July 2011

The demands of the industrial environment are ongoing, with ever-changing trends. Cables that were able to sustain functional and operational integrity a decade ago would not be adequate to survive in the environment of a presentday manufacturing site. Everywhere from the renewable energy industry and automotive assembly plants to the factories that manufacture small office machines, and even in some commercial buildings, the oil resistance of cables has become increasingly important.

Oils serve a dual-purpose role in industrial applications, both as a coolant and lubricant, depending upon the requirements mandated by the end use application. Sustaining trouble-free cable operation under harsh chemical and environmental conditions reduces costly manufacturing downtime and helps to eliminate or minimize periodic maintenance and costly cable replacement. All of the factors mentioned play a major role that is critical to a consistent, smoothly run manufacturing operation, which in the end results in higher profit margins.

Regulatory and Code Changes
With the changes to the National Electrical Code (NEC) in the past 10 years, protective conduit or raceway is no longer required when running an exposed run (-ER) cable from the tray to the equipment or device. Previously, when the cable was extended from tray to machine, conduit or raceway was used primarily as a protection mechanism in helping to prevent cable damage. Originally TC-ER cable (previously printed “open wiring”) had a length limitation of 50 feet from the tray to the equipment. The 50 foot allowances resolved a large “grey” area in the industrial environment and was initially a well-received solution by the industry. Figure 1

Due to the overwhelming acceptance of the 50-foot length allowance, the NEC committee enacted further changes shortly thereafter, permitting unlimited length of TC-ER under Article 336. With the advent of unlimited length, Article 336 also brought other issues, like a greater area of cable exposure and susceptibility to the surrounding industrial environment. Under the typical conditions of operation, consideration for factors such as ambient temperature, a cables’ mechanical strength, unintended movement, and constant exposure to industrial lubricating and coolant oils must be taken into account. When exposed to these conditions the cable inevitably will begin to deteriorate; the overall jacket may swell and/or crack, creating a potentially hazardous condition, along with machine and production downtime. These possible problems are undesirable and necessitate the need to implement cable protection measures. Figure 2

When referring to NFPA 79, the electrical standard for industrial machinery, Machine Tool Wire (MTW) is one type of cable permitted. Under the standard for machine tool wire, UL 1063 passing the Oil Res I test is required, and further severe testing such as the Oil Res II is optional. Environmental resistance tests, such as those per UL Standards were implemented in response to the globalization of industry with the goal of standardizing the oil resistance requirements of cables used in manufacturing industrial machinery throughout the world.

Purpose and Application
Why does oil cause such excessive damage on certain types of insulations and jackets, and how does this occur? All compounds are not the same. For example, certain types of PVC have a higher degree of flame resistance while others have better oil resistance, and some demonstrate improved flexibility characteristics. PVC formulations vary greatly depending on the desired properties and applications. These properties can be achieved by adjusting the formulations of a particular PVC compound. The modification or addition of flame retardants (iodine), stabilizers, and fillers allow the compound to exhibit these types of enhanced characteristics. However, when certain PVC characteristics are improved, the enhancement sometimes comes at a cost, with the cost being that other performance traits are affected or completely lost. Figure 3

The specific application will determine if oil is used as a lubricant and/or coolant. Acting as a lubricant, oil would be applied to a gear system driven by motors to prevent premature wear down and insure smooth operation. Acting as a coolant, oil is applied during the machine lathing process to keep metal from becoming too hot. In the field cables can be exposed to oil in a wind turbine nacelle where oil is used in the gearbox. Cables that lay in the floor of the nacelle are subjected to oil that is unavoidably spilled. These cables are then exposed to oil for very long periods of time, along with other extreme high and low temperatures, causing the lower quality jacket compounds of a cable to crack. There are many factors involved regarding how oil will attack wire and cable such as exposure, ambient temperature, and also possible continued immersion. In general, increases in the amount of exposure, the frequency and the ambient temperature, the faster oil will start the deterioration process. In short, oil attacks the insulating compound, where it will become virtually ineffective in its primary role as an effective insulator. This action can create a possibly very hazardous situation, and not only to human life, but also to the overall function of the industrial machinery to which it is connected. This results in very expensive downtime, costly repair, and in the worst-case scenario, entire replacement of the machine. Figure 4

