Generator excitation loss detection on various excitation systems and excitation system failures

Abstract

Generating steadiness of synchronous generator is highly dependent on their exciter as the direct current from excitation system sustains stator and rotor windings magnetically coupled. But generator loss of excitation weakens stator and rotor coupling which result in mechanical and electrical power imbalance and rotor speed rise beyond synchronous speed. And this phenomenon is able to damage both the generator and the grid if an early protection is not issued through excitation loss relay. This paper presents performance evaluation of excitation loss relay for DC, AC and static (ST) type exciters and various causes of excitation loss. Comparatively the relay shows a good performance in all causes of full loss of excitation than in partial field voltage loss in any type of excitation systems. But the relay detection time in static type exciter is short compare to DC and AC type exciters.