Winergy is a German company long known for its quality and innovation in gearboxes and drive systems for wind turbines. 

At the American Wind Energy Association (AWEA) Windpower Conference and Expo last month, Winergy introduced its new 3 MW HYBRIDDRIVE technology, which combines a 2-stage gearbox and a permanent magnet generator into one product (Winergy press release).

According to Winergy’s press release, the new design provides the advantages of reduced size and weight of the nacelle and drive train:

The direct linkage of the two stage gearbox and the permanent-magnet driven generator shortens the drive train by approximately 35%.  This design allows for a significant reduction of the nacelle size and minimization of the overall weight.

Winergy found the inspiration for its new gearbox and generator combo from work performed by Global Energy Concepts LLC (GEC) in a DOE funded study for the WindPACT program back in 2000 – 2002.

The GEC drivetrain utilized a 2-stage gearbox with a CARB bearing which allows the second stage to free float to maintain alignment between the gear mesh of the first and second stages of helical gears.  This has the benefit of being able to absorb most deflections and off axis loading conditions encountered by the stochastic nature of the wind.

Although it also utilizes a 2-stage gearbox, instead of a CARB bearing, the Winergy HYBRIDDRIVE has a different internal bearing arrangment.  Winergy’s web site doesn’t provide details, but one of the company’s representatives at the AWEA Conference indicated that they have a double row tapered roller bearing arrangement and bushings with elastomeric dampers as well as a torque tube to accommodate loading and deflections.

Two-stage gearboxes are not new for Winergy.  The company also owns U.S. Patent No. 6,459,165 (’165 Patent), which is entitled “Drive train for a windmill” and relates to drive train architecture that utilizes a double row helical set of gearing.  It is possible that this prior IP has contributed to the design of the HYBRIDDRIVE system.

The ’165 Patent is directed to a transmission arrangement for a wind turbine including a rotor (1) with several blades (3) secured in a hub (2).  The rotor (1) is connected to a generator (6) via a two-stage planetary transmission comprising an input stage (4) and an output stage (5). 

The hub (2) is directly connected to the base (10) of the input stage (4) of the two-stage planetary transmission, which is entirely contained in the hub (2).  According to the ’165 Patent, this arrangement provides a more compact transmission suitable for higher outputs:

The object of the present invention is a wind-power plant that is more compact and accordingly appropriate for higher outputs, of 2.5-5 MW, is only slightly heavier, and is less complicated.  Directly connecting the hub to the input stage of the two-stage planetary transmission renders the transmission more compact.

Winergy also owns U.S. Patent Application Publication No. 2010/0160104 (’104 Application), entitled “Epicyclic gearbox for a wind power installation” and directed to a forced lubrication system on a two stage drivetrain. 

Lubrication is an obvious necessity of rotating machinery, but a forced lubrication system saves the cost of a separate external system with pumps and other associated components, and it can also improve overall drivetrain efficiency.  The ’104 Application discusses one way in which a forced lubrication system can be made to work for a two stage gearbox with independent channels for each stage

It remains to be seen if the new Winergy design will prove to be as good as the free floating CARB bearing design in terms of reliability and the ability to absorb loads.  Winergy advertised the HYBRIDDRIVE at 25 tons, which is very light if that metric actually includes the generator weight.  However, it was unclear from the self-contained drivetrain on display at the Expo whether the generator was integrated in what was shown.

One caveat to a lighter weight gearbox is that they need to be able to prevent deflections of the gearbox housing, which can lead to significant reliability issues.  Scrimping on housing mass to save weight might contribute to deflection problems and misalignments of their gears. 

We’ll have to wait and see if this is a long term issue.  If the 25 tons is just the gearbox without the generator, then this isn’t terribly light at all and the extra mass there may serve to inhibit some of those deflections.

The deflection issues are also prevalent because wind turbine OEMs are chasing higher capacity factor ratings with the increased rotor diameters, and the loads on the drivetrain and tower are increasing as a result.  The proof will be in the pudding for Winergy as they test and deploy this solution for Fuhrländer AG for their new 3MW, 120m rotor turbine for IEC Class IIa.