What Happens
All wire and cable insulations are not created equal. Electrical, environmental, mechanical, and chemical attributes will vary depending upon the individual compound formulations. Insulating compounds contain a specific amount of plasticizers in their individual formulations, which help promote flexibility and resistance to fatigue. When compounds are exposed to lubricating and coolant processing oils, the material either absorbs the oil or the plasticizer will diffuse from the compound. When oil is absorbed it causes severe swelling and softening of the compound resulting in degradation of tensile properties. When the oil causes diffusion of the compound plasticizer, hardening will result, and all flexibility and elongation properties are lost. The attached pictures will illustrate the effects that oil can inflict on cable jackets and insulation. Figure 5

These pictures verify that the damage caused by oil exposure is irreversible and creates hazardous conditions. Now, in addition to cable replacement costs, there is also the expense ofreinstallation to be taken into account. To avoid these types of unwanted scenarios the customer must review the properties of the cables they are about to consider for their application and determine suitability for the oil environment. There are UL tests that help determine how a cable will react in the industrial oil environment. These tests are more commonly referred to as the Oil Res I and Oil Res II tests, which involve continuous immersion of the cable samples in IRM 902 at elevated temperatures for a specified period of time. Passing results are determined by the evaluation of mechanical properties and observations of physical damage caused by the oil exposure. In 2000, Lapp as an innovator and leader approached UL about creating tougher standards, which resulted in the creation of AWM style 21098. Table 1 indicates the industry standard tests that are used to evaluate wire and cable oil exposure performance.
 
Example of Tensile and Elongation Test Methods
Let us assume, for example, that the cable jacket of your product is going to be tested for compliance to UL Oil Res II. Tensile and elongation tests must be performed both on the original (unaged) and oil immersed (aged) test samples and must be prepared as defined under UL Standard 2556. Die cut dumbbell specimens are taken from the jacket and are then tested for tensile strength and elongation. As for sample preparation, two marks are applied approximately 1.3 inches apart from each other and equidistant from the center of the dumbbell sample (see Figure 6). These marks are applied at right angles to the direction of the pull in the testing apparatus. The sample is then clamped on the tester with one-inch marks outside of and between the grips. The grips are then separated at the rate of 20 inches per minute until the sample breaks. Results are then recorded for elongation and pound force breakage; tensile strength is calculated by dividing the pound force by the cross sectional area of the specimen. Table 2

Untested die cut samples are aged under the UL Oil Res II requirement of 75°C for 60 days. After 60 days, the samples are removed from the oil for a minimum of 16 hours. They are then tested for tensile and elongation, which must retain 65 percent of the unaged values. You will find an example for an Oil Res II test accompanying this article. Table 3
 
Conclusion
The oil resistance of cables has now become a critical performance parameter when electrical contractors, engineers, and installers specify cables for end use application designs. The continued growing popularity of oil resistance requirements is due to changes in standard regulations and the increased performance characteristics that are mandated by certain industries: renewable energy, automotive assembly plants, and other production facilities. As time moves forward superior oil resistant cables will become standard rather than the exception, and the demand for this type of operating performance will only continue to grow.

The Lapp Group has established a laboratory in the United States that is devoted entirely to the testing, research, and development of wire and cable. Brand new state of the art equipment provides the highest degree of accuracy and insures that all tests performed are compliant with the rigid performance requirements mandated by UL Standards. The laboratory has attained acceptance to the UL Client Test Data Program. This is a milestone that is unique in the wire and cable industry.  

How many of us struggle with tasks that should be easy and straightforward because we chose a tool that isn’t right for the job? Have you ever tried to loosen a screw with a dime, hammer a nail with a wrench, undo a tight nut with pliers, or open a plastic container with your teeth? Pretty frustrating, and not so easy. Thinking we are saving time, taking a shortcut turns an easy job into a nightmare. We all know that if we choose the correct tool, the job is simple. The same can be said about aligning wind turbines, which is a fairly easy task with the right tool in hand. The main purpose of all advanced tools is to make the job fast, easy, and accurate. If we can take the human error out all of our daily functions then we would be less confused and frustrated, wondering where it all went wrong. Technology and innovation is supposed to make our daily lives easier, after all.

