Session - Invited Talks II

  • Wind Energy in the Context of Statistical Physics by Joachim Peinke at 14.00 - 14.45 (CET)
    Abstract: The transition of electrical energy supply to renewable energy sources significantly increases the complexity of this system. In addition to energy consumption, the energy supply is increasingly fluctuating. The replacement of fossil power plants by wind turbines and photovoltaic cells reduces the smoothing effect of the inertia of the rotating machines of conventional power plants. In addition, the underlying statistics of energy supply become very demanding, since wind and solar energy are based on the turbulent energy resources, namely wind and clouds. The statistical challenges of the turbulent resources lie in the multiple correlations and multi-scale properties that cause highly unbalanced dynamics. The power grid is driven by non-Gaussian statistics with extreme events. In this paper a concept of statistical physics is presented, which includes a common multi-point statistic and short-term forecasting. In particular, we discuss the use of Fokker-Planck equations as well as entropy concepts that allow to study fluctuation theorems and to specify singular events.
  • Effects of spatio-temporal correlated fluctuations on networks - The power grids‘ case by Mehrnaz Anvari at 14.45 - 15.30 (CET)
    Abstract: Modern societies highly depend on electricity supply via power grids. Without electricity, people do not have access to food, transportation, medical treatment and so on. Moreover, in an extended outage the security of a community can be in danger. Therefore, stability of the power grid has highest priority. For that, the balance between the energy consumption and the required energy should be provided. Recently, the ongoing energy transition towards renewable generation fundamentally changes the conditions for the operation of the power system. The new sources of energy, such as wind and solar energy, unlike traditional ones are highly variable and are known as sources of fluctuations. These fluctuations, as well as fluctuations caused by demand and energy trading market, can affect the stability of the power grid, leading to the frequent outages or even extended blackout in the system. Therefore, considering these fluctuations and their effect on the power grid give deeper insights for the optimization design of future power grids as well as control schemes. This circumstance holds especially in distributed power grids, where the role of these fluctuations becomes more important because of the smaller size of the grid. In previous works, the footprint of these fluctuations on power grid frequency variations has been demonstrated. Moreover, perturbing a single node in a power grid with different types of fluctuations and considering the response of the network to these fluctuations via linear response theory has been discussed in several papers. In our new work, unlike the previous ones, we investigate the effect of spatially correlated fluctuations in different network topologies, specifically power grids. Therefore, we demonstrate the constructive and destructive effects of these types of fluctuations in networks.
  • Effects of fluctuations and demand control on the complex dynamics of electric power system blackouts by Pere Colet at 15.30 - 16.15 (CET)
    Abstract: The propagation of failures and blackouts in electric networks is a complex problem. Typical models, such as the ORNL-PSerc-Alaska (OPA), are based on a combination of fast and a slow dynamics. The first describes the cascading failures while the second the grid evolution though line and generation upgrades as well as demand growth, all taking place in time scales from days to years. The growing integration of renewable energy sources, whose power fluctuates in time scales from seconds to hours, together with the increase in demand, which also present fast fluctuations, require the incorporation of distributed methods of control in the demand side to avoid the high cost of ordinary control in conventional power plants. In this work, we extend the OPA model to include fluctuations in the demand at time scales of the order of minutes, intraday demand variations and the effect of demand control. We find that demand control effectively reduces the number of blackouts without increasing the probability of large-scale events.
  • Break by All at 16.15 - 16.30 (CET)
    Abstract: Break
  • How topology shapes the vulnerability of complex supply networks by Dirk Witthaut at 16.30 - 17.15 (CET)
    Abstract: Structural failures and perturbations can impair the stable operation of supply networks such as power grids up to the point of complete collapse. But not all elements of a networks are equally vulnerable and not all nodes and links are equally affected. In this talk I discuss how the topology of a network shapes the response to damages and perturbations and how failures spread through the network. We focus on linear flow networks, which describe the operation of power grids or vascular networks to a good approximation. This approach enables deep insights into the interplay of flows, failures, and topology. We elucidate the role of distances and communities and introduce a method to inhibit failure spreading completely.
  • Control of synchronization in two-layer power grids by Simona Olmi at 17.15 - 18.00 (CET)
    Abstract: In this talk we suggest modeling the dynamics of power grids in terms of a two-layer network, and we use the Italian high-voltage power grid as a proof-of-principle example. The first layer in our model represents the power grid consisting of generators and consumers, while the second layer represents a dynamic communication network that serves as a controller of the first layer. In particular, the dynamics of the power grid is modeled by the Kuramoto model with inertia, while the communication layer provides a control signal P_{i}^{c} for each generator to improve frequency synchronization within the power grid. We propose different realizations of the communication layer topology and different ways to calculate the control signal. Then we conduct a systematic survey of the two-layer system against a multitude of different realistic perturbation scenarios, such as disconnecting generators, increasing demand of consumers, or generators with stochastic power output. When using a control topology that allows all generators to exchange information, we find that a control scheme aimed to minimize the frequency difference between adjacent nodes operates very efficiently even against the worst scenarios with the strongest perturbations.