A New Index Extracted From Line Flow Fluctuation To Evaluate Power System Damping

This paper proposes a new index to evaluate the damping effect of a power system on a dominant mode of electromechanical oscillation. The index is obtained from numbers of line flow fluctuations in which the dominant mode is strongly observed even in the normal state of the system. In order to extract the index from the fluctuations, a combined technique is developed which is based on the FFT (Fast Fourier Transform) processing and the principal component analysis. The technique is applied to the field data which have been acquired at a single tie-line of a studied power system in Japan from 1985 to 1989. The regression analysis with respect to the index and the total generation of the system shows an interesting property that the damping effect of the system becomes strong with the increase of the total generation. This property, which is called as “droop characteristic” in this paper, could be used for the identification of a steady-state stability region and data base for on-line stability assessment.