Better Wind Turbines

This comes under the heading of why didn't I think of that.

http://www.technologyreview.com/energy/21666

The new generator runs efficiently over a wider range of conditions than conventional generators do. When the shaft running through an ordinary generator is turning at the optimal rate, more than 90 percent of its energy can be converted into electricity. But if it speeds up or slows down, the generator's efficiency drops dramatically. This isn't a problem in conventional power plants, where the turbines turn at a steady rate, fed by a constant supply of energy from coal or some other fuel. But wind speed can vary wildly. Turbine blades that change pitch to catch more or less wind can help, as can transmissions that mediate between the spinning blades and the generator shaft. But transmissions add both manufacturing and maintenance costs, and there's a limit to how much changing the blade angle can compensate for changing winds.

ExRo's new design replaces a mechanical transmission with what amounts to an electronic one. That increases the range of wind speeds at which it can operate efficiently and makes it more responsive to sudden gusts and lulls. While at the highest wind speeds the blades will still need to be pitched to shed wind, the generator will allow the turbine to capture more of the energy in high-speed winds and gusts. As a result, the turbine could produce 50 percent more power on average over the course of a year, says Jonathan Ritchey, ExRo's chief technology officer. Indeed, in some locations, the power output could double, says Ed Nowicki, a professor of electrical engineering at the University of Calgary, who has consulted to ExRo.

The generator works on the same principles as many ordinary generators: magnets attached to a rotating shaft create a current as they pass stationary copper coils arrayed around the shaft. In ordinary generators, all of the coils are wired together. In ExRo's generator, in contrast, the individual coils can be turned on and off with electronic switches. At low wind speeds, only a few of the coils will switch on--just enough to efficiently harvest the small amount of energy in low-speed wind. (If more coils were active, they would provide more resistance to the revolving magnets.) At higher wind speeds, more coils will turn on to convert more energy into electricity. The switches can be thrown quickly to adapt to fast-changing wind speeds.

Comments

  • waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: Better Wind Turbines

    Well the idea should allow the blades to turn more freely in low wind, thus reducing the incidence of having the blades operating in stall, or semi-stall mode, and this SHOULD end up producing more power, as the blades would usually be operating at a more efficient rotational speed. Interesting idea.
  • icarusicarus Solar Expert Posts: 5,090 ✭✭✭✭
    Re: Better Wind Turbines

    Not that I think this is going to change the small scale wind world,, but the idea of keeping the turbine at a relatively constant speed by electronically add or delete field magnets is also an interesting idea, especially if it can rect very fast to gusting conditions.

    For (what little) I know, one of the big problems with small scale wind is they get torn apart due to the forces in gusts, constantly speeding up or slowing down the turbine.

    Tony
  • 65DegN65DegN Solar Expert Posts: 106 ✭✭✭✭
    Re: Better Wind Turbines

    Switching of coils in DC motors can be a very effective way to control them. I used to work on VCR's when it was a viable business and not only was the speed of the capstan motor that moved the video tape controlled, it was so accurate it even controlled the phase of the motor. That is to say, it continuously controlled where, within a 360 degree rotation, the motor shaft was.
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