Choosing the Right Tools
There are several issues associated with wind turbine alignments that make the job more difficult than traditional shaft alignment. It starts with climbing the tower in all sorts of weather conditions; anywhere from well below zero to over 100o F, plus heights close to 300 feet. When we arrive at the top of the tower, being physically and mentally tired is a normal condition. Shaft diameters are large, so extension chains must be used. There is always the angst over the accuracy of dimensional inputs. Brake calipers are obstructing the rotation over the top, so measurements are made underneath and against normal rotation, which can induce backlash. The generator is mounted at an angle and can slide if all four feet are loose at the same time. To maintain the coupling gap tolerance at +/- 1 mm, only three feet (hold-down bolts) on the generator can be loose at a time. Generators are heavy, so we lift with hydraulics, and most sites don’t have jacking bolts for the horizontal positioning. In most cases the thinnest shims used are only 0.5mm. However, we recommend taking shims from 0.1mm to meet current alignment tolerances. And finally, record-keeping has become essential so storing as found, and finished alignments are required. Now let’s see how easy aligning wind turbines will be by eliminating all of these concerns. Figure 1

After climbing the tower, the mental and physical condition is important. Take the time needed to make your brain and body ready for the alignment process—hydrate, clear your head, and recover your strength. First and foremost, complete all safety checks and lock out /tag outs. Then pre-alignment duties ensue, which involve taking off the coupling guard, in some cases installing a turning gear and a rotor lock, if neither are used the brake will be engaged. After pre-alignment is completed we need to mount the lasers on the gearbox brake disk and generator coupling hub. This step is extremely easy. The GO Wind and XA Wind kits by VibrAlign are configured with customized magnetic mounting hardware for each OEM’s turbine design, including GE, Siemens, Gamesa, Mitsubishi, Vestas, Nordex, and Suzlon. This hardware is designed to eliminate chains and clear all obstructions. Also, the GO Wind and XA Wind alignment process and programming are the very similar, so a “re-learning” process is not required by the technicians. The following process will work in a similar fashion.

The “Verti-Zontal” Compound Move
First step in the alignment is to check for “soft foot.” We need a flat plane for all four feet so that the generator won’t twist. This is done by loosening one foot at a time and seeing if there is any movement with the shims under that foot. Since the generator is heavy, use a pry bar or channel lock to see if the shims slide or move. If the shims move, try a feeler gage or precut shim to determine the amount of soft foot. General industry specifications call for no more than 0.05mm as the maximum allowable soft foot. Place the proper amount of shim under the foot to eliminate the soft foot condition. If there is no movement, tighten the bolt and repeat for each of the four feet. With the GO Wind software, just pick from the list of proper turbines and coupling styles. This will load all the correct dimensions and alignment tolerances. Figure 2

Now the setup is complete and ready to take readings to evaluate the alignment condition. Rotate the shafts so that the laser heads are somewhere near the 9:00 position, press OK, now rotate the shafts out of the shaded area just short of 12:00, press OK, and finally rotate to the 3:00 position and press OK. The result summary screen shows the current alignment condition, or “as found.” If it’s within tolerance, just save the alignment values in the GO Wind for your records; the file format is a bitmap/text file with no need for additional software.

If an adjustment is needed on the generator, a “Verti-Zontal” Compound move will be preformed. With true position sensing, the rotational center lines of each shaft relative to each other is always known at all times, no matter how much you move the generator and/or gearbox. In other words, the GO Wind knows where the generator and gearbox are sitting even when the generator is pushed, pulled, or lifted through the whole alignment. This technology allows for the vertical and horizontal move to be completed without having to re-measure, or more importantly having to loosen and tighten hold-down bolts over and over again. Figure 3

Two rules about the first step in your Verti-Zontal Compound move: Always perform the vertical adjustment first. Never do the vertical adjustment live or in real-time mode, since the values will change as soon as the bolts are loosened. Because there can be only three bolts loose at any time, vertical values at the feet can jump and move around. Adjust the both back feet by the value the GO Wind displays in the summary screen, minus = too low, plus = too high. Here is where the 0.5mm shims can create a mathematical nightmare, so let’s make it easy. The rule to follow is to adjust the feet so that both sets, front and back, will have the same sign, with the back feet a bit larger value than the front. An example would be if the back feet show that you are 0.8mm low (-0.8) and the front shows that you are 0.4mm high (0.4), the easiest solution would be to add 0.5mm to the back feet, making the value -0.3mm and removing 0.5mm from the front making the value -0.1. Now both sets of feet are the same sign, with both low and the back feet a bit lower than the front, and the alignment tolerances are met. However, if the proper shim variation of 0.05mm to 2.0mm are used this calculation can be eliminated. Figure 4

