What's wrong with this simulation (on triplen harmonics)?

Discussion in 'General Electronics Chat' started by powersys2005, Jan 18, 2010.

  1. powersys2005

    Thread Starter New Member

    Jan 3, 2010
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    I tried simulating (using PSPICE) the "3-wire “Y-Y” (no neutral) system" as shown in the following link:
    http://www.allaboutcircuits.com/vol_2/chpt_10/7.html

    The schematic is shown in Figure 1. The voltage across Rline3 and the FFT of voltage (or current) are given in Figures 2 and 3, respectively. It looks to me that my simulation result is different from that described in the link above because triplen harmonics still appear in line current. You may find the simulation files in attachment as well. Kindly advise what's wrong in my simulation. Thank you very much.


    Figure 1
    [​IMG]


    Figure 2
    [​IMG]


    Figure 3
    [​IMG]
     
  2. t_n_k

    AAC Fanatic!

    Mar 6, 2009
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    I've not used Pspice but it appears you may have modeled the various harmonic sources as voltage sources whereas the harmonic sources in the AAC link are modeled as current sources. I'm not sure if this is the issue.
     
  3. powersys2005

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    Jan 3, 2010
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    Thanks for your reply. I follow the tutorial given at the following link:
    http://www.allaboutcircuits.com/vol_2/chpt_10/7.html

    I don't understand why I could not get the same results.
     
  4. t_n_k

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    OK - no problem.

    However are you saying the presence of triplen currents in the line current was unexpected? The link clearly shows there are equal amplitude harmonic currents in the line current case. This is what you appear to have confirmed in your simulation.
     
  5. t_n_k

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    Sorry I missed you had removed the neutral link. Have you tried adding the neutral conductor to confirm the neutral current 'anomaly' in a balanced 3-phase system with harmonics - as shown in the link?
     
  6. powersys2005

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    Thanks again. I will do it now and feedback here soon.
     
  7. powersys2005

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    I added a neutral conductor and the results are still the same. However, the voltage across Rn looks weird. The FFT of voltage across Rline is given in Figure 2, and the voltage waveform across Rn is given Figure 3.

    If you're free and if you wish to simulate it (the model is given in my first post) using PSPICE, which can be downloaded (free) here:
    http://electronics-lab.com/downloads/schematic/013/

    Figure 1
    [​IMG]


    Figure 2
    [​IMG]


    Figure 3
    [​IMG]
     
  8. powersys2005

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    Jan 3, 2010
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  9. t_n_k

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    Well done - this might be worth reporting to the administrator or E-book editor with any corrections to the code you have that produce the expected result. Or simply point to the correctly working version if that exists.:)
     
  10. powersys2005

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    I wished to report my opinion to administrator or E-book editor yesterday but I could not find their emails. Kindly advise.
     
  11. t_n_k

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    Try posting to the Feedback and Suggestions Forum or use the Contact Us link. You should hopefully get a response either way.
     
  12. powersys2005

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    Jan 3, 2010
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    I've read again the article at
    http://www.allaboutcircuits.com/vol_2/chpt_10/8.html
    and it explains why model is implemented the way published in the article. I think there is nothing wrong with the codes. It's my misunderstanding that leads to the weird simulation results.
     
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