Drive & Control Technology for Wind Turbines

The Drive & Control Company Technology for Wind Turbines | Product Overview

Everything is Going Round: Drive & Control Technology

Wind energy continues on its Broad Range of Supplies road to success by greatly No matter whether the traditional increasing its share in electri- concept comprising rotor, gear- cal power production on a box, generator or a direct-drive worldwide basis. The nominal solution is involved: Rexroth offers power of wind turbines has matching gearbox and hydraulics risen from 100 kW to 3,000 kW. solutions for any type of wind Now the first 5-MW installa- turbine. Within our mechanical tions are harvesting power. drive technology segment we Rexroth as producer of hydrau- develop and manufacture all types lic and gear technology sys- of gearboxes required for wind tems is a competent partner turbine installations: efficient and comprehensive supplier generator gearboxes, highly precise to manufacturers of wind yaw drives for permanent wind turbines. tracking purposes and compact pitch drives used for rotor blade adjustment.

Being the world’s leading supplier of industrial hydraulic equipment we also offer hydraulic solutions for wind energy applications: our supply range includes highly dyna- mic hydraulic pitch adjustment systems, reliable drive train brakes as well as yaw drive brakes. Bosch Rexroth. 4 The Drive & Control Company

Rotor Blade Adjustment 6

Electromechanical 7 Rotor Blade Adjustment

Hydraulic 8 Rotor Blade Adjustment

Generator Gearboxes 10 for Systems up to 2,000 kW

Differential Gearboxes 12 for Multi-Megawatt Turbines

Yaw Drives 14

Yaw and Drive Train Brakes 16

Service 18 Technology for Wind Turbines

A Company on the Upswing: Good Reasons for Rexroth

Drive systems to be incor- Experience and Know-how Competence in Marketing porated in wind turbines must For about 100 years Rexroth have and Design satisfy many specific needs: been producing drive system com- The importance of industry- Variable wind loads, higher ponents. Already in the early specific drive system solutions is outputs, less available instal- nineties we built gearboxes for 3.2- steadily growing. Rexroth has taken lation space and minimum MW turbines and thus were among these trends into account by having weights are just a few techni- those that from the beginning took established market-oriented appli- cal requirements designers part in the technical development cation centers. In the application and engineers must observe of wind turbines. Long-standing center renewable energies, product aside from climatically induced contacts with leading universities experts are at your disposal, who strains. and renowned antifriction bearing are not only specialized in drive manufacturers help us to improve technology and hydraulics, but are our products on a constant basis. also familiar with the specifics of Rexroth concentrates its know-how your application. This enables us and technical expertise in its wind to provide tailored solutions for energy product sector and thus each wind turbine project. strengthens its position as sought- after partner of wind turbine manu- Being able to offer customer-specific facturers. engineering services is thus one of our strong points. The advantages our clients can thus expect from us are the result of decades of experience with planetary gears and Simulation hydraulic components as well as our innovative power. Moreover, unpleasant surprises may be avoided thanks to our know-how in engineering, manufacturing and testing. Before a complex component is actually manufactured, we have made sophisticated FEM calcula- tions.

Rexroth gearboxes are designed for maximum safety and reliability. In their design and development activities, our experienced engineers are assisted by modern com- puter software for gearing design and component optimization. Measurements on built-in proto- milling and grinding operations Heat treatment types are performed based on many involved in the manufacture of years of experience. In the field gearbox components and gear teeth we carry out, for example, air- is continually being further devel- and structure-borne noise as well oped and forms the basis of the as torque and load measurements. highest possible product quality. Rexroth invests systematically in Top Performance from advanced production machinery to Start to Finish ensure maximum quality and We know that quality greatly economic efficiency. depends on selecting the right suppliers. Therefore, our suppliers On our test benches all our com- must satisfy the same high stan- ponents are checked to most dards we have adopted. Quality stringent quality criteria prior to also means doing things right from shipment. In our manufacturing the start: from machining, to heat facilities we subject our generator treatment and assembly, including gearboxes to full-load tests up to a inspection, painting and shipment. nominal power of 5 MW; special In this context, our quality man- test configurations may be set up agement system to DIN EN ISO to comply with customer specifica- Grinding 9001:2000 is the basis and guarantor tions. Advanced software packages of a consistently high quality level. enable temperature and noise Another area of major concern to characteristics to be recorded. Assembly of REDULUS GPV Rexroth is environmental protec- tion. For many years we have also been operating an environmental management system to DIN EN ISO 14001 at our locations.