With the reliability of the direct drive systems yet to be proven, it’s great to see innovation on gearbox driven designs which take advantage of 30+ years of development and testing to enable more reliable solutions.  After all, as Winergy says, “Reliability is our profession.”

Totaro & Associates is an innovation strategy and patent search consulting firm.  To find out more please visit www.totaro-associates.com.

I attended the American Wind Energy Association’s 2011 Conference & Expo in Anaheim last week where I was able to see a lot of technology for turbines both large and small.

On the small side, at 3.5 and 7.5 kW, was Sonkyo Energy’s WINDSPOT turbine. 

The WINDSPOT features a proprietary blade pitch control assembly, and the Spanish company owns International Application Publication No. WO 2010/034861 (’861 Application) directed to this technology.

Unfortunately, I was unable to find a corresponding English language patent application, so I was limited to the Abstract of the ’861 Application and my conversation with the folks at Sonkyo’s booth to explain the technology.

The ’861 Application describes a rotating headpiece including a shaft connected to a cross-piece (14), which is connected via intermediate mechanisms (5, 8-11) to the end supports of (7) of the blades (6). 

When the cylinder shaft moves the cross-piece (14) the assembly varies the pitch of the blades (6).  Counterweights (15) can also vary the blade pitch of the rotor head. 

According to Sonkyo’s web site, its variable pitch technology “is a passive mechanism that uses the centrifugal force produced by the turning of the wind turbine to change the attack angle of the blades, which adjust themselves in a movement synchronized by the strength of the wind.”

At the utility scale, Muenster, Germany-based Kenersys’s 2.0 and 2.5 MW turbines employ the company’s SYNERDRIVE technology, which includes electrically excited synchronous generators.

Kenersys owns several international patent applications, including International Application Publication No. WO 2010/034760 (’760 Application), entitled “Excitation machine for a synchronous generator.”  Again, there do not appear to be any English-language counterparts for this application, so we’re limited to the Abstract.

The ’760 Application is directed to an excitation machine for a synchronous generator (13, 14) wherein the synchronous generator comprises at least two excitation modules (10, 9; 8, 9).  The first module (10, 9) is self-excited, and the second module (8, 9) is externally-excited.

According to the Abstract of the ’760 Application, the invention makes it possible to generate high outputs and provide cold-starting and operating capabilities at low rotational speeds or without connection to the utility grid.

by Philip Totaro, Principal, Totaro & Associates

The General Electric Company (GE) recently announced that it would take a 90% stake in Converteam for US$3.2B.  Converteam’s core technology focus is on converters and grid interconnect equipment for solar and wind as well as permanent magnet generators / motors for wind turbines and propulsion systems.

While based in Europe, Converteam has 19 issued patents in the US and 18 pending applications which have published so far.  As it relates to solar and wind, the largest portion of their portfolio deals with frequency and voltage regulation, and more specifically with active and reactive power control.

U.S. Patents Nos. 7,372,174, 7,511,385, 7,656,052, 7,692,321 and 7,755,209 all relate to a full power conversion system with a reactive power control approach utilizing a DC link demand signal as input to converter controller:It is interesting that long-time Siemens AG wind turbine technology thought leader, Henrik Stiesdal is listed as a co-inventor on these patents, highlighting the commercial relationships with Siemens for their 3MW direct drive wind turbine technology. 

With a cross license arrangement on key generator, converter and controls technology between Siemens AG and Converteam, this deal now provides GE with access to IP rights which they may need to continue operating their own technology.

In addition, Converteam has their own flavor of a variable speed control patent with U.S. Patent No. 7,405,490 (‘490 Patent) in which adjustment of active power output from the generator is based on input from the DC to AC inverter which is connected to the power grid. 

In light of the expiration of GE’s noteworthy and heavily litigated U.S. Patent No. 5,083,039 relating to variable speed control with an induction generator, the ‘490 Patent may be part of a suite of patents which helps GE protect the next generation of variable speed technology.

Converteam also has some patents relating to grid interconnection and generator technology.  U.S. Patent No. 7,471,532 is directed to a more efficient converter which requires fewer parts than the previous generation of technology. 

