Applications throughout the World - Hybrid Anisotropic Materials for Wind Power Turbine Blades - page 5

1.3.1 Types of Wind Turbines

Modern.wind.turbines.fall.into.two.basic.groups:.the.horizontal.axis.variety,.
as.shown.in.the.photo,.and.the.vertical.axis.design,.like.the.eggbeater-style.
Darrieus.model,.named.after.its.French.inventor.
Horizontal. axis. wind. turbines. typically. have. either. two. or. three. blades..
The.three-bladed.wind.turbines.are.operated.“upwind,”.with.the.blades.fac-
ing.into.the.wind.

1.3.2 Sizes of Wind Turbines

Utility-scale.turbines.range.in.size.from.100.kW.to.as.large.as.several.mega-
watts.. Larger. turbines. are. grouped. together. into. wind. farms. that. provide.
bulk.power.to.the.electrical.grid.
Single,.small.turbines,.below.100.kW,.are.used.for.homes,.telecommunica-
tions.dishes,.or.water.pumping..Small.turbines.are.sometimes.used.in.con-
nection. with. diesel. generators,. batteries,. and. photovoltaic. systems.. These.
systems. are. called. hybrid. wind. systems. and. are. typically. used. in. remote,.
off-grid.locations.where.a.connection.to.the.utility.grid.is.not.available.

1.3.3 Inside the Wind Turbine

The.units.that.make.up.a.wind.turbine.(Figure.1.3).include:

Anemometer :. Measures. the. wind. speed. and. transmits. wind. speed.
data.to.the.controller.
Blades :.Most.turbines.have.either.two.or.three.blades..Wind.blowing.
over.the.blades.causes.the.blades.to.“lift”.and.rotate.
Brake :.A.disc.brake,.which.can.be.applied.mechanically,.electrically,.or.
hydraulically.to.stop.the.rotor.in.emergencies.
Controller :.Starts.up.the.machine.at.wind.speeds.of.about.8.to.16.miles.
per.hour.(mph).and.shuts.off.the.machine.at.about.55.mph..Turbines.
do. not. operate. at. wind. speeds. above. about. 55. mph. because. they.
might.be.damaged.by.the.high.winds.
Gearbox :. Gears. connect. the. low-speed. shaft. to. the. high-speed. shaft.
and. increase. the. rotational. speeds. from. about. 30. to. 60. rotations.
per. minute. (rpm). to. about. 1,000. to. 1,800. rpm,. the. rotational. speed.
required. by. most. generators. to. produce. electricity.. The. gearbox.
is. a. costly. (and. heavy). part. of. the. wind. turbine. and. engineers. are.
exploring. “direct-drive”. generators.that.operate. at.lower. rotational.
speeds.and.don't.need.gearboxes.
Generator :.Usually.an.off-the-shelf.induction.generator.that.produces.
60-cycle.AC.electricity.
High-speedshaft :.Drives.the.generator.