Application of nearest neighbor algorithm for critical clearing time (CCT) approximation

The nearest neighbor algorithm (NNA) has been applied for calculating the critical clearing time (CCT) of a 4-machine 11 bus system under variations in load, fault location and network structure. The CCT is one significant factor for the operator to set the protective relays and circuit breakers to maintain the transient stability of the power systems during the large disturbances, e.g. three-phase-to-ground faults. In this paper, Sobol sequences (Sob) were applied to the selection of the training patterns of the CCT. The results when compared with time domain simulation methods show less mean absolute errors than using a pseudo random choice of inputs. The nearest neighbor algorithm has been successfully applied for approximating the CCT of the system under those variations.