October 2011

Wind energy off U.S. coastlines holds enormous promise. The U.S. Department of Energy estimates offshore wind capacity—generated in the Pacific, Hawaiian Islands, Gulf, Atlantic, and Great Lakes regions—at 4,150GW. While this projection represents total gross resource potential that doesn’t account for exclusion zones or siting issues, it is four times the current generating capacity of the U.S. electric power system’s 1,028GW. Beyond production capacity offshore wind has proximity value. With the 28 Great Lakes and coastal states in the continental U.S. consuming more than 75 percent of the country’s electricity, offshore wind would significantly reduce transmission costs based on adjacency to high-electricity demand centers.

However, the promise of offshore wind generated along our vast coastline is just that, for the U.S. has yet to place a single commercial turbine in the water. Public opposition aside, conflicting state and federal regulatory guidelines and immature permitting processes have slowed efforts to build the nation’s first offshore farm. These complexities, combined with the lack of a federal Renewable Energy Standard and long-term production tax credits, discourage much-needed investment.

Still, the untapped bounty is hard to ignore. The East Coast, particularly, has attracted the attention of developers who’ve pushed forward with permitting and related development phase efforts including marine surveys, wind resource characterization, power-purchase agreement (PPA) negotiations, leasing, and financing. For example, Cape Wind recently received its final permit after a decade-long slow boil, though it still faces financing and legal challenges, while Fishermen’s Energy projects off the New Jersey coast and Deepwater Wind projects off Rhode Island continue to make headway. Fishermen’s has in place all its N.J. state permits for its demonstration project in state waters and is awaiting approval from the New Jersey Board of Public Utilities of its OREC (offshore renewable energy certificate) application, while Deepwater has negotiated the PPA for its Block Island demo site and is conducting survey studies so it can obtain its permits.

The multi-layered issues that have slowed offshore efforts, particularly the Cape Wind project, have catalyzed federal and state agencies to shorten the development phase. One stated objective of recent initiatives announced by the DOE and Department of the Interior (DOI) is to streamline permitting processes, which they acknowledge are overly complicated. Not only are these processes untested by project stakeholders, including permitting bodies themselves, they suffer from a lack of baseline site data. While project development with its various permitting stages accounts for a small percentage of offshore wind’s estimated total lifecycle costs, these efforts have thus far consumed an inordinate amount of time and resources, and with the vast majority of ongoing work still in the development phase, it’s where project efficiency efforts should currently focus (see Figure 1).

“Offshore oil projects get permits in less than two years, but the offshore wind permitting process has so far taken up to nine years,” says Paul Williamson, director of the Maine Wind Industry Initiative, a multi-industry supply chain collaborative focused on developing the state’s wind energy resources. He cites the fact that the permitting process currently requires that developers invest in gathering survey data for an environmental impact statement (EIS) just to set up the meteorological tower or buoy to measure a proposed site’s wind resources. And then, if these resources are deemed viable, they have to conduct another EIS to pursue construction permits. “Oil developers don’t have these environmental requirements.”

Site selection and permitting takes into account a multitude of environmental, commercial, recreational, navigational, archaeological, and competing use factors. With offshore wind in its infancy there’s insufficient wind resource, seabed, and other site data to create the baseline needed to streamline future projects. As part of its Offshore Wind Innovation and Demonstration (OSWInD) initiative, DOE has stated it will work to coordinate data sets collected across a range of marine projects and create national databases for shared use by developers and other entities. But with permitting currently hampered by a shortage of this critical site data, the focus is turning to expedient data acquisition. Collecting the complex data sets required by BOEMRE (Bureau of Ocean Energy Management, Regulation, and Enforcement) in federal waters, the U.S. Army Corps of Engineers in state waters, and a range of other groups, requires a marine research team highly experienced not only in marine data acquisition, but in partnering with developers and other service providers to provide the best-quality data sets cost effectively.

As these teams increasingly collect and archive critical data across different projects, best practices for permitting and other aspects of the offshore wind development phase will emerge. With baselines in place and best practices to build on, developers, agencies, and other stakeholders will be positioned to work together to shrink project timelines, reduce costs, ease PPA negotiations, encourage investment, and spur development of the materials supply chain that will provide turbine components, foundation structures, cabling, installation ships and O&M vessels, and related elements.

A Challenging Goal
With broad estimates of more than 5,200MW of energy in first-generation offshore development underway in the Atlantic and Gulf of Mexico, developers—and the regulating agencies themselves—have seen the challenges caused by immature permitting processes and other development-centric regulations. Freshwater efforts in the Great Lakes won’t have to deal with federal regulations but will likely face their own intra-state regulatory issues. Projects in the Great Lakes include a pilot by Lake Erie Energy Development Corp. (LEEDCo), which has 20-30MW under development in Lake Erie’s Ohio waters. Through this effort stakeholders expect to gain experience with regulatory requirements and foster collaboration among permitting agencies as they move to larger project scenarios of 1,500MW up to 5,000MW. In addition, the New York Power Authority is reviewing proposals for 120-150MW of development in Lake Erie and/or Lake Ontario as part of its Great Lakes Offshore Wind (GLOW) initiative. First-generation offshore ocean efforts and projected energy output are outlined in  Figure 2.

In spite of its highly publicized problems, Cape Wind offered valuable insight into development phase difficulties, driving new federal initiatives and funding to speed projects. “Cape Wind was unique, with some very well-financed opposition to getting it in the water,” says Dan Shreve, director of MAKE Consulting, a Boston-based market intelligence and advisory group focused on wind energy. “We don’t expect those particular problems to be repeated, and they also catalyzed movement to streamline development processes [for site selection and leasing].”

