Current Security Analysis Techniques and Shortcomings: Mitigation Strategies and Need for Probabilistic Analysis

The power industry currently relies on planning methods that underestimate the probability and consequences of loss-of-load events. Power supplies are vulnerable to the increasing frequency of severe weather events (polar vortex, wildfires, etc.), constraints on fuel availability, and correlated changes in the output of meteorologically dependent resources. Current resource adequacy and security analysis methods assume independent asset failures with invariant asset outage probabilities. Consequently, they do not adequately recognize the probability of correlated impacts on the output of multiple resources; accurately measure the frequency or severity of loss-of-load events; or fully account for their economic, public health and safety impacts. Grid planners have long relied on deterministic N-1 analyses to assess security of the system, which is designed to identify risks from the failure of the largest individual transmission lines and generators. This approach worked reasonably well in an era where the resource mix was dominated by dispatchable thermal generators with a high degree of fuel security. However, such an approach may no longer be adequate given increased meteorological dependence of generation, with concomitant increases in reliance upon storage and transmission to mitigate temporal and spatial supply imbalances, and the increasing interdependencies with other critical infrastructure systems such as natural gas and communications networks.