The move towards medium voltage on the power grid has been part of the emerging trends for the industry in the hopes of providing more efficient transmission of energy. 

U.S. Patent No. 7,675,271 deals with generator technology which helps the generator ramp up from standstill.  U.S. Patent No. 7,768,169, entitled “Magnet retaining arrangement,” and U.S. Patent No. 7,714,473, entitled “Electrical machines with reduced cogging,” both deal with permanent magnet generator technology which helps to enhance efficiency and improve reliability.

Converteam also recently announced that they are developing a superconducting generator, which they have termed HYDROGENIE for the hydro-power market.  According to a February 21^st press release (Converteam_Release) the company has successfully completed some basic testing of this technology and are moving towards full scale testing of a 1.7MW generator later this year. 

The superconducting generator technology is likely to be the subject of numerous patents and is also highly likely to be leveraged into their other lines of business, such as wind generators and propulsion.

This acquisition is a notable example of the previously identified trend in the wind industry for “grid friendly” wind turbines which utilize permanent magnet synchronous generators as well as full power conversion with the ability to control power factor and provide VARs to the grid.

With the Converteam patent portfolio, GE has now added to their 300+ patents in the wind sector with key technology that further strengthens their position in these future technology areas.

Please visit www.totaro-associates.com/articles for more information and to obtain the firm’s full wind turbine patent landscape study results or to download an offline copy of the summary.

GE, already dominant in the U.S. wind turbine market, is getting into the wind tower business, with a recent announcement that it would buy Wind Tower Systems (Wind Tower). 

Wind Tower is a Park City, Utah, company that designs towers for mounting utility scale wind turbines.  While most existing utility-scale wind turbine towers stand at 65-70 meters, the company’s modular tower technology and lift system enable taller towers (100 meters high). 

As this Greentech Media piece notes, taller towers permit longer turbine blades, which means more power per turbine.

Wind Tower’s product offerings include the Space Frame Tower and the Hi-Jack System for assembly and disassembly.  The company owns at least one U.S. Patent and several U.S. patent applications relating to its tower structure and lift system technology.

U.S. Patent Application Publication No. 2010/0226785 (’785 Application) is entitled “Structural tower” and is directed to a wind tower assembly that includes composite damping members or struts to dampen wind-induced vibrations in the tower structure.  Embodiments of damping members contemplated by the ’785 Application include a viscous or hydraulic damper and a spring element.  

The Hi-Jack System is protected U.S. Patent No. 7,877,934 (’934 Patent), which issued last month.  Entitled “Lifting system and apparatus for constructing wind turbine towers,” the ’934 Patent is directed to apparatus and methods for erecting a wind tower and turbine assembly.

The lifting apparatus (320) includes a pair of hydraulic rams (370) connected to telescoping members (375) of each of first and second lifting trusses (330, 331) via each hydraulic ram’s cylinder unit (371).  When the hydraulic rams (370) are retracted, the transverse beam (345) is positioned fore of the top bay assembly (317).

According to the ’934 Patent this position facilitates hoisting of a turbine, after which the hydraulic rams (370) are extended, causing the lifting apparatus (320) to pivot.  This raises the transverse beam (345) above the top bay assembly (317) to a position where the turbine can be lowered and secured to the top bay assembly.

U.S. Patent Application Publication No. 2010/0236161 (’161 Application) focuses on the hoisting part of the process.  The ’161 Application is entitled “Lifting system and apparatus for constructing and enclosing wind turbine towers” and is directed to Wind Tower’s gin pole lifting component.

According to the ’161 Application, a ginpole (601) can be used together with the lift apparatus (660) to lift or control the lift of the turbine or blade assembly (675) and can be used raise or lower the lifting apparatus (660) itself.

With GE scooping up Wind Tower’s IP relating to wind turbine assembly technology, Philip Totaro’s wind patent trendspotting piece predicting the increased importance of “‘on-site’ assembly procedures” looks very prescient.

We at Totaro & Associates have published a new study of the U.S. patent landscape of wind turbines to determine which technological trends have emerged so far and what we might be able to infer for the future direction of wind turbine technology.

