New England test system, IEEE 39 Bus System, 10 generators, in PSS/E format (version 29): If you use these data take a look at the reactive consumption; it seems to be too high at some loads. Static and dynamic data have been obtained from the example files of PST toolbox, which seems to be no longer available. Dynamic data have been slighty modified in order to include typical subtransient reactances and subtransient time constants.

Some parameters appear in the book "Energy function analysis for power system stability", M.A.Pai (thanks to Marija Zima for the tip).

Another reference: http://www.ee.washington.edu/research/pstca/