Distributed Online VAR Control for Unbalanced Distribution Networks with Photovoltaic Generation

Jiayong Li, Chengying Liu, Mohammad E. Khodayar, Ming Hao Wang, Zhao Xu, Bin Zhou, Canbing Li

Research output: Journal article publicationJournal articleAcademic researchpeer-review

23 Citations (Scopus)


The unbalanced nature of the distribution networks (DNs) and communication asynchrony pose considerable challenges to the distributed voltage regulation. In this paper, two distributed voltage control algorithms are proposed to overcome these challenges in multiphase unbalanced DNs. The proposed algorithms can be leveraged in online implementations to cope with the fast-varying system operating conditions. By adopting the linearized multiphase DistFlow model, the voltage control problem is formulated as a convex quadratic programming problem for which a synchronous distributed algorithm is developed based on the dual ascent method. To account for communication delays, an asynchronous distributed algorithm is proposed evolving from the synchronous one by incorporating an event-triggered communication protocol. Furthermore, closed-form solutions to the optimization subproblems are derived to enhance the computational efficiency, and communication complexity is reduced significantly to the extent that only neighborhood information exchange is required. Finally, the convergence of the proposed algorithms to the global optimality is established analytically. Numerical tests on the IEEE 123-bus network not only corroborate that our proposed algorithms are more efficient in eliminating voltage violations and minimizing network loss compared with two benchmarks but also validate their effectiveness for online implementations.

Original languageEnglish
Article number9105062
Pages (from-to)4760-4772
Number of pages13
JournalIEEE Transactions on Smart Grid
Issue number6
Publication statusPublished - Nov 2020


  • Distribution networks
  • multiphase unbalance
  • online voltage control
  • synchronous and asynchronous distributed algorithms

ASJC Scopus subject areas

  • Computer Science(all)


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