Estimating order reduction for large power systems

Results are presented for reduced order models of power systems as large as 254 generators, 2500 buses, based on the modal coherency method of model reduction. Extension of order estimation, based on balanced realizations, to larger systems is discussed. An alternative order estimation approach based on the intergenerator coherency ranking table is introduced and compared to the balanced realization approach. The alternative approach is consistent with the balancing results and two orders of magnitude faster.