Wind Mill Designing with Permanent Magnet Generators

It is very critical to understand the concept of wind before one thinks of generating electricity from it. There are many basics like wind blade designs, speed of wind, tower height, site location etc. which should be given due importance before going into windmill construction. This series of posts will help understand these things and take further toward the completion of windmill designing. Here two important concepts of Height and Power of wind mills will be talked about

Height

Turbines are usually 100-120 m high. Increase in the diameter of the blades will increase the height. With more height, the wind power increases and power yielded is more. But then the costs increases too and hence a balance is sought when deciding on the height of the tower.

Power

Power in watts yielded by the wind turbine alternator equals the angular velocity (radians per second = 2 pi RPM/60) multiplied by the torque which is in Newton-meters. In case of a permanent magnet alternator, voltage and current are proportional to the RPM. Hence the power is proportional to the square of the RPM.

A very important thing to note here is that wind speed is not a one to one function of the speed. In fact energy increases by the cube of the wind speed. If the wind speed is doubled, result is eight times the energy. Hence looking at the maps becomes all the more important. Even a small difference in wind speed within a given area can have a big impact on the amount of energy a wind turbine can generate. It is also one of the reasons why a taller wind tower can make much difference. One can can get a sense of the energy produced by the turbine by the power curve graphs given by the manufacturers along with the turbine.