availon_onservice_01-2012_en_01

Focus on

The Availon journal for multibrand wind energy service | January 2012

WTG access monitoring: Set your sights on metal thieves. Page 7

Spain: Effi cient service in achallenging economy. Page 17

Internal crane system: Safedespite shaky ground. Page 10

Higher performance on less space: Repowering is particularly interesting to investors and large energy

suppliers. Is it also a worthwhile investment for operators of individual turbines or smaller wind

farms? Comparison on Page 4

Repowering or turbine maintenance?

4 7

10 14

IMPRINTPublished by: Availon GmbH · Jacksonring 2 · 48429 Rheine · Germany Fon +49 5971 8025-0 · Fax +49 5971 8025-109 · www.availon.euEdited and designed by: EXPECT MORE Kommunikation GmbH · Breite Straße 4 48431 Rheine · Germany · Fon +49 59 71 80 40 9-0 · Fax +49 59 71 80 40 9-100 · www.expect-more.de Responsible according to German press law: Availon GmbH Fotos: Ulrich Wozniak ( pp. 6, 9, 10, 12, 13, 15, 16, 19 )Copyright: All contributions (text, photos, graphics, logos and tables) published in ON Service are copyright protected. The copyright is owned by Availon GmbH, unless stated otherwise. Reprinting, storing in databases,on online services and Internet pages or copying onto data media is only allowed with prior written permissionby Availon GmbH. Number of copies: 500

CONTENTS | January 2012

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Focus onCover story: New turbine or turbine maintenance?

Turbine access monitoring: Foiling the plans of metal thieves.

Current newsInternal crane system: Generator exchange in a former opencast mining area.

TopicUpgrade: Optimum nacelle adjustment thanks to new transformer.

FeatureSpain: Alternative service concepts to navigate diffi cult times.

4 Fokus

Against the background of the current payment scheme provided by the German Renewable Energy Sources Act (EEG) for the dismantling of old turbines and the construc-tion of new WTGs with at least twice the rated power, repowering is particularly interesting to investors and large energy suppliers. More-over, if the turbines are located in a designated priority area with high average wind speeds, the increase in turbine performance can result in increased yield. However, an important prerequisite is that the fi nancing arrangements for the existing wind farm have already been concluded.

Priority areas in focus Investors are currently focusing greater attention on wind farms in priority areas. Their primary interest being to secure the areas for eventual repowering, often irrespective of the condition of the current WTG inventory. These future sites with high yield potential are therefore becoming a decisive factor for investment. However, the growing interest in designated priority areas for the exploitation of wind energy has also resulted in staggering rent increases. This means that, if you calculate the costs of the new turbines together with the necessary added investment costs, ambitious

“The science of planning consists in preempting the diffi culties of the execution.” The Marquis de Vauvenargues. The wonderful thing about such astute observations is their timelessness. Although the French philosopher, moralist and author died in 1747, this quotation not only provides a nice entry into the theme of the leading article of this issue of ON Service but also an elegant introduction to the following question: Repowering or improved maintenance of existing turbines – which “recipes” can reduce yield risks?

repowering projects require immense fi nancial resources.

Subdued developmentIn addition to the current restrictions on the height and spacing of repowered turbines, this may be one of the key factors contribu-ting to the low percentage of repowering as compared with new WTG installations: only 3.6 percent in the fi rst half of 2011, measured according to total number of turbines. The goal of covering a major part of the addi-tional generating capacity with repowering is doubtful in view of such numbers. However,

Focus on4

Repowering or turbine maintenance?

5 Fokus

the growing interest of investors, particularly in the designated priority areas for WTGs, gives cause for hope that this development will take a diff erent course in the future. This is particu-larly true given that the outcomes of incen-tives provided by the Renewable Energy Act (EEG) will not become apparent until much later due to the comparatively long planning times for repowering projects.