For example, in the aftermath of Cape Wind, DOI, as part of its Smart from the Start Initiative, instituted a program to ease site selection and leasing by creating Wind Energy Areas (WEAs). Through the program, BOEMRE identifies specific zones suitable for development based on such criteria as water depth, proximity to seacoast, and navigational hazards, and packages pre-approved leases. Thus far the agency has identified four mid-Atlantic development zones on the Outer Continental Shelf (OCS)—off Delaware, Maryland, New Jersey, and Virginia—for commercial leasing by developers and has announced it would do so for sites off Massachusetts, Rhode Island, and North Carolina. It has initiated processes for both competitive and non-competitive leasing proposals and is expected to begin the commercial leasing process as early as next year.

After a WEA bid is accepted, the developer must then seek BOEMRE approval for several consecutive phases, each of which depends on satisfactory data. Based on exclusive rights to the leased area it submits its development plan; a site assessment plan for deploying meteorological towers or buoys for wind resource characterization; and finally a construction and operations plan, to which it attaches detailed site characterization data captured through oceanographic, geotechnical, geophysical, environmental, and archaeological surveys. Figure 3

“Permitting is seen as a major impediment to offshore wind because Cape Wind had a way of coloring the entire process as inherently impossible, but that view is getting tempered through recent efforts to streamline permitting,” says Jesse Broehl, advisor at MAKE Consulting. To date, it has taken up to nine years for developers to get full permitting in part because they had to do two EISs: one to get approval for the meteorological tower or buoy, and a second to pursue construction. The DOI is moving to allow conditional use permits to install met towers without conducting a full front-end EIS, which Broehl says “should knock two to three years off the permitting process.”

The More Data the Better
Each phase of an offshore wind farm lifecycle—from development, to turbines and transmission infrastructure construction, to full operations and, finally, to decommissioning—requires an enormous amount of marine survey data. Based on hard lessons learned in oil and gas projects, and more recently offshore wind projects in Europe, developers have learned that the more data they gather, the better chance the project will meet budget projections and timeline deliverables.

Given the challenges inherent in conducting data acquisition in dynamic and unpredictable marine conditions, developers must be able to rely on experienced research teams that emphasize data quality, efficiency, and safety as they employ the latest survey techniques to meet state and federal regulatory requirements. If developers cut corners on front-end data acquisition there’s a good chance they’ll suffer consequences down the road, as experience in gas and oil development has proven. While data acquisition accounts for a small percentage of overall wind project costs, an effort that is properly funded and thoroughly and efficiently conducted quickly pays for itself. Moreover, comprehensive data sets deliver exponentially larger financial benefits because they can, for example, prevent the need to remobilize personnel, vessels, and related assets caused by insufficient data for permitting and other requirements. In other words sound, sufficient data collection is relatively cheap insurance for protecting stakeholder investments.

For research teams to fully exploit their collective experience to gather the best possible data sets, they require a platform with state-of-the-art survey and deployment equipment, hardware, and software technologies. Though teams might be able to lease research vessels from universities or temporarily retrofit other-use vessels for survey activity, these approaches can negatively affect costs and efficiency. University research vessels, for example, are typically booked for university projects and therefore aren’t readily available for commercial work. And commercial research vessels already working in the Gulf on oil and gas projects might not have the financial incentive to leave the area, where they can currently charge up to a third more than they can for wind projects off the East Coast.

The best possible scenario is to hire coordinated data acquisition teams experienced in wind energy projects and get them onboard a dedicated survey research vessel, optimally one on which they’ve already worked gathering multiple-use data. The conditions in which these vessels must operate demand strong seakeeping in both shallow and deeper waters, superior positioning capabilities, line-keeping performance, and ideally a propulsion system that provides tight maneuverability with little noise disturbance. For surveying activity the vessel should be outfitted with dedicated cranes and winches, and incorporate progressive design modifications that enable numerous approaches to equipment deployment for geotechnical, geophysical, environmental, hydrographic, archaeological, and oceanographic surveys.

To maximize project efficiencies, research vessels should also be equipped for extended periods at sea—providing overnight accommodations, freshwater and fuel reserves, and onboard laboratories—to mitigate the costs and time incurred when traveling between a port and study sites. A laboratory with onboard data processing is particularly advantageous, as it allows for realtime data assessment. Onboard data analysis is a cost and efficiency differentiator for any offshore project, since it allows research teams to determine if a survey design needs to be modified while they’re already mobilized; for example, if survey data reveals that a cable route should be remapped. If teams demobilize and then determine through subsequent data analysis that they need to modify designs, they face a costly remobilization effort.

Don’t Reinvent the Wheelhouse
As part of the OSWInD initiative, DOE is working with DOI to coordinate efforts to help offshore projects deliver a targeted 54GW of offshore wind generating capacity by 2030, at a cost of $0.07 per kWh. It’s an ambitious goal given progress to date and the challenges involved. Agencies, developers, and other stakeholders must collaborate to shrink development stages to get projects into operation, or they can’t prove that offshore wind energy can be delivered at competitive price points.

The agencies’ joint National Offshore Wind Strategy plan includes an initial $50.5 million to fund proposals that encourage development of wind assets by improving technology and removing market barriers—including the lack of baseline marine and wind resource data—that drive up costs. And as part of Smart from the Start, BOEMRE recently announced that it is preparing a draft environmental assessment (EA) to gather public and other stakeholder comment on environmental impact before issuing commercial leases for potential WEAs. These EAs, according to BOEMRE, can potentially streamline efforts by helping agencies determine whether more comprehensive EISs are required before projects can move forward with preliminary wind resource characterization.

