a generator isn't quite the same as a negative load in MATPOWER

[sharnett]

Since the voltages are fixed at the generators, but free at the loads. I think. Verify this, then probably convert MATPOWER cases to the Jabr/distribution network style.

[sharnett]

Couple solutions:

1. (better) add more fixed voltage constraints to Jabr formulation, beyond just u1 = v1^2/sqrt(2)
2. take original Jabr solution generator voltages, add those to MATPOWER, solve, compare

[sharnett]

I'm looking at case_ieee30_tree.m, where the Jabr method gives a different answer from Newton.

Proposed solution #1 seems to result in an infeasible model. Making them inequality constraints doesn't help. Removing the load flow constraints on the extra generators (so they're all slack buses) makes it feasible again, but the answer is still different from Newton.

I guess I'll try solution #2.

[sharnett]

I think I'll try #3 first: alter MATPOWER case file to remove generators, make all but one bus a load.

[sharnett]

Actually, generators are 'PV' buses -- the reactive power isn't fixed, just the real power and voltage magnitude. But removing only the reactive flow constraint at the extra generators didn't seem to do the trick. Needs further investigation.

[sharnett]

Is it possible that there are multiple solutions? This is no longer a distribution network.

[sharnett]

Look into trying different starting points for both Jabr and MATPOWER.

[sharnett]

Using the Jabr solution as a starting point for Newton didn't change Newton's answer on case_ieee_30. Can try using the Newton solution as a starting point for Jabr, but that probably won't do it since Jabr is a convex problem. Worth trying anyway.

If that fails, just convert everything to a distribution network, letting voltages vary freely at all buses but one.

[sharnett]

GOT IT. There were some extra settings in the (shunt susceptances and tap ratios) that I needed to set to zero.

[sharnett]

Verified on case_ieee30 and case118_v2. I think we might finally be done here.