The FusionDrive combines a gearbox and PM generators into one unit.

Wind gear manufacturer Moventas and generator manufacturer The Switch, have announced the delivery of the first commercial order for FusionDrive, a gearbox and generator combination. The first delivery is going to Germany-based DeWind.
“We think FusionDrive is the next big thing for the wind industry. It includes the benefits of a hybrid drive, but Moventas and The Switch have taken the integration even further,” says Dr. Sungkon Han, Managing Director of DeWind Europe.

The developers say FusionDrive is the answer to the challenge of turbines needing to be bigger in size and power, while the race is on to lower the cost of energy. The developers say FusionDrive is the smallest and lightest combination of gearbox and generator. Studies have confirmed that it is a technically optimized solution to limit rotational speed. More important to turbine manufacturer and energy provider, the unit provides the highest energy yield and the best serviceability in the market, say the two companies.

The unit requires minimal maintenance, say the companies. The gear and generator can be split, and all components are changeable in the nacelle enabling best serviceability in the market.
Moventas

Moventas.com

Windpower Engineering & Development

Danotek manufacturers permanent magnet generators, such as the one above, and power controls for them. The company was recently granted state funds to encourage more exporting to foreign countieries.

Danotek, a Michigan-based manufacture of efficient and reliable permanent magnet generators, has been approved for funding from that state’s new State Trade Export Promotion (STEP) program.

The program, funded by the U.S. Small Business Administration and administered by the Michigan Economic Development Corporation (MEDC), is intended to increase the number of Michigan companies that export and to introduce current exporters to foreign markets and buyers.

This three-year pilot trade and export initiative was authorized by the Small Business Jobs Act of 2010, offering matching-fund grants for states to assist eligible businesses to expand their global exports. The STEP program aligns with President Obama’s National Export Initiative, which calls for doubling U.S. exports in five years, supporting two million new jobs as well as giving America a stronger competitive edge in the global market. The program provides federal government funding for 65 to 75% of program costs, with states supplying the remainder.

Danotek President and CEO Don Naab said, “The company is thankful for all the help and assistance of the SBA and MEDC, with special thanks to Jeanne Broad of the US Commercial Services Department, MEDC. With 80% of the world’s wind energy business in overseas markets, we appreciate the importance of exports in Danotek’s growth. Although we are already supplying our advanced generation systems to wind turbine producers in Europe, there are many more opportunities that this program will help us to develop.”

As a qualified Tier 2 company, Danotek’s approval is for one year, although the program can be extended for up to three years. The company will use the funds to support its exhibit at the AWEA WINDPOWER Expo (www.windpowerexpo.org) in Atlanta, GA in June. For more information on the STEP program:  http://www.michiganadvantage.org/STEP.

Danotek
www.danotek.com

Windpower Engineering & Development

The company says the formula for lowering the cost of solar and wind energy from any source is ultimately simple: Lower overall capital investment costs, equipment lifetime operation and maintenance (O&M) costs and fuel costs while boosting the amount of energy generated. This formula becomes even more attractive with wind and solar – as the cost of fuel is already free!

The Switch has taken a closer look at 4 ways to lower the costs of energy that affect the remaining variables:

1. Raise annual energy production

High availability and efficiency curves make for a winning combination to boost annual energy production (AEP).

Availability
The simplest way to increase AEP is to keep turbines or solar plants up and running. Though the wind and sun may come and go, the equipment must continue to operate and produce a constant stream of high quality energy. Technology such as PMG (permanent magnet generation) can help reduce failures. Minimizing the downtime of the equipment and scheduling regular maintenance and tune-ups for low wind or solar periods also helps keep equipment operating at its highest availability.

Efficiency
When it comes to efficiency curves, PMGs also excel. Operating at peak efficiency or power does not account for better AEP rates. Rather, improved AEP comes from the amount of time a wind turbine spends generating electricity over all wind speeds. PMGs demonstrate higher efficiency at partial loads where they spend the greatest number of their operating hours, resulting in a proven higher efficiency curve. Moreover, PMGs start producing power at lower wind speeds, enabling them to add more power to AEP rates.

