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.

I. Nomenclature

The parameter Beta is the constant of proportionality between the change in generation or load and the resulting frequency change. We will use Beta beginning with an upper case B to represent Beta for the entire interconnection. The same term beginning with a lower case letter would be the same parameter for some part of the interconnection, such as a control area. The upper and lower case Greek letters could well be used, but we have not done so in this paper.