Stakeholders should also leverage lessons learned in offshore oil and gas projects and European wind installations to gather marine data in the most efficient, cost-effective ways possible. Reinventing data collection processes for U.S. offshore wind projects is cost-prohibitive and wasteful when best practices from oil and gas sectors and existing wind installations can be adapted.

The offshore wind industry benefits from a mindset that combines engineering and environmental innovation to drive next-generation energy technologies and production. While immaturity in the U.S. market has slowed projects, development efforts continue, delivering survey data necessary for wind characterization, turbine design, cable transmission routes, air and sea navigation, environmental impact, and a multitude of related assessments. Comprehensive national databases built from these studies will help provide the information needed to design an offshore infrastructure capable of cost-effectively delivering the output the U.S. requires to create a sustainable energy portfolio. 

With global wind capacity increasing by 22 percent in 2010 alone, according to the Global Wind Energy Council, this budding industry is currently undergoing a period of rapid growth and globalization. To help foster this continued development, suppliers to the wind-power industry need to understand the key trends and challenges associated with generating wind energy.

The wind-power industry must continue to seek new ways to increase the lifespan and reliability of wind turbines. Wind turbines not only require extreme protection against weather and mechanical forces, but also solutions that are long-lived and robust since no one wants to provide maintenance for an offshore system twice a week. As many engineers know, machines are only as good as their parts, and it is often the case that the smallest of components have the potential to have the largest influence on the lifespan and reliability of the entire system. Figure 1

Sealing—the act of preventing something from escaping or entering—is just one example of how a somewhat simple concept can play a critical role in the successful workings of the overall system. From a basic O-ring seal to more complex multi-part sealing systems, the simple act of “keeping something in or out” is a vital aspect in the proper function of wind turbines.

But with sealing, like many other functions within a wind turbine, you are only able to control one aspect of the process: in this case, the seal or sealing system. Other factors such as the counter surface (roughness, hardness), conditions of use (vibrations, shaft eccentricities), environmental conditions (extreme heat or cold), internal media (oil and grease) and so on are uncontrollable, and even unpredictable at times. As a result seal suppliers must recognize and understand these challenges in order to identify and develop the proper sealing solutions for the current and future applications and their accompanying environments.

A Singular Industry
The effort to develop and implement sealing solutions that maximize service life, while also minimizing costly downtime, can be influenced by a number of outside factors including environmental conditions (extreme temperatures, ozone containments, ultraviolet (UV) rays, and salty air) and surface characteristics, as well as external media and lubrication requirements.

Whether onshore or offshore, wind turbines need to withstand large-scale temperature changes. As a result sealing components need to be made with materials that are able to withstand these extreme fluctuations, especially extreme cold, without comprising shape, structure, or sealing ability. This makes the choice of material a critical component in the development of a proper sealing system.

In addition to extreme temperatures, these machines are also subject to a variety of harsh conditions on a daily basis. UV rays that affect a component’s rubber matrix and material characteristics and ozone containments that cause material cracks and breakdown, as well as geographic-specific conditions such as salty air, are all at odds against the proper sealing of a wind turbine. Further, the system’s surface conditions can also impact performance and seal behavior. The accurate evaluation of surface characteristics can provide engineers the needed information to better select or develop the best solution for the given application. Figure 2

Finally, internal media such as the oil and grease used for lubrication pose a particular challenge to sealing systems. Improper lubrication can cause increased friction and wear, which can result in decreased seal life as well as increased maintenance requirements.

To address these conditions wind turbine sealing suppliers are working to advance current technologies, as well as create new designs and systems, to prolong the service life of the overall system. The following will identify four unique wind-power challenges and discuss how sealing suppliers have successfully developed, or are working to develop, solutions to meet these evolving needs.

Wind Industry Challenge #1
• The Challenge: Sealing and protecting the pitch and yaw bearings of wind turbine generators.
• The Obstacles: High-pressure peaks in grease; tight fit (especially at low temperatures); and weather and media exposure.
• The Solution: Next generation material solutions and customer-specific profile seal designs that combine multiple disciplines to achieve the extreme sealing protection needed for this application.

New sealing material and design innovations are driven by the consistently evolving needs of the industry. As a result, there is an array of pitch seal options available to fit the specific geometries of various pitch bearings applications. A crucial element in addressing pitch and yaw bearing sealing challenges is improved materials solutions. Even more than design enhancements, material innovations are key to properly addressing wind-power sealing challenges, as the quality of elastomeric sealing materials is decisive for the functional reliability of the wind turbine generator.

Many factors can influence a material’s sealing ability and the service life of the overall system including mechanical loads, temperatures, greases and other media, ozone, and salt water. As a result, materials for wind-power sealing need to be durable, compatible with oil and grease lubricants, resistant to UV rays, the ozone, salty water, and more.

Two examples of industry-specific material solutions are the newly enhanced line of nitrile butadiene rubber (NBR) Ventoguard™ materials that have been specifically designed to offer superior low compression set (which is a direct measure for its durability as it determines the elastomeric lasting), grease and ozone resistance, and low-temperature capability. Ventoguard 453 and Ventoguard 454 are the next generation of Simrit’s line of established NBR materials designed for use in slewing bearing profile seals in wind turbines. Each material was developed to address a specific wind power-related challenge with the ultimate goal of helping prolong the maintenance cycle of the sealing application. Figure 3

Ventoguard 453 is a premium material that offers excellent cold flexibility, very good compression set, and demonstrates superior aging in several greases, including Klüber, Fuchs, and Mobil. Simrit’s Ventoguard 454, also a new premium material, provides superior compression set and is optimized for use in Shell Rhodina BBZ greases.

