Over the past decade, land-based wind turbines have grown considerably. This up-scaling has caused problems by subjecting gearboxes and drive trains to heavy loads and stresses. In order to reduce loads and increase turbine lifespan, Clipper Windpower of Carpinteria, California, USA, has developed the 2.5MW Liberty wind turbine.

With increasing turbine size, dynamic loading of the tower increases. With dampers, these loads can be reduced. The mass of conventional pendulum dampers is approximately 4% of the total turbine. The Tuned Liquid Column Damper (TLCD) provides a new solution that enables significant tower mass reduction, using only 2% of the effective mass. The tuning possibility facilitates on-site optimisation of damping characteristics. The TLCD enables reduction of the ‘cost of energy’ for both new and existing turbines.

For many years most modern large wind turbines were erected in areas like Denmark and northern Germany, where earthquakes are rare and normally weak. However, more recently wind farms have been developed in Asia, Africa and southern Europe, where strong earthquakes are much more likely to occur. As a consequence, the question arises as to how wind turbines perform in an earthquake of a given magnitude, and especially to what extent the stability of the overall structure and integrity of the machinery are guaranteed. This article describes how building codes for seismic loading of structures are used for site approvals for wind farms and shows results for the simulated dynamical behaviour of a wind turbine in an earthquake. The simulation has been carried out with the new simulation code SiWEC, which is also introduced in this article.

Imagine a kite that looks like an aircraft and can be flown like one. An efficient, reliable and stable design. Such a kite is a portable pulling force in the air. With this force it is possible to do all kinds of exciting things such as pull ships and generate energy. At the Delft University of Technology, Faculty of Aerospace Engineering, kites are maturing from ‘toys’ to a serious force to be reckoned with.

The operation of modern and increasingly high-capacity wind energy installations makes many demands on automation technology. Modern pitch-controlled systems, which satisfy requirements of more precise and controlled power output in practically all wind and plant configurations, need relatively complex active control systems that can no longer be supplied by a simple programmable logic controller (PLC). In addition, increasingly common and urgent demands from network operators to correct frequency or reactive power fluctuations in the whole park call for previously unknown communication abilities. In this article, Bachmann electronic describe the capabilities of their new M1 control system, which was designed to meet these demands.

By Gabriel Schwanzer, Director Sales and Automation, Bachmann electronic, Austria

Setting the Framework for the Sahara Wind Energy Development Project