Excitation system limiter models for use in system stability studies

Models which may be used to represent excitation system limiters in power system stability studies are described in this paper. Presented are overfluxing, overvoltage and both instantaneous and time delayed overexcitation limiters. Two types of underexcitation limiters are presented, one based on stability considerations and the second based on generator load capability considerations. An additional model for a generator armature current limiter is presented. The models also show discrete outputs that may be used as alarm or protective features. Also included is a modified version of the ST1A model showing where the various limiting signals may be introduced into the control loop