Topology Scheduling for Power Network Stability

Todd Murphey 

Wednesdays@NICO Seminar, Noon, May 22 2013, SPECIAL LOCATION: ITW Classroom in the Ford Engineering Design Center. Enter the main entrance and go two flights up the stairway

Prof. Todd Murphey, Mechanical Engineering Department, Northwestern University


How should instabilities be addressed when control authority is limited to discrete changes in the network? Power networks with changes in their topologies are hybrid systems--they have a finite set of governing equations that depend on time and possibly the state of the network. Designing these discrete changes to either minimize or maximize some objective function is the purpose of hybrid optimal control. For instance, one may wish to design time-dependent changes in transmission lines to stabilize a multimachine power network that would otherwise go unstable. Solving the associated optimal control problem is challenging due to the integer constraints on the inputs found in the governing equations. In this talk I will discuss a method that does not require a priori discretization and does not relax the optimization, but does provide guarantees on both convergence and computational complexity. Moreover, at every iteration the algorithm returns a dynamically feasible solution. The method parallels classical gradient descent methods from finite dimensions, but in an infinite-dimensional and nondifferentiable setting, making implementation of the algorithms reasonably straightforward. I will illustrate the algorithmic technique on a standard IEEE power network test case.


Todd Murphey received his undergraduate degree in mathematics from the University of Arizona and a Ph.D. in Control and Dynamical Systems from the California Institute of Technology. He was a postdoctoral scholar at Northwestern University for a year, after which he worked for the Aerospace Corporation in the Electro-Mechanical Control Department. He was an Assistant Professor of Electrical and Computer Engineering at the University of Colorado at Boulder from 2004 to 2008 and is now an Associate Professor of Mechanical Engineering at Northwestern University. He is the recipient of a National Science Foundation CAREER award.