Modern heat treatment methods have a decisive impact on the quality of gearings and components. Our vast experience in heat treatment technology is a most significant quality factor ensuring our gearboxes meet maximum standards in terms of strength, load-carrying capacity, compactness and service life. The know-how we have gained over several decades in the various Technology for Wind Turbines | Pitch Drives MOBILEX GFB

Facing the Wind Optimally: Rexroth Solutions for Rotor Blade Adjustment

100 m above ground. A strong wind is blowing at this height. The pitch drives of the wind turbines – com- pactly arranged at the root of the three rotor blades – constantly rotate with the rotor and make sure the blades are correctly po- sitioned. They must meet highest requirements with respect to design and functional safety. Aside from reliability, precise positioning is of utmost importance. By providing both hydraulic and electromechanical pitch drives, Rexroth is capable of satisfying these technical needs. Technology for Wind Turbines | Electromechanical Pitch Drives MOBILEX GFB

MOBILEX GFB Pitch Drives The Rexroth supply scope includes a complete range of MOBILEX GFB planetary gearboxes for all wind turbine sizes. To this end we can draw on 40 years of experience in the manufacture of swing gears for mobile equipment, such as exca- vators or cranes. The proven technological solutions in that field have been advanced to electromechanical pitch drives. The pitch drive supply range spans from small, two-stage planetary gears with output torques of about 1 kNm and ratios of 60:1 to three-stage types featuring output torques of about 20 kNm and ratios of 200:1. These space-saving drives consist of a compact two- or three-stage planetary gear unit equipped with output pinion and electric motor. Since electromechanical pitch drives are constantly rotating together with the rotor hub they are provided with special seal systems. Where confined mounting Technical Features situations are encountered, an MOBILEX GFB Pitch Drives: angle-type input gear stage is avail- • Output torques from able as necessary. 1 to 20 kNm • Ratios ranging between 60 – 200 • Compact, space-saving two or three-stage planetary gearboxes • Optional bevel gear stage • Sturdy antifriction bearing • For the attachment of electric motors • Easy to install • Convenient oil change • Low-noise running characteristics Technology for Wind Turbines | Hydraulic Pitch Drives

Hydraulic Pitch Control The hydraulic pitch drive com- bines all desirable characteristics in a single system: high positioning forces, compact size, distributed intelligence, high dynamics as well as long service life and reliability.

Plug & Play After assembly all pitch drives are checked for correct functioning on the test bed. Moreover, our staff makes sure all electrical modules are attuned to each other. This enables the pitch drives to be mounted and put into operation as soon as they arrive on site. Thus complex matching of signals and other electrical characteristics can be dispensed with – plug & play.

Fail-Safe Properties The Fail-Safe operation of the individual pitch drives is achieved by establishing logical connectives between the individual hydraulic components.

Lead-in

Their functions are based on purely High-quality hydraulic compo- mechanical principles and are nents from company-own fabri- highly reliable. Nevertheless, should cation, amply sized filters for highest complications arise all the same, oil purity as well as coolers and the rotor blade, powered by hydrau- heaters ensuring optimum operat- lic accumulators, will move into ing temperature are prerequisite to the safe end position without ex- a long service life. ternal control action being necessary. Using hydraulically pressure- controlled variable displacement Distributed Intelligence pumps in conjunction with hy- Proportional valves with inherent draulic accumulators results in processors and storage modules high actuating forces and spare are capable of performing all neces- capacity with only minimum space Technical Features sary actions from simple open- requirements and efficient energy Electrohydraulic Pitch loop control duty to complex utilization. Control System: closed-loop feedback control func- • Precise controllability tions. This will reduce the loads Decentralized Arrangement • Highly integrated acting on the control system and The individual functioning • Compact design also the bus system. modules of the hydraulic system • Reliable fail-safe function need not necessarily be arranged • Integrated safety functions Hydraulic Pressure Supply side by side. Providing flexible • Easy commissioning Nothing goes without pressure. connections between the indivi- • Long service life Even the most intelligent hydraulic dual modules enables the entire • Highly environmentally system needs pressure to get things hydraulic system to be optimally compatible moving. Since oil has no definite integrated into the wind turbine. • Flexible arrangement shape the hydraulic unit can utilize • All common analog and even the smallest mounting space. digital interfaces 10 Technology for Wind Turbines | Generator Gearboxes REDULUS GPV | for Ratings between 660 and 2,000 kW