2. Minimize total life cycle costs

Cutting back on total life cycle costs (TLC) means scrutinizing the expenses associated with both the initial capital investment as well as the O&M costs over the lifetime of the equipment. These two essential expenses must be optimized to bring about the best long-term results.

Capital investment
Going for a low-cost initial equipment investment may not always be the wisest. In fact, it may even lead to higher hidden expenses when it comes to O&M costs throughout the equipment’s lifetime of 20 years or more. Technology such as a double-fed induction generator (DFIG) can help cost about 30% of initial investment costs because it uses a partial converter rather than a full-power converter. However, it is important to factor in all additional costs of getting the DFIG connected to the grid according to the latest international grid code requirements, as this may entail much more costly connectivity solutions and lost production time.

Operation and maintenance
When maintenance is scheduled for low seasons in wind and solar, it is cheaper and faster. Moreover, when a recommended maintenance program is followed, it is possible to minimize breakdowns and ensure smooth operation.When comparing the maintenance costs of a PMG turbine with a DFIG turbine, the potential savings are considerable. The estimated maintenance time between failures (MTBF) for a PMG and full-power converter is 8,000 hours compared to only 1,500 hours for a DFIG.

3. Extend the lifetime of equipment

Typical renewable energy generating units, like wind turbines or solar panels, have an estimated operating lifetime of 20 years with today’s technology. By lengthening this time with an additional three to five years, the cost of energy can be lowered dramatically.A good purpose-built design, well-selected materials and components, and a carefully planned maintenance program can lengthen the lifetime of the equipment substantially. For example, a well-designed drive train minimizes cogging torque, reducing the amount of vibration and lengthening the lifetime of all components. Another way to extend the lifetime of equipment and increase its production efficiency is through upgrades, retrofitting and recycling of components.

4. Boost the quality of electricity

In the end, the success of renewable energy depends on the quality of electricity it feeds into the grid. News from recent incidents of wind turbines not connected to the grid has overshadowed some of the earlier favorable progress. Now the industry and governments alike are responding – with stricter and more uniform grid code regulations.

The Switch
www.theswitch.com

Windpower Engineering & Development

The panel was built for a wind turbine OEM. The whitepaper authors say that leveraging panel-building services from a global supplier gives a turbine OEM standards compliant, custom, control, and electrical distribution panels, while the OEM focuses time and internal resources on its core competencies.

The paper is authored by Industry Consultant Dave Schaetz and Safety Program Manager Steve Ludwig, both with Rockwell Automation.

In a nutshell, the principles are

• Establish a global supply chain with regional experience
• Outsource electrical control panels
• Design for high availability and reliability
• Conduct a standards and safety audit
• Provide compliance to regional electrical and safety standards
• Integrate WTG safety into the control system design to reduce complexity

Of course, the paper expands on each point explaining why and how they makes sense. Down load the complete whitepaper from Engineeringwhitepapers.com 

Windpower Engineering & Development

A Colorado-based company claims its axial gap, permanent magnet, direct-drive generator can produce the same torque with less than half the mass of comparably rated iron-core, direct-drive versions. The proprietary air-core stator, developed by Boulder Wind Power (boulderwindpower.com), contains no ferromagnetic material, so it eliminates all magnetic attraction between rotor and stator. This feature allows using lightweight, flexible, stator and rotor-support structures.

The BWP generator is constructed of multiple, identical segments. This modularity provides favorable logistics, such as low transportation costs, and lets crews make generator repairs up-tower. The simple ‘plug-and-play’ stator segments can be replaced by a standard two-man crew without a land-based crane.

Boulder Wind Power Product Manager Peter Smith says the design will be simpler, more efficient, and less costly to maintain than other wind-turbine generators. The firm aims to produce electricity at a significantly lower cost than existing equipment and competitive with fossil fuels. “We’ll provide our generator and controls to wind-turbine manufacturers for incorporation into their products, along with turbine design and engineering services.”

