ECE Seminar Series

Joint Electrical and Computer Engineering and Computer Science Seminar

Title: Bridging the Gap between Real-Time Inverter Control and Steady-State Optimization in Distribution Systems
Speaker: Emiliano Dall'Anese
Affiliation: National Renewable Energy Laboratory (NREL)
Day: Monday, March 30, 2015
Time: 11:00 am - 12:00 pm
Location: CSB 130

Abstract: Since distribution systems were designed to sustain unidirectional power flows to residential neighborhoods and commercial premises without accounting for endogenous power generation, the increased deployment of inverter-interfaced renewable sources of energy with existing operational practices has precipitated a set of unique power- quality and reliability-related challenges. Accordingly, recent academic and industrial efforts have looked at the design of decentralized real-time inverter-control strategies to regulate the delivery of real and reactive power based on local measurements, so that terminal voltages are within acceptable levels (e.g., local Volt/VAR and active power curtailment). On a different time scale, communication-based methods have been proposed where steady-state inverters' setpoints are obtained by solving a possibly large-scale optimization problem.

In an effort to bridge the temporal and spatial gap between real-time control and network-wide steady-state optimization, this talk outlines one way to addresses the synthesis of feedback inverter controllers that provably steer the inverter output powers towards solutions of relevant optimization problems; for example, the controllers continuously seek solutions of steady-state AC optimal power flow (OPF) renditions that encapsulate economic objectives and voltage-regulation constraints. The guiding motivation is to ensure that renewable-energy systems operation and control strategies are adaptable to changing ambient conditions and loads, and enable seamless end-user participation without compromising system efficiency. The design of the controller is grounded on dual epsilon-subgradient method, whereas semidefinite programming relaxations are advocated to bypass the NP-hardness of AC OPF problems. Throughout the talk, global convergence of inverter output powers will be demonstrated under mild technical conditions, for the case where affordable computational limits and communications constraints involve asynchronous updates of the controller signals. A distribution-system-specific rendition of the OPF, which accommodates ancillary-service-oriented objectives, will be also outlined.

Bio: Emiliano Dall'Anese received the B.Sc Degree M.Sc Degree from the University of Padova, Italy, in 2005 and 2007, respectively, and the Ph.D. in Information Engineering from the Department of Information Engineering, University of Padova, Italy, in 2011. From January 2009 to September 2010, he was a visiting scholar at the Department of Electrical and Computer Engineering, University of Minnesota, USA. From January 2011 to November 2014, he was a Postdoctoral Associate at the Department of Electrical and Computer Engineering and Digital Technology Center, University of Minnesota, within the group directed by Prof. Georgios B. Giannakis. Since December 2014 he has been a Senior Engineer within the Distributed Energy Systems Integration (DESI) group at the National Renewable Energy Laboratory (NREL). His research is centered around the analysis, algorithms, and application of Optimization and Statistical Signal Processing methods to energy management in power systems, cyber-physical systems, and grid informatics.