Small-Signal Stability Assessment

Power system stability can be affected by many factors, such as the growth of demand, the use of more large-capacity generators installed at remote locations, longer transmission lines, and the heavier power flow on tie-lines. The techniques of monitoring and estimation of power system stability are key issues to prevent power outages. This chapter describes the small-signal stability assessment with phasor measurements. Particularly, the stability of the interarea low-frequency oscillation mode is investigated by adopting the method to identify the oscillation dynamics with a simple oscillation model. The filtering approach improves the accuracy of the estimated eigenvalues. The stability can be evaluated successfully by the filtering approach. The chapter compares two filtering methods namely, discrete wavelet transformation (DWT)-based filtering and fast Fourier transformation (FFT)-based filtering by focusing on the accuracy of the mode identification. It also discusses stability assessment based on phasor measurements and based on frequency monitoring.