Once we have corrected the vertical we now can complete the Verti-Zontal Compound move by selecting the correction key (shim icon) and moving the generator in a side-to-side or horizontal move. Do not tighten the bolts, since we are moving horizontally first. The GO Wind makes this simple by displaying arrows pointing in the direction you need to move. Adjust by using a jack bolt kit, and move the largest value slowly. Once in tolerance the arrows appear as arrowheads only, and the offset and angularity icons will have clear backgrounds. Now tighten the hold-down bolts in a crisscross pattern in three passes—first snug, then tight, and now tightest. Since torque wrenches may not be used at all times, it’s good practice to have the same technician loosen and tighten all four bolts. Figure 5

Now measure for our final alignment condition. After the measurement is completed the summary screen will show that the alignment just completed has the correct tolerances, and the final condition can now be recorded.  Save the measurement, and you are done with the alignment process. Using this Verti-Zontal Compound move process alignments now can be completed in under 30 minutes.

Conclusion
Pretty easy, wouldn’t you say? What makes the alignment process easier now for the wind industry is the Verti-Zontal Compound move, which eliminates two to three steps of the old aligning process, not to mention less wrench turning in the process. This is why aligning a wind turbine just got easier. So the next time you’re performing this operation remember that taking a moment to choose the right tool will result in greater accuracy and fewer headaches! 

If you ask a wind turbine blade manufacturer what he or she is most concerned about, they will tell you without hesitation that it is getting to market faster. The vast majority of firms are expressing the need to produce more blades in less time. They are setting the bar very high, in fact, seeking to produce blades sometimes two to three times faster than is now the case.

Indeed, current engineering and manufacturing processes typically entail numerous manual steps, including the creation of technical drawings based on sketches and paper-based data. Multiple verbal interactions between stress analysts, designers, and manufacturing engineers also occur, requiring meetings, phone calls, and even trips. Cutting with scissors and kitting of the hundreds or thousands of composite plies and pieces of core that go into a blade is also required, as are manual layup operations using human labor at high costs and long cycles, and there are many untracked corrective actions coming in the form of last-minute decisions taken on the factory floor. As a consequence, what is manufactured is often different from what is designed or analyzed. Worse yet, many changes are typically not documented so that everyone concerned can appreciate their impact and cost.

Further, the blade development process also ends up being quite disconnected between design, stress, and manufacturing engineering as well as tooling and production methods and processes. That’s because different tools and software may be used, and information does not flow freely and easily between disciplines and geographical locations.

Trimming Costs
In today’s competitive environment, it is incumbent on wind blade manufacturing companies to reduce engineering and production costs, the number of prototypes and pre-production units, labor costs and material waste, and the length of engineering and production cycles. Manufacturers also need to maintain better control of blade quality. A more repeatable manufacturing process leads to easier control of laminate quality and detection of recurring defects. By adhering to a more cohesive approach, better quality is achieved and results in less downtime in the field and premature blade failures. Those failures are extremely detrimental to the company’s bottom line and image. Ultimately, the goal is to reduce the total cost of blade ownership. Figure 1

Finally, manufacturing companies must support continuous improvement of their blade and turbine performances. Lighter blades are needed in order to continue extending the size of wind turbines and to offer added yield. More customization is demanded to adjust and optimize the turbines to wind and site profiles. New designs are investigated to further modularize blade construction and offer variants at lower cost. Here the composite design environment must enable the engineer to easily and quickly explore more complex designs without incurring undue costs of time and money.

Designing for Manufacturing
Designing composite parts requires unique expertise. For instance, in contrast to the metal industry, composite designers and stress engineers have both the ability and the burden to actually “design the material.” We can choose any arrangement of fibers and resins, weave or stitch architecture, tow size, fiber directions, and sequences. Ply shapes and many other parameters enter into the making of the final part from the various elementary constituents. Figure 2

Then we can choose from a number of manufacturing processes and variants, both old and new. More and more, robots are replacing—or are being considered to replace—manual operations. This will create a more repeatable process that will result in time and cost savings. But the challenge is in the details, and there are many on the spot decisions currently made by layup experts that a machine will not make unless told to do so by some built-in intelligence that understands the design intent in all of its complexity.

So in order to draw all the possible benefits from the use of composite materials, we must be able to design the part specifically for the selected manufacturing process. We must be able to account for the limitations, as well as all the capabilities of the tools that we have decided to use to make the part. And the design must also accommodate the precise interfaces between components and mating parts.

