1 paper accepted to IEEE TNSE

Our paper [1] on synchronization of phase-coupled oscillators was accepted to appear in IEEE Transactions on Network Science and Engineering

[1] [doi] A. Gushchin, E. Mallada, and A. Tang, “Phase-coupled oscillators with plastic coupling: Synchronization and stability,” IEEE Transactions on Network Science and Engineering, vol. 3, iss. 4, pp. 240-256, 2016.
[Bibtex] [Abstract] [Download PDF]

In this article we study synchronization of systems of homogeneous phase-coupled oscillators with plastic coupling strengths and arbitrary underlying topology. The dynamics of the coupling strength between two oscillators is governed by the phase difference between these oscillators. We show that, under mild assumptions, such systems are gradient systems, and always achieve frequency synchronization. Furthermore, we provide sufficient stability and instability conditions that are based on results from algebraic graph theory. For a special case when underlying topology is a tree, we formulate a criterion (necessary and sufficient condition) of stability of equilibria. For both, tree and arbitrary topologies, we provide sufficient conditions for phase-locking, i.e. convergence to a stable equilibrium almost surely. We additionally find conditions when the system possesses a unique stable equilibrium, and thus, almost global stability follows. Several examples are used to demonstrate variety of equilibria the system has, their dependence on system’s parameters, and to illustrate differences in behavior of systems with constant and plastic coupling strengths.

@article{gmt2016tnse,
  abstract = {In this article we study synchronization of systems of homogeneous phase-coupled oscillators with plastic coupling strengths and arbitrary underlying topology. The dynamics of the coupling strength between two oscillators is governed by the phase difference between these oscillators. We show that, under mild assumptions, such systems are gradient systems, and always achieve frequency synchronization. Furthermore, we provide sufficient stability and instability conditions that are based on results from algebraic graph theory. For a special case when underlying topology is a tree, we formulate a criterion (necessary and sufficient condition) of stability of equilibria. For both, tree and arbitrary topologies, we provide sufficient conditions for phase-locking, i.e. convergence to a stable equilibrium almost surely. We additionally find conditions when the system possesses a unique stable equilibrium, and thus, almost global stability follows. Several examples are used to demonstrate variety of equilibria the system has, their dependence on system's parameters, and to illustrate differences in behavior of systems with constant and plastic coupling strengths.},
  author = {Gushchin, Andrey and Mallada, Enrique and Tang, Ao},
  doi = {10.1109/TNSE.2016.2605096},
  journal = {IEEE Transactions on Network Science and Engineering},
  keywords = {Synchronization},
  month = {09},
  number = {4},
  pages = {240-256},
  title = {Phase-coupled oscillators with plastic coupling: Synchronization and stability},
  url = {https://mallada.ece.jhu.edu/pubs/2016-TNSE-GMT.pdf},
  volume = {3},
  year = {2016}
}

1 paper accepted to PSCC

Our paper [1] on unified frequency control and congestion management has been accepted to Power System Computation Conference!

[1] [doi] C. Zhao, E. Mallada, S. H. Low, and J. W. Bialek, “A Unified Framework for Frequency Control and Congestion Management,” in Power Systems Computation Conference, 2016, pp. 1-7.
[Bibtex] [Abstract] [Download PDF]

The existing frequency control framework in power systems is challenged by lower inertia and more volatile power injections. We propose a new framework for frequency control and congestion management. We formulate an optimization problem that rebalances power, restores the nominal frequency, restores inter-area flows and maintains line flows below their limits in a way that minimizes the control cost. The cost can be squared deviations from the reference generations, minimizing the disruption from the last optimal dispatch. Our control thus maintains system security without interfering with the market operation. By deriving a primal-dual algorithm to solve this optimization, we design a completely decentralized primary frequency control without the need for explicit communication among the participating agents, and a distributed unified control which integrates primary and secondary frequency control and congestion management. Simulations show that the unified control not only achieves all the desired control goals in system equilibrium, but also improves the transient compared to traditional control schemes.

@inproceedings{zmlb2016pscc,
  abstract = {The existing frequency control framework in power systems is challenged by lower inertia and more volatile power injections. We propose a new framework for frequency control and congestion management. We formulate an optimization problem that rebalances power, restores the nominal frequency, restores inter-area flows and maintains line flows below their limits in a way that minimizes the control cost. The cost can be squared deviations from the reference generations, minimizing the disruption from the last optimal dispatch. Our control thus maintains system security without interfering with the market operation. By deriving a primal-dual algorithm to solve this optimization, we design a completely decentralized primary frequency control without the need for explicit communication among the participating agents, and a distributed unified control which integrates primary and secondary frequency control and congestion management. Simulations show that the unified control not only achieves all the desired control goals in system equilibrium, but also improves the transient compared to traditional control schemes.},
  author = {Zhao, Changhong and Mallada, Enrique and Low, Steven H and Bialek, Janusz W},
  booktitle = {Power Systems Computation Conference},
  doi = {10.1109/PSCC.2016.7541028},
  keywords = {Power Networks; Frequency Control; Congestion Management},
  month = {06},
  pages = {1--7},
  title = {A Unified Framework for Frequency Control and Congestion Management},
  url = {https://mallada.ece.jhu.edu/pubs/2016-PSCC-ZMLB.pdf},
  year = {2016}
}