Online analysis and early warning method for low-frequency oscillation of electric power system

The invention discloses an online analysis and early warning method for low-frequency oscillation of electric power system, relating to the safe operation of electric power system. The method comprises the steps that: oscillation frequency is obtained by carrying out K point median filtering over collected relative power angle in a power grid wide-area measurement system and via Teagar energy operator; and when power oscillation with the oscillation frequency between 0.1-0.2 Hz exists in power grid, the damping ratio dominating oscillation mode can be worked out through a signal energy analysis method based on EMD, thus to realize online analysis and early warning for low-frequency oscillation. The advantages of the invention include that the Teagar energy operator can rapidly work out the frequency of the relative power angle in the power grid; the algorithm of the damping ratio is simplified; large amount of integral operation can be avoided; the calculation is much simpler and morerapid; and the online analysis and early warning for low-frequency oscillation in power grid is realized.