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market.Essentially MEASNET enables a number of distributed test
stations to act as one entity as an alternative for one centralised
accredited testing laboratory.
The demand for small capacity wind turbines vanished slowly
in favour of medium-size grid-connected turbines. At the same time
the wind turbine market developed from a domestic to a continental
and intercontinental one. It was the Danish manufacturers who
started selling their machines to diferent European countries
and were very successful in exporting them to the United States.
2.2
National Programs
In parallel to the developments described above, as of the late
seventies, national governments commissioned large technology
firms like MBB, MAN, Boeing and Stork and research establish-
ments like Risø (DK), ECN (NL) and SERI (USA) to develop large
experimental wind turbines. These projects were elements of
various national R&D programs, which also incorporated resource
assessment, grid integration, technology assessment (vertical
versus horizontal wind turbines), aerodynamic rotor modelling,
aero-elastics, structural dynamics, design tools, component testing
and standards.
The first large-scale turbines were commissioned in 1979 (NIBE
1 and 2 in Denmark) and the last experimental, non-commercial,
turbine was completed in 1993. In total some 30 non-commercial
experimental machines were built with substantial support from
national governments. The technical layouts of these wind turbines
were very diverse. Many of the innovations dating from before
1960 were improved and implemented.
The spectrum of concepts included:
• Rotors with 3, 2 and 1 blade(s) for horizontal-axis turbines
and 3 and 2 blades for vertical-axis machines;
• Fixed, teetering and flexible hubs;
• Fixed blades, stall control and full and partial pitch control;
• (Nearly) constant and variable rotational speed transmission
systems, incorporating multiple control options.
Also spectacular installation techniques were realised. The
methods varied from conventional installation by means of cranes
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