Tracking the Eastern interconnection frequency governing characteristic

The authors have systematically kept track of Eastern interconnection frequency governing characteristic, called beta, for a period of more than 10 years. While there are some errors inherent to the process followed, we believe that the errors do not obscure the overall trend. We have found that Beta has been declining, and has reached a level of 31 MW/mHz. The true beta is probably somewhat lower. This has important implications in system behavior and simulation, particularly in simulations involving islanding.