Risk assessment of integrated transmission and distribution systems considering load transfer

Integrated transmission and distribution system (ITDS) analysis is gaining increasing attention from academics and industry. Load transfer, a critical factor in maintaining system reliability and reducing system risk during outages, is often overlooked in conventional system risk assessment. This paper proposes a framework that incorporates load transfer capabilities into ITDS modeling, enabling a comprehensive evaluation of its impact on risk mitigation. The framework integrates the uncertainty of electricity demand, initial outages suggested by contingency motifs, and detailed ITDS models. A centralized model using mixed-integer conic programming is formulated to identify optimal load transfer strategies. Recognizing the typical operational separation of transmission and distribution systems, a practical two-stage optimization method with limited information exchange is also proposed to determine degraded system states. Case studies demonstrate that incorporating load transfer can significantly reduce system risk, underscoring the importance of integrating this capability into risk assessments and operational strategies.