Professor Steven Low of California Institute of Technology, USA

Topic: Optimal Power Flow for Distribution Systems

Distribution systems will play an increasingly critical role in decarbonizing our power systems.  This talk consists of two self-contained sessions on optimal power flow (OPF) problems for distribution systems that are radial and in unbalanced three-phase operation.

In the first session, we formulate OPF problems in the bus injection model initially for single-phase (or balanced three-phase) operation and then unbalanced three-phase operation.  It is well known that OPF is nonconvex and NP-hard.  We describe semidefinite relaxations of OPF and present sufficient conditions for exact relaxations in both single and three-phase radial networks.  

In the second session, we formulate OPF problem in the branch flow model for both single-phase and three-phase radial networks.  We describe semidefinite relaxations for these models and explain their equivalence.  Finally, even though OPF is hard in theory, it seems ``easy’’ in practice in the sense that, empirically, semidefinite relaxations are often exact and local algorithms often yield global solutions.  We present necessary or sufficient conditions for an OPF problem to both have exact relaxation and no spurious local optimal.

Format:

10.00 AM - Introduction by Chathurika Mediwaththe, School of Engineering, The Australian National University

10.05 AM - 10.50 AM - Session 1: OPF and Bus Injection Model

10.50 AM - 11.00 AM - Audience Q&A

11.00 AM - 11.10 AM - Break

11.10 AM - 11.50 AM - Session 2: OPF and Branch Flow Model

11.50 AM - 12.00 PM - Audience Q&A

12.00 PM - Close

Biography:

Steven Low is the F. J. Gilloon Professor of the Department of Computing & Mathematical Sciences and the Department of Electrical Engineering at Caltech, and an Honorary Professor of the Electrical & Electronic Engineering Department at Melbourne University.  He was a co-recipient of IEEE best paper awards, an awardee of the IEEE INFOCOM Achievement Award (2021) and the ACM SIGMETRICS Test of Time Award (2021), and is a Fellow of IEEE (2008), ACM (2020), and CSEE (2020).  He was well-known for pioneering a mathematical theory of Internet congestion control and semidefinite relaxation of optimal power flow problems in smart grid.  His research on networks has been accelerating more than 1TB of Internet traffic every second since 2014.  His research on smart grid is providing large-scale cost-effective EV charging to workplaces, from K-12 and universities to municipalities to Fortune Global 50 companies.  He received his B.S. from Cornell and PhD from Berkeley, both in EE.