Posts Tagged ‘Science’

Active and Reactive Power.

July 6, 2010

At this moment, the book I most admire on the Wind Power field, it is this one written by Ackermann. He can transmit dept concepts of power systems by using a clear vocabulary and illustrative examples. In this book, for example, there is an appendix in the chapter three, that explains in a very easy way how the Power System works by using a long bike as an equivalent.

Imagine a long bike with much cyclists running on a flat and straight road. We are the manager of this team and we want to keep the bike at a constant speed (the same frequency) and in an upright position (the nominal voltage equals to 1). How can we achieve this?

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Types of Wind Turbines.

July 3, 2010

Wind Turbines can be classified in two big groups: HAWT (Horizontal Axis Wind Turbines) which its rotor is connected to a horizontal shaft, and VAWT (Vertical Axis Wind Turbines) which have a vertical shaft.

HAWT

Since 1980’s, most of the commercial wind turbines are included in this group. The HAWT consist of a tower and a nacelle that is mounted on the top of the tower. The nacelle contains the generator, gearbox and the rotor.

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The Wind.

June 29, 2010

Earth is surrounded by a fluid that we call air. When air is heated creates High pressures in the atmosphere, and wind flows from High (H) to Low (L) pressure points. But, why does our planet have different temperatures? And even the most important, how can we take advantage of this natural power? In order to explain these questions, on this post we will see how wind acts and the latest researches on the aerodynamic field to convert the wind power in a useful and ecological energy.

There are some reasons to explain why the atmosphere has temperature gradients. Since Christopher Columbus discovered that Earth is a sphere (or almost) five hundred years ago, now we can understand easily that Sun’s radiations impinge on the surface with different power depending on the latitudes. Also, we have the rotation. When the Earth’s face is in front of the Sun, it means that the another face is in the dark, and as we know, days are usually warmer than nights. Finally, our planet’s axis is inclined and when it is summer in the North means it is winter in the South. Furthermore, our planet has other peculiarities (clouds, oceans which keep better the heat than land, white glaciers, so on) that provoke High and Low pressures in the atmosphere.

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