When Hertz Can Hurt

摘要

The frequency stability of the interconnected electric grid in North America is a marvel of engineering. As shown in Fig-ure 1, the deviation is rarely beyond 0.05 Hz from the nominal 60 Hz. In fact, during a given hour time period, this deviation is more like +/-0.02 Hz from the nominal value. Over several months, we were able to track the frequency at three monitoring sites separated by more than a thousand miles to be basically identical at any point in time. This kind of synchronization and coordination across miles and miles of wire may tend to lull us into thinking that frequency is not on the list of potential power quality phenomena to be concerned about.