Higher performance on less spaceThe goal of repowering is not only to replace smaller turbines with more powerful WTGs, thereby reaching the ambitious goals set by the German Federal Government to consid-erably increase the percentage of electricity generated by wind power. Repowering also means a reduction in the current number of turbines combined with the restructur-ing of potential WTG locations. In other words: Higher performance on less space. But this is precisely the root of one of the biggest problems facing the WTG land-scape in Germany, which is now character-ized by a large number of turbines on widely dispersed sites. Some of these turbines will have to be “collectivized” as part of repow-ering, as formulated in the report “Vorbe-reitung und Begleitung der Erstellung des Erfahrungsberichtes 2011 gemäß § 65 EEG” [Preparation and supervision of the compi-lation of the 2011 progress report pursuant

to Article 65 of the Renewable Energy Act], which was commissioned by the German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety. According to the report, very few such projects have yet to be implemented and as a result, the consolidation of locations in the desired form has yet to be carried out.

Many turbines no longer eligibleIn view of long planning times and high investment costs, the subject of repowering is probably of less interest to operators of small wind farms or a few turbines. Priority areas for the use of wind energy were not desig-nated until 1996. Some of the more than 6,000 turbines, which are more than 15 years old, would therefore not come into consideration for repowering at the same location.

Possibilities of “pooling”However, one possibility could be for owners to cooperate by pooling their turbines in a priority area to essentially create a wind farm. In view of the trend towards rising electricity prices, the operators of such a wind farm would also be in a position to market the elec-tricity directly, thereby obtaining spot market prices above the Renewable Energy Act (EEG) feed-in rates. Such activities would not be practicable for an operator with only a few turbines since an additional outlay is required

for the procurement of information for direct marketing. What is more, the precision of fore-casts for wind-generated electricity supply is reduced in relation to the size of the wind energy unit. In an association, however, the activities for electricity marketing could be pooled, especially since the quantity of elec-tricity increases, thereby decreasing the fore-casting risk.Options of this kind or similar ones tend to be theoretical considerations, however, as demonstrated by the 2011 progress report pursuant to Article 65 with regards to problems associated with the consolidation of WTG locations.

Maintenance of the WTG inventoryThe maintenance of existing turbines is there-fore a realistic policy for owners of stand-alone turbines or smaller wind farms. Although the EEG ultimately determines the basis for cal-culating wind power yields, the interaction between the WTG location, actual wind con-ditions and the turbine technology also contribute to yield risk. The fact that experts assess the yield risk as regards availability as relatively low for onshore turbines seems surprising in this respect. That said, it becomes less surprising given the knowledge that such an assessment is based on comprehensive maintenance and service management as an important prerequisite.

5Focus on

6 Focus on

Full maintenance is becoming increasingly relevantMore than ever before, comprehensive service provisions should be the standard for operators focused on the possible long-term maintenance of their WTG inventory: By increasing the availability of their turbines they ulti-mately reduce yield risks. A majority of the operators have already recognized this, as demonstrated by the growing interest in full maintenance contracts for WTGs. Finally, it’s just a question of which service provider to choose.

Scarcely any diff erence?Judged soley on the basis of their range of services, there are few discernable diff erences in the full maintenance off ers of independent WTG service providers. As a rule, they consist of basic services such as remote monitoring, fault analysis and troubleshooting as well as preventive mainte-nance. The more comprehensive full maintenance off ers include wear packages and more extensive maintenance work, such as maintenance work on frequency converters, rotor blades and transformer installations. Moreover many off ers cover drive train analyses, safety engineering checks and the provision of spare parts including main compo-nents and, needless to say, an availability guarantee.

Decision-making aid “soft skills” When the spectrum of services fails to provide a signifi cant basis for choosing a service provider, then price naturally becomes a decisive factor. However, in addition to com-paring the scope of performance with the calculated costs, so-called soft skills should also play a role here. Such soft skills include the general impression conveyed by the independent service provider as well as the reputation of reliability and quality of the service teams, their reaction times and, fi nally, an assessment of the company’s consul-tancy services.

Full maintenance until the end of service life?A central decision making factor is whether a multibrand service provider off ers the prospective customer fl exible decision-making options as part of a full maintenance agreement, e. g. with optional performance modules which the customer can integrate in the full maintenance as required. Last but not least, the question as to whether a service provider is prepared to off er full maintenance until the anticipated end of the service life of the turbine is not insignifi cant in view of the calculated operating life of a turbine of 20 years. This issue alone is sometimes enough to quickly separate the wheat from the chaff .With regard to the maintenance of old turbines, it is less a question of whether to purchase a full maintenance contract or not, but rather which service provider can best deliver on a long-term partnership in the interests of high turbine availability and reduced yield risks.