BWP says it has also developed design tools to prescribe a stator circuit etched on a printed circuit board. Automated printed circuit-board (PCB) manufacturing provides a design, manufacturing, and assembly simplicity unique to wind-turbines. Smith says a 3-MW generator is in test now at a site in Montana, but details are proprietary.

A problem with conventional multi-MW generators is that they are manufactured using low-volume production methods that depend on skilled labor. This introduces quality control issues. BWP VP of Engineering James Smith asks: “How precisely can they control the installation and assembly loads applied to the coils?

Installation involves hammering coils into the slots of an iron-core, then pulling them out axially through the slot in each direction to apply a tape to the end turns. What ensures that the insulation has not been damaged or disturbed in the process, or afterwards when coil ends are brazed? A tiny imperfection in the insulating tape can be the difference between a generator that lasts 30 years and one that fails after five.

The competitive landscape for direct-drive generators illustrates the torque density of the BWP drivetrain, a 50% improvement over the best-in-class PMDD versions. Torque density is based on torque-per-mass rather than torque-per-volume because the developer believes it represents a more relevant figure of merit and more closely aligns with drivetrain costs. Source: Boulder Wind Power

In contrast, James Smith adds, the BWP stator is manufactured using mature and repeatable PCB operations perfected by the electronics industry over the past 50 years. These advanced processes support the BWP insulation and conductor uniformly over the entire conductor surface. End-turn areas are encapsulated and supported in the same manner as working area conductors. BWP says this is superior to conventional construction.

James Smith also says the design eliminates iron losses associated with flux reversals in the stator. “Stator losses are limited primarily to conductive losses (I²R). The design minimizes eddy-current losses and eliminates hysteretic losses associated with all iron-core generators.” The high-torque density avoids torque limitations that constrain iron-core machines and allows large rotor diameters that deliver more than 30% more power than comparabe systems in low-wind speeds.

A comparison highlights the partial-load efficiency of the air-core PM generator to a modern direct drive (DD), iron-core PM machine and a DD wound-field synchronous machine. The BWP air-core machine hits efficiencies over 96% at rated power. A state-of-the-art, iron-core PMDD machine might reach 95% at rated power, while a representative DD, wound field-synchronous machine might be 93.5% efficient at rated power6 to account for rotor excitation losses. Although each design could theoretically exceed these efficiencies, their economics in multiMW, low-speed applications are unfavorable because the incremental financial benefits generally do not justify the additional costs for higher efficiencies. Source: Boulder Wind Power

The BWP generator is constructed of multiple, identical segments, modularity that provides favorable logistics and lets crews make generator repairs up-tower. “The simple ‘plug-and-play’ stator segments can be replaced by a standard two-man crew without a land-based crane,” says Peter Smith.

The U.S. DoE selected the company for a grant under the DoE’s Wind Power Next Generation Drivetrain Development program. It provides up to $700,000 of funding in the first phase, during which the company will develop a design and test program for a 6 MW, offshore wind turbine. The company will also validate the scalability, feasibility, and economic advantages of its patented technology in a 10-MW offshore wind turbine. WPE

Windpower Engineering & Development

Wind turbine generator -ABB

PM or permanent-magnet generators use the magnetic field generated by magnets mounted on a rotor. Variations on this design put magnets on the stator and let the coils rotate. There are advantages to each.

The wind industry prefers magnets made of relatively expensive rare-earth elements for the field strength they generate. They are worth the expense because the PM generator then needs no external power source to initiate a magnetic field, an advantage for wind farms in remote locations. Selfexcitation also means a bank of batteries or capacitors for other functions can be smaller.

Other plusses for PM generators are that the high energy density eliminates some weight associated with copper windings, along with problems of degrading insulation and shorting. Another great advantage of PM generators is that a large-diameter design allows dispensing with the potentially troublesome gearbox.

On the downside, rare-earth magnets do not tolerate high temperatures. They can permanently lose magnetic field strength, which demands more from a generator’s cooling equipment. In addition, the cost of rare-earth-permanent magnets is a concern because key raw materials, mostly from China, are not available in significant quantities in the U.S. However, with the rise in PM costs, sources other China will likely come online in the next few years. That will keep prices in what has been a recent downward trend.

