Summary
The project is associated with the analysis and control of large scale networks, and involves the development of corresponding theoretical tools as well as the study of related applications associated with engineering and biological networks.
In particular, for the case of engineering networks our research focuses on the design of decentralized control policies with a plug and play capability, i.e. stability guarantees are provided for the network when heterogeneous subsystems are added or removed from the network. This is a major requirement in many important applications such as smart grids and power networks, where the increasing presence for distributed generation, such as renewable energy sources, and the introduction of load-side participation schemes impose severe challenges associated with the ability to ensure a stable network with good performance. The results developed improve the efficiency and reliability of the network and facilitate the implementation of such highly distributed control schemes .
For the case of biological networks our research focuses on the analysis of the effects of noise in biochemical reaction networks at the molecular level. Molecular fluctuations are inevitably present in biochemical reaction networks and the significant impact they can have in the underlying functionality has been reported in recent years both theoretically and experimentally. These can drive metabolites away from desired concentrations or be sometimes advantageous contributing to diversity and evolution. In our work we use advanced tools from control theory to analyse this stochasticity and derive hard bounds for its estimation. We also derive optimal feedback policies for such stochastic models which we use to improve our understanding of the role and limitations of feedback in epidemiological models.
Publications
Laib K., Watson J., Ojo Y., and Lestas I., Decentralized stability conditions for DC microgrids: Beyond passivity approaches, arXiv:2109.02708. Accepted for publications in Automatica, 2022.
Li M., Laib K, and Lestas I., Convergence Rate Bounds for the Mirror Descent Method: IQCs and the Bregman Divergence, arXiv:2204.00502, 2022. Preliminary version accepted at IEEE CDC 2022.
Li M., Lestas I., Qiu L. Parallel feedforward compensation for output synchronization: Fully distributed control and indefinite Laplacian. Systems & Control Letters 164, 105250, p. 1-8. 2022.
Holding T., and Lestas I. Stability and instability in saddle point dynamics - Part I. IEEE Transactions on Automatic Control, 66(7), p. 2933-2944, 2021.
Holding T., and Lestas I. Stability and instability in saddle point dynamics Part II: the subgradient method. IEEE Transactions on Automatic Control, 66(7), p. 2945-2960, 2021.
Kasis I., Monshizadeh N, and Lestas I. Primary frequency regulation in power grids with on-off loads: chattering, limit cycles and convergence to optimality. Automatica, 131(109736), p. 1-15, 2021.
Highlighted by the Editor-in-chief as Editor’s choice for the issue.
Watson J., Ojo Y., Laib K., Lestas I. A scalable control design for grid-forming inverters in microgrids. IEEE Transactions on Smart Grid, 12(6), p. 4726 - 4739, 2021.
Kasis I. and Lestas I. Frequency regulation with thermostatically controlled loads: aggregation of dynamics and synchronization, IEEE Transactions on Automatic Control, 2021.
Watson J., and Lestas I. Frequency and Voltage Regulation in Hybrid AC/DC Networks, IEEE Transactions on Control Systems Technology, 29(5), p. 1839 - 1849, 2021.
Laib K., Watson J., Ojo Y., and Lestas I. Decentralized Stability Conditions in DC Microgrids. In Proc. 60th IEEE Conference on Decision and Control, Dec 2021.
Ojo Y., Watson J., Laib K., and Lestas I. A decentralized frequency and voltage control scheme for grid-forming inverters. In Proc. IEEE PES Innovative Smart Grid Technologies Europe (ISGT-Europe), Oct 2021.
Watson J., and Lestas I. Control of Interlinking Converters in Hybrid AC/DC Grids: Network Stability and Scalability. IEEE Transactions on Power Systems., 36(1), p. 769-780, 2020.
Kasis I., Monshizadeh N., and Lestas I. A distributed scheme for secondary frequency control with stability guarantees and optimal power allocation. Systems & Control Letters. 144, 2020.
Kasis I., Monshizadeh N., and Lestas I. Secondary frequency control with on-off load side participation in power networks. IEEE Transactions on Control of Network Systems, 7(2), p. 603-613, 2020.
Pugliese Carratelli G., Lestas I. Variance bounds for a class of biochemical reactions with bursts using a discrete expansion. In Proc. 59th IEEE Conference on Decision and Control, Dec 2020.
Laib K., Watson J., Lestas I. Decentralized Stability Conditions for Inverter-Based Microgrids. In Proc. 59th IEEE Conference on Decision and Control, Dec 2020.
Ojo Y., Benmiloud M., Lestas I. Frequency and Voltage Control Schemes for Three-Phase Grid - Forming Inverters. In Proc. 21st IFAC World Congress, July 2020.
Monshizadeh, N. and Lestas, I. Secant and Popov-like conditions in power network stability. Automatica, 101, pp.258-268, 2019.
Kasis, A., Monshizadeh, N., Devane, E. and Lestas, I. Stability and optimality of distributed secondary frequency control schemes in power networks. IEEE Transactions on Smart Grid. 10(2), pp.1747-1761, 2019.
Kasis A., Lestas I. Frequency regulation with thermostatic load participation in power networks. In Proc. 58th IEEE Conference on Decision and Control, Dec 2019.
Watson, J.D., Watson, N.R. and Lestas, I. Optimized dispatch of energy storage systems in unbalanced distribution networks. IEEE Transactions on Sustainable Energy, 9(2), pp.639-650, 2018.
Kasis, A., Monshizadeh, N. and Lestas, I. Stability of primary frequency control with on-off load side participation in power networks. In IEEE Conference on Decision and Control, 2018.
Watson, JD and Lestas, I. Frequency and voltage control of hybrid AC/DC networks. In IEEE Conference on Decision and Control, 2018.
Monshizadeh, N. and Lestas, I. Secant Conditions in Power Network Stability. In European Control Conference, 2018.
Kasis, A., Monshizadeh, N. and Lestas, I. A novel distributed secondary frequency control scheme for power networks with high order turbine governor dynamics. In European Control Conference, pp. 2018.
Research Team
Ioannis Lestas (PI)
Khaled Laib (RA)
Jeremy Watson (RA)
Xiaodong Cheng (RA)
Menmou Li (RA)
Giovanni Pugliese Carratelli (PhD student)
Yemi Ojo (PhD student)
Nima Monshizadeh (former RA, now Assistant Professor at University of Groningen)
Andreas Kasis (former RA, now a Marie Curie Research Fellow)