One often-overlooked aspect of advanced composite engineering is what can be referred to as “the cascading impact of design changes.” With composite assemblies made of thousands of pieces of plies and cores, one single design change will typically affect tens or hundreds of parameters in the design. This must be understood and managed during the design cycle. It is well known that designers and stress analysts spend a majority of their time making changes; it is such an expected part of the process that they don’t even think of it as the burden even though it impedes the entire development process. Understanding and predicting the impact of design changes is one of the major benefits brought about by modern composite design software. Figure 3

Composite engineering software has been around for at least 15 years, but it has borrowed surprisingly little from the metal industry. The fact is that composite parts are made from fabric or fiber tows impregnated with resin, which from a design and manufacturing process standpoint is light years away from any process found in metallurgy. For the most part, specialized software tools developed for metal manufacturing have little applicability to composites. By and large the composites industry has had to devise its own specialized software for design, analysis, and manufacturing.

Examples from Aerospace
The aerospace and defense industries were early adopters of advanced high performance composites, so it is no surprise that the bulk of the expertise is owned by people who have worked in those industries. Some of that expertise is transferable to other applications, such as wind turbines. For instance, the preliminary design methodologies used to develop aircraft wings and fairings are similar to the process for developing blades. Similarities also exist in the areas of:

• Detailed ply layup definition developed for complex laminates;
• Producibility simulations developed for a large spectrum of fiber and resin combinations;
• Automated exchange of accurate composite definition between design and stress analysis;
• Automated creation of ply books, technical drawings and manufacturing instructions;
• Automated creation of manufacturing data, including for cutting, positioning, and automated layup.

However, it is important to note that the wind energy industry is by no means a carbon copy of aerospace and defense. The wind industry presents some major differences in terms of part size, material types, layup processes, and design approach. For example, a large variety of multi-axial and multilayered matte/woven/uni materials are used on wind blades. Some ply draping and covering techniques are more pertinent to composite blade design, such as the extensive use of 2D-to-3D mapping of rolls of material, as opposed to aerospace where most plies, which are much smaller, are defined in 3D and then flattened for cutting.

At the end of the day, most wind blade manufacturers are currently looking for the right partners to develop their new processes and tools for composites. These partners can share knowledge from other industries and use that expertise to accommodate the unique challenges of wind blade design as well as rapidly adapt the existing methods and processes or develop new ones.

Flexible Environment
In order to support their new advanced composite engineering and manufacturing processes, wind blade manufacturers must look beyond just acquiring a collection of point solutions. What companies are really looking for is to create an open and flexible Product Lifecycle Management (PLM) environment with the best in class assets that can maximize efficiency and effectiveness.

Indeed, implementing a PLM-integrated composite design, analysis, and manufacturing methodology is a must if you want to develop a better and faster engineering process. The PLM environment must be open and flexible so that engineers can easily and rapidly adapt to the needs of the wind turbine industry, as well as specific customer requirements. It must also allow the company to select the best software components, be it the CAD platform for design, the CAE solution for analysis, CAM software for manufacturing, or a PDM system for data management. Figure 4

The fact is wind firms are finding that efficiency, profitability, and optimization are most readily attained by working within a flexible environment that is comprised of best in class solutions as opposed to a rigid, one-stop vendor solution. The problem with an inflexible, single-vendor solution is that typically it will not only fail to provide the best elements, it will also end up being more expensive to purchase and maintain. In the end, such a setup is more convenient and effective for the vendor than the customer, and that fact should not give potential customers a good feeling.

As the linchpin of the PLM environment, the composite design software must support a diversified CAD and CAE base. It must also account for easy and reliable data transfer across the supply chain and different engineering sites that may use different CAD, CAE, CAM, and PDM platforms.

Composite Software Advantage
There are many benefits to adopting an open and flexible design environment anchored around best in class composite engineering software, including:

• Single, complete, and detailed master model of the blade;
• Streamlined end to end process for moving from conceptual design to manufacturing;
• Automated creation of geometric and composites data;
• Integrated design and analysis loop for faster structural optimization and more accurate design validation;
• Design-based simulation of the manufacturing process;
• Direct link from design to the manufacturing floor;
• Design for manufacturing process (DFM) approach;
• Support for manufacturing aids and future robotic systems;
• Reliable and rapid engineering change management process.

