Session - Invited Talks I

  • Welcome by Organizers at 08.55 - 09.00 (CET)
    Abstract: Welcome by the Organizers
  • Data-driven control in autonomous energy systems by Florian Dörfler at 09.00 - 09.45 (CET)
    Abstract: Inspired by recent end-to-end data-driven approaches for power systems operation, power electronics control, and building automation, we consider the problem of optimal and constrained control for unknown systems. A novel data-enabled predictive control (DeePC) algorithm is presented that computes optimal and safe control policies using real-time feedback driving the unknown system along a desired trajectory while satisfying system constraints. Using a finite number of data samples from the unknown system, our proposed algorithm uses a behavioral systems theory approach to learn a non-parametric system model used to predict future trajectories. We show that, in the case of deterministic linear time-invariant systems, the DeePC algorithm is equivalent to the widely adopted Model Predictive Control (MPC), but it generally outperforms subsequent system identification and model-based control. To cope with nonlinear and stochastic systems, we propose salient regularizations to the DeePC algorithm, which are founded on recent advances in distributionally robust optimization. We illustrate our results with experimental and simulation case studies from autonomous energy systems.
  • Model predictive control framework for congestion management with large batteries in subtransmission grid. by Jean Maeght (RTE, France) at 09.45 - 10.30 (CET)
    Abstract: RTE will build and put into operation 3 large battery storage systems in 2021 (10MW/20MWh). These batteries, together with intermittent renewable generation curtailment and line switching, will be used to manage congestions in 3 small subtransmission zones (63kV or 90kV). A local controller will send orders to the battery, to power plants and switches every 5 seconds, using all the flexibility offered by permanent and emergency ratings. This local controller will not have any forecast and will not be able to manage preventive actions, so a higher level scheduler will be in charge of security analysis (N-1 analysis), battery preventive actions, pre-discharging the battery for forthcoming congestions. Moreover, this higher level scheduler will be in charge of computation of capacity tunnels; these capacity tunnels will to share the use of the batteries with other services when there are no congestions.
  • Scalability limitations in distributed primary and secondary frequency control by Emma Tegling at 10.30 - 11.15 (CET)
    Abstract: The ongoing paradigm shift in power networks, where local, small-scale generation resources are increasingly replacing large-scale centralized power plants, will both enable and require frequency control schemes to be distributed and scalable. In this talk, we will model prototypical power system dynamics and take a closer look at distributed primary and secondary frequency controllers from a performance perspective. Specifically, we will highlight situations where a uniform performance bound in terms of, for example, expected frequency deviations, cannot be maintained as the number of nodes (generators) grows. In other words, where there are fundamental limitations to the controllers’ scalability. We will discuss how these limitations depend on the network topology, the availability and quality of measurement signals, and, in the case of secondary frequency control, the degree of controller centralization.
  • Break by All at 11.15 - 11.30 (CET)
    Abstract: Break
  • Dynamics of High Voltage Power Grids under Power Outages and Fluctuations by Philippe Jacquod at 11.30 - 12.15 (CET)
    Abstract: Because of growing power demand, increasing difficulties with grid upgrades, and the emergence of intermittent new renewable energy sources, electric power systems are more and more often operated closer to their maximal capacity. The increasing penetration of new renewable energy sources furthermore reduces the overall mechanical inertia available. All this raises important grid stability issues over short to medium time scales, which can be answered only through in-depth investigations of power grid dynamics over large geographical scales. I will first describe PanTaGruEl, a dynamical grid model we constructed to investigate voltage angle and frequency dynamics following disturbances in the synchronous grid of continental Europe. PanTaGruEl will then be used to corroborate theoretical predictions (i) on global grid robustness, (ii) on the location of local grid vulnerabilities, (iii) on the optimal location of mechanical inertia and of primary control and (iv) on the propagation of frequency waves following local disturbances. Time and spatial scales are identified, which separate regimes with different dynamical behaviors.
  • Topological Determinants of Perturbation Spreading in Networks and Power Grids by Xiaozhu Zhang at 12.15 - 13.00 (CET)
    Abstract: Spreading phenomena essentially underlie the dynamics of various natural and technological networked systems, especially AC power transmission grids which are intrinsically exposed to fluctuating inputs. The spatiotemporal propagation pattern of an external perturbation determines whether and how far it may undermine the stable operation of a power transmission network, yet how such a pattern emerges from a complex network topology remains largely unknown. Here we propose a novel approach that reveals universal features determining the spreading dynamics in diffusively-coupled networks such as power grids, and disentangles them from factors that are system specific. In particular, we first analytically identify a purely topological factor encoding the interaction structure and strength, and second, numerically estimate a master function characterizing the universal scaling of the perturbation arrival times across different network topologies. The proposed approach provides intuitive insights into the complex propagation patterns in power grids as well as accurate predictions for the perturbation arrival times. Thereby it may help in estimating the time window for reactions and countermeasures against power fluctuations and developing guidelines for power grid design and control.