Repowering requiresimmense fi nancial resources

and long planning times.

In focus: The question is not reallywhether full maintenance makes sense,but for whom?

7 Blick

Crime Site Wind TurbineAccess monitoring prevents damage, failures and high losses in yield.

These are booming times for metal thieves. Remote areas such as wind turbine sites are particularly popular, since the thieves know they can usually “work” undisturbed. The problem is that they not only steal metal but can also cause considerable damage resulting in lengthy WTG standstills, and occasionally, in high losses of yield. A new WTG access monitoring system can eff ectively foil the plans of these brazen criminals.

Changes 7

8 Changes

Although the German Federal Government does not collect exact data regarding metal theft, the extent of damage caused by such cases is well documented in the state of North Rhine-Westphalia (NRW). According to the state criminal police (LKA), until the beginning of Novem-ber 2011 metal thieves struck around 260 times in NRW causing an estimated damage amounting to approx. 5.4 million euros. Remember that this only refers to damages in one German state!

“Undisturbed” crime sitesMetal thieves are increasingly focusing their attention on WTGs due to the fact that they are primarily located in remote sites, thereby greatly reducing the risk of being caught in the act. Some typical newspaper headlines draw an even clearer picture: “Ten wind turbines out of service after break-in – total damage approximating 20,000 euros,” “Cable thieves break into wind turbines – estimated damage approximating 40,000 euros,” “Thieves – tons of copper cable stolen from wind turbine generators – the damage is estimated to be around 50,000 euros” or “Trans-former stations in the wind farm cleared out – approxi-

mately 60,000 euros of damage caused by break-in during the night.”

Large amount of damage, immense lossesBesides reading about the immense damage costs aris-ing from the break-ins, readers rarely learn the details behind the statistics, namely the boldness of the thieves. For example, thieves broke into a transformer station and a WTG in a remote wind farm in Saxony-Anhalt in August 2011. The culprits did not think twice about climbing up the ladder to the turbine tower and removing 30 meters of copper cable. Altogether they made off with around one ton of cable.Raids of this kind are normally carried out with a great deal of brute force and therefore cause considerable damage to WTG equipment. Remote monitoring systems and machine components are frequently stolen at the same time and the outer area of the WTG entrance is often vandalized. In addition to the immediate damage, repair work, resulting plant shutdowns and subsequent yield losses as well as owner costs including insurance deduct-ibles are equally annoying.

Small upgrade with a big impact:The motherboard of the turbineaccess monitoring system.

99Changes

Prevention and deterrenceThe only possibility of avoiding such problems from the outset is prevention combined with systematic deterrence. In other words, a WTG access monitoring system that eff ec-tively discourages thieves from breaking into turbines in the first place. The multibrand service provider, Availon, has developed a new access monitoring solution that oper-ates independently of WTG control systems. The upgrade consists of a motion sensor installed in the entrance area of the WTG and connected to the remote monitoring divi-sion via a GSM modem: a signaling device that triggers an acoustic alarm directly in the turbine, as well as an acoustic sensor installed in the interior of the tower.

“Keep out!”If an unauthorized person approaches a WTG, they will see a sign that clearly says that the turbine is protected by an access monitoring system. However, should the person nonetheless enter the detection zone of the motion sensor, an alarm signal is sent to the remote monitoring divi-sion via a GSM modem and a localized alarm is triggered. Anybody not bent on mischief would naturally leave the WTG entrance area at this point in response to the audible “Keep out” warning signal. Once they leave the detection zone, the alarm automatically switches off .

Nothing goes unnoticedIf the “uninvited guest” remains in the entrance area, however, the remote monitoring division can connect to the interior of the turbine via the acoustic sensor and thereby “listen in” to the interior of the WTG. If any suspi-cious noises indicate unwelcome activities, the remote monitoring staff can respond accordingly by, e. g., inform-ing the police. On the other hand, a maintenance team wanting to enter the turbine in order to carry out on-site repairs can simply call the remote monitoring division to report in. The access monitoring system is then deactivated. Should a member

of a service team inadvertedly enter the entrance area with-out previous notifi cation, thereby triggering a false alarm, they need only exit the detection zone so that the alarm desists before reporting in and legitimately entering the WTG.

