More words about safety - Electronic load as brake

A project log for WinDIY - HAWT Wind turbine

Mostly 3D printed HAWT windturbine incl. 3D printed disk-generator and brake system.

FabFab 06/19/2020 at 14:160 Comments

As you may have noticed, I am also trying to equip WinDIY with a few (in my opinion) important security systems. I planned a mechanical brake and the possibility to adjust the angel of attack on the wings.

In addition, I would always want to keep the generator in a certain load state via an artificial load.

Because what naturally always brakes a wind turbine is the load on the connected generator. You already know this from a small bike generator: as soon as the bike light is switched on, you have to push the pedal harder. What you can also notice (admittedly with a little sensitivity in the legs) is that the resistance of the dynamo increases with higher speed.

The principle is also clear for the wind turbine: the more load connected to it, the more the wind has to exert itself to accelerate the turbine. To a certain extent, when the wind is constant, you can also regulate the speed by regulating the load.

This means that by controlling the energy drawn from the generator, you can also control the braking effect on the wind turbine and thus protect it from excessive speeds. But what to do if the load connected to the wind turbine is not large enough? 

If, for example, a connected battery is already fully charged, there is no way to load the generator of the wind turbine. There is simply no way to get rid of the produced energy.

In this case, the load on the generator would decrease, which in turn would reduce the braking effect. If strong winds occur now, this can lead to dangerous speeds of the wind turbine.

In order to have a "reserve load" available in this case, I planned to mount load resistors on a heat sink and attach them to the boom of the wind turbine. This additional load can easily be switched on if required. The heat generated can then be released into the ambient air via the connected heat sink.

Here a photo of the heat sink and the resistors i received and plan to integrate soon into winDIY.