Composite power system risk assessment and weak links identification considering cascading failures

Blackouts generally stem from cascading failures in power system operation. Their diminution requires very much the development of approaches and algorithms that analyze cascading failure risk and identify weak links of power system. Different from optimal load shedding model widely used in conventional risk assessment, this paper considers the impact of cascading failures on power system, and adopts a practical re-dispatch model. A fault chain model is established to better describe the propagation process of cascading failures and to calculate the occurrence probability of cascading failures quantitatively. To better understand how cascading failures propagate and to effectively identify weak links that are crucial for cascading failure propagation, this paper proposes the index called "risk participation factor" to measure the effect of branches on the reliability level of power system. Besides, Monte Carlo simulation method is applied to assess these indices. The proposed cascading failures model and fault chain model are validated on the IEEE 39-bus system. Results show that the proposed model that considers the propagation of cascading failures can provide more weak links information for power system planning and operation.