Transient excitation boosting at Grand Coulee Third Power plant: power system application and field tests

Transient excitation boosting (TEB) has been installed on the Grand Coulee Third Power Plant hydrogenerators (three 600 MVA units and three 700 MVA units). The authors describe the application and implementation of transient excitation boosting based on direct detection of a critical disturbance. Using telemetry, a signal is sent to inject a decaying pulse into the excitation systems of large generators with very powerful static exciters. This open-loop control improves interarea transient stability. TEB is initiated for outages of the 3100 MW Pacific HVDC intertie, and results in a decaying pulse input to the generator voltage regulators. TEB temporarily raises Pacific Northwest transmission voltages which increases voltage-sensitive loads. The increased load brakes Northwest generators which are accelerating because of the loss of HVDC intertie power. Transient stability of the parallel Pacific AC intertie is thus improved. Power system-wide commissioning tests were conducted on May 7, 1991. The tests are described and test results compared with simulation results