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BenG
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Joined: 09/11/2008
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Posts: 2

Posted: 12:48pm 09 Nov 2008

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Hi all,

I am looking at building a grid-tied windmill system (no batteries if possible), but I have a few questions.

1- How far from nearby objects should windmills be?
2- If using an f&p motor, what is generally the output directly from the motor?
3- How would I ensure consistent 240Vac to connect to mains?
4- Will a 24Vdc to 240Vac inverter still function if input is 12Vdc for example?

I am thinking at this stage that a regulator and diode would be required between windmill and inverter.

Any advice would be greatly appreciated.

Kind regards,

Ben

GWatPE

Senior Member

Joined: 01/09/2006
Location: Australia
Posts: 2127

Posted: 09:32pm 09 Nov 2008

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Hi Ben,

Connecting to the grid is not easy. Electronically, a grid connect inverter is much different to a stand alone inverter. You will probably damage a stand alone inverter with spectacular results if you try. There are many rules and regulations as well.

I have successfully used SMA1700, SMA1100 and PVE1200 grid connect inverters with my windmills. I am redesigning my setup to have 24V battery with 24V stand alone inverter with a 48V nom grid inverter for surplus back to the grid.

I would check local regulations and have a sparky OK your plans.

Gordon.

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Gill

Senior Member

Joined: 11/11/2006
Location: Australia
Posts: 669

Posted: 10:21am 10 Nov 2008

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G'day BenG,
Welcome to the forum.
Gee, you do want to dive in at the most difficult place.

Your questions indicate a lack of basic wind power generation concepts and a lot of reading is best as books worth of info is needed to explain the answers to your few simple questions. Still I'll tackle your quires knowing the gaps and that other questions will become apparent.

1. As far as possible. Going high is often the most practical solution. No one wants to live in a Lake Eyre.

2. I'm guessing you mean an unmodified F&P. Say up to 1,000 Volts; 3phase; wild AC (voltage, amps and Fq. varies with rpm.

3. Use a commercially manufactured grid tie inverter. Latronics are currently evaluating a battery less wind system though existing grid tie systems must use a battery as a buffer.

4. No. Inverters have a set voltage input range and are designed to shut down on under and over voltage. (Hence the battery again. Latronics system excluded)

Might I suggest you make a simple basic wind gen first to get the feel of what your getting into. It can become quite addictive.

was working fine... til the smoke got out.
Cheers Gill _Cairns, FNQ

BenG
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Joined: 09/11/2008
Location:
Posts: 2

Posted: 10:44am 10 Nov 2008

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Hi Gordon and Gill,

Thanks for your replies. The reason I asked the above questions is that I have done a bit of reading, and some of the setups that people have *apparently* used for grid-tied systems do not make much sense to me. For example, they appear to essentially plug the wind turbine (unmodified as far as I can ascertain) directly into a grid-tie inverter.

Gill your answers are basically what I suspected. As far as the distance from objects goes, I remember reading a formula somewhere determining minimum distance from objects based on the diameter of the blades.

With regards to the grid-tie inverters, I have read up a bit on the inverters that Gordon mentions from SMA. They advertise that they work at up to 400Vdc, but do not advertise a lower range. Does anybody know what this may be?

GWatPE

Senior Member

Joined: 01/09/2006
Location: Australia
Posts: 2127

Posted: 12:40pm 10 Nov 2008

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My SMA SunnyBoy 1700 has an upper voltage limit of 400VDC and the lowest operating voltage I have seen was 139VDC. My unit was reprogrammed for the minimum voltage of 140VDC to suit my Sunpower modules. The WindyBoy, is the wind version of the SMA grid connect inverter. I know you will need very good voltage limiting of the mill output, as during the grid connection phase, the inverter does not load the windmill.

I have a Latronics PVE1200, nom 48V. My F&P 100S in delta with capacitors can direct feed this inverter at windmill output power levels above 150W. This inverter will operate without a battery if a battery substitute of at least 100000uF 100V capacitor is used. There is a black box supplied by Latronics that performs this function. The PVE1200 has an upper voltage limit of 100VDC, and cuts out below 54VDC, or about in NON-PV mode.

I agree with Gill. Get a feel for how a windmill works before committing $ in grid connection. I have spent over a year testing aspects of my grid connect system. I still had to add components to the PVE1200 to improve the performance.

The last thing I need to look at is better use of the RE if the power fails. At the moment systems shut down and energy harvest is wasted.

Good luck with your exploits.

Gordon.

become more energy aware

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