Changes in Cascading Failure Risk with Generator Dispatch Method and System Load Level

TL;DR

This paper investigates how cascading failure risk varies with system load and generator dispatch methods, revealing that risk does not always increase with load and is significantly affected by dispatch strategies.

Contribution

It introduces a detailed analysis of how load levels and dispatch methods influence cascading failure risk using Monte Carlo simulations on IEEE test systems.

Findings

Risk does not always monotonically increase with load.

Dispatch methods significantly impact cascading failure risk.

Minimum cost dispatch can increase long-distance power transfers and risk.

Abstract

Industry reliability rules increasingly require utilities to study and mitigate cascading failure risk in their system. Motivated by this, this paper describes how cascading failure risk, in terms of expected blackout size, varies with power system load level and pre-contingency dispatch. We used Monte Carlo sampling of random branch outages to generate contingencies, and a model of cascading failure to estimate blackout sizes. The risk associated with different blackout sizes was separately estimated in order to separate small, medium, and large blackout risk. Results from $N-1$ secure models of the IEEE RTS case and a 2383 bus case indicate that blackout risk does not always increase with load level monotonically, particularly for large blackout risk. The results also show that risk is highly dependent on the method used for generator dispatch. Minimum cost methods of dispatch can result in larger long distance power transfers, which can increase cascading failure risk.