Our study focused on the most prevalent sector of wind turbine technology – utility grade, horizontal axis wind turbines.

The methodology involved searching and aggregating relevant results using technology keyword classification, then analyzing those results to identify the degree of relevancy to the industry for each patent.  We found and analyzed over 1450 patents just for the US.

I.  Today’s Wind Patents:  (Mostly) Yesterday’s Solutions

Most of today’s wind patents solve yesterday’s problems.  The largest majority of inventions are directed towards blades, electrical systems and generators.  These are the components which have required the most quality, efficiency and reliability enhancement in the past 10 years. 

However, our study finds that controls and sensors have recently jumped towards the top of the list of patented wind components.  This signals a shift in focus towards performance optimization, load mitigation and grid integration in the coming years.

II.  Tomorrow’s Wind Patents:  Five Trends to Watch

Based on more recent filings as well as an analysis of more forward looking industry competitive intelligence we have been able to determine future technology trends.  New technologies, and subsequently the patents, will likely be directed towards five core areas. 

Reducing Component Weight and Manufacturing Costs

The first is component weight / cost reduction, and derives from the desire to maintain a tower head mass ratio (mass / annual kWhr) that is comparable to or better than today’s technology. 

Additionally, most OEMs equate mass with cost in their competitive cost of energy (COE) benchmarking, and rightly so given the expense of commodities, so many wind turbine manufacturers have introduced “cost-out” programs in the recent years. 

Expect these projects to lead to cost cutting innovations for which top tier OEMs will look to capture IP.

Facilitating Component Transport and Assembly

The next area of focus is on component transportation and assembly, which relates back to the mass and cost concepts as well as the physical transportation constraints which exist. 

As component sizes grow due to larger turbines being developed, the mass increases correspondingly, but excessive mass may incur excessive transportation cost.  The use of advanced modeling tools to optimize the amount of material used and predict failure modes becomes important. 

Furthermore, blades with a root diameter or towers with a base diameter beyond ~4.3 meters will face transportation hurdles in a land-based environment.  While it is possible to manufacture such structures inside these physical constraints, more material will be required to reinforce them, which is not an optimal solution in a cost competitive industry. 

Therefore, segmentation of towers and blades as well as “on site” assembly procedures and tools are likely to become of significant importance.  Proactive manufactures have already captured some of the core IP in this area.

Monitoring and Controlling Wind Turbines

The third trend relates to fleet management technology which centers around condition monitoring and control of turbines and wind farms.  While the first two future trends were focused on reducing COE from the capital cost side of the equation, this trend is solely based on minimizing recurring O&M cost. 

Technologies like condition monitoring systems (CMS), which can determine health of individual turbines in a wind farm as well as their components to the integration of CMS with control systems to enable optimal turbine output while still functioning within a dynamic operational envelope are being investigated and even deployed.  

Continuing to operate the turbine in an effort to mitigate unscheduled maintenance as well as planning of scheduled maintenance to maintain as much on-line capacity and up time as possible are important to both OEMs and the owners / operators of wind farms.

Integrating into the Utility Grid

Grid integration is the next trend, and the move towards the “grid friendly” turbine is already underway. 

Turbines based on induction generator technology have found it more difficult and costly to achieve ride-through, allow for curtailment or handle a “black start” where the grid is not present. 

Technologies around providing ancillary services to the turbine, as well as VAR support to the grid are of particular interest. 

The use of permanent magnet synchronous generators enables better efficiency and performance without sacrificing much in the variable speed range, and now with a high degree of interest in direct drive the use of this technology is likely to continue.

Optimizing Performance

Lastly, wind turbine and wind farm performance optimizations will continue.  This is something we have termed “Max energy output, all the time.” 

Controls for both curtailment and “uprating” due to prevailing conditions are being actively investigated by multiple OEMs. 

Also, as mentioned before, the integration of CMS with control systems will enable the determination of remaining useful life of components and the ability to operate the turbine to the maximum potential without incurring further damage.

The days of fixed pitch and fixed speed are over.

Please visit www.totaro-associates.com/articles to obtain the full study results or to download an offline copy of the summary.