Digital filter for power system stabilizer

Abstract

A digital filter for a power system stabilizer in a generator power system. The filter comprises a multi-stage filter having a low DC gain, a phase lead in the region of power oscillations (approximately 0.1 to 2 hertz) of the power system, a torsional reject characteristics (approximately 13.5 to 45 hertz) associated with mechanical resonances of the system, and high attenuation at the fundamental power frequency (e.g. 60 hertz). The filter is comprised of four digital filter sections, the first providing a lead and lag characteristics, the second and third providing a torsional reject characteristic, and the fourth providing a substantially zero DC gain characteristic for the elimination of any DC signal offset as well as a line freqeuncy notch, which tracks the fundamental line frequency. The first section, moreover, comprises a separate stage so that its characteristic can be independently adjusted in the field while the second, third and fourth sections are combined in a composite stage whereby the band reject and signal notch requirements are implemented.

Dependencies are inferred from the claim text.