The Mawson turbines are modified from the standard E-30 turbines manufactured by the German company Enercon. The modifications to accommodate Antarctic conditions include:

• low temperature steel used in all tower sections, castings, and structural components;
• shorter tower (34 m) due to high winds and crane restrictions;
• extra insulation and heaters (rarely used) in the nacelle;
• brush seals on nacelle to exclude blown snow;
• control software modifications to ramp-down output power when the wind speed was in the range of 25 m/s to 34 m/s (a high proportion of winds at Mawson are above 15 m/s);
• special cold-porch attachment at tower entrance to exclude snow; and
• no de-icing systems required due to the dry atmosphere.

The powerhouse control system

A critical part of the Mawson wind farm is the computerised powerhouse control system, supplied and installed by Darwin company, Powercorp. The system is designed to optimise and balance the station heating and electrical loads (around 250kW each) against the available wind power and the diesel generator output.

The initial design also recognised the requirement for a storage device such as a flywheel to smooth the grid output and to prevent blackout conditions with the high wind penetrations envisaged. To achieve these requirements Powercorp developed a Boiler Grid Interface (BGI). The control system and BGI switch excess wind energy into and out of an electric boiler (which provides heat for the station buildings) at such a rate that the voltage and frequency on the grid become stable despite variable turbine output due to wind gusts. The BGI operation is similar to that of a flywheel (except that heat rather than electrical energy is extracted back from the system) and adds spinning reserve to the diesel generator sets.

Performance

Baseline statistics were recorded in 2002, the year prior to installation of the turbines. In that year the average winter population was 19 and the average summer population was 41. Annual wind penetration (the percentage of station energy load provided by wind) during the first four years of operation has averaged 34%. Monthly fuel savings have been as high as 58% compared with the corresponding month in 2002.

Table 1. Statistics for operation of Mawson station wind turbines

(March 2003 – March 2007)

		The Boiler Grid Interface (BGI)

http://www.aad.gov.au/apps/operations/electrical.asp