Cascading Failure Analysis With DC Power Flow Model and Transient Stability Analysis

When the modern electrical infrastructure is undergoing a migration to the Smart Grid, vulnerability and security concerns have also been raised regarding the cascading failure threats in this interconnected transmission system with complex communication and control challenge. The DC power flow-based model has been a popular model to study the cascading failure problem due to its efficiency, simplicity and scalability in simulations of such failures. However, due to the complex nature of the power system and cascading failures, the underlying assumptions in DC power flow-based cascading failure simulators (CFS) may fail to hold during the development of cascading failures. This paper compares the validity of a typical DC power flow-based CFS in cascading failure analysis with a new numerical metric defined as the critical moment (CM). The adopted CFS is first implemented to simulate system behavior after initial contingencies and to evaluate the utility of DC-CFS in cascading failure analysis. Then the DC-CFS is compared against another classic, more precise power system stability methodology, i.e., the transient stability analysis (TSA). The CM is introduced with a case study to assess the utilization of these two models for cascading failure analysis. Comparative simulations on the IEEE 39-bus and 68-bus benchmark reveal important consistency and discrepancy between these two approaches. Some suggestions are provided for using these two models in the power grid cascading failure analysis.