# CMX Lunch Seminar

*,*Gilloon Professor

*,*Computer Science and Electrical Engineering

*,*Caltech

*,*

Steven H. Low is a Professor of the Computing and Mathematical Sciences Department and the Electrical Engineering Department at the California Institute of Technology. He is known for his work on the theory and mathematical modeling of Internet congestion control, algorithms, and optimization in power systems. Low received his BS in electrical engineering from Cornell University in 1987, and PhD in electrical engineering from the University of California, Berkeley under the supervision of Pravin Varaiya in 1992. He was with AT&T Bell Labs in Murray Hill, NJ, from 1992-1996, the University of Melbourne, Australia, from 1996-2000, and joined Caltech in 2000.

Line failure in power grid propgates in non-local, intricate and counterintuitive ways because of the interplay between power flow physics and network topology, making the mitigation of cascading failure difficult. The conventional approach to grid reliability is through building redundant lines. In this talk, we present an opposite approach to grid reliability through failure localization, by judiciously removing lines and adopting a new class of frequency control algorithms at real time. The topology design partitions the network into regions that are connected in a tree structure. The frequency control automatically adjusts controllable generators and loads to minimize disruption and localize failure propagation. This approach is derived from a spectral view of power flow equations that relates failure propagation to the graphical structure of the grid through its Laplacian matrix. We summarize the underlying theory and present simulation results that demonstrate that our approach not only localizes failure propagation, as promised by the theory, but also improves overall grid reliability even though it reduces line redundancy.

_{(Joint work with Daniel Guo, Chen Liang, Alessandro Zocca, and Adam Wierman)}