By putting a composite design environment in place and taking advantage of the above mentioned features, users typically reduce prototyping costs, cut material waste, ensure a quality design process, and enjoy the enhanced accuracy that results from a having a repeatable manufacturing process.

Leveraging Composites Expertise
As recently as two years ago there were only a few composite wind turbine blade manufacturers that were truly focused on improving their engineering processes. Now it is a hot topic for most of these companies, especially the top global players. In fact, VISTAGY has seen a tremendous uptick in interest in composite design software among the leading companies in the wind blade industry; indeed, a number are reengineering their processes around our FiberSIM® composites engineering software. These firms tell us that being able to draw on our nearly two decades of experience developing software and services for composites was a big consideration in how they decided to move forward. Figure 5

Given the inherent challenges of working with composites, it is our belief that the wind turbine blade firms that collaborate with thought leaders who possess extensive and hard-won composite engineering software experience are the ones that will achieve dominance in the years to come.

The rail belt stretches from the south in Seward all the way north to Fairbanks, Alaska’s second-largest city in the center of the state. The remote communities—otherwise known as “villages,” which are situated along the rail belt corridor—are able to tap into the existing power infrastructure for electric service to power individual residences and public facilities. The Southwest Alaska community of Kokhanok, like most villages in the state, is a beautiful and remote settlement of just under 200 people located on the south side of Lake Iliamna, within the Lake and Peninsula Borough. Kokhanok is not in close proximity to the rail belt, and villages such as these that are completely off the grid must maintain their own infrastructure for power generation. The challenge involved finding a realistic way to make this happen.

Centralized Power Generation
Because electricity in remote Alaskan villages usually costs six to eight times more than it does in villages along the rail belt, the State of Alaska tasked the Alaska Energy Authority with implementing the PCE (Power Cost Equalization) program to assist remote communities with meeting their power generation needs. In its literature the authority writes that “PCE fundamentally improves Alaska’s standard of living by helping small rural areas maintain the availability of communications and the operation of basic infrastructure and systems, including water and sewer, incinerators, heat and light. PCE is a core element underlying the financial viability of centralized power generation in rural communities.” Figure 1

In order to assist residential village customers in offsetting costs, the PCE program requires communities to provide monthly and annual reporting to remain in compliance with state regulations. Kokhanok’s village utility clerks were diligent and accurate in their reporting, so in an effort to ensure uniform and regular payment schedules “Ampy” prepay meters were installed in residences to ensure collections. These units also assisted community members in learning how to conserve energy and lower their individual usage. The Ampy meters eliminated disconnect and reconnect fees, allowed those customers with overdue balances to restore their service with PCE, and provided the utility with consistent collections.

Luckily, the village’s power plant already possessed properly sized and loaded diesel gensets, and the utility’s operating procedures demonstrated a history of consistent documented maintenance practices that maximized their fuel savings. This standard of excellence set the stage for a wind-diesel hybrid project, which can only succeed with a well-maintained diesel plant and a well-managed electric utility.

Integrated Energy
The village electric utility currently operates a diesel power plant with a total installed capacity rating of 490 kW with a peak operating load of approximately 110 kW. The Lake and Peninsula Borough (LPB) considered their ever-present wind as a viable source for alternative energy. The subsequent Alaska Energy Authority study of 2006 showed that Kokhanok has a Class 6 wind resource with negligible turbulence, no adverse avian issues, and no other permitting problems.

Transporting diesel fuel from Anchorage or Seattle to the village of Kokhanok is an expensive logistical challenge. Fuel must be barged to the village, preferably up the Kvichak River. When that route is unavailable due to low water levels, fuel must be traversed from Anchorage or Seattle to Williams Port, transferred to trucks and driven over the mountains, then transferred to a barge for shipment across Lake Iliamna for delivery to Kokhanok. When the fuel barge could not navigate the Kvichak River in the fall of 2008, fuel had to be flown into the community at $7.20 per gallon for an entire year. In 2008 the Kokhanok Electric Utility was forced to charge residents $.90/kWh for power in order to cover their cost to produce power. Figure 2

In July of 2009 the village and the LBP committed to integrate wind energy with diesel power to provide a local renewable low-cost energy resource for the community. Marsh Creek, LLC, was awarded the engineering, procurement, and construction contract on July 11, 2009, for a high penetration wind-diesel system with coincident thermal energy production; the first of its kind in Alaska. “High penetration” means that diesel generators may be shut down during high wind availability, that auxiliary components are required to regulate voltage and frequency, and that a sophisticated control system is required. Peak instantaneous penetration is 100-400 percent, while the annual average is 50-150 percent.

