Support and foundation structures for wind turbines

Steel tower with longitudinally oriented subshells

The SKI engineering company engaged in supporting and establishing structures for onshore wind turbines. The offshore variants are found in offshore wind energy plants under a separate heading.

The range of services includes static and dynamic structural analysis using numerical simulation tools for the following applications:

Support structures:

Bonding techniques:

Foundation structures:

Rotor blades:

The development of the system size and power rating

Development of the system size and power rating of series-built wind turbines

With increasing hub heights and plant sizes pushes the previous standard solution as a conical tubular steel tower is reaching its limits. The rapid growth of mass-produced wind turbines in terms of rated power, the rotor diameter and hub height can be seen in Figure 2.3. While the rotor diameter of a wind turbine in 1982 was D = 15 m, in 2008 are now systems with up to D = 125 m and 5 MW available. Prototypes with even greater benefits are currently being tested.

The continuous development of even larger turbines is closely linked to the increase of the dimensions of the support structures. In GASCH & TWELE 2005 is a compilation of specific tower masses as a function of hub height to be found. The required tower masses rise according to the structural load in an approximately square with the hub height. For a prototype with 6 MW rated power production of the bottom tower section would be possible as pure tubular steel construction only with increased manufacturing and assembly costs, with the tower manufacturer come up against technical production limits in steel construction. For example, in most plants, the round rolls of heavy plates with a thickness up to 70 mm is not yet a limiting factor. During transportation to onshore locations, there are many road bridges because of limited vertical clearance of 4.3 m, a further restriction on the tower diameter.

Led as higher production and transportation costs for the tower diameter is greater than 4.3 m to alternative solutions, such as the reinforced concrete tower, which is produced on site with a climbing formwork. Alternatively, a few years since precast concrete towers for large hub heights, the lowest tower segments are transported upright and as part of shells to the site.

If above concrete tower sections or steel tower sections are used, then one of these combined design variant to the category of hybrid towers.

To future larger plant types continue to run starting with steel supporting structures of the base of the tower, the sandwich tower was developed, with which the shell stability and load capacity can be increased. The transport problem of diameter greater than 4.3 m is to be achieved by a new manufacturing concept.