Potential impact of load curtailment on the day-ahead Iberian market : a preliminary analysis

ABSTRACT: Demand response (DR) in electricity markets may offer a variety of financial and operational benefits. Typically, customers respond to DR events by adopting curtailment and shifting strategies. This article focuses on the former strategy and assumes that consumers are encouraged to avoid consuming electricity during specific hours of a 24 h day, because the energy price is above a given threshold. It presents a study on the Iberian market, conducted with the help of an agent-based simulation tool, called MATREM. The results are very favorable to the adoption of the load curtailment strategy (as a consequence of the enrollment in different DR programs).info:eu-repo/semantics/publishedVersio

Hydro-wind balance in daily electricity markets : a case-study

ABSTRACT: The European Union has been one of the major drivers of the development of renewable energy. In Portugal, renewable generation is subject to specific licensing requirements and benefits from a feed-in-tariff. This paper pays special attention to wind and hydroelectric technologies. Typically, wind farms produce more energy during the night (off-peak periods), when the demand is lower, contributing to a reduction of the market price. Hydroelectric power plants use off-peak periods to pump water, and produce energy in the periods of a 24 hour day where the prices of electricity are higher (peak periods). This paper presents a case study aiming at analyzing the behavior of hydroelectric power producers—that is, in power systems with large renewable generation, producers typically use the periods of the day with lower energy prices for pumping, and the other periods (with higher energy prices) to produce electricity. The simulations are performed using MATREM (for Multi-Agent Trading in Electricity Markets). The results confirm (and rebate) the typical behavior of hydroelectric power producers.info:eu-repo/semantics/publishedVersio

Neural networks with dynamical synapses: from mixed-mode oscillations and spindles to chaos

Understanding of short-term synaptic depression (STSD) and other forms of synaptic plasticity is a topical problem in neuroscience. Here we study the role of STSD in the formation of complex patterns of brain rhythms. We use a cortical circuit model of neural networks composed of irregular spiking excitatory and inhibitory neurons having type 1 and 2 excitability and stochastic dynamics. In the model, neurons form a sparsely connected network and their spontaneous activity is driven by random spikes representing synaptic noise. Using simulations and analytical calculations, we found that if the STSD is absent, the neural network shows either asynchronous behavior or regular network oscillations depending on the noise level. In networks with STSD, changing parameters of synaptic plasticity and the noise level, we observed transitions to complex patters of collective activity: mixed-mode and spindle oscillations, bursts of collective activity, and chaotic behaviour. Interestingly, these patterns are stable in a certain range of the parameters and separated by critical boundaries. Thus, the parameters of synaptic plasticity can play a role of control parameters or switchers between different network states. However, changes of the parameters caused by a disease may lead to dramatic impairment of ongoing neural activity. We analyze the chaotic neural activity by use of the 0-1 test for chaos (Gottwald, G. & Melbourne, I., 2004) and show that it has a collective nature.Comment: 7 pages, Proceedings of 12th Granada Seminar, September 17-21, 201

Critical and resonance phenomena in neural networks

Brain rhythms contribute to every aspect of brain function. Here, we study critical and resonance phenomena that precede the emergence of brain rhythms. Using an analytical approach and simulations of a cortical circuit model of neural networks with stochastic neurons in the presence of noise, we show that spontaneous appearance of network oscillations occurs as a dynamical (non-equilibrium) phase transition at a critical point determined by the noise level, network structure, the balance between excitatory and inhibitory neurons, and other parameters. We find that the relaxation time of neural activity to a steady state, response to periodic stimuli at the frequency of the oscillations, amplitude of damped oscillations, and stochastic fluctuations of neural activity are dramatically increased when approaching the critical point of the transition.Comment: 8 pages, Proceedings of 12th Granada Seminar, September 17-21, 201

GeMs/GSAOI observations of La Serena 94: an old and far open cluster inside the solar circle

Physical properties were derived for the candidate open cluster La Serena 94, recently unveiled by the VVV collaboration. Thanks to the exquisite angular resolution provided by GeMS/GSAOI, we could characterize this system in detail, for the first time, with deep photometry in JHK$_{s}$ - bands. Decontaminated JHK$_{s}$ diagrams reach about 5 mag below the cluster turnoff in H. The locus of red clump giants in the colour - colour diagram, together with an extinction law, was used to obtain an average extinction of $A_V =14.18 \pm 0.71$. The same stars were considered as standard - candles to derive the cluster distance, $8.5 \pm 1.0$ kpc. Isochrones were matched to the cluster colour - magnitude diagrams to determine its age, $\log{t(yr)}=9.12\pm 0.06$, and metallicity, $Z=0.02\pm0.01$. A core radius of $r_{c}=0.51\pm 0.04$ pc was found by fitting King models to the radial density profile. By adding up the visible stellar mass to an extrapolated mass function, the cluster mass was estimated as $M=(2.65\pm0.57) \times 10^3$ M$_{\odot}$, consistent with an integrated magnitude of $M_{K}=-5.82\pm0.16$ and a tidal radius of $r_{t}=17.2\pm2.1$ pc. The overall characteristics of La Serena 94 confirm that it is an old open cluster located in the Crux spiral arm towards the fourth Galactic quadrant and distant $7.30\pm 0.49$ kpc from the Galactic centre. The cluster distorted structure, mass segregation and age indicate that it is a dynamically evolved stellar system.Comment: 16 pages, 24 figures, 2 Tables, accepted by MNRAS; corrected typo