In addition to material improvements, a seal’s design is also evolving to meet the sealing requirements of the wind-power industry. As an example, Simrit has developed customer-specific profile seals targeted for large bearing movement that, due to a more subtle sealing lip contour, offers increased flexibility. This flexibility is particularly important as it helps ensure the proper performance during large changes in sealing gap caused by extreme operating conditions—windstorms or strong gusts of wind, for example.

The design incorporated an enlarged sealing bead for the rotating bearing rings, which reduces the profile movement considerably. This next-generation profile provides an enhanced groove fit to also increase the profile’s pressure resistance.

Wind Industry Challenge #2
• The Challenge: Ensuring consistent and reliable sealing of wind turbine transmissions.
• The Obstacles: Long-term, reliable sealing of the critically important main gear transmissions of wind turbines.
• The Solution: Labyrinth seals, a dynamically working seal that uses centripetal effects of fluids to prevent leakage.

Labyrinth seals work as a contactless and frictionless solution that provide extreme service life (20 years in some cases) and require little if any service/maintenance. For decades metal labyrinths have been an established solution for a variety of industries. For the wind industry metal labyrinths have shown to be difficult to assemble, especially at the bigger shaft diameter used in turbines.

One example of supplier innovation is the recently developed polytetrafluoroethylene (PTFE) labyrinth seal, which was specifically designed for large gearbox applications. Simrit is currently the only manufacturer of this type of seal. The Radiamatic RCD seal—which stands for reject, collect, and drain, the three key principles of function in what are known as liquid-collecting labyrinth seals—is a highly efficient solution that offers the prospect of a service life spanning several decades. The seal consists of two parts and features a rotating inner ring and a stationary outer ring. The inner ring is open (optionally) and kept in place on the shaft by springs that adjust to axial movements. The outer ring sits securely in the housing bore. Designed specifically to meet customers’ application requirements, the seal is adaptable to various designs and easy to assemble. Figure 4

The main components of the seal are made of PTFE, which means that they are chemically resistant to additive oils, are ozone resistant and slow to age, all of which are relevant for wind turbine gears. This, in conjunction with the non-contact operation of this sealing solution in wind turbine gears, means that the service life of these seals is expected to last several decades.

Wind Industry Challenge #3
• The Challenge: Preventing the contamination of elements in the main bearing seal.
• The Obstacles: External media such as dust, dirt and salty air.
• The Solution:  Innovative designs that incorporate new features, such as dust lips, to address wind-specific challenges.

Simrit worked to examine current designs of competitors to identify and improve their points of weakness. What resulted was the Simmerring Radiamatic R55 seal with a dirt deflector, which combines the main sealing and pre-sealing function into one design.

Previously used in steel mills, the design—which will be introduced to the wind industry shortly—consists of a static part made of rubber and fabric, as well as a seal lip made of rubber and containing a garter spring. The new design is compatible with mineral oils and greases. The solution also offers increased lifetime and better wear resistance, higher chemical, ozone and salty air resistance, and ease of assembly. Figure 5

Wind Industry Challenge #4
• The Challenge: Long-term, reliable sealing for harsh wind environments.
• The Obstacles: Extreme temperatures, dirt and dust, ozone, UV rays, etc.
• The Solution: Development and use of durable materials that extend the life of the seal and system. 

One example of an evolved solution that addresses the extreme environmental challenges associated with the wind industry is the Simmerring Enviromatic seal, which offers excellent protection against both dust and salty air. This innovative solution was created using a small line contact of seal lip, contrary to the standard use of V-rings, to guarantee protection of the main seal. Uniquely, the seal operates with the separate functions in individualized, optimized parts.

Working to strengthen the sealing lip of previous V-ring designs, Simrit developed its Enviromatic seal as a premium solution. By incorporating the improved HNBR material Ventoguard 467 and optimizing the design using finite element analysis, the new solution offers improved stiffness, contour, and function that results in more reliable protection and increased wear resistance.

Conclusion
During this time of rapid growth and evolution, wind-power suppliers are tasked with continually driving the development of solutions that address the unique needs of this extreme industry. Adding to the complexity is the sheer size of wind turbines as well as the difficult service conditions, especially in offshore locations.

With the ultimate goal of increasing reliability and lifespan always top of mind, new products and systems need to be expertly constructed and tested, as only the most superior of innovations will allow the wind industry to continue to grow at its current pace. 

In the United States today the total wind fleet stands at approximately 41,000MW, creating enough clean energy to supply 10 million homes. In the first part of this year 1,100MW of new capacity was installed. At the same time about half the power consumed in the United States today is generated with coal. Nuclear is next at 20 percent, natural gas at 18 percent, and hydroelectric at 7 percent. Together, renewable sources like wind and solar make up only 2 percent of all the power generated in the United States. As wind power is the fastest growing sector in the global power generation industry it is projected to continue in the same trajectory.

Our collective demand for power continues to increase, and in the next 20 years our demand for energy is expected to double. To meet our ever increasing energy needs, new and improved alternative and renewable energy sources are becoming an extremely viable solution verses the past. Wind power is a critical part of the solution.

Robust, Reliable Circuit Protection
Simply put, wind power is remote and variable. Wind resources are often far from significant markets and plant output varies with wind conditions, creating a variety of public and electrical industry challenges. As wind projects need to be at the site of the wind source, the generation location is often remotely located from the electric load, and there is often reliance on long-distance transmission. Wind farms require a complex collection of equipment that needs to work together efficiently so as to generate electricity and transmit it to the grid. Industry leading manufacturers are engineering equipment able to address the unique needs of wind power applications. Figure 1

Medium-voltage circuit breakers with enhanced capabilities and industry leading protective and monitoring devices make it easier to get generated power into the system, so that it can be distributed and used. While addressing the requirements of wind turbine applications there are circuit breakers engineered to improve uptime, reliability, and sustainability while enhancing safety.

