Power flow data for 9 bus, 3 generator case.

Based on data from p. 70 of:

Chow, J. H., editor. Time-Scale Modeling of Dynamic Networks with
Applications to Power Systems. Springer-Verlag, 1982.
Part of the Lecture Notes in Control and Information Sciences book
series (LNCIS, volume 46)

which in turn appears to come from:

R.P. Schulz, A.E. Turner and D.N. Ewart, "Long Term Power System
Dynamics," EPRI Report 90-7-0, Palo Alto, California, 1974.