Month: May 2012
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WTG Components: an introduction
Blades: Most wind turbines have three blades, though there are some with two blades and even with a single blade. Blades are generally 30 to 50 meters (100 to 165 feet) long, with the most common sizes around 40 meters (130 feet). Longer blades are being designed and tested, but the main problem with bigger…
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Economics of an onshore wind farm
The total cost of a wind farm is made of the sum of the following expenditures, in this chronological order: Feasibility study, including wind analysis, preliminary layout, environmental studies, economical models and so on. Technical/Juridical costs associated with the start up: power purchase agreement, legal permits, right of way with the landowners, etc. Engineering: civil…
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Anchor Cage assembly
Here you have several picture of an anchor cage we assembled a few days ago. The anchor cage is a system conceived to transfer the loads to the foundation more effectively, anchoring the tower to the foundation. It is made of two ring-shaped steel plates, an anchor plate and a load distribution plate, secured by…
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Cable trenches layout design
We try to design cable trenches as straight as possible, avoiding pronounced angles. There are several national norms on the minimum bending angle, for instance UNE 20435/2 in Spain. For environmental and technical reasons we try to design the trench parallel to the access road. When we have to cross an obstacle such as an…
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Vertical transitions curves in wind farm
The main problem with turbine tower trailers is that they are very low. For this reason we normally use long transition curves in vertical alignment, with a parameter of the parabola (Kv) of 400 or even more. This is the best approach, as for instance the alternative of a minimum length definition of the transition…
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Meteorological towers in a wind farm
In a standard wind farm, 3 different Meteorological Tower (known as Met Mast) are installed. First of all, a tower is needed to provide several years (normally at least 2) of wind data. This tower is used to collect not only wind data, but also other information such as temperature, humidity, rain and so on….
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Crane pads shape and dimension
Reading the wind farm BoP related info of several companies in the sector, such as Gamesa, Vestas and Nordex, I’ve found a variety of proposed shapes and dimension for the crane pads. Basically a rectangular solution looks like the more reasonable option, but sometimes triangular, polygonal and even circular pads are found. I think that…
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Wind Turbine erection: 2 cranes working together
To lift the biggest component of the WTG, such as the tower segments or the blades, two cranes are used at the same time. A principal crane, normally a Liebherr 1600 or a Demag CC2800, is helped by a smaller crane, often a rubber-tired rough terrain crane, for instance a Terex RT1120. Both cranes start…
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Anchor cage foundations
Anchor cage foundations are an alternative to the embedded ring and they will be a de facto standard in the future. Basically an anchor cage is a set of bolts, kept together by an inferior and superior steel rings. It normally arrives disassembled to the site, and it is mounted by workers in a few…