Tracking the Eastern Interconnection frequency governing characteristic

The Eastern Interconnection frequency governing characteristic, sometimes called Beta, has been tracked by one of the authors for a period of more than 15 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 approximately 25 MW/mHz. This has important implications in system behavior, particularly in situations involving islanding. Study assumptions need to reflect this observed reduction in governing response.