Reexamining the Distributed Slack Bus

Sairaj V. Dhople, Yu Christine Chen, Abdullah Al-Digs, Alejandro D. Dominguez-Garcia

Research output: Contribution to journalArticlepeer-review


Power flow formulated with a distributed slack bus involves modeling the active-power output of each generator with three elements: a nominal injection modulated by a fraction of the net-load imbalance allocated via a participation factor. This setup acknowledges generator dynamics and system operations, but it has long been plagued by ambiguous and inconsistent interpretations of its constituent elemental quantities. In this paper, we establish that, with the: i) nominal active-power injections set to be the economic dispatch setpoints, ii) participation factors fixed to be the ones used in automatic generation control, and iii) net-load imbalance considered to be the total load and loss unaccounted in economic dispatch, the power flow solution best matches results from a simulation unto steady state of the system differential algebraic equation (DAE) model. Numerical case studies tailored to the New England test system validate the analysis by demonstrating that solutions obtained from a distributed slack formulation offer lower errors (with respect to DAE-model simulations) compared to the exhaustive set of all single slack bus choices.

Original languageEnglish (US)
Article number9072426
Pages (from-to)4870-4879
Number of pages10
JournalIEEE Transactions on Power Systems
Issue number6
StatePublished - Nov 2020


  • Automatic generation control
  • distributed slack bus
  • economic dispatch
  • participation factors
  • power flow

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering


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