WTGs are not the only locations monitoredIn addition to monitoring WTGs regardless of turbine type, this solution also monitors transformer stations or substa-tions, which are also “favored targets” of metal thieves. For even higher security, a monitoring camera can be option-ally installed in the interior of the turbine in order to provide visual monitoring in addition to an acoustic sensor.This Availon upgrade is easy to install and can spare opera-tors a lot of unnecessary aggravation. More specifi cally, it is highly eff ective at preventing unauthorized approaches of individuals to a WTG through a deterrent loud on-site alarm, among other things. In addition, the motion detector trig-gers a silent alarm signal, which is relayed to the remote monitoring division so that they can discern whether there are any suspicious activities at the entrance to the turbine. If this is the case, an immediate reaction is possible and unauthorized entry of the WTG can be prevented.

Poor prospects for thieves and vandalsMetal thieves may be experiencing boom times at the moment, but the installation of the access monitoring system will hinder their ability to breaking into turbines undetected in the future. As a result, operators can avoid the consequence of high losses of yield and costly repair work.

Severe damages in every senseof the word: More than a ton of coppercable was stolen from this turbine.

1010 Current news

1111Current news

“David”overcomes another big challenge with gearbox exchange.In an article titled “David versus Goliath” in the September issue of ON Service, we reported on the development of an internal crane system that can be used to exchange generators in turbines of the type Vestas® V80 VCS®, V90 2.0 MW and V66 without the use of a heavy-duty crane. Since then, the system, which was developed by Availon, has proven itself in several practical applications. In response to a very specifi c need, the crane system is currently undergoing further development to expand its use for the exchanging of the helical gear. But let's start at the beginning …

The operator of a wind turbine is faced with massive problems. As a result of damage to a gear unit his WTG has been at a standstill for quite some time now. The turbine is located in a former opencast mining area, in which the mines have been fi lled in and compacted as part of the renaturation of the area. However, because of a landslide, which occurred there in the not so distant past, the operator has been prohibited from transporting heavy equipment, e.g. a heavy-duty crane, to the turbine. What to do then when time is fl ying by, no yields are being produced and the gearbox manufacturer says that a repair of the helical gear directly in the turbine is out of the question? In search of alternative solutions to the use of a heavy-duty crane, the turbine insurer heard about Availon and the devel-opment of its internal crane. Having completed an on-site inspection of the turbine, the technicians of the multi-brand service provider said they would be able to tackle this problem.

Further development necessary“No easy task when you consider that the vertical position of the helical gear in the nacelle means that it has to fi rst be rotated for disassembly, and other turbine components have to be removed beforehand to make space for the exchange. What is more, in order to successfully complete the project, it was necessary to develop special tools to be used in combination with the internal crane. The lifting beam originally designed for exchanging the generator also had to be modified, in order to enable the lifting of the helical gear without a great loss of lifting height in

the cramped nacelle. Everything was carefully thought through in the preparation process, so that nothing was left to chance,” explains Jochen Holling, development engineer for “Upgrades for Mechanical Components” at Availon.

Comprehensive testing instead of unpleasant surprisesFor this reason, all activities planned in the actual turbine were tested beforehand on a test rig using the newly developed tools, in order to prove the practicability of the developed concept. In this respect, the gear unit was in exactly the same position, in which the service technicians would fi nd it in the turbine. According to Martin Bergmann, another development engineer responsible for “Upgrades for Mechanical Components” on the Availon internal crane project team, “The work on the test rig showed that our well-considered concept could be put into practice. However, we still had to carry out additional modifi cations to the lifting beam, which we had further developed with respect to the tolerances on the casting radii. Not until each movement was perfect and all the components and systems developed by us were shown to be fi t for purpose did we start with the organization of the actual job.”

“Vestas” and “VCS” are registered trademarks of Vestas Wind Systems A/S, DK.

