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Advancing wind powerwith the Pitch Bearing Unit
The energy transition is an important topic that has become an integral part of our present and our future. The aim is to convert the energy supply to renewable energy sources on a sustainable basis - and at competitive costs. The resulting economic and technical requirements pose new challenges for the industry. This is where thyssenkrupp rothe erde comes in and presents a groundbreaking product innovation: the Pitch Bearing Unit, or PBU for short.
Pitch Bearing Unit: Innovation for wind energy
In recent years, the number of wind turbines in onshore and offshore applications has increased worldwide – and a further rapid increase is planned to achieve the climate targets. With our slewing bearings from thyssenkrupp rothe erde, which are used in wind turbines for example, we are already making a decisive contribution to the energy transition. We think there is more to be done! That's why our experts have developed the Pitch Bearing Unit in a development project with HAWE Hydraulik SE and ITH Bolting Solutions, offering a customized solution for future generations of onshore and offshore wind turbines.
The structure of wind turbines at a glance
What do the components of wind turbines look like in detail? That's quickly explained! They are made up of three parts: the tower, the nacelle and the rotor. And this is exactly where our slewing bearings are used.
The tower ensures that today's wind turbines reach a hub height of more than 100 meters above the ground. This allows optimum use to be made of the wind, depending on the location. The rotor consists of a rotor hub, the pitch bearings and the rotor blades. The rotor converts the kinetic energy of the wind into mechanical energy for the drive train. The nacelle forms the heart of the turbine, as it contains the generator and the gearbox.
In focus: Mastering the challenges of wind turbines
In order to understand what the Pitch Bearing Unit is and what advantages it brings, we first look at the current and future challenges facing wind power.
"A key challenge in wind power is the further development of the technology, especially in light of the growth in turbine size," explains Dr. Daniel Becker, Head of Bearing Calculation & Tools. The engineer has been working at Rothe Erde for 13 years and, together with his team, primarily deals with calculation topics and corresponding development projects - including the PBU.
“These challenges apply especially to very powerful systems that are located offshore, i.e. on the sea. The focus here is not primarily on the logistics or transportation of the individual components or assemblies, but rather on the technological growth in size of the components,” Becker continues.
This is the case, for example, with the rotor hub or the rotor blade itself, which in turn creates additional challenges for the blade adjustment or pitch bearing system at both component and assembly level.
However, technological development is not the only issue the industry needs to address. Another key focus is on so-called total costs. These include the procurement costs of the component as well as expenses for logistics, installation and on-site assembly.
As a result, more fundamental topics such as industrialization and productivity improvements across the entire supply chain—from manufacturing through to assembly—are also becoming increasingly important for developers such as Daniel Becker and his team. In addition, there is growing pressure to shorten product development cycles while managing increasing coordination requirements between individual suppliers, along with greater standardization and modularization of individual components.
The Pitch Bearing Unit opens up new possibilities
With the Pitch Bearing Unit, thyssenkrupp rothe erde has added a new product to its own core competencies. Current development trends in multi-megawatt wind turbines show that deformations on the rotor hub and rotor blade side can have a significant impact on the performance and therefore the service life of the pitch bearings during operation. This is precisely where the Pitch Bearing Unit can help.
“The PBU also acts as a stiffening element between the hub and pitch bearing. It significantly increases the structural stability and rigidity in this area of the wind turbine, which is particularly evident with large and therefore potentially soft hub bodies,” explains Dr. Martin Neidnicht, Group Manager FEM Applications in the Bearing Calculation & Tools department at Rothe Erde.
PBU: Three functions in one unit
In addition to the mechanical advantage, the PBU offers further benefits for the wind turbine of tomorrow. The Pitch Bearing Unit is a completely ready-to-install unit and combines three functions in one. The PBU combines the functions of conventional blade bearings, hydraulic or electric blade adjustment and the optimization of mechanical system stiffness. This means that the hydraulic or electric blade adjustment system can be integrated directly into the PBU without a connection to the hub. The advantage: the supply chains of the hub and pitch drive can be specifically separated. This saves logistics costs as well as processing and assembly work for the hub manufacturer. The blade adjustment system can already be set and tested during the assembly of the PBU, which significantly reduces both the complexity and the overall effort involved in the final assembly of the wind turbine on site thanks to the plug-and-play concept.
But what is the difference in the hubs with and without the PBU? Thanks to its conical shape, the Pitch Bearing Unit makes it possible to completely rethink the design of hubs. "By using the PBU, for example, the hub can be made smaller without changing the rotor blade size. At the same time, the blade loads, i.e. the forces and torques that the rotor blades can withstand and which are used to generate the energy, remain unchanged," says Dr. Daniel Becker. Alternatively, the PBU can be used to increase the rotor blade diameter without changing the hub size, for example to use different materials on the rotor blade side, to install different rotor blades or to specifically increase the rotor blade length.
A simpler and smaller hub also ensures less complex production, which reduces manufacturing costs. However, transportation costs are particularly relevant for onshore turbines, as the components are usually transported by road in special transports. Increasingly larger components place special demands on the means of transportation due to their size and weight. And on some routes, long detours have to be accepted, for example due to low bridge heights. By using the PBU with a smaller hub body, cost advantages can be achieved here.
Another advantage of the Pitch Bearing Unit is the possible standardization and modularization of the hub component. Standard hub designs could be used for certain size ranges of wind turbines in the future. Initially manufacturer-specific, i.e. platform-dependent, and in a further step even manufacturer-independent. Such standard hubs could be adapted to different rotor blade diameters and pitch concepts using different PBUs. "By standardizing the hub and modularizing the pitch unit, optimizations and cost savings in the supply chains of wind turbine manufacturers are conceivable, similar to the automotive sector," says Dr. Becker.
Full wind power ahead: New opportunities and prospects for the future of the wind energy sector
For wind power, the Pitch Bearing Unit developed by Dr. Ing. Daniel Becker and his team opens up a number of opportunities and areas of development. This primarily concerns the supply chains of wind turbine manufacturers against the backdrop of standardization and modularization, which allows for further cost optimization. Other starting points include less on-site assembly work during the installation and commissioning of the wind turbine and the targeted reduction of manufacturing, processing and road transportation costs for the hubs.