It appears to be a numerically difficult problem. Relaxing the lower bounds on 
the generator buses and starting with voltage angles equal to zero allows some 
of the solvers to find the solution.

I suppose it should not be surprising that it is numerically difficult … 
- branch reactances of zero
- resistances large enough that have the generation goes to losses, half to load
- solution voltage at the load bus is 0.5

-- 
Ray Zimmerman
Senior Research Associate
B30 Warren Hall, Cornell University, Ithaca, NY 14853
phone: (607) 255-9645



On Dec 17, 2013, at 6:35 PM, Arash Alimardani <[email protected]> wrote:

> Dear matpower community,
> 
> I have a simple 4 bus system with 3 branches to deal with. The figure of the 
> system is attached, and here is the data of it:
> 
> mpc.baseMVA = 1;
> 
> mpc.bus = [
>     1    3    0    0    0    0    1    1    0    0    1    1    1;
>     2    2    0    0    0    0    1    1    -2    0    1    1    1;
>     3    1    0    0    0    0    1    1    -4    0    1    1    0;
>     4    1    0.5    0    0    0    1    1    -5    0    1    1    0;
> ];
> 
> mpc.gen = [
> 1    .5    0    1    -1    1    100    1    2    0    0    0    0    0    0   
>  0    0    0    0    0    0;
> 2    .5    0    1    -1    1    100    1    2    0    0    0    0    0    0   
>  0    0    0    0    0    0;
> ];
> 
> mpc.branch = [
>     1    3    .2    0    0    inf   0    0    0    0    1    -360    360;
>     2    3    .2    0    0    inf   0    0    0    0    1    -360    360;
>     3    4    .4    0    0    inf   0    0    0    0    1    -360    360;
> ];
> 
> mpc.gencost = [
>     2    0    0    3    0.0430293    20    0;
>     2    0    0    3    0.0430293    20    0;
> ];
> 
> In essence, it's a system with 2 generators with fixed voltages and variable 
> active and reactive powers. However, it doesn't converge. Could someone 
> please comment on this?
> 
> I should add that the system is feasible and the solution is:
> x=[
>     0
>     0
>     0
>     0
>     1
>     1
>     0.9
>     0.5
>     0.5
>     0.5
>     0
>     0];
> 
> 
> Regards,
> Arash Alimardani
> University of British Columbia
> <Visio-Drawing1.pdf>

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