From: tgray@igc.apc.org (Tom Gray)
Newsgroups: sci.energy
Subject: --Dutch Develop Variable Speed
Date: 25 Jan 93 19:26:00 GMT
Nf-ID: #N:cdp:1466300154:000:4759
Nf-From: cdp.UUCP!tgray    Jan 25 11:26:00 1993


/* Written 11:22 am  Jan 25, 1993 by tgray@igc.apc.org in igc:en.energy */

DUTCH SCORE SUCCESSES
WITH VARIABLE SPEED
 
While attention in the United States has been focused on U.S.
Windpower's $20 million development of its 33m VS variable-speed
wind turbine, Dutch development of the variable-speed technology
has been largely overlooked here.
 
Although the variable-speed idea is not new (Bergey Windpower Co.
of Norman, Okla., has been building grid-connected small wind
turbines operating at variable speeds for more than a decade), it
was the Dutch who first employed the concept on utility-scale
machines.
 
Several years ago, Stork-FDO Wind Energy, a consortium of two Dutch
aerospace companies designed a series of variable speed wind
turbines for the Dutch government's energy research program.  Four
turbines were eventually installed, and two are still in service,
one in the Netherlands, the other on the Caribbean island of
Curacao.
 
Building on this experience, Lagerweij, a small Dutch manufacturer,
has installed nearly 250 smaller variable-speed machines during the
past six years (see accompanying item).
 
Variable speed is attractive because it enables designers to gain
greater rotor efficiencies by allowing the rotor speed to vary in
response to changes in wind speed.  There may be additional
benefits as well: slower rotor speeds in light winds may lower 
noise emissions just when aerodynamic noise of the blades is most 
noticeable, and variable speeds may reduce dynamic loads on the 
turbine's drive train, thus extending the turbine's life.
 
Not all manufacturers are convinced that it is sufficiently
attractive to justify variable speed's greater cost. Nevertheless,
the concept has long attracted the interest of designers.
 
Stork-FDO began development of variable-speed turbines in the early
1980s, using the technology then available. The Dutch consortium
first built a 26.5-meter (87-foot), 300-kW turbine called the
NEWECS-25.
 
Three of the two-bladed upwind machines were built, two in the
Netherlands and one on Curacao, an island in the Netherlands
Antilles. Only the turbine on Curacao is still operating.
 
The NEWECS-25 was a forerunner of a 1-MW turbine, the NEWECS-45,
now operating at Medemblik on the shore of the Ijsselmeer, the
large Dutch inland sea formed by closure of the Zuider Zee.  Both
designs incorporate a variable-pitch rotor driving a variable-speed
generator through a planetary transmission.  The turbines generate
utility-compatible electricity by conditioning the generator's
output with power electronics.
 
The NEWECS-25 on Curacao has logged more than 43,000 hours of
grid-connected operation since its installation in September, 1985.
The extremely well maintained turbine has been in near-continuous
service since a control failure destroyed the turbine's brake in
1988, and the power electronics manufactured by Brown Boveri
Nederlands have continued to perform to the local utility's
satisfaction.
 
The turbine, located at Boca San Pedro on Curacao's northeast 
shoreline, is the only intermediate-size wind machine still 
operating in the Caribbean, according to Margo Guda of Curacao's 
Fundashon Antiyano Pa Energia.  Guda characterizes the Stork-FDO
turbine as the unsung success story of Dutch wind turbine
development. 
 
Neither Stork nor FDO currently manufacture wind turbines.  The
chief designer of the NEWECS turbines for Stork-FDO, Paul Hensing,
later engineered the corporate takeover of Belgian turbine maker
Windmaster by the Dutch Begemann conglomerate. 
 
Lagerweij has essentially commercialized the variable-speed concept
in the Dutch domestic market and has begun to export turbines to
nearby Germany.
 
===============================

The American Wind Energy Association (AWEA) has authorized me to offer
an electronic edition of its newsletter, _Wind Energy Weekly_, from
which the above article is excerpted, at no cost.

For those of you who have not previously seen excerpts from back issues
on Usenet or Bitnet, the _Weekly_ reports on the outlook for renewable
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edition normally runs about 10kb in length.

If you would like a free electronic subscription, send me an e-mail
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*******************************************************************
Tom Gray                                 EcoNet/PeaceNet: tgray@igc
Internet/Bitnet: tgray@igc.apc.org            UUCP: uunet!cdp!tgray