Circuit Protection for Wind
Fundamentally, wind turbines convert the energy captured from wind into electricity. A turbine captures wind’s kinetic energy and converts it into electricity through the action of blades, which are connected to a generator. The generator converts the blade’s rotational movement into electricity at low or medium voltage. Typically this voltage for small- and mid-sized wind applications ranges from 500 to 700 volts (V), although utility-scale turbines are capable of generating thousands of volts. From the generator, electricity flows through heavy electric cables to a substation transformer, which increases the voltage of the electric power to a distribution voltage. The distribution voltage is usually in the thousands of volts range; a common distribution voltage range is 15 kilovolts (kV) to 38 kV. From the transformer, the distribution power flows to a collection point, where the power can be combined with other turbines. In some cases the electricity is utilized locally, though it is typically sent to a substation where the voltage is increased to a high transmission level for efficient delivery to faraway cities and facilities. Figure 2

Eight Key Characteristics
With the right equipment and support, wind farms are able to lower lifecycle costs. Remotely located equipment should be selected based on its reputation for minimal downtime, operational longevity, extended maintenance requirements, and extra performance capabilities.

As the design and operation of wind plant power systems has unique challenges, electrical equipment manufacturers can help address these concerns. Intermittent power generation can pose problems for the supporting electrical equipment, which may not be designed to cater to these notable variations. Evaluating and monitoring processes of all electrical systems within wind plants should focus on a range of issues, including: the unpredictable nature of wind power, remote locations, frequent generator operation, voltage regulation, frequency considerations, thermal and fault issues, system dynamics including capacitor operations, reactive power management, event analysis, and system and equipment performance.

Specifically, medium-voltage vacuum circuit breakers can address the rigorous requirements of wind turbine applications and improve uptime, reliability, and sustainability, while enhancing safety. Specific considerations for specifying such circuit breakers include:

1) Proven Technology: Incorporating proven vacuum interrupting technology, medium-voltage circuit breakers should be designed to reliably switch normal and high-stress currents. A global manufacturer, Eaton is applying more than 80 years of innovation and experience to its circuit protection solutions for wind power applications.

2) Green and SF6 Free: Avoid use of Sulfur Hexafluoride (SF6), which poses environmental and safety concerns. SF6 is a colorless, non-flammable gas often used in circuit breaker applications above 38kV. It is finding its way into lower voltages in the U.S. in the form of as insulated switchgear (GIS), which uses SF6 for its insulation system. In the case a leakage occurs during system operation, or if cleanup is required after equipment failure, toxic byproducts can be produced, and SF6 poses safety concerns. Further, dismantling and disposing of circuit breakers that rely on SF6 can result in similar exposure. If there is excessive moisture, toxic byproducts can be produced during the course of normal arc interruption. Today you do not need to rely on SF6 gas for insulation materials. A leading power management company, Eaton developed industry leading vacuum interrupting technology that requires no cooling or ventilation systems, and avoids the use of SF6. Eaton has been solid-insulation technology in a wide range of applications for more than 50 years.

3) Compact Footprint: Using compact circuit breakers can mean that the switchgear footprint is compact as well, by enabling the voltage transformers to be in the top compartment of the switchgear. For example, Eaton VCP-Wind breakers allow the assembly to be mounted above the breaker to save space.

4) Remote Racking for Enhanced Safety: Remote racking devices connect to breakers and allow personnel to insert and remove them while standing outside the arc flash protection boundary. Eaton engineered remote racking devices to increase distance between the operator and the front of the switchgear lineup during racking operations, putting 25 feet between the operator and the switchgear.

5) Protected Components Reduce Maintenance: Pole units that are encapsulated protect high-voltage components from the environment. The Eaton VCP-Wind breaker is engineered to require reduced maintenance over the product lifecycle.

6) Easy Access: A direct roll-in configuration, like that of Eaton VCP-Wind breakers, makes it easier to handle and relocate the breaker.

7) Customized Design: Circuit breakers engineered for wind applications can be customized to accommodate specific installations with the right accessories, making it easier to integrate the breaker into a switchgear design. For example, Eaton engineered:

• Spouts accommodate the mounting of six sets of current transformers per phase;
• Distinct latch positions for disconnect, test and enclosure;
• Coding pins so that only breakers of the correct ratings can be inserted into the enclosure;
• Trip-free interlocks prevent moving a closed breaker into or out of a the connect position;
• Self-aligning and coupling primary and secondary disconnecting devices.

8) Certified to Meet and Exceed Requirements: Since wind is relatively new to the generation market, policies, opinions, and available electrical equipment have a tendency to favor older and long-established generation techniques. Be confident your equipment is rated to meet and exceed minimum requirements. Eaton VCP-Wind circuit breakers meet American National Standards Institute (ANSI) and Institute of Electrical and Electronics Engineers (IEEE) C37.09 standards.

Eaton is investing significant resources into developing a wide range of solutions to meet the demands of the wind power industry. Building on more than 80 years of circuit breaker innovation, Eaton engineered circuit breakers to specifically accommodate for the conditions in wind power applications. Designed for wind farm collector substations, the Eaton VCP-Wind breakers help to improve system reliability, efficiency, sustainability, and enhance safety. 

The successful development of wind power projects requires reliable projections of the productivity and longevity of the assets being installed. The wind itself is a complex, variable, and intermittent resource, however, which introduces a high degree of uncertainty into any prediction. Recently, cutting edge techniques based on laser technology have been pioneered which tackle key contributions to this uncertainty.

