Optimal Load-Side Control for Frequency Regulation in Smart Grids

Changhong Zhao, Enrique Mallada, Steven Low

Research output: Contribution to journalArticlepeer-review

134 Scopus Citations


Frequency control rebalances supply and demand while maintaining the network state within operational margins. It is implemented using fast ramping reserves that are expensive and wasteful, and which are expected to become increasingly necessary with the current acceleration of renewable penetration. The most promising solution to this problem is the use of demand response, i.e., load participation in frequency control. Yet it is still unclear how to efficiently integrate load participation without introducing instabilities and violating operational constraints. In this paper, we present a comprehensive load-side frequency control mechanism that can maintain the grid within operational constraints. In particular, our controllers can rebalance supply and demand after disturbances, restore the frequency to its nominal value, and preserve interarea power flows. Furthermore, our controllers are distributed (unlike the currently implemented frequency control), can allocate load updates optimally, and can maintain line flows within thermal limits. We prove that such a distributed load-side control is globally asymptotically stable and robust to unknown load parameters. We illustrate its effectiveness through simulations.
Original languageAmerican English
Pages (from-to)6294-6309
Number of pages16
JournalIEEE Transactions on Automatic Control
Issue number12
StatePublished - 2017

NREL Publication Number

  • NREL/JA-5D00-70834


  • demand-side management
  • optimization
  • power system control
  • power system dynamics


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