Not sure what's going on here, but I wanted to pass on what I've noticed
initially. Something is strange. Normally the following should produce
something that converges immediately without iterating at all the second time,
but in this case it diverges ...
opt = mpoption('OUT_BUS', 0, 'OUT_BRANCH', 0, 'VERBOSE', 2);
mpc = loadcase('grid');
r0 = runpf(mpc, opt);
r = runpf(r0, opt);
I also noticed that there are 3 reference buses even though it is a fully
connected network (which I assume is an error). When I change two of the
reference buses to PV buses, the AC PF no longer converges.
Hopefully, this may trigger some ideas for ways to track this down. But, the
fact that the 2nd run above diverges makes me think I should double-check how
the code handles cases with multiple reference buses. I probably need better
error checking somewhere.
--
Ray Zimmerman
Senior Research Associate
419A Warren Hall, Cornell University, Ithaca, NY 14853
phone: (607) 255-9645
On Mar 13, 2012, at 4:44 AM, Hua Bowen wrote:
> Dear all,
>
> I have a case with more than 5,000 nodes. I wonder why the DC power
> flow results in meaningless solution (the angle of all nodes turns out
> to be NaN) while AC power flow has a normal result. Some branches have
> a reactance as small as 1e-6 p.u. and zero resistance. I thought that
> make the B matrix ill-conditioned. But even after I changed all those
> small reactances to 1e-2, the result didn't change. I couldn't figure
> it out.
>
> The case file is included in the attachment. Thank you for your help.