Knowing the Unknowns
Project uncertainty can be broadly described using two categories. Typically, wind data are acquired from instruments on a met mast at a location somewhere on the project site and the conditions at other proposed wind turbine locations are approximated from these data using wind flow models which represent the influence of the terrain, obstacles, and other wind turbines on the flow. The uncertainty introduced by these approximations is an example of what might be termed “space-domain” uncertainty, which arises because our data obtained via measurements do not directly represent the full spatial extent of the wind power project, just the mast location. Another example of space-domain uncertainty is the extrapolation of measurements to heights above the top of the mast.

“Time-domain” uncertainty occurs because our datasets do not directly represent the full life cycle of the project, but rather a short term measurement campaign of one or two years during which data have been acquired. This uncertainty can be reduced by comparing the short term data from the project site with data obtained over the same period at another reference site for which longer term data are available. The relationship between the sites established using the short term data is then applied to the long term data to form the basis of predictions of the resource available for exploitation over the life of the project.

Progress in reducing time-domain uncertainty is slow and piecemeal, relying on the adoption of ever more sophisticated statistical and mathematical techniques to tease from the short term data information that can be applied to long term projections. However, dramatic reductions in space-domain uncertainty are now available as a result of LiDAR technology which enables significant improvement in our understanding of flow across the site in the space-domain. This is important since the level of uncertainty pertaining to a project determines the level of annual energy production that can be taken to be sufficiently reliable to service the debts raised to finance the project.

Rise of the Virtual Mast
For a few years now the limitation of masts, in terms of being restricted to a single location rather than acquiring data from multiple locations across the project site, has been mitigated to some extent by the adoption of first-generation remote sensing solutions. These have been seen as “virtual masts”—robust, compact, portable solutions that can be simply and easily deployed to locations of interest to acquire mast-like data using sonic or laser probes. In this way they remotely measure the wind at height, for example, to distinguish which of two differing model predictions most accurately represents reality. As a result the contribution to project uncertainty from the influence of the terrain can be reduced. More recently LiDARs, which use laser technology, have been seen as offering a greater degree of flexibility and accuracy than SoDARs, while at the same time SoDARs, which use sound pulses, do not represent the same expense.

Second-Generation LiDAR
The laser beams used by LiDARs interact with the wind in such a way that a single beam does not provide a measurement of the wind speed; rather, the data from multiple beam orientations must be processed in combination to derive a wind velocity vector. If a single device is used to achieve these beam orientations by scanning the beam, then the beams necessarily diverge from the device and define a volume in space. One important consequence of this is that if the flow is not uniform, for example, as a result of the influence of complex terrain, the wind velocity will vary within this volume, exposing each individual beam to different velocities such that a single unambiguous wind velocity cannot be derived from the resulting measurements.

This issue was one of the principal motivations for the development of the second-generation of LiDARs for wind power applications. First-generation LiDARs have a single degree of freedom. This limits the range of beam orientation they can use. Second-generation LiDARs have two degrees of freedom: both the azimuth and elevation angle of the beam can be adjusted, and so the beam can point anywhere unencumbered by restrictions and implement any pattern of beam orientations, or “scan geometry,” including the one most suitable for any given application. So whereas first-generation devices are limited to surveying the wind immediately above them like virtual masts, second-generation LiDARs can measure anywhere within the range of their laser. And whereas first-generation LiDARs must use models in complex terrain to approximate the non-uniformity of the flow within the volumes defined by their scan geometries so that they can adjust their measurements to compensate for it, second-generation LiDARs directly measure these inhomogeneities, and so do not compromise the priority of direct measurement over model approximation by adjusting any measurements.

The Arc Scan
An example of a second-generation scan geometry is the arc scan. This involves varying the direction of the beam through a range of bearings, or azimuths, while maintaining a constant low elevation angle, close to horizontal, to measure the wind some distance from the device. Figure 1 shows an example of this. Laser beams are shown emitted from the device location to scan through a reference mast located 500 meters away. The wind speed time series measured over a two-week period by the mast and the second-generation LiDAR are compared in Figure 2, where the mast data is shown in blue and the LiDAR in green. Excellent agreement is observed. Indeed the arc scan measurements easily satisfy all published acceptance criteria for the performance of first-generation devices installed immediately adjacent to the mast, except in this instance the measurement has been made from a distance of 500 meters away using second-generation techniques.

From Pixel to Picture
Comparison studies to determine the extent to which remote sensing devices replicate the capabilities of mast mounted anemometry will always be necessary as long as only mast mounted instruments can be assessed under controlled conditions in wind tunnels which have been inspected and certified as compliant with national standards, since this establishes the traceability of the accuracy of field measurements. Nevertheless, a mast only provides a single pixel of the more complete picture that represents flow across the entire project site. Second-generation instruments deliver this complete picture. Figure 3 shows a plan view of wind turbine wakes directly measured using a second-generation LiDAR that has scanned its beam across the site over the course of about one minute. Here we see the accuracy demonstrated above for an individual pixel by the arc scan extended to the visualisation of flow across an entire site.

Productivity and Longevity
The complex nature of the wind has significant consequences beyond the predictability of power production. Some resources are relatively benign: the loads imposed on a hydro plant in the routinely inspected and maintained confines of a turbine hall are constant and predictable. In comparison, the loads the wind imposes on wind turbines, of which there are many more situated in locations that present access challenges, are much more severe. In comparison to other resources, the wind is constantly trying to break our machines. The urgency with which we must increase the sophistication of our assessments of the loads imposed by the wind on wind turbines is only rendered more intense by the creeping inadequacy of the models and methods we currently use which, while useful hitherto, are gross oversimplifications in relation to the conditions prevailing across the rotors of the larger machines now being developed and installed. The kind of detailed, precise, and accurate representation of flow across an entire site illustrated by Figure 3 contains critical information that is indispensable for the assessment of site suitability.