In addition, because gearboxes are expensive to maintain, wind turbine designers have been experimenting and commissioning turbines with drivetrains that have no gearboxes. This makes PM generators essential. Still, the PM generator in multi-megawatt machines call for a certain circumferential speed to function properly. This means the generator may be 5 to 6-m in diameter, and this size loses its weight advantage.

The solution may be a hybrid design in which a one or two-stage gearbox increases the rotational speed to provide a required output. This hybrid design also allows a lowest weight drivetrain, lighter than a direct drive design for a given power production.

Future generator designs may get around the rare-earth cost penalty and weight handicaps by using superconductive materials that work at temperatures a few degrees above absolute zero. These would also allow generators in 10 to 15-MW range without the weight penalty of conventional designs. At least two superconducting generator concepts are in development but don’t expect to see prototypes for at least three years.

Windpower Engineering & Development

Jukka-Pekka Mäkinen, The Switch President and CEO

The Switch came to the market five years ago on a mission to bring better drive train technology to wind power generation and allows more energy per turbine. The drivers today remain the same: better quality power, more energy, and more robust, compact design for PMGs.

Despite the technology transition, we’re living in a world now marked by constant turmoil. Although many things are moving forward, there is always some force pushing true success in the renewable energy industry down. This makes it impossible to predict volumes as before.

There is a demand for higher quality products with lower prices. The times are forcing turbine manufacturers to focus on their core competences and select value-adding partners who can carry responsibility for their products and services.

The players aiming to survive and thrive in the renewable energy industry must develop organizations with an ability to work in an networked manner. Vertical integration worked fine when there were shortages of components and the industry was still emerging. But those times are past. Vertically integrated companies find themselves facing challenges due to volatile market conditions when it comes to technology, production, and inflexible organizations. They’re feeling the pain of trying to do it all themselves.

The way forward for these turbine manufacturers requires a new way of working – even a new business model – that embraces cooperation and collaboration, which leads to greater effectiveness. The perfect business model during our unpredictable times is based on specialists that know how to network and add value for better end results.

Five reasons for optimism
In spite of market uncertainty, we see reasons to believe in a bright future. For example:

• Money is available from private equity, which hasn’t been there before. This is because the wind-power industry is finally mature enough and ROI becoming more attractive due to the short payback times of wind-power installations.
• Positive signs continue for offshore, especially in certain regions or countries such as Germany, France, Denmark, the UK – and eventually China and the U.S.
• Public opinion still favors renewable energy. Most governments still have it on their agendas despite the global economic crisis.
• Real advancement in nuclear power has stalled, creating gaps between the nuclear output planned and rising energy demands. The decisions in Germany are now being followed by other countries – and are putting renewable energy back into plans with greater interest.
• In good wind locations, wind power is the cheapest way of all to produce energy. Not only is it the safest, most secure energy generation investment with the shortest payback time, it is also the fastest to build.

China’s steps ahead
China has finally placed quality ahead of quantity and wants to evaluate the performance of the turbines they are installing. Growth in the overall market has slowed, but the value of higher performance equipment has been realized. Some Chinese power producers now specify PMG and fixed price contracts in their requirements.

China’s internationalization may not have materialized as expected a few years ago. The image of poor Chinese quality slowed the process. Nevertheless, the country’s turbine manufacturers and power producers have set their sights on internationalization. This will not be the “takeover” scenario of earlier feared by many, but rather a gradual and natural internationalization process, including localization of operations with new job creation.

Time: the biggest threat to growth
Time is one of the biggest threats to a rosier growth outlook. For example, how long will it take the Chinese government to regain trust and move forward? How long will it take for turbine manufacturers to get their offshore turbines developed and installed at sea for qualification? How long will it take before turbine manufacturers realize that vertical integration is an outdated model that will actually choke their future?

The way manufacturers handle their time pressure will be critical to their success. Aligning with partners long term can alleviate some of this pressure and lead to even greater added-value innovations for the industry at large.

