Mechanism Study of Large Power Oscillation of Inter-area Lines Caused by Local Mode

Based on eigenvalue analysis of small signal stability analysis, mechanism of large power oscillations of inter-area lines caused by local mode is studied by right eigenvector characteristic and generator power-angle characteristic. Eigenvalue of local mode is changing with running conditions and relations between the elements of right eigenvector of all generators also are changed. When power deviations´ sum of all generator units located in one area caused by local mode oscillation is very large value, large power oscillations in inter-area lines will emerge, and the synthetic direction of power deviations of the generators in other area is similar to the strong participation generator of local mode, is contrary to the generators located in the same area with the local mode generator. A field data case of West Inner Mongolia power grid oscillation has proved the oscillation mechanism being, and corresponding analytic method and improved measures are proposed.