A frequency relay capable of under/over frequency and rate of change of frequency measurements has been implemented on a digital signal processor using an instantaneous frequency measuring algorithm. Careful attention to the filtering aspects of the relay is needed under dynamic conditions due to frequency modulation of the input signal. An algorithm for avoiding unwanted relay operation due to impulsive changes in the input signal is presented. Results are shown for simulated tests using computer-based relay testing equipment, and for overloads on a micromachine power system simulator
Published in:
Power Delivery, IEEE Transactions on
(Volume:11
,
Issue:
4
)
Date of Publication: Oct 1996