Quiet and Reliable: The REDULUS GPV Generator Gearbox

An offshore wind farm in the It is the central element in the And this is what REDULUS GPV North Sea off the coastal region of wind turbine’s drive train. While a does. Day after day. Denmark. A hard southwesterly car gearbox is designed for a wind of 8 Beaufort is blowing lifetime of two thousand hours here. A rough climate – and high the generator gearbox shall re- stresses for the generator gear- liably operate for 20 years, i. e. box as well. about 175,000 operating hours.

Offshore- wind farm Horns Rev 11

Technology for Wind Turbines | Generator Gearboxes REDULUS GPV | for Ratings between 660 and 2,000 kW 11

REDULUS GPV generator gear- gearboxes meet maximum stan- Technical Features boxes of compact design com- dards in terms of strength, load- REDULUS GPV for Turbines prising a combination of one plan- carrying capacity, compactness between 600 and 2,000 kW: etary and two helical gear stages and service life. We are of course • Ratios ranging between 50 – 120 have meanwhile been in use in a aware of our customers’ wishes for • Tailored design solutions variety of wind turbines with power optimum gearbox noise character- • Compliance with Rexroth design ratings of up to 2 MW. Rexroth istics. Already 40 years ago we guidelines to ensure maximum develops customer-specific solutions built large-size low-noise gear service life best matched to the needs of the units for cruise vessels. What at • Compact design due to com- relevant turbine configuration. that time helped passengers to bining a planetary stage with two The external teeth of our gears are sleep well contributes today to the helical gear stages case hardened and the ring gears’ quiet operation of generator • Case hardened and ground internal teeth are nitrided. Our gearboxes. Aside from our design external gears vast experience in heat treatment strategy, a highly precise profile • Helical planetary gear stage technology is a most significant grinding process assists in keeping • Ground, nitrided ring gears quality benefit ensuring our the noise level in the nacelle down. • High-grade antifriction bearings • Injection lubrication for planet gear bearings and cooling system optional • Connection of rotor shaft and hollow input shaft via shrink disk • Sensors for pressure and temperature monitoring purposes • Low-noise characteristics 12 Technology for Wind Turbines | Differential Gearboxes REDULUS GPV | for Ratings between 2,300 and 5,000 kW

Slender and Compact: REDULUS GPV-D for the Multi-Megawatt Class

Design engineers have to master more and more stringent challenges to keep pace with the trend towards multi-megawatt wind turbines. The developers’ requirements specifications frequently include demands for more compact drives with the gearbox weight to be minimized as well. Rexroth with its innovative differential gearbox of type REDULUS GPV-D now satisfies precisely these needs by providing a multiple power-split design solution.

There is a significant difference in comparison to the conventional generator gearboxes of the multi- megawatt class: In the input stage of this unit it is not four or more planet gears that revolve around the sunwheel. Instead, REDULUS GPV-D includes two input stages each fitted with three planet gears which offers advantages in terms Technology for Wind Turbines | Differential Gearboxes REDULUS GPV | for Ratings between 2,300 and 5,000 kW 13

