Modeling Cascading Failures in Power Systems: Quasi-Steady-State Models and Dynamic Models

The majority of efforts to model cascading failures in power systems leverage some type of computer simulation where one encodes the protective mechanisms of interest for the analysis at hand. The two main groups of simulators that researchers and practitioners use are: (i) quasi-steady-state (QSS) models, where most of the information for where the simulation goes next is captured in the current state of the system, and (ii) dynamic models, where one explicitly includes variables (and their necessary mathematical relationships) that keep a memory of the system elements (for example, generators or loads). In this chapter, we explore side to side the statistics and particular cascading path characteristics for two simulators that belong to the same family of codes, that is, they are both open source in the same programming language, tunable, and share a great part of the basic code infrastructure. One simulator is QSS and the second one is dynamic, that way we are able to explore differences that should stem from this characteristic, and not from major implementation discrepancies, as it has been observed in previous benchmarking efforts by relevant groups. We follow the analysis recommendations from the IEEE cascading failure working group in recent publications and present here new results for these two benchmarks.