Adaptive cost-sensitive assignment method for power system transient stability assessment

•The fault severity of each sample is calculated as an additional label to participate in the training process.•The differences of samples with different fault severities are considered.•The idea of dynamic adjustment is applied for transient stability assessment.•An adaptive cost-sensitive assignment method is presented, which is robust to abnormal training samples. In power system transient stability assessment (TSA), the misclassification cost of unstable samples is much more serious than that of stable ones. Besides, for both unstable samples and stable samples, the impacts of critical samples on the assessment rules are more important than those of non-critical ones. Thus, an improved cost-sensitive assignment (ICSA) method based on the fault severity is proposed. Larger cost coefficients are assigned to critical samples compared with non-critical samples. Furthermore, sufficiently learning the information of misclassified samples is helpful to modify the assessment rules quickly and accurately. Meanwhile, the assessment rules may be greatly disturbed due to the existence of abnormal samples among training samples. Therefore, on basis of the ICSA method, an adaptive cost-sensitive assignment (ACSA) method is presented in this paper. In the process of model training, the cost coefficients of misclassified training samples are adaptively adjusted to improve the assessment rules. Then, the impacts of the abnormal samples on the assessment rules are eliminated by assigning their cost coefficients to 0. Finally, simulation experiments are carried out in the IEEE 39-bus system and a realistic system. It can be shown that the proposed ACSA method has high classification accuracy and excellent generalization ability.