for May 13 to 15 2011, at the Timonium Fairgrounds. WPE

Windpower Engineering & Development

Bonfiglioli Riduttori S.p.A.  partners with manufacturers of mini wind plants for weak wind, high turbulence conditions. The company developed electronics for the energy conversion and grid connection system, drawing from experience in regenerative inverter applications. The system receives energy from a sensorless permanent magnet synchronous  generator installed in the turbine’s nacelle, and feeds it into the distribution grid. An inverter controlled gearmotor can control turbines with active yaw or pitch control systems.

The turbines usually have a tubular steel mast with a nacelle at the top containing the generator, yaw, and pitch gearmotors, and the rotor the glass fibre blades are attached to. The electronic systems are installed in the electric panel at the foot of the mast.

The regenerative electronic system consists of a two stage IGBT inverter with active bridges at both front ends. A vectron AEC regenerative active front end stage interfaces with the electrical grid, while an ACU vectorial field oriented control stage provides active control of the current from the PMSG in the nacelle.

A sensorless vector control provides open loop control of the PMSG. The angular position is estimated by a special calculus algorithm, which reduces the number of components and wires without any loss of performance from the generator, even at low rotations speeds. The ACU stage of the regenerative system also has to provide four quadrant control of the generator in order to achieve regeneration during normal operation under wind action, and to force motion as required by a test protocol implemented by the wind turbine control program in the PLC to check the mechanical efficiency of the rotor at regular intervals.

While the PLC is transmitting torque reference signals to the ACU Inverter, the ACU is controlling current from the generator and transmitting it to the AEC regenerative stage. (short circuit protections, phase failure, etc).

The system can be equipped with a communication field bus module or digital and analogue input and output interfaces, ensuring immunity from interference and constant monitoring of connection status. The regenerative stage also includes filter components to eliminate conducted EMI and harmonics reflected from the grid, ensuring a constant sine wave current in the phase with grid voltage.

Inverter controlled gearmotor

A sensorless vector control system simplifies technology in mini wind plants. The system for the PMSG converts energy without needing an external transducer.

The ACU stage ensures calculation and filtration of the EMF’s harmonic components, starting fromthe generator’s electrical phase quantities, voltage, and current. An automatic alignment function allows the inverter to recognize the reference postition on start-up and store it in memory throughout normal functioning.

The inverter calculates the exact position of the rotor at all times and performs the mathematical transformations needed to control the current vector and cancel the magnetizing component, converting the generator’s mechanical energy into electrical energy. The system is  able to transform even small gusts of wind into significant electrical current to feed into the grid. Grid connection efficiency exceeds 95%.

To control risks of dangerous overspeed and variability of the wind, the nacelle and the blades must be able to rotate around their axis to assume the position required  by the control system. These rotations, the yaw and pitch, can be achieved by the manufacturer’s Transmital 700 series planetary gearboxes driven by brake motors controlled by inverters that provide vector speed and torque control.

Bonfiglioli

bonfiglioli.com

Windpower Engineering & Development

Improved energy capture comes from the shrouded design, an established aircraft principle, says inventor Joel Neumann. In addition, should a bird fly into the turbine, it is more likely to be ejected alive rather than harmed.

A turbine rotor designed for use in slow moving creeks, streams, rivers, tidal flows and ocean currents (no-head water) has shown promise as a rotor for wind turbines. Inventor Joel Neumann, Palatine, Ill, says that in wind-tunnel model tests the 7-in. diameter BNBES turbine equaled a 12-in. two bladed standard design in stall torque. The B N Balance turbine is now scaled to a 3-ft diameter and shows efficiency improvements over a conventional three-blade rotor of the same size. The BNBES turbine sports other features, such as being made from inexpensive materials that would be creature friendly. “Birds or bats that might fly into the rotor would not find themselves injured because of the relatively soft materials, neoprene and so forth,” says Neumann. “Indications now are that it may be completely wildlife friendly because of the soft materials and a design that allows for ejection over chopping,” he says.

Neumann acknowledges that the turbine differs from conventional designs and results will probably be questioned. “Still, the results indicate about a minimum of 35% more energy captured on both model and field tests, and a greater theoretical potential when fully optimized,” he says. Furthermore, calculations performed by members of the engineering department at the Northern Illinois University agree with his predicted results.

One reason for the improvement is that the design uses 100% of its diameter. The blades on a conventional turbine, in contrast, occupy only about 15% of the swept area. In contrast, wings on the new design are self-shrouding and flexible to conform to variable wind speeds. He says it is almost silent in 30 mph wind, the highest speeds during current field tests.
The turbine also works well in winds that are not head-on. “For instance in a field test, gusts up to 30 mph and 90° to in-flow spun the turbine with a generator at 100 rpm, so we believe the design could withstand 90 mph winds while continuing power production. WPE

Windpower Engineering & Development

The Windy Boy 8000US inverter expands the company lineup to five models that range from 3,000 to 8,000 W.

The Windy Boy 8000US includes special firmware that permits a direct grid-tied operation with a broad range of wind turbines. Its longevity is enhanced by SMA’s patented OptiCool active temperature-management system and rugged cast-aluminum outdoor-rated enclosure. The inverter features a CEC weighted efficiency of 96%, resulting in exceptional energy yields. It is also certified to the UL 1741/IEEE1547 standard.

Designers can take advantage of the unit’s versatility. For instance, the wind inverter can be installed with a direct grid-tied connection or as part of a micro-grid in conjunction with the company’s Sunny Boy solar inverter, and Sunny Island battery inverter and management system, providing grid-quality power to remote locations.

Windpower Engineering & Development

The SET is the work of U.K. inventor Rupert Sweet-Escott, whose would like to put “a SET on every house.” The turbines range in power from 50 to 250 watts and start around $1,132.00.

Wind turbines on houses are not always practical because some home owner associations would object to the noise it might make, or neighborhoods that restrict changes in aesthetics. A U.K. inventor may have solved the problem with a design called the Secret Energy Turbine (SET) because it disguises the turbine as part of a chimney. The small vertical axis turbine, painted the same color as the bricks in a chimney, make it appear to be a ordinary chimney stack. The unit is said to work in near silence because of its unusual design, which features vertically mounted blades fixed under the influence of two opposing magnets. The result is said to be an efficient turbine with only one moving part that tolerates winds over 90 mph.

Windpower Engineering & Development

Award recipients are:

Intertek Testing Services NA Inc. in New York,

Kansas State University,

The Alternative Energy Institute at West Texas A&M University, and

Windward Engineering LLC in Utah.

One goal of the Regional Test Center project is to support the U.S. small wind market by increasing the number of organizations qualified to conduct small wind-turbine-standards testing and to drive down testing costs. Test results are used by certification bodies, such as the Small Wind Certification Council, to certify small wind turbines for durability and performance.

Certification testing lets small wind turbine buyers make informed choices and provides states with the data needed to determine turbine eligibility for incentive programs. These Regional Test Center awards are provided by DOE and NREL in a continuing effort to support the growth of the U.S. small-wind-turbine market and lets U.S. manufacturers sell their small wind turbine products abroad.

Windpower Engineering & Development