12 Current news12

The very fi rst operationOn 14 November 2011, led by construction site supervisor Niels Wilke, the project team traveled to the damaged turbine. At a height of 100 meters, the generator was fi rst disassembled and lowered through the open nacelle fl oor to the base of the turbine by means of the internal crane. "The plan was to disassemble the generator completely on the fi rst day, but unfortunately there were problems with the steel cable of the internal crane. We had already lowered the generator to 20 meters below the nacelle when a sharp edge caused the outer layer of the rope to detach from the inner layer. We therefore decided to abort the operation and order a new rope, with the result that the generator arrived at the foot of the turbine a day later than planned." Although this created a delay in the overall timing, Bergmann also draws positive conclusions from unplanned delays of this kind: “Such problems provide important information for further service assignments. For example, in the future we will design and use an electric winder for the 8-strand rope, which has so far been wound up and down by hand in a laborious process.”

Special tool for the sun pinionWhile the generator was being packed to protect it from eff ects of the weather and prepare it for storage at the foot of the turbine until its re-installation, the disassembly of the high-speed drive shaft began in the nacelle. The tube for accommodating the hydraulics and the electrical system was subsequently removed. The cover was then removed from the low-speed gearbox and a specially developed tool inserted in the gear unit to extract the sun pinion, which connects the planetary and helical gears. In the next step, the turbine fl oor below the gearbox was removed, the lifting beam was prepared and the torque links to the planetary gear were broken.

Separation of the helical and planetary gearsThe helical gear could now be separated from the planetary gear with the aid of jack screws. At this point the lifting beam with the internal crane was already in the necessary position for attaching the helical gear to the system, which took up the six tonne load. The helical gear was moved forwards using the crane trolley, rotated by 90 degrees and

, led by construction site supervisor Niels Wilke,

13Current news 13

lifted at the same time. After the requisite position had been reached, the helical gear could be subsequently be lowered through the open fl oor of the nacelle to the base of the turbine.

New gearbox ready and waitingA truck with the new gearbox, which was to be installed in the turbine in the reverse order to the procedure described above, was already waiting a few meters away. “Unfortunately another delay resulted during the attachment of the helical gear, because the area between the helical and planetary gears had to be heated up to 25 °C in order to be able to connect the two gears.” After the generator was back “on board,” the additional exchange of other components such as cooling units and hoses could begin, the nacelle fl oor could be closed and fi nally the gear unit and the generator could be aligned with the gear unit.

Successfully breaking new groundAltogether it took the team from Availon three weeks from the complete exchange of the gear unit to the starting up of the turbine. “Enormous

1. The lifting beam originally developed for exchanging generators was modifi ed for lifting the helical gear.2. The new gearbox is prepared for installation.3. Danger of landslide: The use of heavy-duty cranes is prohibited at the site of the WTG in a former opencast mining area.4. The gearbox manufacturer confirmed that such damage cannot be repaired directly in the WTG.

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challenges and unpredictable problems have to be overcome when breaking new ground. Nevertheless we are very pleased with the result. After all, we are talking about the exchange of a large component here. If we disregard the unexpected delays, which occurred in this first operation, I am confi dent we can reduce the time frame for changing a gearbox to two weeks for similar operations as a result of the experi-ence gained. We will also examine whether our system is suitable for exchanging the helical gears of other gearbox manufacturers. However, this depends to a large extent on the design of the gearbox,” conclude Holling and Bergmann. The development engineers from Availon have a right to be pleased, because the latest application of the internal crane has revealed new potentials in the system, which will frequently eliminate the need to use heavy-duty cranes to exchange large com-ponents, thereby saving a great deal of time, money and organizational work.

14 Topic

Confidence is good, control is better.

If the orientation of the nacelle to the wind direction is corrected via the yaw system, three stop functions normally ensure that the nacelle cannot turn out of the wind again. Firstly, the so-called friction brakes generate a correspond-ing counter-torque. Secondly, the motors have self-locking worm gear units, which also prevent the nacelle from drifting out of the wind. Last but not least, electromagnetic brakes on the electric motors ensure that the nacelle is locked in the wind direction.

