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Home | Seminars and Symposia | Past seminars/symposia: Wednesday, October 21, 2015

DTC Seminar Series

Stochastic optimization for optimal operation and design of electricity distribution networks with photovoltaic generation


Nikolaos Gatsis
University of Texas at San Antonio

Wednesday, October 21, 2015
4:15 p.m. seminar
5:15 p.m. reception

405 Walter Library

Modern electricity distribution networks feature programmable loads as well as distributed photovoltaic (PV) generators, which respectively offer demand response and reactive power control capabilities. This talk presents a scheme to optimally determine the demand response schedule of programmable loads that accounts for the stochastic availability of solar power, as well as to control the reactive power generation or consumption of PV inverters adaptively to the real power injections of PV units. These uncertain real power injections by PV units are modeled as random variables taking values from a finite number of possible scenarios. Through the use of second order cone program (SOCP) relaxation of the power flow equations, a convex stochastic programming problem is formulated with objectives to minimize the negative user utility, cost of power provision, and thermal losses. A decentralized solver featuring closed-form updates per node and per scenario is developed based on the alternating direction method of multipliers. Sufficient conditions that guarantee the optimality of SOCP relaxation will also be presented. As the previous scheme constraints nodal voltages to be within prespecified limits for all scenarios, a risk-averse formulation that instead guarantees nodal voltages to remain close to their nominal value with a specified probability is also presented. In addition, towards the end of the talk, a two-stage stochastic program is presented to optimally place and size PV inverters in a radial distribution network under solar irradiance and load uncertainties. First-stage variables include binary PV unit placement as well as real and apparent power capacities of the inverters. Second-stage decisions comprise reactive power compensation, power flows, and nodal voltages, while the objective will be to minimize installation cost and expected thermal losses on the network.


Nikolaos Gatsis received the Diploma degree in Electrical and Computer Engineering from the University of Patras, Greece, in 2005 with honors. He completed his graduate studies at the University of Minnesota, where he received the M.Sc. degree in Electrical Engineering in 2010, and the Ph.D. degree in Electrical Engineering with minor in Mathematics in 2012. He is currently an Assistant Professor with the Department of Electrical and Computer Engineering at the University of Texas at San Antonio. His research interests lie in the areas of smart power grids, renewable energy management, communication networks, and cyber-physical systems, with an emphasis on optimal resource management. Prof. Gatsis served as a Technical Program Committee member for symposia in IEEE SmartGridComm 2013, 2014, and 2015; and also as a Technical Co-Chair of the Symposium on Signal and Information Processing for Optimizing Future Energy Systems in IEEE GlobalSIP 2015.