An ME-SMIB Based Method for Online Transient Stability Assessment of a Multi-Area Interconnected Power System

Transient stability assessment (TSA) of the power system is essential to the safe operation of the power grid. The TSA of the multi-area interconnected power system is a challenging task due to its special multi-area power grid structure. New features, which are the time-variable instability mode and untypical two-group instability mode, emerge in the transients of the interconnected power system and affect the accuracy of conventional TSA methods. To address these problems, we propose a novel TSA method based on the modified equivalent single machine infinite bus (ME-SMIB) system. Two key technologies, namely generator groups identification and generator selection, were presented in the proposed method. Generator groups were identified at each time-step to track the time-variable instability mode. Two groups of generators that were of good coherency and closely related to the current instability mode were selected to construct the ME-SMIB system. The transient instability was finally identified by the concave-convexity-based method. The proposed method was tested in the 16-generator 68-bus power system and China interconnected power system. Results show that the proposed ME-SMIB system can avoid the misjudgments caused by new transient features of the multi-area interconnected power system, presenting superior reliability than the conventional E-SMIB system.