Whereas Figure 3 illustrates a plan view of wind flow, a vertical cross-section can also provide useful insights. Figure 4 shows a wind shear anomaly known as a low level jet surveyed using this technique. The color scale shows the wind speed. High wind speeds are observed at one height while lower wind speeds are seen above and below it. The variation of wind speed with height can impose serious loads on a wind turbine. In this instance the low level jet was observed in a location in mid-plains U.S., where its diurnal evolution during the summer months results in a short period of 10 minute to half an hour during which turbine killing loads are imposed across the rotor. The low level jet rises and becomes more intense during the course of the morning and imposes its most extreme wind shear loads on the rotor and drive train as it passes the top tip of the rotor. The comprehensive investigation of this phenomenon has only been made possible by the advent of second-generation LiDAR.

Complex Terrain Issues
The silver bullet that dispenses with the issues that plague first-generation devices in complex terrain is the implementation of a convergent scan geometry. Rather than use beam orientations that diverge from a single device to define a volume within which flow inhomogeneity can be manifested, we can use multiple second-generation devices to direct our beam orientations to converge at a point. This is illustrated in Figure 5, where data are presented comparing measurements made using three LiDARS implementing a convergent scan geometry with a reference mast. At heights where more than one reference instrument is installed on the mast it is seen that the LiDAR measurement lies between the reference measurements; that is, the LiDAR agrees with the reference instruments better than the reference instruments agree with each other.

Looking Forward
The need to deliver the greatest reduction in project uncertainty for a given investment in data acquisition will continue to entail the operation of different kinds of instrument used in the manner that most effectively exploits their respective complementary strengths. The main cost of a mast is incurred during installation, and so these are most useful for acquiring a year or more of data. In addition they are well understood and so are good reference instruments to which other devices can be compared on site to verify their performance. SoDARs are relatively inexpensive and have low power consumption, and so they have an important role to play in any measurement campaign.

In many instances when the cost-benefit of using a LiDAR in a virtual mast role to acquire a single pixel of data is analyzed, it is found that better value can be achieved using a real mast. Achieving optimal cost-benefit of LiDAR requires that it is used to do things that are difficult or impossible to achieve otherwise. In general the possibility of acquiring the complete picture as opposed to an individual pixel indicates we must ultimately dispense with the mast analogy to unlock the value of LiDAR. Only then can we realize the ambition to eliminate project uncertainty that arises due to our incomplete understanding of flow across the site, leaving only uncertainty due to the intrinsic variability of wind over time.  

The ability to inspect a wind turbine without the risk of personal injury is only one of the benefits of the new AutoCopter™ industrial strength, unmanned radio controlled helicopter. We have already demonstrated the benefits of this tool with cell tower and transmission wire inspections, so wind turbines were a natural area of our focus.

To provide a little background, we began with roof inspections of hail damage, and we then moved to aerial photos and videos of farms. We next worked with cell tower companies, and then with the utility companies. The AutoCopter provides the aerial platform for any type of viewing and recording, for determining present conditions, and/or for documentation of completed repairs and inspections, etc. With over 200,000 turbines in the world—and almost 50,000 in the United States, with the numbers growing—we felt the market was a good one for us to enter. In preparing for this article we found that there is a shortage of climbers, resulting in inspection schedules that are difficult to keep. We believe that our solution will be warmly received. We also found that the industry needs proper training, the need for safer methods to conduct the inspections, and the reduction of danger of the overall inspection process. Figure 1

In terms of their dimensions, AutoCopters are 62” long, 20” tall, and they will fly to the necessary height required for wind turbine inspections. The ability to survey the area from above provides an “eye in the sky” perspective on current conditions or damages. Stabilized software, and AutoPilot software models are available. Features include full auto take-off, waypoint (GPS) tracking, and auto landing. The ability to know the exact location of the camera at any given moment allows for complete documentation while the inspection is in progress.

Our original vision was to be the alternative to the manned helicopter. We have the ability to provide close-up aerial visibility, and to record it without the risk of injury to personnel. The fact that our UAV helicopter costs less than two dollars per hour to fly, will fly all day on a five-gallon can of gasoline, and produce the same visual results as a manned helicopter has been one major reason for our success.

Flexibile Flight
Within five minutes of unloading the AutoCopter it can be at the top of the wind turbine, carefully examining the structure and the blades from any angle. As it flies it is filming in HD video. The ground control station receives live video and is able to see what the helicopter sees as it flies. While this is being done all personnel are safely on the ground, incurring no risk whatsoever. Figure 2

We know that the wind turbine inspection process also requires an internal check of the mechanical and electric heart of the turbine. The AutoCopter can climb to the top in less than 10 seconds, provide aerial shots from above, and methodically view and record from top to bottom. The overall process time is reduced and the results of the inspection are improved because they are recorded in one or two formats: HD video, and infrared/thermal. In addition, the process of observing and recording each turbine blade does not require repositioning the blades after the system has been stopped and turned off. They can be filmed wherever they cease rotation, which helps to reduce downtime. The foundation area directly around the turbine will also be captured on film for immediate analysis.

Maximizing Manpower
We see this “power tool” as an addition to the arsenal of tools and skilled operatives in the wind building and maintenance company’s toolbox. Training takes less than three days, inspection capabilities will be enhanced, your risk of personal injury will be dramatically reduced, and you will be able to allocate staffing ways not possible before. Figure 3

From a simple staffing viewpoint, the operator of the AutoCopter does not need to be a climber or a technician. He or she can be a less costly remote-control helicopter pilot trained for the tasks required. The areas of concern are the flight, recording, video downloads, and creation of the DVD. A recorded history of each wind turbine inspection will be available on the site for future inspections, in the office, and at the client’s location. This would help to expand the limited supply of climbers, thus enhancing the abilities of the inspection team/company. There is also the ability to view and record the condition of bolts, cables, ladders, paint, oil spills, and safety equipment in minutes. Once the exteriors have been viewed, filmed, and analyzed, the AutoCopter crew—both man and machine—can move on to the next location.

