Thank you Dr.Zimmerman. Here's a single slack bus version of the same network. Oddly enough, the first problem you mentioned still exist.
Also I noticed that the DC power flow in MATPOWER is simply done by matrix left division. I wonder that DC load flow doesn't need iteration and why the result is NaN? On Tue, Mar 13, 2012 at 10:01 PM, Ray Zimmerman <[email protected]> wrote: > 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. > >
grid.m
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