Extreme loadsHowever, if the friction brakes of a motor fail as a result of poor maintenance, the full load of the wind has an eff ect on the remaining motors and their gearboxes. In addition, dynamic imbalances in the rotor caused by a blade angle, which has not been optimally set via the pitch system can increase the stress. A poorly calibrated rotor weight can also

occasionally promote such imbalances. All these factors ultimately cause extreme loading of the control gear.If an actuator gearbox becomes defective as a result of the problems described, the remaining functioning drives must inevitably take over its task. “In a specifi c case, we measured a rated power of 2.2 kW for each actuator in a turbine and a rated current of 3.0 amperes, whereby the actual load current was only 1.5 amperes. If only two of the total of four actuators of the yaw failed in this turbine, the remaining motors would have to supply their maximum rated power, in order to compensate for the power of the defective drives. As the weakest link in a drive system, the gearbox simply cannot withstand such loads on a continuing basis. Damage will there-fore occur sooner or later,” explains Lorenz-Theo Feddersen,

“Upgrades” development engineer at Availon.

Danger from undetected damageIt is potentially fatal if defects in control gear initially go unnoticed, even where the motors and gear wheels continue to rotate during regular inspections and no problems are apparent. Failures of the entire nacelle adjustment, an unscheduled standstill of the turbine and consequent losses in yield as well as high repair costs to exchange all the defective components are no longer avoidable.

Yaw monitoring system registered for patent However, there is no need for this to happen in the fi rst place. A new upgrade for WTGs, particularly for turbines of the type Vestas® V80 and V90, which has been registered for patent by Availon, now ensures that failures of the yaw control gear will no longer remain undetected in future. The concept for this upgrade is as simple as it is eff ective: an eff ective function check of the yaw drives by monitoring the current consumption of the driving motors.

Comparison of load current with no-load currentIn this regard, a compact current transformer is installed for each actuator, and one current phase of the motor is connected to the conductor terminal through the converter in each case. Since the current transformer functions in principle as a current probe, the actual control technology is unaff ected. The magnetic fi eld generated by the fl owing

The perfect interaction between the pitching of the rotor blades and the nacelle adjustment by the yaw system makes a substantial contribution to the performance of a wind turbine (WTG) and is therefore crucial for a high energy yield. However, the actuators of the yaw system are subjected to high stresses, particularly in complex WTG locations. If problems occur in the yaw drives, they frequently remain undetected for far too long. The failure of an actuator then often causes a chain reaction, since the remaining drives have to operate under overload. The failure of further components and therefore costly repairs are virtually inevitable. A new upgrade means that these problems are now safely under control.

Functional control of the yaw drives prevents costly dangers.Functional control of the yaw drives prevents costly dangers.

15Topic

WTGs that rotate incorrectly can causeexpensive damage as well as yield losses.

16 Topic

current is picked up by the current transformer and used for the measurements, whereby the load current of the respective actuator is compared with its no-load current. If deviations from normal operation arise in the comparison, they can be immediately detected. An error message can be subsequently sent to the turbine controller, the operator of the turbine and the remote monitoring division for each GSM module.

Prevent expensive consequential damage It only takes two hours to install the new upgrade. Afterwards any failure of a gearbox can be detected early on, so that targeted measures such as the planning and completion of a repair can be initiated in good time. At the same time, an emergency program can be initiated within very short time via the turbine control system as a reaction to the problem, e. g. a reduction in the number of orientation operations, in order to protect the yaw drives until the damage is repaired. There is therefore no longer any danger of expen-sive consequential damage and high yield losses. The following sample calculation shows just how costly it could be without this upgrade. If a turbine fails as a result of problems in the yaw drives which are not detected in time, the costs of a repair can very quickly add up to more than 22,000 euros. The yield loss caused by an unscheduled turbine shut-down in good wind periods also has to be taken into account at approximately 6,000 euros. The total cost would therefore amount to 28,000 euros. By compar-ison, the non-recurring installation costs of the yaw moni-toring system add up to less ten percent of this amount. High follow-up costs caused by the failure of an actuator could be avoided as a result of the upgrade, since early detection is followed by a prompt reaction, and maybe only one damaged component would have to be exchanged. In such a case, repair costs of only approximately 6,500 euros are by all means realistic. What’s more, the potential yield losses would not have any material impact in contrast to the fi rst scenario.

