Smart Grid Seminar

In AC power systems, the voltages and currents are approximately 50 or 60Hz sinusoids. They are never perfect sinusoids due to nonlinear loads and switching in power electronic converters. These non-idealities can be represented as higher frequency harmonics. Excess harmonic distortion can cause high resistive losses, faulty tripping of protection devices, vibrations in motors and generators, and transformer failure. The growing number of converter-interfaced renewables and energy storage devices is increasing harmonic distortion in power systems, and it is unclear what problems may arise.

Today, harmonics are managed locally by the filters in converters. This is expensive and does not ensure that the aggregate level of harmonic distortion will be small. In this talk, I present Harmonic-Constrained Optimal Power Flow (HCOPF) for managing harmonics at the network level. HCOPF consists of conventional OPF and constraints on the total harmonic distortion in the network. We model the harmonics with the frequency coupling matrix (FCM), which maps fundamental frequency currents and voltages to the resulting harmonics.

The FCM of a converter may not be known in practice. We give an algorithm to estimate FCMs from PMU and metering data. We also give a network reduction theorem that enables us to model unobservable portions of the network with virtual FCMs.

BIO:  Josh Taylor is an assistant professor in the Department of Electrical and Computer Engineering at the University of Toronto. He received the B.S. degree from Carnegie Mellon University in 2006, and the S.M. and Ph.D. degrees from the Massachusetts Institute of Technology in 2008 and 2011, all in Mechanical Engineering. From 2011 to 2012, he was a postdoctoral researcher at the University of California, Berkeley. His research focuses on control and optimization of power systems.