Abstract
In December 2002, a new wind-diesel system, rated 30 kVA, was commissioned on the island of Osmussaare, Estonia, by the Swedish company PitchWind Systems AB. The wind-diesel system is the only power source on this isolated island, where a radar station is under construction. The end user is the Estonian Border Guard and the project was carried out in cooperation with a local partner, Empower EEE AS, which also supplied the tower of the wind turbine.
PitchWind's wind turbines are especially suited for wind-diesel applications, because of the variable speed operation and special control system. The concept, originally developed by Chalmers University of Technology, saves expense by not requiring a dumpload, rotary converter or custom-built diesel genset. The system efficiency results from the use of power electronic interfaces, robust, but sophisticated, control and the special characteristics of the wind turbine. On Osmussaare, it was decided to include a battery bank in the system to increase fuel savings, because of the very high cost of fuel on the island, but the system works also without the battery bank.
The power electronics used in the project are standard industrial products made by ABB and the wind-diesel control system, based on LonWorks technology, was supplied by the ÅF Group. LonWorks is a wide-spread technology for open, distributed control systems, and brings several important benefits for hybrid power systems.
During 2003, PitchWind plans to install a similar wind-diesel system together with Empower EEE on Vaindloo, another remote Estonian island.