2 NEW MEASURING ALGORITHMS FOR GENERATOR AND TRANSFORMER RELAYING

This paper presents new digital measuring algorithms for generator and transformer protection. Two methods are proposed to make the estimati on of amplitudes of the fundamental frequency component and the higher harmonics immune to frequency deviations. The first method bases on t he software re-sampling of the physical data window and on the simulta neous iterative estimation of the frequency. The second algorithm empl oys the amplitude estimator having unique frequency response in the en tire frequency spectrum and enables direct compensation for the freque ncy deviations. Also a new Volts/Hertz inverse-time algorithm is propo sed which does not call for the direct measure of frequency. It relies on the second method and uses the amplitude estimator having the gain close to the inverse of the frequency; therefore, it acts as a direct amplitude-to-frequency estimator. The proposed algorithms were analyz ed analytically and tested using EMTP simulations.