A small-signal stability index for power system dynamic impact assessment using time-domain simulations

In this paper, a three layer small-signal stability index to assess power system dynamic simulations is presented. The index is calculated from an estimate of the eigenvalues of the system, which are determined using time-series from dynamic simulations. The methodology assumes that no other information about the system (model) is available. In the first layer, which is the main future of the index, a scalar (positive or negative) indicates if any of the modes have a damping ratio less than a predefined value. In the second layer, a vector is used to specify which pre-defined damping ratios were violated and finally, in the third layer a matrix is used to retrieve precise information about which mode has violated the pre-defined damping requirements of the system. The proposed index is first illustrated using synthetic data and then the index is validated using simulation data from the KTH-Nordic32 system.