Connect with us

power station question

Discussion in 'General Electronics Discussion' started by donkey, Feb 10, 2017.

Scroll to continue with content
  1. donkey

    donkey

    1,298
    56
    Feb 26, 2011
    there is NO reason for this question other than I want to know.
    so I understand the basic of ac theory. a wavelength goes up and down this frequency or hz of the voltage. in Australia the difference is 240volts from top to bottom and changes 60 times per second (so I assume -120 to 120 and back to the bottom 60 times per second)
    the question I have is: if what I said is right, which I am assuming it's not, then when you add even a second power plant into the equation how do the 2 power plants synchronise together?[​IMG]
    it would end up looking something like the above diagram right? so on average they cancel each other out......
     
  2. Harald Kapp

    Harald Kapp Moderator Moderator

    11,713
    2,719
    Nov 17, 2011
    The mains voltage in Australia is supposed to be 230 V, down from formerly 240 V for reasons of harmonization.
    Anyway, 240 V or 230 V is the RMS value. Which means for a sinusoidal voltage the peak voltage is
    Vpeak = 240 V*sqrt(2) = 340 V. That's from zero to one peak. Peak-to-peak volateg is twice that:
    Vpp = 2 * Vpeak = 480 V.
    However, since you measure always between phaase and neutral, you "see" only 240 V (RMS).

    The plant to be connected to the grid senses the phase and amplitude of the voltage already present on the grid. It then adjust its generators by running them a bit faster or slower so the phase and amplitude of the generated power matches that on the grid. Only then will the new plant be connected. Here's some stuff to read.
    If it weren't for that, the resulting power swing could destroy an entire power plant.

    Btw: According to Wikipedia mains frequency should be 50 Hz in Australia, not 60 Hz, bit I'm sure you know better :D
     
    Arouse1973 likes this.
  3. donkey

    donkey

    1,298
    56
    Feb 26, 2011
    I don't know nothing....... that's why I ask questions lol
     
  4. Bluejets

    Bluejets

    5,043
    1,053
    Oct 5, 2014
    double negative...that means you must know something......you can have that one for free.:)
    Also Harald is correct..50Hz...always has been.
    Paralleling generators is a common occurance with the sugar mills coming online with supply authorities..... running up the generators is known as synchronising. (hence the term "in sync")
     
    Arouse1973 likes this.
  5. duke37

    duke37

    5,364
    772
    Jan 9, 2011
    I believe that in the early days, a bulb was connected between the two supplies. When this went out, the contactor was energised.
    Three phase supplies used three bulbs.
     
  6. spaceman

    spaceman

    67
    0
    Nov 5, 2016
    Be careful when synchronizing the generator manually. If the auto don't work a lot of the time it is because a ground is lifted.If your not parallel with the system it will blow the fingers off the generator.
    Also when bringing the unit up to speed do not wait too long to get past high vibrations from harmonics. Similar to why a car engine has a harmonic compensate on the end of the crank. If you do the unit will rub and be damaged permanently. This in turn downgrades the units megawatt output.
     
  7. Bluejets

    Bluejets

    5,043
    1,053
    Oct 5, 2014
    Yes, there were a couple of variations on this but the dark indication was preferred.
     
  8. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,499
    2,839
    Jan 21, 2010
    That's a great story told by our energy regulators.

    In reality, I believe absolutely nothing has been done to change the voltage.

    Western Australia used to have 250V, and now it has a nominal 230V. But check the standard for 230V. It allows up to 254V,.

    If one were cynical, one might think that the standard was written to allow harmonisation without any actual work needing to be done.

    :-O

    Here is a reference (although not the one I was after)

    http://electricalconnection.com.au/when-voltage-varies/
     
    Last edited: Feb 12, 2017
    davenn likes this.
  9. donkey

    donkey

    1,298
    56
    Feb 26, 2011
    So I have a related question.... lets say that I was doing something stupid like taking 2 inverters from solar setup..... they don't have a way to sync do they??? only the grid connect ones would I assume...
    Once again for knowledge not dumb enough to try unless there is an inverter that has this inbuilt
     
  10. Harald Kapp

    Harald Kapp Moderator Moderator

    11,713
    2,719
    Nov 17, 2011
    A well constructed inverter will sense the mains voltage and control the output accordingly to allow power flow into the mains grid without creating disturbances on the grid.
    Connecting two inverter output together without a mains source as reference signal? I don't know what will happen, probably nothing, meaning no output at all. Unless the inverter(s) are meant for standalone (off grid) operation. Then they may even work 180 ! out of phase and be destructed if no proper safety means are incorporated.
     
  11. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

    4,960
    652
    May 8, 2012
    I'm bummed out on the double negative thing. I wanted to post that reply.

    Regarding syncing phase of parallel sources I would think that voltage would have to be matched also. If not the dominant source would back feed into the lower voltage source. Or am I missing something?

    Chris
     
    Bluejets likes this.
  12. Bluejets

    Bluejets

    5,043
    1,053
    Oct 5, 2014
    There is absolutely no place for "thinking about doing something stupid" with respect to any mains connections or devices. This can never be stressed enough and yet there are some that think it might be something they can try. After all, it's only 3 wires, how hard can it be?
    Best advice , stay away from it. There's energy enough in them-thar-wires to blow you to kingdom come and come back for more.
    Well, except maybe in South Australia at times.:rolleyes::p
    Inverters designed for connection to the grid have internal circuitry that tracks the incoming supply and connects (or disconnects) itself as it sees appropriate. This is a pre-programmed sequence by others that know the requirements.
    Trust that answers your query.
     
  13. donkey

    donkey

    1,298
    56
    Feb 26, 2011
    the reason I am asking is I am trying a solar setup in the back yard. the 12volts stuff is pretty simple. I really DON'T want to touch 240volt if possible. but having said that I don't want to have 100 power chords running from the back yard to the house. so I was RESEARCHING to see if any inverters could link together to provide more amps. I have an electrician friend that was going to wire a new RCD box for the solar alone to help me out which would make life so easy but ah well looks like its a lost cause
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-