Over Excitation Limiter Oscillation Analysis And Damping Measures For Alstom Excitation System Of Nuclear Power Unit

This paper analyzes the over excitation limiter (OEL) simulation model of the ALSTOM P320 V2. excitation system used by nuclear power generators in China. The way of OEL output received as input to the main loop is presented for studying on the OEL oscillation occurred at an actual Nuclear Power Plant. The oscillation phenomenon is reproduced in time domain simulation and the oscillation mechanism is revealed by frequency domain root locus analysis. The concept of critical gain of the over excitation limitation control loop of ALSTOM excitation system is proposed, and the tuning range of the main loop differential time constant is recommended. The feasibility and correctness of the damping measures on OEL oscillation are verified by field test at a real nuclear power unit.