A Test-Bed for Protection Studies of Synchronous Generators and its Interaction with the Underexcitation and Overexcitation Limiters

A test-bed implemented in a real time digital simulation environment is presented in this paper to perform coordination studies between protection functions and excitation limiters of automatic voltage regulators (AVRs) of synchronous generators. A hardware-in-the-loop (HIL) simulation is implemented in laboratory to test and evaluate several protection schemes (ANSI 21, 24, 27, 40, 59 and 81) during underexcited and overexcited events. The interactions among the underexcitation and overexcitation limiters (UEL and OEL) with these protection functions are investigated and the best settings for their coordination are proposed. The main results are presented and discussed.