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Wind turbines connection to the grid

  • 31-03-2011 10:15pm
    #1
    Agri contractor
    Registered Users, Registered Users 2 Posts: 141 ✭✭


    I have a few questions on wind turbines could anyone help. If you have a 10kw wind turbine single phase say to power a farm and supply excess back to the grid, how does this work when you can only supply 6kw back through a smart meter. Say on a 12 hr day we produce 120kw and can only send back 12hrs by 6kw = 72kw through a smart meter, could the remainder 48kw be stored in a battery so that if the wind turbine did not turn after the first 12 hrs this extra power could be sold into the grid ?


Comments

  • #2
    quentingargan
    Registered Users, Registered Users 2 Posts: 1,627 ✭✭✭quentingargan


    Strictly speaking, the ESB restricts the TURBINE to 6kw on a single phase system. You should really have three phase to connect 10kw, even if you restrict the inverter to 6kw. However, there are companies that have got around this so there may be a derogation (otherwise known as a fudge).

    It would be possible to put a voltage sensing circuit in place which diverts excess power to a heater. For example, many inverters come with a wind interface which switches on a DC heater to prevent the voltage rising above the permitted input of the inverter. I know one of these on which that can be reduced from the standard 530V to about 320V. That would use an IGBT (solid state switching) to power up a DC heater when the 6kw inverter has reached its peak. Costs about €350.

    However, that just limits your production to 6kw, not your exports. So if you were using 2kw on the 230V circuit, you would only be able to export 4kw. The amount of time that a turbine spends at the top end of its output is not that significant, so the losses might not be worth the cost of doing something about it.

    It is technically possible to put a second inverter onto a battery charger, but this is a bit complicated. The inverter charger would consume 20W or so when not in use, so you would need to signal this to "wake up", then connect the second inverter, which would take about 20 seconds. This could be implemented with switching when the heater load mentioned above comes on. However, if you get a night like last night, with winds steady for 8 to 10 hours, you will need to be able to store about 40Kw Hrs of power. That would be 3,000Ah of batteries at 12V. I think not .... Dumping the surplus as heat is probably the cheapest option.


  • #3
    Capt'n Midnight
    Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 93,563 Mod ✭✭✭✭Capt'n Midnight


    quentingargan wrote: »
    However, if you get a night like last night, with winds steady for 8 to 10 hours, you will need to be able to store about 40Kw Hrs of power. That would be 3,000Ah of batteries at 12V. I think not .... Dumping the surplus as heat is probably the cheapest option.
    and don't forget you'd have to replace all the batteries every few years

    if you had a pair of lakes you could use pumped storage

    wonder if you could recycle metals by electrolysis with all the free energy ?


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