Eff ective early detection“The extent to which the individual yaw drives are stressed can be seen from the measurements taken directly after the installation of the yaw monitoring system. It is therefore already apparent at this point whether any problems are likely to arise in the foreseeable future, which necessitate a service call. If this is not the case, eff ective early detection ensures that you are always on the safe side for the future,” says Feddersen. “Apparently, nobody has yet taken the trouble to look at the load currents of the yaw motors when addressing this problem, although they provide a great deal of information about the actual loading of the drives. Availon's system is therefore as simple as it is eff ective,” says Dr.-Ing. Dieter Frey of Engineering Offi ce Frey from Sprötze near Buchholz.

Further potentials of the issue of yawThe engineering expert has dealt with the issue of yaw for several years. However, on a completely diff erent level than Availon: the optimization of the nacelle adjustment of WTGs. “For various reasons, it can be assumed that the optimum orientation of the rotor to the wind is not known. And therein lies the potential for optimization.”From observations and subsequent systematic measure-ments, Engineering Office Frey forecasted a potential higher yield of several percent through an optimized nacelle adjustment. In a next step, an optimization strategy was conceived and tested. To date, a system patented by the Engineering Offi ce has been installed in approximately 60 WTGs. The system is able to orient the rotor of a WTG to the wind better than a WTG control system without the appropriate optimization strategy by linking the wind speed, wind direction and electric power measured in the nacelle. “The yields obtained through our system are between two and six percent higher. The system causes the nacelle adjustment to orient itself to the wind in an optimum manner in diff erent ways depending on the WTG type. Since it is neither practical nor possible to integrate the devices required for our system in existing turbines or the logic in the existing control system, we equip the WTGs with an additional wind direction and performance measurement. The external controller is subordinate to the WTG control system, in order not to compromise the safety of the WTG. At the same time, the optimization proceeds within the original operating limits,” explains Dr. Frey.

“Vestas” is a registered trademark of Vestas Wind Systems A/S, DK

Invisible but always in sight:An eff ective function checkof the yaw control gear ensures that potential failures nolonger remain undetected.

1717Feature

Exceptional situations call for exceptional measures. Alternative concepts bridge the service gap in Spain.

Experience has proven that meticulously designed service concepts, together with a comprehensive detailed knowledge of turbine technology, result in the high technical availability of wind turbines (WTGs). This not only ensures the constant investment value of WTG assets but also guarantees stable returns over the entire lifecycle of the turbine. However, what happens when a gap develops between the necessity for long-term investment in turbines or wind farms and the availability of a comprehensive high-level WTG service concept due to challenging general economic conditions? Spain is a good example of this situation. As the world’s leading multibrand service provider for WTGs, Availon demonstrates, using Spain as an example, how to bridge this gap with eff ective alternative concepts for investors, turbine owners and operators.

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Increasing uncertaintySpain continues to suffer from the repercussions of the property bubble. The global fi nancial crisis has also contrib-uted to hindering the economic recovery on the Iberian Peninsula. In addition, the capping of the feed-in tariff, originally also available for pre-existing turbines and wind farms, has reduced feed-in revenues as a whole and made things more diffi cult for owners and operators of WTGs in Spain. Moreover, in addition to the few major operators, there are a large number of smaller service companies competing to survive the economic crisis.

“In view of these negative developments, wind farm opera-tors are becoming increasingly concerned. The poor general economic conditions and the reduction of feed-in tariffs have resulted in the need for noticeable budget reductions,” reports Dörte Nölting, responsible for the Global Business Development division at Availon. In response, competition in the service market has become increasingly fierce. It is, however, question-able whether all services packages contain the tech-nical expertise required to properly service specific turbine classes and the related complex problems and questions.

New, cost-effi cient service concept“Availon is synonymous with technically high-quality and sophisticated service. However, operators and owners of

WTGs or wind farms who are searching for cost-eff ective alternatives for WTG services as a result of the challenging economic situation in Spain, can continue to count on us as a reliable partner,” assures Nölting.Availon has made this possible by developing a new service concept tailored to the specifi c requirements of customers with WTGs in countries with economical diffi cult conditions. The concept was fi rst implemented in Spain in the summer of 2011. It off ers WTG operators the ability to maintain their turbines with state-of-the-art technology with a fl exibleand cost efficient approach that includes high-quality services as well as the provision of spare parts and large components.

