Trustworthiness Viability of Closed-Loop Online Power-System Defense Under Evidence and Response-Time Constraints

Online power-system defense increasingly depends on automated assessment, strategy generation, and real-time implementation. However, the accuracy of a single model or controller does not establish the trustworthiness of the complete closed loop. This paper proposes a mission-level framework for closed-loop trustworthiness under physical, informational, and temporal uncertainty. Trustworthiness is defined as the lowest finite-horizon mission-success probability over all probability laws consistent with available evidence. The resulting trustworthiness viability domain contains the joint physical, evidence, dependence, and response-time states from which a required trustworthiness level remains achievable. A recursive characterization supports model-conditional certification and boundary warning. Additional evidence can reduce maintainable trustworthiness when its acquisition delay removes feasible recovery actions. Safe abnormality identifiability requires diagnostic actions to remain inside the viability domain, while a counterfactual deficit measure locates abnormalities with the largest mission-level effect. Conditions are also derived for heterogeneous redundancy and certified fallback. On a modified Reliability Test System–Grid Modernization Lab Consortium (RTS-GMLC) system, 14.3% of test states were physically secure but were not certified at the required trustworthiness level. Under the scenario-based model, 94.6% of abnormal cases met the 0.95 trustworthiness threshold with runtime selection. Texas2k tests quantified the accuracy–runtime tradeoff at a larger network scale.