Power System Control Under Cascading Failures

3Understanding Cascading Failures

Cascading blackouts of transmission systems are complicated sequences of dependent outages that lead to load shed. Of particular concern are the larger cascading blackouts; these blackouts are rare and high‐impact events that have substantial risk, and they pose many challenges in simulation, analysis, and mitigation. In the last chapter, we introduced several cascading failure models that can produce massive amounts of data regarding line outages, generator tripping, and load shedding. However, simulations cannot produce statistical insight or metrics with actionable information without a carefully designed information extraction method. In this chapter, we will discuss several theories and models that can extract useful and actionable information from simulated cascading data to help understand why and how cascading failures happen in electric power grids. Specifically,

• The self‐organized criticality (SOC) theory in statistical physics [1–6] provides an explanation about why and how large‐scale systemwide failures can happen. There has been evidence that indicates power system blackouts are governed by SOC.
• The branching process model [7, 8] provides an overall statistical description about how cascading failures propagate among the components in the system [9, 10]. The descriptive parameters of the branching process can characterize the system resilience to cascading. For example, the average propagation quantifies the extent to which outages ...