Opportunities for the industry in 2012
We also see that permanent-magnet  technology has good application opportunities in areas such as marine. High-speed motors are also in wider use and replacing the geared systems used in compressors and pumps.

The graph plots investments in clean and fossil-based generating capacity from 2004 to 2010 ($billion). Public opinion remains favorable towards renewable energy and positive signs continue for offshore. Despite the volatile economic situation, there is growing proof that New Energy competes effectively as a source of power generation. The installed capacity of clean energy from 2004 to 2010 has nearly matched that of fossil-based generating capacity. Source: Bloomberg New Energy Finance, November 2011

We are confident about thinking once again like a winning start-up company – and are open to new partnerships and technologies that make products even better together. For instance, the horizontal supply chain collaboration between Moventas and The Switch led to the innovative FusionDrive wind turbine drive-train concept.

The company’s Model Factory concept lets clients move into new production areas such as, near-shore parks. This creates local jobs at locations convenient to final wind-farm sites.

The company is in a position to take more control in customers’ production facilities, ramping up and down in a flexible manner, and to enter regional production cooperation with them.

A recommendation for the future is to outsource risk to proven added-value partners, divide responsibility among specialists in a networked team for value-added business collaboration, and innovate new-generation turbines for the future.

The Switch
Theswitch.com

Windpower Engineering & Development

Motor efficiency can be determined with greater accuracy in MotorSolve v2.6 due to improved loss predictions.

The latest release of MotorSolve, electric-machine design software, is now available. Engineers from a wide range of industries use Infolytica software to design and analyze applications such as electromechanical devices, non-destructive testing (NDT), induction heating, power electronics, sensors, and industrial transformers.

The software sports new features, including synchronous-reluctance motor templates and improved loss predictions. Stator winding modeling has been enhanced to allow 3D viewing and more accurate end effect calculations.

The software allows accounting for mechanical factors such as friction, windage, and stray losses. Companies looking to design motors without permanent magnets, due to rising costs, can use the new synchronous reluctance templates which have been added to the package.

Other improvements in the latest release:

• Slot liner modeling
• Assymetric overhangs
• Vertical or horizontal layering of windings
• Magnetic impact of shaft components
• Improved temperature settings

MotorSolve v2.6 is available for PC’s running Microsoft Windows XP, Vista and 7. Maintained clients can visit support.infolytica.com to download this update.

Infolytica Corporation
www.infolytica.com

Windpower Engineering & Development

Tecogen of Waltham, MA, is a manufacturer of natural gas fueled engine-driven cogeneration systems. Since 2005, Danotek has supplied Tecogen with more than one hundred PM generators for the company’s cogeneration modules, specifically the flagship InVerde Ultra 100 CHP module.

Danotek says their PM generators are thermally optimized high power density systems that reduce operating costs by their performance and reliability. High efficiencies at rated and partial loads are critical in enabling Tecogen’s CHP systems achieve overall efficiencies exceeding 90%, and the lightweight generator’s unique reluctance design produces negligible cogging torque making its performance ideal for cogeneration and distributed generation applications. High performance is supported by robust operations, especially the PM generator’s low operating temperatures, high quality class H insulation, and lack of brushes and slip-rings that  enhance reliability and durability.

“Tecogen is pleased to continue the successful relationship we’ve had with Danotek,” said Mr. Robert Panora, Tecogen’s President and Chief Operating Officer. “Our InVerde Ultra 100 CHP systems deliver high efficiency and reliability that maximize our customers’ energy-related cost savings. With their excellent performance and low maintenance needs, PM generators developed by Danotek are vitally important components within our CHP systems.”

All forty PM generators are scheduled to be delivered from Danotek’s Canton, MI, facility in 2012 with deliveries commencing mid-February. They will be installed in colleges, schools, hospitals, nursing homes, large residential facilities, hotels, and similar facilities that have a demand for electrical and thermal energy.