A fl exible off er for operatorsNölting explains: “The customer can commission a reliable local company to carry out regular maintenance or minor repair work at a reasonable price, i. e., work that does not require an in-depth knowledge of the WTG. However, in those cases where dedicated turbine know-how and extensive experience are required in order to identify and repair larger turbine malfunctions, the customer can rely on a higher level of expertise. Our new service concept allows us to off er turbine owners and operators the option to decide on a case-by-case basis, whether and to what extent they wish to take advantage of our expertise and services.”

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Technical support at a fi xed priceThis new service concept also off ers large wind farm opera-tors access to our technical support hotline at a previously agreed fixed price for general enquiries and particular problems. For more complex issues, a qualifi ed technician familiar with the turbine’s technology can be made available to off er guidance and troubleshooting. The fi xed price of the technical hotline combined with the provision of a service specialist on request, makes it easier for wind farm operators to calculate their long-term service costs.

High cost transparency for smarter decisionsIn addition customers can choose to what degree Availon should provide them with spare parts management. This allows for additional cost control within the service concept.

“With respect to spare parts, Availon has its own supply chain, which guarantees the prompt availability of the required spare parts. Our customers also profit from our high cost transparency since our price lists for the most important spare parts separate material and labor costs. This makes it easier to compare our spare parts costs with other providers and to decide whether to purchase parts and labor from us or to ask for a separate cost calculation exclusively for the exchanging of components in a turbine,” explains Nölting.

Greater fl exibility in the exchange of large componentsSpanish customers can therefore continue to rely on the in-depth, fl exible support of an experienced service provider particularly in the case of serious turbine problems, e.g. defective large components. If a large component has to be exchanged, Availon’s transparent price lists offer operators maximum flexibility in deciding to what extent they want to take advantage of our products and services. Dörte Nölting outlines the potential of this innovative service concept: “For example, if a generator exchange is pending, a turbine or wind farm operator can now decide to purchase the large component from us but source the crane for the installation from another supplier. They are also free to decide whether we should do the installation. Alternatively, they could purchase the large component from another provider, but commission our service techni-cians to carry out the exchange work.”

A cost-effi cient, modular service system Avalon’s innovative new service concept is based on a modular principle, in which all products and activities required for high quality service are divided into indi-vidual modules and units. This offers customers the flex-ibility to select services and products to the degree and extent that they need in order to meet their current requirements both from a technical and an economic perspective. For the first time, Availon has provided turbine owners in Spain with a highly eff ective instrument for WTG services, which will help secure turbine avail-ability and future revenues, even in a difficult economic environment.

Alternatives are in demandWhen full maintenance or extensive service packages from a single source are eliminated due to diffi cult general eco-nomic situations, as has been the case in Spain, WTG owners are forced to carry a greater share of risk. As a result, taking the time and energy to fi nd an alternative solution for the organization and completion of service work will become an important priority for WTG owners. Some of them have already taken the fi rst steps in securing their future facing of Spain’s difficult economic situation. “Our alternative service concept has already resulted in a confi rmed order from a large wind farm with a capacity of more than 100 MW,” says Nölting.

Dörte Nölting, responsible for“Global Business Development” at Availon.

Feature 19

International VDI-Conference 2012

Maintenance of Wind Turbines

Organized by VDI Wissensforum | www.vdi.de/maintenance | Phone +49 211 6214-201 | Fax +49 211 6214-154

Internationally renowned technology leaders will present their latest results on the following topics:

Changes in customer and market requirements concerning the maintenance of wind turbines

Comparative studies and cost assessments of various maintenance and service concepts

Availability of manpower, required qualifications and professional development strategies

Monitoring methods, damage identification and forecasting

Damage mechanisms and maintenance & repair of different components

Place and Date:

Hamburg, Germany May 8th and 9th, 2012

Moderation and Conference Director:

Prof. Dr.-Ing. Andreas Reuter Director Fraunhofer Institute of Wind Energy and Energy System Technology (IWES), Bremerhaven, Germany

In Cooperation with:

Source: Availon GmbH

Workshop:

O&M Contracts: Typical features, risks and contractual solutions

Hamburg, May 10th, 2012

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organized by VDI Wissensforum

www.vdi.de/maintena

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