I currently have a one phase connection on my farm and have been told that I need to pay for a split phase connection upgrade to get my turbine connected. I am lost why I need this upgrade as my supply comes from a 50kw transformer on a telegraph pole. Any ideas why the power company are doing this will be most helpful as I'm not getting any clarity from my installer.

My guess in simple terms is your connection to the grid is not of sufficient power to return current back to the grid.
Is any one else powered off your transformer - if so then you could find their supply voltage rising excessively on windy days.

I also guess you your turbine despite being small may be 3 phase.
Why are you not aiming a little higher say 70/100kw turbine ?

I'm 9km away from the nearest three phase 11kV over head cable so to keep costs down three phase is not financially viable.

Ok, I am not sure how split phase works, but are you saying they are doing this because of rising volts? Doesnt volt drop?

If you are so far from 11kv transformer then you may have relatively poor voltage regulation.
Split phase means you would have 2No 230vAC feeds (3 wire + earth) which are 180 Degrees out of phase - ie. 460vAC across the two lives.

Volts 'drop' from generator to load, so on turbine generation your own supply would rise to feed power back to grid..... making your own supply go up and down considerably. Suggesting a Split phase supply will overcome this to a certain extent.

A certain turbine supplier in North Yorkshire deals with many farm based installations, and generally look at turbines 100 to 275Kw. If you have sufficient wind power on your land I would recommend higher rating with payback to include costs of 3phase connnection to the grid.

I'm 100m from the transformer pole. Back to the three phase 11kV network from the 2 wire 11kV cable is 9km.

Just out of curiousity, how do you calculate volt rise?

I can see where you are coming from.
It will still cost to get a split phase supply.

There is a temptation to suggest referal back to a 20kW single phase turbine, no change to supply cabling and limit the turbine so it does not export power, so for your own use only.

IMO find the cost the above, split phase then 3 phase option, then review the possibilities, whilst looking at the different size trubines available.

"..how do you calculate volt rise? "
The same way as volts drop - if you are generating power at your site then your voltage will be X volts above the grid to export to it.

It sounds like you can't get single phase at all due to voltage rise and that split phase or adjusting the voltage ratio of the transformer is the only viable solution to accommodate 20kW of wind generation. G59/2 considers the rating of the generator and thats what DNOs consider (depending on their interpretation) as the maximum export under no/minimum load conditions (worst case scenario).

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Been trawling this forum and found the Formula mV/A/m for single phase. If I found the value for the supply cable, I could work out if the DNO is pulling my leg. How can i use the formula for split phase?

Thanks

I'm not sure how you would use a volt drop calc. to see if someone is pulling your leg......

"There is a temptation to suggest referal back to a 20kW single phase turbine, no change to supply cabling and limit the turbine so it does not export power, so for your own use only."

If I were you I would go for a 70/100kW turbine and have electric heating in the house, barn, cowshed, outhouse and export 3/4kw just to take advantage of the feed-in tarrif !

Hate wind turbines spoiling the countryside. Your 20KW would come under the heading of a small wind turbine. Naturally, I am reading from a booklet, the electrical connection may to a single or three-phase supply, depending upon the type of electricity supply to your property. In order to use the electricity generated by the turbine, it needs to connect to the mains electrical supply via an electrical panel.
The panel performs a number of functions including:

1. It contains a rectifier which converts the three phase "wild" AC from the turbine into DC suitable for use by the inverters.
2. It holds the inverters(s) which convert from DC to grid synchronised AC
3. It has safety fuses and isolator switches, for the input from the turbine, and output to the grid
4. It holds various meters for measuring the energy generated by the system and the voltage and current coming from the turbine.

(Applicable only in NI), you may also get credited with Renewable Obligation Certificates (ROCs) which are in effect a bonus for generating renewable energy, in Northern Ireland you will get 4 ROCs for each KW hour you generate
This is paid for all the energy you generate no matter if it is used by you or exported to the national grid.
How daft is that Robin Hood in reverse. (Meaning, the poor consumer over time pays for your little windmill).
Anyhow, good luck with your project, if metal pole do not invite lighting into your farm also fit a lightning conductor electrode.
Regards,
jcm

We manufacture load banks so would be able to supply multiple intelligent heating solutions if required

Regards

Paul Smethurst IEng MIET
www.hillstone.co.ukwww.hillstone.co.uk
paul@hillstone.co.uk