“We highly value our close and highly cooperative relationship with Tecogen” said Danotek’s Senior Program Manager, Greg Bac, “This latest multi-unit purchase order is a further testament to our capabilities to deliver equipment and support services that add value to Tecogen. We are very excited about the products Tecogen is developing for the marketplace and being a part of providing customers with clean and efficient energy solutions.”

Danotek

Windpower Engineering & Development

An electrical discharge has found its way to ground through the bearing. The result is a “fluting” pattern on the race. There are many “band-aids” to remedy this situation. You must detect it before fixing it. The easily detected vibration appears in the chart to the right.

Most of the recent end-of-warranty inspections in the US market seem focused on gearbox health. This is rightfully so because the component has a rather high failure rate and associated costs. But what about the generator? How do you inspect the generator which is also a high-ticket item to repair? Moreover, what do you look for? You cannot exactly “bore scope” a generator as you can most of the gearbox. This is where vibration condition monitoring detects the three most common generator problems: misalignment, electrical discharges, and lubrication.

Misalignment between gearbox and generator is the first common problem. Paul Berberian of Easy Laser, a company that manufacturers wind turbine alignment tools, explains, “Misalignment is easy to detect and correct, but there are no standards per se because everything moves around so much. The gearbox moves back axially and differently from tower to tower. Secondly, temperature variations make for a wide margin of allowable misalignment.” In addition, environmental temperatures vary upwards of 100 degrees from season to season, and component temperatures vary due to non-wind days, seasons, and periods. The thermal growth and physical movement make for a loose alignment tolerance. Therefore, seeing misalignment in vibration readings is common, along with prematurely wearing high-speed-shaft bearings. Generator input bearings then become collateral damage.

There are three different types of directional misalignment. A moderately misaligned gearbox and generator will add stress on associated components. It is common to see post-alignment vibration readings significantly drop on the bearings on both sides of the coupling. But the location still must be monitored to see if permanent damage was caused by the corrected condition. Yes, it is possible to cause significant damage with an easy fix of an alignment check.

Motors and generators suffer from the same ailments, such as stray currents. These discharges find the path of least resistant to ground, often through bearings.

A vibration spectrum (velocity readings) will show a high-amplitude peak at the generator’s running speed. The higher this amplitude at 1x generator/hss (high speed shaft) running speed, the higher the level of misalignment. Vibration signatures show before (tall) and after an alignment in the accompanying plot. The “before” peak at generator running speed is quite high, likely affecting efficiency and jeopardizing reliability.

Electrical discharge in the generator is another common issue. The phenomenon occurs as stray electrical currents find a path to ground and do so through the generator bearing. Detecting electrical discharge in a generator provides an example of the electrical line frequency in a vibration spectrum.

The accompanying photo (below) also shows what happens when an electrical discharge is not addressed. It electrically flutes the bearing race, as shown by the clearly visible bearing outer race defects (BPFO: Ball Pass Frequency Outer race). If left to discharge, the bearing likely seizes.

By: David Clark/Condition Monitoring Consultant

Lubrication is the final common generator issue. Over lubrication and under lubrication both contribute to bearing failure. The chart, When generator bearings become discharge paths, is from another generator bearing in which the cage defect (FTFI labels) for this bearing shows multiple harmonics in vibration, albeit at low levels. Now would be the time to check the maintenance interval and lubrication before amplitude and damage increase. A follow-up reading to monitor changes would determine if the damage increases over time. BPFI indicates inner race defects for this generator bearing. The amplitudes are approaching an alert level in vibration. It’s time to lubricate and monitor for an improvement or decline.

All three common generator-related issues – misalignment, electrical discharge, and lubrication – are detectable in vibration measurements. In fact, wind-turbine manufacturers would be wise to monitor for these common failures prior to or during commissioning so the unit will not have under-warranty issues related to these failure modes. Obviously, owners would be wise to monitor for these common failure modes for the next 18 years out-of-warranty when they will have to foot the bill. Even wiser would be to inspect the generator as well as the gearbox during end-of-warranty inspections. WPE

(for full charts see November print issue of WPE)

Windpower Engineering & Development