Failure Localization in Power Systems via Tree Partitions
For power system operators, this provides a rigorous framework to spatially localize cascading failures by strategically switching lines, potentially improving grid robustness against large-scale outages.
This work uses tree partitions of transmission networks to analytically characterize line failure localizability in power systems, showing that failures on non-bridge lines propagate only within defined 'cells' while bridge-line failures propagate globally. The approach is illustrated on the IEEE 118-bus test system, where switching off a negligible portion of lines significantly localizes failure impacts without substantial congestion changes.
Cascading failures in power systems propagate non-locally, making the control and mitigation of outages extremely hard. In this work, we use the emerging concept of the tree partition of transmission networks to provide an analytical characterization of line failure localizability in transmission systems. Our results rigorously establish the well perceived intuition in power community that failures cannot cross bridges, and reveal a finer-grained concept that encodes more precise information on failure propagations within tree-partition regions. Specifically, when a non-bridge line is tripped, the impact of this failure only propagates within well-defined components, which we refer to as cells, of the tree partition defined by the bridges. In contrast, when a bridge line is tripped, the impact of this failure propagates globally across the network, affecting the power flow on all remaining transmission lines. This characterization suggests that it is possible to improve the system robustness by temporarily switching off certain transmission lines, so as to create more, smaller components in the tree partition; thus spatially localizing line failures and making the grid less vulnerable to large-scale outages. We illustrate this approach using the IEEE 118-bus test system and demonstrate that switching off a negligible portion of transmission lines allows the impact of line failures to be significantly more localized without substantial changes in line congestion.