Power system disturbance monitoring using spectral analysis techniques

This paper considers the problem of measuring and analysing the frequency and phase angle variations which occur in a power system after a fault or disturbance. This is an important problem because the results of the analysis are used in implementing control strategies to avert generator cutout. Commonly, the frequency is not measured directly, but is inferred from the instantaneous power at the substation. Since there is a complicated non-linear relationship between the power and the frequency, some bias is incurred in the measurement. This paper proposes instead that the angle and or frequency be obtained directly via an analytic signal readily constructed from the 3-phase output of the power system. The paper also proposes enhancements for some of the currently employed signal analysis techniques, and a new technique based on an extension of Thompson´s (1982) harmonic line test