Performance of Excitation Systems Under Abnormal Conditions

Modem generator excitation systems provide good voltage regulation at normal system frequency and assist in maintaining transient stability during disturbances. However, a number of abnormal system operating conditions should be considered in evaluating excitation system performance. Some of these conditions are extended periods of operation at other than normal frequency, or voltage, or both, simultaneously. These system conditions can cause excessive output from the generator excitation system and impose overloads on the generator and step-up transformer.