of static determination paired with Functional Principle of the freely adjustable sun pinions. Differential Design Power splitting takes place in the first REDULUS GPV-D offers major planetary gear stage. Via the rotor benefits in that it has slender outer speed, part of the power is directly transferred from the planet carrier into diameters with the total length just the first planetary stage, the other part being increased slightly. If higher is transmitted into the revolving ring turbine capacities are involved gear of the second planetary stage as lossless coupling power. The power weight advantages of up to 15 % distribution percentage is subject to may thus be achieved compared to the stationary gear ratio of the three planetary stages. the gearbox concepts currently in use, without compromising relia- The speed of the first planet stage sun bility. In this context, component gear also coincides with that of the sizes also contribute: The dimen- planet carrier of the differential stage summing up the power. Moreover, the sions of the internally and exter- speed of the sun gear of the second nally toothed gears, antifriction planetary stage corresponds to that of bearings and planet carriers of the rotating ring gear of the differential stage summing up the power. The REDULUS GPV-D are similar to speed rates of ring gear and planet those used in the 1.5- to 2-MW carrier of the differential stage result Technical Features class gearboxes. Benefits for our in a cumulative speed of the sun gear REDULUS GPV-D for Turbines where the split power is brought customers: By utilizing reliable, together again. between 2,300 and 5,000 kW: reproducible production processes • Ratios ranging between 70 – 150 we manufacture these components • Tailored design solutions already today in large quantities • Compliance with Rexroth design and with constantly high quality. guidelines to ensure maximum service life • Differential design concept with two planetary stages, one differential and one parallel shaft gear stage • Case hardened and ground external gears • Ground, nitrided ring gears • High-grade antifriction bearings • Circulating lube oil system to feed oil to all tooth meshing points and bearings; cooling system optional • Sensors for pressure and temperature monitoring • Low-noise characteristics • Easy to service due to modular design 14 Technology for Wind Turbines | Yaw Drives MOBILEX GFB

Keeping on Track: Yaw Drives MOBILEX GFB

Schleswig-Holstein – land between the seas. Days without wind blowing there are the exception, not the rule. Even in the brightest sunshine wind turbines may operate at an appreciable load. If the sensors signal to the control system a wind direction change of 8° towards NNW the yaw drives are activated and position the nacelle exactly as necessary. Precision and the behavior of the meticulously matched individual drive systems are decisive factors. No problem for our robust and powerful yaw drives of type MOBILEX GFB. 15

Since 1968 planetary gearboxes have The drives consist of a compact been part of the Rexroth supply four-stage planetary gearbox range. In the eighties, starting from equipped with output pinion and the technological experience gained electric motor. The planetary with these gears in cranes we de- gearbox has four planet stages veloped drives needed for optimum offering high transmission ratios yaw control of the nacelle. Whether for highly sensitive rotational big or small, we have available a movements. The ever increasing complete supply range of MOBILEX size of the nacelles makes of course GFB gearboxes for any type of higher torque rates necessary. turbine size. The output torques These can be achieved by arranging here range from 3 kNm to 150 kNm several drives arranged around the while the ratios of the four-stage yaw bearing. All in all, more than planetary gears are between 700:1 10 gearboxes may be employed for Technical Features and 2,000:1. the yaw control system. MOBILEX GFB Yaw Drives: • Output torques between 3 and 150 kNm • Ratios ranging between 700 – 2,000 • Compact, four-stage planetary gears • Sturdy antifriction bearing • For the attachment of electric motors • Easy to install • Convenient oil change • Low-noise running characteristics 16 Technology for Wind Turbines | Drive Train and Yaw Drive Brakes

Both Strong and Gentle: The Drive Train and Yaw Drive Brakes

It’s inspection time for a wind the rotor is secured in a safe So, this enables the Rexroth staff turbine. Before the engineers can position. Compared to the past, to do what is expected of them: access the nacelle the wind tur- this is easily accomplished today: Carry out the inspection. bine must be stopped. In fact, the electrohydraulic brake con- exactly in a predetermined po- trol stops the rotor exactly in the sition. After all, the service staff required position and automati- must be able to gain access to cally engages the rotor arresting the hub. This necessitates that system.

Brake Gently and Secure Firmly until the rotor arresting function slipping pressure and the entire If the design provides for the wind has been activated. Following this, nacelle is then moved by action of turbine to be stopped by the drive the brake is released eliminating several yaw drives. As soon as the train brake alone, extremely high loads otherwise acting on the drive new position is reached the orig- brake torque rates will act on the train which is in the interests of a inal pressure is restored which also generator gearbox. Therefore, stop- long service life of the entire wind results in the yaw drives to be ping the turbine solely for service turbine. relieved. Using proportional valves work purposes would cause undue for slipping pressure control will strains and unnecessary wear. For Always Facing the Wind bring down wear significantly. this reason Rexroth distinguishes When the wind direction changes between emergency braking and the entire nacelle has to be moved And when the cables between service braking operations. When into a new position. For this pur- nacelle and tower are untwisted the rotor is stopped in the desired pose the clamping pressure exerted the nacelle quickly rotates “back- position it only needs to be secured by the yaw brakes is reduced to wards” due to the yaw clamping

