Hello (quick intro)

[Thomas O Sullivan]

Hi every one.
I'm building a 4.2m Hugh Piggott designed turbine.
I've signed in here to get some inspiration in relation to inverters and electronic requirments before i wind my coils.
I hope to find an electronic schematic of something simular to my build. (with DC isolation, overovltage protection, rectifier, fuse, inverter, grid disconnect, etc, etc)
I'm not experienced with electonics but the aurora 3600 appears to be working here in Ireland.

Tom

[Rob Beckers]

Hi Thomas,

Welcome to the forum!

The Hugh Piggott design is primarily meant for direct battery charging (unless there's something new that I'm not aware of). Great turbine though!

Changing over to direct grid-tie throws a bucket of wrenches into the works that you need to consider. I'm not saying it can't be done, most battery chargers can be converted to grid-tie, but it does add a number of complications.

Normally the batteries provide a constant load for the turbine, limiting its voltage (and therefore largely its RPM). Without batteries (ie. grid-tie) this doesn't happen and it is up to you to provide overspeed protection, both for the turbine so it doesn't self-destruct, as well as for the inverter (overvoltage). You can take a look at the overvoltage protection wiring diagram I put up at http://www.solacity.com/Docs/Wind%20Turbine%20Overvoltage%20Protection.pdf
The two options described there provide a reliable way to protect the inverter, and the second option allows you to switch on a dump load to keep the rotor under control.

Even with the ability to furl (and it should furl at around 11 - 12 m/s wind speed!), you'll need to provide a dump load to control the rotor speed. A setup as mentioned above, where the inverter gets switched out of the path of the turbine voltage is highly recommended, as it's about the only sure way to protect the inverter.

Most places in Ireland gets lots of wind. That's great for energy production! It also stresses the need for protection as mentioned above. For a 4.2m diameter rotor you should be OK with a 3.6kW Power-One Aurora wind inverter. Using reasonable efficiencies that rotor will produce around 4kW at 11 m/s, but alternator and inverter efficiency will come off that, bringing output power down closer to the 3kW level (most depends on the alternator efficiency).

The Aurora inverter is pretty flexible, it can handle 50V DC through 550V DC, making it pretty easy to match the alternator. The limit for the inverter (besides the upper voltage) is the input current, which is 32A. that means you need to hit at least (about) 140 Volt DC in the inverter input to be able to get 3600 Watt out. Since you have control over the alternator windings you can do better though, by raising the voltage. That will lower the overall losses, you'll be able to use thinner wiring between turbine and rectifier/inverter, and the inverter will be more efficient. A good value to shoot for is around 300 to 350 Volt DC at max output power (so loaded voltage), or around 220 to 255 Volt AC phase-to-phase for a 3-phase alternator. This still gives a large enough margin from the 600V DC limit of the inverter, while providing good efficiencies.

I don't know what the design TSR is for Hugh's design, likely around 7. If so, you would need about 0.71 AC Volt (loaded) per RPM, phase-to-phase. How much that translates to unloaded will very much depend on the alternator efficiency. With that number you'll get around 250V AC at the 350 RPM that a TSR of 7 makes at 11 m/s wind speed.

Hopefully this will give you something to get started with. Once you know unloaded alternator voltage, and the resistance of the windings, I can calculate the MPPT table needed for the inverter.

-RoB-

[Shaun Burgess]

hi rob and thomas .. i built a 4.2mtr hv stator i used .80mm wire for the coils it worked very well with the eurora inverter .. cut in was around 100v and i had dump set to around 450v ..think the best peak i had was around 2100watts. there was one small problem at a certain speed there was a terriabe moan out of stator anti vibrations on the stator made it better .i sold it. and i believe its still running .. great design