Self-erecting onshore wind turbines with hub height above 120m - hybrid tower with hoisting device for self-assembly

  Hydraulic valve Copyright: © ifas

The Renewable Energy Sources Act (EEG) stipulates that renewable energies should cover a share of at least 80 percent of gross electricity consumption by 2050. In recent decades, wind energy has ensured the increase in energy yields required to achieve this through larger rotors and increasing hub heights. As a result, the limits of conventional tubular steel towers are repeatedly reached due to transport limitations. An alternative is provided by so-called hybrid towers, in which the lower segment is erected on site (e.g. lattice tower) and the upper segment continues to consist of a tubular steel tower. However, the erection of the high tower by means of special cranes results in an increase of the main investment costs. Therefore, a reduction of the erection costs is to be aimed at in order to ensure a positive overall balance.

 
Benefit Procedure
Reduction of material, transport and erection costs of a wind turbine

Load modelling of the WTG during construction / final stage

Guidelines for the optimized dimensioning of self-constructed WTG

Modeling of the lifting and stabilizing device

Simulation of the lifting process on the basis of different control approaches

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New approach to the construction of wind turbines

The aim of this research was to increase the power generation yield by increasing the hub height while reducing the erection costs. In this research project, a self-erecting wind turbine with a steel hybrid tower was therefore developed, which does not require the use of special crawler cranes.

The steel hybrid tower consists of an 80 m high lattice tower with a special transition piece and a 100 m high tubular steel tower. To reduce erection costs, the tower will be erected conventionally up to a height of 100 m (installation height) using a crane. The tubular steel tower will be assembled in parallel inside the lattice tower and temporarily fixed. After completion of the lattice tower, the tubular steel tower together with the wind turbine will be lifted to its final position by means of a strand lifting system.

 
 

Stabilisierungssystem

Working cycle of the stabilization system Copyright: © ifas Working cycle of the stabilization system

The horizontal forces, bending and torsional moments during the lifting process are absorbed by stabilizing cylinders arranged in four planes orthogonal to the tower axis in the transition piece. These align the tower and absorb the bending moment during the lifting process via a pair of forces. The system offers the advantage of passive stabilization of the tower during lifting. Only when the dead centers (TDC or BDC) are reached must the cylinders be moved in a controlled manner. Thus, the control of the cylinders is not critical to safety, since the tower is always passively stabilized.

 
  Simulation of the stabilizing forces Copyright: © ifas Simulation of the stabilizing forces

As part of the development, design principles of the system were worked out, allowing the number, orientation and size of the stabilizing cylinders to be calculated. Furthermore, the system was modeled using the 1-D simulation software Amesim. By means of the simulation model, the stability of the system and the acting loads under dynamic wind loads were investigated.

 
 

Acknowledgement

The IGF project „Selbsterrichtende Onshore WEA mit Nabenhöhe größer 120m – Hybridturm mit Hebevorrichtung zum Selbstaufbau“, IGF-Projekt Nr. 20604 N, of the Forschungsvereinigung Stahlanwendung e. V. (FOSTA), Sohnstraße 65, 40237 Düsseldorf is founded via the AiF within the context of des programme for the funding of the joint industrial research (industriellen Gemeinschaftsforschung (IGF)) by the Federal Ministry of Economics and Energy on the basis of a resolution of the German Bundestag. We would like to take this opportunity to express our sincere thanks for this funding.

  Copyright: © AIF
 
 

Publications

Title Author(s)
Selbsterrichtende Windenergieanlage mit Nabenhöhe von 180 m
Journal Article (2021)
Pak, Daniel (Corresponding author)
Korte, Sebastian (Corresponding author)
Kemper, Frank (Corresponding author)
Friehe, Mirko (Corresponding author)
Fontecha Gonzalez, Robert (Corresponding author)
Reese, Christian (Corresponding author)
Schmitz, Katharina (Corresponding author)