US Residential Grid Simulator

Discussion in 'The Projects Forum' started by fallow, Jan 16, 2016.

  1. fallow

    Thread Starter New Member

    Nov 2, 2015
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    I wonder if anyone knows of a small portable device that would simulate the voltage waveforms of the split-phase US residential electric grid.
    Just need the reference voltage waveform, no need for any appreciable current sourcing or sinking (the device would have a high-Z output – see below).
    Preferably an off-the-shelf device, or something that can be easily modified for that purpose. I try to avoid building one using the sine wave generator, phase shifter, boost converter, amplifier, etc – too much trouble that way.

    Ideally envision a black box, with a low-voltage DC power supply input (say 12 Vdc).
    The output is 3-wires, like the US residential grid split-phase transformer: L1, L2, N (N can be bonded to ground).
    When measured between the output wires the sineusoidal voltage is just like the grid: 120Vac rms (N-L1 and N-L2), and 240 Vac rms (L1-L2), with the 180 deg phase difference between L1 and L2.

    Thanks for any ideas, Jack
     
  2. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    May we ask the purpose of this "black box"?.

    It's often easier for us to help solve your problem, than help solve your solution. ;)

    Ken
     
    Last edited: Jan 16, 2016
    WBahn, Kermit2, RichardO and 3 others like this.
  3. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    That has to be the best thing I've ever read on this board,
     
  4. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    @KMoffett knows how to communicate - that was good.
     
  5. fallow

    Thread Starter New Member

    Nov 2, 2015
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    Thanks Ken, I hear about the problem/solution, but I am afraid that's the only viable solution to my problem.
    This is to be used as a reference signal for some other instrumentation, don't want to go too deep into it as it would divert from the simulator box.
    The other instrument is unrelated to the grid simulator, except that it uses it's signals for reference.
    Jack
     
  6. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    IT sounds like a grid tie inverter type of problem.
     
  7. JohnInTX

    Moderator

    Jun 26, 2012
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    Some additional information about your specific application would help. Can you elaborate and maybe provide a sketch or block diagram?
     
  8. DickCappels

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    Aug 21, 2008
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    @fallow , what is your application?
     
  9. profbuxton

    Member

    Feb 21, 2014
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    Just use a standard inverter. DC input AC output. Connect to a transformer with centre tapped output at required voltage.
     
  10. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    Or go old school and hook a small DC motor to a small alternator. Plenty of such available through amazon or ebay.
    You would have your own generating system. If you load it down with incandescent bulbs, you could create a scenario in which power could be fed back into this model grid and relieve the loading on your alternator.
     
  11. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    fallow,

    As you can see, if you don't get really specific about what you want the "reference" for and what tolerances you need, people will go off in all different directions. As opposed to your statement of "don't want to go too deep into it as it would divert from the simulator box". ;)

    Ken
     
    ebeowulf17 likes this.
  12. fallow

    Thread Starter New Member

    Nov 2, 2015
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    The application is a portable instrument, a unit for active harmonic current (and voltage) control, where nonlinear AC loads (switched mode power supplies, variable freq drives, etc) are present and affect the AC power quality (which cannot be used as the reference).
    The block diagram is simple, the split-phase grid reference signal simulator box connected on 3 wires to the control unit.
    Some time ago I played with single-phase and split-phase PSW inverters and transformers to generate this reference waveform, which needs to stay within about 3-5% THD in the voltage waveform. The split-phase bi-directional inverter-charger was too big and heavy for this project. In the single-phase inverter/transformer something burned up in its output stage (apparently the inverter's output was not bi-directional or not high-impedance, and not designed to absorb the energy coming from the control unit under some conditions).
    The electro-mechanical solution DC motor/alternator will not work for this application, has to be more stable and reliable than that.
    Hopefully this gives enough info about the application, and the tolerances in the reference voltage waveform I need.
     
  13. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    See, that didn't hurt. ;)

    Ken
     
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