“Kokhanok Village, as with many villages, faces uncertain times when it comes to the future of electrical power production and heating due to high fuel prices,” according to Nathan Hill, village administrator. “Installing a high penetration wind-diesel system will help us stabilize these costs, thus making village life as we know it more sustainable. We are looking forward to working with Marsh Creek as we build capacity to operate our new system and of course reap the benefits of a more predictable and sustainable source of energy.”

Offsetting Traditional Sources
Construction began on the $1.94-million project in May 2010 and was completed on time and on budget in October 2010. Included in the project were two reconditioned Vestas V-17 turbines rated at 90kW each on 85’ lattice towers with 56’ rotors, and 180 kW of connected wind capacity. The 1991 turbines were remanufactured by Halus Power Systems in 2010.

A synchronous condenser and grid forming inverter were installed, along with 336 kWh of nominal battery storage. As of February 2011, the refurbished Vestas wind turbines were fully operational, as they remain today. Figure 3

The system stores excess energy to the battery bank for use during non-wind times. Additionally, the excess electricity from the wind turbines heats up water and feeds it to the existing jacket water heat recovery system and into the local school’s recirculation system. The hybrid system is expected to displace half of the village’s previous annual fuel consumption.

The Hybrid Wind Turbine Integration Project also included a substantial power plant controls upgrade, a remote operations monitoring and control system, and wind system operator training. The advanced supervisory control and data acquisition (SCADA) system allows engineers in Anchorage to view wind turbine production and to manipulate the parameters of the controls via a computer connection. The SCADA system monitors and gathers information and relays it back to the central site in Anchorage. It displays information in a clear and logical fashion and creates an instant alert if there is a problem. Remote monitoring, and the ability to manipulate the system operations from Anchorage, provides the community’s local operators with a measure of confidence in their ability to manage the system with advice from engineers available at a moment’s notice. It also saves travel expenses, making the project possible.

This unique hybrid system, with an installed wind capacity of 180 kW, has the potential to offset the traditional diesel power plant production by 19,297 gallons of fuel, or 51 percent, potentially saving the village over $110,000 in fuel costs annually.

“We normally burn upwards of 141 gallons of fuel in a 24 hour period,” says John Mike, power plant operator. “When the wind is blowing and the turbines are operating, we only burn about 70 gallons, or half the amount of fuel we usually do. When the computer controls are fully operational this coming July the system will be completely automatic, making our lives a lot easier.”

Villagers and project team members attended the ribbon cutting ceremony in October of 2010 to celebrate their new wind turbines. Village Elders Francine Andrew and Annie Mike were two who took advantage of the beautiful day to mark the occasion. Figure 4

On March 10, 2011, the Kokhanok Hybrid Wind Turbine Integration Project was awarded “Most Innovative Project” at the 2011 International Wind-Diesel Workshop in Girdwood, Alaska. The workshop was designed to bring the wind-diesel community together to share the status of current technology, discuss applications that work and those that do not, and to shed light on areas for improvement. Following the workshop, approximately 17 attendees boarded planes and flew from Girdwood to Kokhanok for an on-site tour of the wind turbines. Commissioning activities were completed shortly thereafter.

Project Summary
With this successful project completed on time and on budget, Marsh Creek will enter into a five-year maintenance and training agreement with the village, which is a key element in the program. This long-term commitment of training, operation, and maintenance between the village and Marsh Creek will ensure continuity of maintenance provided by professionals, and it is a critical component for both parties. The agreement will also ensure that the village remains current on training with Marsh Creek’s professional staff. 

Until now, the wind power industry has been moving forward at a relatively steady climb. The onshore industry is powered today primarily by two types of drive train technologies: one based on double-fed induction generators, and the other based on permanent-magnet generators (PMG). Double-fed induction generators have been a good choice for smaller powers in onshore installations. At less than 2MW, they prove to be competitive in price and performance. However, when moving offshore, double-fed induction generator drive trains are no longer a viable option. With extra components, slip rings, and greater losses, the risk of maintaining at sea is simply not one that wind turbine manufacturers are willing to take.

Therefore, critical components used offshore must unquestionably be more reliable than their onshore counterparts. Unscheduled maintenance is extremely difficult, and even though offshore winds are in fact more consistent, wind turbines must be able to withstand powerful storms, corrosive elements, and turbulent atmospheric conditions.

