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Optimization and Control of Power Flow in Distribution Networks


Farivar, Masoud (2016) Optimization and Control of Power Flow in Distribution Networks. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/Z9JW8BSM.


Climate change is arguably the most critical issue facing our generation and the next. As we move towards a sustainable future, the grid is rapidly evolving with the integration of more and more renewable energy resources and the emergence of electric vehicles. In particular, large scale adoption of residential and commercial solar photovoltaics (PV) plants is completely changing the traditional slowly-varying unidirectional power flow nature of distribution systems. High share of intermittent renewables pose several technical challenges, including voltage and frequency control. But along with these challenges, renewable generators also bring with them millions of new DC-AC inverter controllers each year. These fast power electronic devices can provide an unprecedented opportunity to increase energy efficiency and improve power quality, if combined with well-designed inverter control algorithms. The main goal of this dissertation is to develop scalable power flow optimization and control methods that achieve system-wide efficiency, reliability, and robustness for power distribution networks of future with high penetration of distributed inverter-based renewable generators.

Proposed solutions to power flow control problems in the literature range from fully centralized to fully local ones. In this thesis, we will focus on the two ends of this spectrum. In the first half of this thesis (chapters 2 and 3), we seek optimal solutions to voltage control problems provided a centralized architecture with complete information. These solutions are particularly important for better understanding the overall system behavior and can serve as a benchmark to compare the performance of other control methods against. To this end, we first propose a branch flow model (BFM) for the analysis and optimization of radial and meshed networks. This model leads to a new approach to solve optimal power flow (OPF) problems using a two step relaxation procedure, which has proven to be both reliable and computationally efficient in dealing with the non-convexity of power flow equations in radial and weakly-meshed distribution networks. We will then apply the results to fast time- scale inverter var control problem and evaluate the performance on real-world circuits in Southern California Edison’s service territory.

The second half (chapters 4 and 5), however, is dedicated to study local control approaches, as they are the only options available for immediate implementation on today’s distribution networks that lack sufficient monitoring and communication infrastructure. In particular, we will follow a reverse and forward engineering approach to study the recently proposed piecewise linear volt/var control curves. It is the aim of this dissertation to tackle some key problems in these two areas and contribute by providing rigorous theoretical basis for future work.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Convex Optimization, Power Distribution Networks, Optimal Power Flow, Distributed Computation, Smart Grid, Renewable Integration, Inverter Control
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Electrical Engineering
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Hassibi, Babak (advisor)
  • Low, Steven H. (co-advisor)
Thesis Committee:
  • Hassibi, Babak (chair)
  • Low, Steven H.
  • Wierman, Adam C.
  • Chandrasekaran, Venkat
  • Chen, Lijun
Defense Date:2 June 2015
Non-Caltech Author Email:mfarivar (AT)
Record Number:CaltechTHESIS:12092015-021431773
Persistent URL:
Related URLs:
URLURL TypeDescription DocumentBranch Flow Model: Relaxations and Convexification—Part I DocumentBranch Flow Model: Relaxations and Convexification—Part II DocumentInverter VAR control for distribution systems with renewables DocumentOptimal inverter VAR control in distribution systems with high PV penetration DocumentEquilibrium and Dynamics of Local Voltage Control in Distribution Systems DocumentLocal Voltage Control in Distribution Systems: An Incremental Control Algorithm DocumentPseudo-gradient Based Local Voltage Control in Distribution Networks DocumentBranch Flow Model: Relaxations and Convexification
Farivar, Masoud0000-0001-7298-3526
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9317
Deposited By: Masoud Farivar Asanjan
Deposited On:10 Dec 2015 20:36
Last Modified:22 Jan 2016 15:05

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