Seminar Details:

**LANS Informal Seminar***"Anti-Islanding in Transmission Switching AND Using Symmetry to Optimize Over Extended Formulations"*

DATE: November 9, 2011

TIME: 15:00:00 - 16:00:00

SPEAKER: Jim Ostrowski, *Postdoctoral Appointee, DIS*

LOCATION: Building 240, 4301, Argonne National Laboratory

**Description:**

Two talks for the price of one! I will present 2 topics on mixed-integer linear programming (MILP), one application (transmission switching), and one theoretical results (optimizing over extended formulations).

Transmission switching provides a way to increase the efficiency in power systems operations by altering the topology of the transmission network. Altering the transmission topology can affect the reliability of the network. Incorporating reliability into the optimization problem increases the difficulty of an already complex optimization problem. We present an algorithm to deal with the islanding problem caused by transmission switching that can significantly decrease computation time.

We improve upon the LP relaxation bounds by computing the bound given by the Sherali-Adams extended formulation for highly symmetric MILP problems. Typically the extended formulations of Sherali-Adams relaxations can be very large. Symmetry can be used to generate an LP with significantly fewer variables that has an identical objective value. We demonstrate this by computing the bound associated with the level 1, 2, and 3 relaxations of several highly symmetric binary integer programming problems.

Please send questions or suggestions to Charlotte Haley: haley at anl dot gov.