Complete power unit Control block Control block for controlling all for brake controlling at for characteristic curve-controlled braking functions exact speed or torque soft braking 17

action being completely released to this purpose a bore arranged in the reduce wear. rotor shaft is brought in alignment with the arresting cylinder which Mechanically Blocked for can then be engaged. If to be per- Safety Reasons formed manually, at least two or Technical Features If persons are to perform work on three persons are needed for this Electrohydraulic Brake Control: or inside the rotor it is mandatory work – an electronic control • Precise open-/closed loop control in the interest of safety that the system does it automatically. capability rotor is mechanically arrested. For • Very compact design • Integrated safety functions • Easy commissioning • Highly environmentally compatible • Designed for an operating time customary for this application • Tailored solutions based on modular concepts • Drive rating between 0.18 and 4.0 kW • Volumetric flow rates from 1.2 to 14.8 l/min • Tank capacity from 1 to 60 l

Pressure control valve • Tank of steel, aluminum or plastic with electrical activation 18 Technology for Wind Turbines | Service

No Matter Where, When or Why. Our Service – At Your Disposal.

One thing’s for sure: In the event preciate but help to achieve as repairs: no matter what Rexroth problems arise in your wind tur- quickly as possible. In more than component is concerned – our bine installation our service team 80 countries and on a 24/7 basis, qualified experts and dependable will be quickly on site to give our service division is ready to service people will be pleased to professional servicing assistance. provide assistance. Rely on our help you. To find a Rexroth expert “Set them up and harvest power” unexcelled service competence near your location visit: – is the objective of all wind farm and performance. In-the-field www.boschrexroth.com. owners, which we not only ap- support from failure analysis to Endoscopic examin- ation of the generator gearbox

Gearbox Inspection and Proactive Spares The Drive & Control Company Electric Failure Detection This Rexroth service segment is Rexroth is unique. No other brand Drives and Preventive maintenance of the characterized by speed, compe- on the world market can offer its Controls gearbox improves the availability tence, efficiency, and world-wide customers the full range of drive of your wind turbine installation logistics. We will furnish original and control technologies, both Hydraulics and its operational efficiency. Our spares of OEM quality, spares kits on a specialized and integrated qualified service engineers have and upgrading sets for existing basis. This is one of the reasons Linear comprehensive experience regard- equipment – even after a given why we are best-in-class on a Motion and ing the early detection of failures. production series has expired. worldwide basis when it comes Assembly They use proven inspection soft- to furnishing technological Technologies ware and perform measurements driving, controlling and motion and tests with the help of modern solutions; a standard to be con- Pneumatics equipment and systems. stantly confirmed by mastering new challenges. In more than 80 Service Repairs countries around the world, with Our comprehensive gearbox design about 30,000 employees. This knowledge makes sure faultless is possible thanks to an infra- repairs are carried out on a cost- structure purposefully designed effective basis. Overhauls and the with partnership and customer re-manufacture of equipment proximity in mind. items are effected based on original drawings which are also As a company Bosch Rexroth drawn upon when gearteeth must looks back on more than 200 be reground. Prior to delivery, any years of tradition. As a wholly repaired gear unit is tested on our owned subsidiary of Robert test benches according to most Bosch GmbH, we are part of a stringent quality criteria with globally operating technology relevant reports being issued. group. All this is both our drive and our commitment. And it is unique – just like Bosch Rexroth. The Drive & Control Company. Ground, helical planetary gear – original spares of Rexroth quality Bosch Rexroth AG www.boschrexroth.com/windenergy

Gear Technology

Bosch Rexroth AG Mannesmannstraße 58455 Witten, Germany Phone: +49 2302 877213 Fax: +49 2302 877335 [email protected]

Hydraulics

Bosch Rexroth AG Hydraulics Zum Eisengießer 1 97816 Lohr, Germany Phone: +49 9352 181237 Fax: +49 9352 181222 application-centre@ boschrexroth.de

Title motive and photo on page 2: Printed in Germany Jan Oelker, Radebeul RE 76110/09.07