A Large-Scale Solution for Grid Connection of Wind Farms Using Power Transmission Pipelines

Europe's ambitious plans to expand and support renewable energy will lead to large-scale construction of offshore wind turbines. The vast amount of power has to be transmitted with the lowest possible losses and impact on the environment. Power Transmission Pipelines or PTP are one possible way of satisfying these demands and still meeting the necessary bulk-power-transmission requirements. This article focuses on the connection of the wind farms within the German Bight.

By Dipl.-Ing. Markus Siebert, Leibniz Universität Hannover, and Dipl.-Geogr. Anja Drews, Carl von Ossietzky Universität, Germany

Design, Implementation and Characterisation

In applications such as radar and wind turbines, it is often necessary to transfer power across a constantly rotating interface. As the rotation is continuous, it would be impossible to use wires to transfer the power as they would soon become twisted and stretched and the system would fail. The widespread solution to this problem is to use a slip-ring.

By Dr B. A. Potter, Moog, UK and Dr S. A. Shirsavar, University of Reading, UK

The US wind power industry experienced growth of 45% in 2007, with over 5,200MW installed. According to a new technical report published by the US Department of Energy, the installed wind energy capacity could reach 300GW to meet 20% of the US electricity demand by the year 2030. However, the availability of wind energy is estimated at around 15 to 30%. To avoid frequency and voltage drifts due to short-term wind variations, and to lower the need for spinning reserves due to the intermittent nature of the wind in a system with higher wind energy penetration, different techniques may be utilised. Some tools that can be employed are rotor inertia, in variable speed wind turbines, and ultracapacitors for short-term and battery energy storage for long-term, power levelling.

By Adel Nasiri, Assistant Professor, Power Electronics and Electric Motor Drives Laboratory, University of Wisconsin-Milwaukee, USA

A recent report from the British Wind Energy Association on the small wind industry in the UK identified an annual growth rate of about 80%, and suggested that this was set to continue at a similar rate for the foreseeable future. However, despite the evidently huge market potential, some critics are still saying that much of the technology is not suited to the built environment and that the available equipment is generally expensive, with long payback times. It is easy to understand these views when you see a typical horizontal axis wind turbine (HAWT) sited in an urban setting, continually hunting for the wind on a blustery day, and when the cost of one of the helical type vertical axis wind turbines (VAWTs) is £25,000 before installation costs of a further £10,000-15,000. However, a newly developed VAWT, designed to meet this demand and costing about  £12,000 fully installed and connected, is to go onto the market shortly.