You would have to confirm the cause of the non-convergence before drawing any 
conclusions. You may find FAQ #5<https://matpower.org/doc/faq/#pfconvergence> 
helpful.

   Ray

On Sep 12, 2020, at 6:43 AM, Surbhi Aggarwal 
<surbhiaggarwa...@gmail.com<mailto:surbhiaggarwa...@gmail.com>> wrote:

Hello
If the system does not converge within 10 iterations, can we say that it is one 
of the most severely affected lines in contingency studies?
Or any other explanation for this non-convergence?
Regards
Surbhi Aggarwal


On Sat, Sep 12, 2020 at 10:40 AM Surbhi Aggarwal 
<surbhiaggarwa...@gmail.com<mailto:surbhiaggarwa...@gmail.com>> wrote:
Hello
Thank you all for your help and I'll definitely look out for the solutions.
Thank you so much
Regards
Surbhi Aggarwal


On Fri, Sep 11, 2020 at 7:16 PM Ray Daniel Zimmerman 
<r...@cornell.edu<mailto:r...@cornell.edu>> wrote:
Hi Surbhi,

It looks like you were using the default Newton power flow. To increase the 
number of iterations, you can increase the pf.nr.max_it option. However, this 
is rarely necessary. If the Newton method is going to converge, it usually does 
so in less than the default 10 iterations. If it is not converging within 10 
iterations, it is likely that the problem has no solution or that you need a 
better starting point.

   Ray


On Sep 11, 2020, at 5:48 AM, Mirish Thakur 
<mirishtha...@gmail.com<mailto:mirishtha...@gmail.com>> wrote:

Hi Surbhi,

First of all why do you want to increase the number of steps/ iterations in the 
calculation? Is there any specific need? Actually the number of iterations 
depends on the power flow optimization tolerance. Maybe you can focus on the 
mpoption function and read it carefully. You can update something like here:
mpopt = mpoption('pf.alg', 'FDXB', 'pf.tol', 1e-4)
I'm not 100 % sure about it but it may help you. Thanks.

Kind regards
Mirish

On Fri, Sep 11, 2020 at 8:41 AM Surbhi Aggarwal 
<surbhiaggarwa...@gmail.com<mailto:surbhiaggarwa...@gmail.com>> wrote:
Hello Everyone,
I tried your suggestions and it somehow helped me.
Now my doubt is " If I want to increase my number of iterations, what steps I 
have to do"?
Please help me out
Regards
Surbhi Aggarwal


On Wed, Sep 9, 2020 at 7:50 PM Ray Daniel Zimmerman 
<r...@cornell.edu<mailto:r...@cornell.edu>> wrote:
I also suspect that the network becomes disconnected by removing certain lines. 
You can check the connectivity using 
case_info()<https://matpower.org/docs/ref/matpower7.0/lib/case_info.html> or 
find_islands()<https://matpower.org/docs/ref/matpower7.0/lib/find_islands.html>.
 If there are islands, then each island needs to have its own reference bus, 
and the local generation needs to be able to meet the local load in each island.

    Ray


On Sep 9, 2020, at 4:57 AM, Mirish Thakur 
<mirishtha...@gmail.com<mailto:mirishtha...@gmail.com>> wrote:

Hi Surbhi,

Could you please check the continuity of the system before running opf? I mean 
to say if you run opf for (n-1) criteria the system should be still well 
connected. There shouldn't be any island within the system itself. Perhaps you 
can test your model by removing any one parallel line (which you can observe 
later for analysis) and run the model under (n-1) criteria. This could be the 
easiest way to test the model. Thank you.

Kind regards
Mirish


On Wed, Sep 9, 2020 at 9:11 AM Surbhi Aggarwal 
<surbhiaggarwa...@gmail.com<mailto:surbhiaggarwa...@gmail.com>> wrote:
Dear All,
I am working on optimal power flow to find the contingency (N-1) situation of 
the system. For some of the line outage, certain output pops out

MATPOWER Version 7.0, 20-Jun-2019 -- AC Power Flow (Newton)
Warning: Matrix is singular to working precision.
> In mplinsolve (line 75)
  In newtonpf (line 110)
  In runpf (line 260)
Warning: Matrix is singular to working precision.
> In mplinsolve (line 75)
  In newtonpf (line 110)
  In runpf (line 260)
Warning: Matrix is singular to working precision.
> In mplinsolve (line 75)
  In newtonpf (line 110)
  In runpf (line 260)
Warning: Matrix is singular to working precision.
> In mplinsolve (line 75)
  In newtonpf (line 110)
  In runpf (line 260)
Warning: Matrix is singular to working precision.
> In mplinsolve (line 75)
  In newtonpf (line 110)
  In runpf (line 260)
Warning: Matrix is singular to working precision.
> In mplinsolve (line 75)
  In newtonpf (line 110)
  In runpf (line 260)
Warning: Matrix is singular to working precision.
> In mplinsolve (line 75)
  In newtonpf (line 110)
  In runpf (line 260)
Warning: Matrix is singular to working precision.
> In mplinsolve (line 75)
  In newtonpf (line 110)
  In runpf (line 260)
Warning: Matrix is singular to working precision.
> In mplinsolve (line 75)
  In newtonpf (line 110)
  In runpf (line 260)
Warning: Matrix is singular to working precision.
> In mplinsolve (line 75)
  In newtonpf (line 110)
  In runpf (line 260)

Newton's method power flow (power balance, polar) did not converge in 10 
iterations.

>>>>>  Did NOT converge (7.38 seconds)  <<<<<

What to do to correct this error. It would be of great help.
Regards
Surbhi Aggarwal



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