MATPOWER does not handle 3 winding transformers directly, so you would have to 
convert it to an equivalent star formation of 2 winding transformers. The 
psse2mpc() function can convert a 3-winding transformers in PSS/E RAW format 
into the equivalent for MATPOWER, in case that would be useful.

    Ray


> On Nov 27, 2019, at 12:24 PM, Winnie apiyo <winnieapiy...@gmail.com> wrote:
> 
> Ray,
> Bus 92 was missing. I have f 400 kV , 220 kV, 132 kv , 66 kV,  33 kV and  
> 11kV voltage levels. How do you model three winding transformers?
> 
> i have the following error after running pf
> Warning: Matrix is singular to working precision. 
> > In newtonpf (line 89)
>   In runpf (line 204)
>  
> Warning: Matrix is singular to working precision. 
> > In newtonpf (line 89)
>   In runpf (line 204)
>  
> Warning: Matrix is singular to working precision. 
> > In newtonpf (line 89)
>   In runpf (line 204)
>  
> Warning: Matrix is singular to working precision. 
> > In newtonpf (line 89)
>   In runpf (line 204)
>  
> Warning: Matrix is singular to working precision. 
> > In newtonpf (line 89)
>   In runpf (line 204)
>  
> Warning: Matrix is singular to working precision. 
> > In newtonpf (line 89)
>   In runpf (line 204)
>  
> Warning: Matrix is singular to working precision. 
> > In newtonpf (line 89)
>   In runpf (line 204)
>  
> Warning: Matrix is singular to working precision. 
> > In newtonpf (line 89)
>   In runpf (line 204)
>  
> Warning: Matrix is singular to working precision. 
> > In newtonpf (line 89)
>   In runpf (line 204)
>  
> Warning: Matrix is singular to working precision. 
> > In newtonpf (line 89)
>   In runpf (line 204)
>  
> 
> Newton's method power flow did not converge in 10 iterations.
> 
> >>>>>  Did NOT converge (0.17 seconds)  <<<<<
> 
> On Wed, Nov 27, 2019 at 7:13 PM Ray Zimmerman <r...@cornell.edu 
> <mailto:r...@cornell.edu>> wrote:
> Do you have some bus numbers (either in the bus or branch matrix) that are 
> not positive integers?
> 
>    Ray
> 
> 
>> On Nov 27, 2019, at 6:14 AM, Winnie apiyo <winnieapiy...@gmail.com 
>> <mailto:winnieapiy...@gmail.com>> wrote:
>> 
>> Good evening Ray,
>> It is now running but with this error:
>> Array indices must be positive integers or logical values.
>> 
>> Error in ext2int (line 148)
>>                     bs(n2i(mpc.branch(:, F_BUS))) & ...
>> 
>> Error in runpf (line 109)
>> mpc = ext2int(mpc);
>> 
>> On Tue, Nov 26, 2019 at 10:58 PM Ray Zimmerman <r...@cornell.edu 
>> <mailto:r...@cornell.edu>> wrote:
>> You’ll have to show us exactly what commands you are using to attempt to run 
>> it. It sounds like you may be calling runpf(mpc) without first loading the 
>> case into mpc. Normally, you’d do something like …
>> 
>> mpc = loadcase('case118');
>> results = runpf(mpc);
>> 
>> … or simply …
>> 
>> results = runpf('case118');
>> 
>> Hope this helps,
>> 
>>    Ray
>> 
>> 
>>> On Nov 26, 2019, at 12:18 PM, Winnie apiyo <winnieapiy...@gmail.com 
>>> <mailto:winnieapiy...@gmail.com>> wrote:
>>> 
>>> It is only running with no results. mpc empty , undefined function or 
>>> variable mpc.  I have been troubleshooting with no results. What are the 
>>> possible mistakes?
>>> 
>>> Sent from my iPhone
>>> 
>>>> On 26 Nov 2019, at 20:26, Ray Zimmerman <r...@cornell.edu 
>>>> <mailto:r...@cornell.edu>> wrote:
>>>> 
>>>> There is no explicit limit to the size. Power flow for a 582 bus case 
>>>> should be extremely fast, only a fraction of a second. On my 5 yr old 
>>>> laptop a 13,000 bus system solves in ~0.3 sec.
>>>> 
>>>>     Ray
>>>> 
>>>>> On Nov 24, 2019, at 3:12 PM, Winnie apiyo <winnieapiy...@gmail.com 
>>>>> <mailto:winnieapiy...@gmail.com>> wrote:
>>>>> 
>>>>> Thank you 
>>>>> 
>>>>> Sent from my iPhone
>>>>> 
>>>>>> On 24 Nov 2019, at 21:54, Abhay Kumar <abh...@mtu.edu 
>>>>>> <mailto:abh...@mtu.edu>> wrote:
>>>>>> 
>>>>>> A list of test cases are available in Appendix D (Table D-18 to Table 
>>>>>> D-23) of the MATPOWER user manual 
>>>>>> <https://matpower.org/docs/MATPOWER-manual.pdf>  I’m not sure if there 
>>>>>> is a limit but MATPOWER can definitely handle 582 buses. 
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>>  
>>>>>> Abhay Kumar
>>>>>> Graduate Teaching Assistant | Michigan Tech | Dept of ECE
>>>>>> E:  abh...@mtu.edu <mailto:abh...@mtu.edu>
>>>>>> A: EERC 617, 1400 Townsend Dr Houghton MI 49931
>>>>>> 
>>>>>>> On Nov 24, 2019, at 1:33 PM, Winnie apiyo <winnieapiy...@gmail.com 
>>>>>>> <mailto:winnieapiy...@gmail.com>> wrote:
>>>>>>> 
>>>>>>> good evening,
>>>>>>> What is the maximum number of buses that can be run in MATPOWER.? I 
>>>>>>> have 582 buses and can't run power flow or it is just taking long to run
>>>>>>> regards
>>>>>> 
>>>> 
>> 
> 

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