We realize it would be illogical to think that the climber could be removed from the equation. We also know our “power tool” would help to expand existing resources, dramatically shortening part of the inspection process and allowing for a different focus for the climbers. Additionally, the cost is reduced and the quality of the inspections has actually been improved because the helicopter uses better optics to view and record what it sees. The additional benefit is that the AutoCopter does not get cold or tired, or need strength and agility to observe the surface. What now takes half a day manually will take only 15 minutes with the AutoCopter, at most. The need for cranes on location might be reduced, and tighter scheduling can be incorporated if the inspections are reduced from weeks to days.

Safe Strategy
Perhaps the most important feature of utilizing the AutoCopter is the ability to keep people on the ground for the entire exterior inspection process. While the helicopter is flying and recording, the images are being sent to the “ground control station” for observation. Skilled technicians can monitor the flight and ask the pilot to go back or to zoom in as it flies. Because the GPS location and altitude are visible on the ground control station as it flies, you can pinpoint the areas needing attention, repair, or just another look. Figure 4

When and if repairs are needed, the team knows the exact location on the turbine. Because it is GPS enabled, it also points to the repair’s exact location on the turbine. The inspection team has looked at it up close while still on the ground and knows exactly what tools and materials are needed before they climb the tower. The ability to reduce the number of climbs would have a beneficial effect on personnel and safety.

The need for inspection often conflicts with tightening budgets and the resistance to taking the unit out of service. When taking pictures from the ground you’re looking up, which can’t provide the same view as if you were at eye level. How would you get pictures from above as part of the routine inspection before the AutoCopter? Slight leaks might be visible in the air but not from a ground camera, because of the angle or location.

Increased Efficiency
For the turbine to maintain the maximum output, the blades need to be inspected and maintained regularly. If blade maintenance is a critical factor and would benefit from more frequent inspection schedules, there is now the possibility to send someone to inspect, armed with this new power tool and record conditions.

With the growing number of wind turbines operating out of warranty this poses additional worry, because they must be serviced more frequently. It would not be too costly to send man and machine for a quick check after lightning or hail storms, for example. And since time equals money, the following scenario detailing the inspection of 45 turbines might be useful to consider:

Plan A
• Inspection and shutdown on August 1 forward;
• Inspect the wind turbines, typically two per day;
• Projected total time for inspections is 22-plus days (min.);
• As external damages are discovered, they would be repaired;
• If internal repairs would be needed, they would be repaired;
• Timeframe of total group inspection varies as requirements dictate.

Plan B
• Planned inspection and shutdown on August 1
forward;
• Inspect all units first with the AutoCopter’
• By August 3, all exterior inspections are complete;
• In less than two days (plan for 10-12 minutes per turbine inspection) all turbines are inspected;
• The results have been recorded, documented, and archived on DVD;
• Images of damages found can be forwarded to the home office for repair provisions, if not available in the field;
• While the internal inspections still remain, all exterior inspections are completed and any repairs needed can be started;
• The knowledge of the condition of the exteriors of the towers and blades before the end of the second day will enhance planning and staffing.

So, in less than three days 45 turbines have been inspected. If the results are that six of the 45 have exterior damage and are in need of repair, and four have items to watch but do not represent an immediate need, the time spent in the field is reduced. Therefore, if you take Plan B into consideration you would inspect four per hour, with the inspection of 28 per day (seven hours of inspection), resulting in 140 per week. Assuming bad weather and other variables, one man travels to sites for 120 working days per year. With a total of 3,360 wind turbines inspected, if you assume a cost of $400 per day—$200 pay plus $200 expenses—the cost for all 120 days is $48,000, and the cost per turbine inspection is under $15.00. We believe this is a number that deserves some attention.

Infrared Recording
Our work using an HD video and the infrared/thermal camera with a fire department in Europe expanded our capabilities to add this inspection tool to the aerial platform. The structure flaws result in temperature variations and are shown on film. A complete infrared/thermal recording can be done while the HD video is recording. This does not extend the time of flight because both cameras are recording at the same time. Maintenance and repair schedules can be amended after such a thorough inspection, helping to prioritize maintenance and reduce repairs. Figure 5

Last Call
When a turbine is constructed the need to evaluate the condition before it is turned over might be helped by the aerial inspection of the AutoCopter. A physical and infrared/thermal evaluation while the contractor is watching the ground control station might help confirm questions, issues, and mutual agreements.

When a turbine warranty is about to expire, the “last call” for issues both visible and hidden is important for the cash flow future of the turbine. The ability to predict and prevent costs is important. How much better is it to be able to illustrate on film the issues requiring attention and/or repair? Because the film is recorded to DVD there is a written, embedded date and time stamp that meets the best evidence rule as a legal document, all the way up to the Supreme Court. If you had an Infrared benchmark record and you provided an end of warranty record, how do you think your complaint might be received? It also eliminates the process of handwritten notes and visual inspections with geo-referenced, recorded video that captures critical information meeting annual inspection requirements.

Based in Charlotte, North Carolina, the AutoCopter Corp. help solve problems on four continents in various applications: cell tower inspection, real estate, agriculture, industrial inspections, firefighting, search and rescue, observation and surveillance. The company’s products are easy to use, designed for use in the field, and ready to use when shipped. Just uncrate, add gasoline, and you’re on top of the wind turbine in seconds.