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

Thread Starter

powersys2005

Joined Jan 3, 2010
29
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



Figure 2



Figure 3
 

Attachments

t_n_k

Joined Mar 6, 2009
5,455
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.
 

Thread Starter

powersys2005

Joined Jan 3, 2010
29
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.
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.
 

t_n_k

Joined Mar 6, 2009
5,455
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.
 

t_n_k

Joined Mar 6, 2009
5,455
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?
 

Thread Starter

powersys2005

Joined Jan 3, 2010
29
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?
Thanks again. I will do it now and feedback here soon.
 

Thread Starter

powersys2005

Joined Jan 3, 2010
29
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?
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



Figure 2



Figure 3
 

t_n_k

Joined Mar 6, 2009
5,455
Hi... I think I've found the reason why my simulation gave weird results. This is because the codes given at http://electronics-lab.com/downloads/schematic/013/ are wrong, and contradicted with the notes given at http://www.allaboutcircuits.com/vol_2/chpt_10/8.html
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.:)
 

t_n_k

Joined Mar 6, 2009
5,455
Try posting to the Feedback and Suggestions Forum or use the Contact Us link. You should hopefully get a response either way.
 
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