The drive train and all other critical components must have an exceptional track record onshore before they have a chance to be considered for the much more challenging offshore application.

The Next Frontier
At the same time that offshore is gaining momentum, wind farm owners and utilities are moving toward higher powers with onshore installations. The 3MW range of wind turbines are quickly taking over as the new mainstream power for onshore. For these new wind turbines, the obvious choice is PMG. That is because PMG offers superior energy output, even at partial loads. Furthermore, PMG guarantees proven reliability in highly volatile wind conditions and better quality energy for the grid. Therefore, most of the major wind turbine manufacturers have now switched over to this next-generation drive train technology. Figure 1

Other new trends that are emerging in the 3MW onshore range are that turbines are featuring bigger rotors and longer blades to be able to capture more energy from winds at low speeds. Here, too, PMG is ideal. Permanent magnet generators come in a range of speeds—low, medium, and high—with each filling a specific need when it comes to the environmental and wind conditions in question at the actual site of installation. Offshore is now showing more encouraging signs of taking off in a big way, with new projects getting green lights in different parts of the world. Many believe—as we do at The Switch—that offshore wind generation will be the next new frontier.

A few European countries such as the U.K., Germany, Belgium, and Denmark are leading the growth. Other European countries are currently struggling to obtain permits while the United States, although enthusiastic, is still wrestling to get the financial backing required. Another trend is the increase in power classes, from multi-megawatt to offshore-class turbines of 6MW through 8MW, and even up to 10MW of power generating capability. The technology for these super-power offshore turbines already exists, in fact.

Offshore Electrical Drive Trains
As far as we have seen at The Switch, it is extremely difficult to deploy turbines with a double-fed induction generator for offshore use. We already have had success with our 4MW direct-drive PMG and full-power converter packages now operating in some of the gustiest coastline conditions in Norway. The Switch has been focusing on providing optimized PMG and full-power converter packages since the company’s start in 2006. Today it has 5GW of installed capacity throughout the world in all kinds of challenging operating conditions. Figure 2

As we currently prepare our concepts for optimized 6MW and 8MW offshore-class packages, we’re planning to take two paths ahead. Although direct driven offers the ultimate in reliability and efficiency that is so critically needed in offshore applications, the generator alone can easily weigh up to 150 tons at these high power ratings, creating challenges with handling and overall costs. Therefore, we see that the direct-driven PMG drive train is the best option and most competitive for power ratings ranging from 1.5MW to 8MW.

For power ratings of 3MW up to 10MW, a medium-speed option may be the best bet, in his opinion, with reliability nearly as high as direct-drive drive trains. The Switch—together with another Finland-based company, Moventas—has launched a revolutionary wind power drive train called FusionDrive™, which provides an optimum balance of lighter weight and high reliability rates with its integrated gear and medium-speed drive train. FusionDrive is specifically designed for a power range from 3MW to offshore class. Additionally, the lightweight medium-speed model is compact, offering lower lifetime costs.

An Integrated Solution
FusionDrive offers optimal availability by harnessing all the advantages of medium-speed wind power generation technology. It is extremely compact in size and offers the lowest weight in the market. “The lower the nacelle weight, the more cost competitive the turbine,” adds Jukka Jäämaa, CEO of Moventas, one of the biggest wind gear manufacturers in the world. “Nacelle weight relates directly to both foundation and construction costs of the turbine as well as manufacturing, transport, and assembly costs in the whole supply chain.”

The FusionDrive integrated solution with perfect alignment between gear stages and the generator, along with an integrated lubrication system, simplifies the nacelle structural design, which lowers the nacelle weight and improves total turbine cost effectiveness. The low number of bearings, low cogging torque, and the construction with no current passage through bearings, slip rings, or rotor windings also contribute to the proven reliability of medium-speed technology. Figure 3

FusionDrive uses medium-speed wind power generation technology, as it has been proven for the highest possible availability in wind power generation. It is designed on a scalable platform that extends from 3MW to offshore class, all in an onshore size. The compact size of the complete drive train allows easier transport and assembly.

Ingenious Fusion
For wind park owners, reliability in practice means high availability and lower operation and maintenance costs. In addition, FusionDrive guarantees optimized efficiency, even at partial loads. Regardless of which path turbine manufacturers feel is best to go out to sea, these two paths forward will help them stay ahead of the pack.