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Forum Index : Windmills : Induction Windmills
| Author | Message | ||||
| Wes Lemarr Newbie  Joined: 07/09/2008 Location: United StatesPosts: 35 |
I an looking for advice about how to conect a 5kw induction wind generator to the grid. I have read many articles on the internet, but none explain how to connect the induction generator to the grid in a way that allows the generator to sync with the grid, but without causing the generator to run continuously when thear is no wind, any suggestions. Thank You for your help. |
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| flc1 Senior Member  Joined: 20/11/2011 Location: New ZealandPosts: 242 |
gday Wes, do you have any pics to show and spec ? Fred |
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oztules Guru  Joined: 26/07/2007 Location: AustraliaPosts: 1686 |
You will need a tacho to measure the shaft speed. The induction motor is asynchronous, so does not require syncing.. it is automatic. Assuming 50hz mains. A 4 pole motor will therotically start to produce feed into the grid at 1501rpm and continue to increase after that. At 1500rpm, it will freewheel, but no generation.... In fact it will not really motor significantly until the slip speed is near 1480rpm So measure the rpm, and when the is rpm greater than say 1510 rpm, then connect to grid... and when it drops to 1495rpm, then cut off and free wheel. There will be hysterisis to be worked through, so these figures will change to get it to run smoothly in the transition states... but that will get it started as a project. Make sure the brakes work, as thats all you will have to stop it. There is a lot of other things we monitored before connecting, but they are ancillary really, and once you have the tacho auto connecting, you can then monitor the grid frequency, voltage, wind speed etc etc to help make the decision to let the brakes of and then connect when up to speed.... if youuse the wind speed to initiate a trial start, then you can motor it up to speed... knowing that the wind will be strong enough to support generation. As you can see there are lots of different ways to go about control, but the guts of it is that it is auto syncing, and for 4 pole anything above 1500rpm is gong to generate something, and anything below won't. Be aware that you can break the sync if the wind is too strong, so you will need an over rpm braking device there as well. ..........oztules Edit... here are the ones I am familiar with down here windmill They have been replaced now with a massive 1mw and 300kw one now. Village idiot...or... just another hack out of his depth |
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| kitestrings Senior Member Joined: 23/04/2014 Location: United StatesPosts: 102 |
There were a number of wind designs in the early -mid eighties in the US that used induction designs. I worked for one of them when I was a young lad. What they mainly did on turbines of this size was to simply monitor the wind speed with an anemometer mounted near the hub-height of the turbine. It connected to a circuit board that used an RC circuit to basically average the available wind speed. Above about 8-9 mph a relay signal would connect the thing to line power (most 240V, 60 Hz) via a heavier relay/contactor. The blades were then motored up to speed, and as the wind pushed it above it's synchronous speed (1,800 rpm) the current would change direction and it would generate power. There were more sophisticated control strategies that monitored rpm, and allowed for free-wheeling in light winds, but this was among the simplest and most reliable schemes. You might google Enertech, or Aerowind, or Carter probably could still find a controller for one of the Enertechs - and they had a 5 kW unit. Good luck ~ks |
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