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Artículos en revistas Islands are facing considerable challenges in meeting their energy needs in a sustainable, affordable and reliable way. The present paper develops an integrated approach to economically assess initiatives that can transform island power systems into smart ones. Single and multi-action initiatives fostering the deployment of renewable energy sources (RES), energy storage systems (ESS), demand-side management (DSM), and electric vehicle (EV) are considered. An hourly unit commitment on a weekly basis is proposed to assess the impact of the initiatives on the system operation costs of five prototype island power systems, which have been identified by applying clustering techniques to a set of sixty islands power systems. The different investment costs of the initiatives are accounted for determining their corresponding internal rate of return (IRR) through their lifetime. The economic assessment of single and multi-action initiatives for five prototype islands representing sixty island power systems quantifies which initiatives are most suitable for which type of island power system. The assessment shows that islands of different sizes and features require different initiatives. Larger islands tend to DSM initiatives, whereas smaller islands tend to RES initiatives. Multi-action initiatives achieve highest system operation cost reduction, whereas single action initiatives yield to highest IRR. info:eu-repo/semantics/publishedVersion

Modeling electricity storage to address challenges and opportunities of its applications for smart grids requires inter-temporal equalities to keep track of energy content over time. These constraints present crucial modeling elements, which may affect case study results. Hence, correct modeling improves conclusions as to which extent energy storage applications can enhance future electric power systems sustainability, reliability, and efficiency. This paper presents a novel and improved mixedinteger linear problem (MILP) formulation for energy storage of plug-in (hybrid) electric vehicles (PEVs) for reserves in power system models. It is based on insights from the field of System Dynamics, in which complex interactions between different elements are studied by means of feedback loops as well as stocks, flows and co-flows. Generalized to a multi-bus system, this formulation includes improvements in the energy balance and surpasses shortcomings in the way existing literature deals with reserve constraints. Tested on the IEEE 14-bus system with realistic PEV mobility patterns, the deterministic results show significant changes in the scheduling of the units, often referred to as unit commitment (UC) . info:eu-repo/semantics/draft

Artículos en revistas This paper presents a new arc furnace model which copes with the two main voltage disturbances normally associated with arc furnaces: voltage fluctuations; and harmonics. The model is based on the stochastic nature of the electric arc current-voltage characteristic. The model has been estimated from measurements made in two actual electric plants. Although a single-phase model has been normally proposed, this paper develops a three-phase model in order to fully represent the unbalances that are present in real industrial plants and which play a central role in the behavior of compensation devices such as SVCs. The model has been implemented using the SIMULINK environment in order to facilitate later simulation of advanced disturbance control systems. Finally, the simulation results are compared with actual data in order to validate the accuracy of the model. info:eu-repo/semantics/publishedVersion

This paper proposes a model to compute nodal prices in oligopolistic markets. The model generalizes a previous model aimed at solving the single-bus problem by applying an optimisation procedure. Both models can be classified as Conjectured Supply Function models. The Conjectured Supply Functions are assumed to be linear with constant slopes. However, the price sensitivity as seen for each generating unit depends on the system line s status (congested or not congested). Market equilibrium is defined in this framework. A procedure based on solving an optimisation problem is proposed. It only requires convexity of cost functions. However, existence of equilibrium is not guaranteed in this multi-nodal situation, and an iterative search is required to find it if it exists. A two area multi-period case study is analysed. The model reaches equilibrium for some cases, mainly depending on the number of periods considered and on the value of conjectured supply function slopes. Some oscillation patterns are observed that can be interpreted as quasi-equilibria. This methodology can be applied to the study of the future Iberian electricity market. info:eu-repo/semantics/draft

Capítulos en libros In concert with increasing co-ordination of energy markets, transmission planning for location-constrained generation is forcing a shift from regional to wide-area transmission network planning. Planning for locationconstrained generators, notably wind and solar resources, is complicated by uncertainty in policies driving their growth. To design transmission systems robust to uncertain future expansion of location-constrained generators, planners must incorporate stochastic generation into models. The size of the transmission expansion problem makes this computationally intractable. This paper presents a screening model to reduce the number of transmission investments which must be considered. The screening model combines sampled generation expansion scenarios with a two-stage relaxed planning model to identify corridors of interest. A St.Clair curve-based filter translates corridors to investment variables. In a 240 bus model of WECC, this method reduced the number of corridors of interest 98% from 19,503 to 303 and reduces the number of investment variables 99% from 58,503 to 432. info:eu-repo/semantics/publishedVersion

Artículos en revistas This paper investigates the application of adaptive control to the Spanish load-frequency regulation scheme, Automatic Generation Control (AGC). The Spanish AGC system regulates the frequency and the power exchange between France and Spain. The system is hierarchically structured with one master regulator that coordinates four control areas. Each control area is composed of several generating units providing AGC service. Coordinating signals are sent to the control areas so that the global system response achieves the objective established by the System Operator. The participation of each control area in the service is set according to the rated share that it has obtained in the secondary-reserve market and its relative response speed compared to that of the rest of the control areas. Some problems, such as the lack of sensitivity to the quality of the reserve provided by the control areas, have been detected in the operation of the current AGC scheme. A new design, which is presented in this paper, has been developed in order to overcome these problems. This paper attempts to outline how this new design improves the global AGC system response and the distribution of the regulation effort among the control areas. The proposed strategy is compared with the present design by means of simulation. info:eu-repo/semantics/publishedVersion

The EU-28 is one of the largest emitters of CO2 in the world and the most committed to reducing emissions. However, the national environmental strategies of the Member States are still diverse. This study is aimed at evaluating the environmental performance of European economies by analysing the fluctuations of CO2 emissions and their links with economic activity over the period 1950e2012. The methodological framework is based on a dynamic factor analysis to determine an index of the EU fluctuation of CO2 emissions in parametric form. This index can be used to monitor the progress towards common behaviour across Member States, with a time-varying recursive method. Following this approach, we also track the efforts made to decouple CO2 emissions from GDP. Based on these analyses, we develop a CO2 emissions-GDP linkage matrix to attain useful information on the EU Member State environmental performance.

Abstract To investigate heat demand, one can usually base the estimation on sales data for the energy carriers or even use the data directly. This works for companies, regions, towns and sectors (e.g., industry or domestic sector). But for the waste heat produced by the industry it is not that simple: waste heat is an output value, which neither costs nor earns any money and it is therefore seldom measured or reported. In this paper, different methods to estimate the excess heat of industrial production within a region are categorized and compared. Besides the obviously necessary distinction between theoretical, technical and economic potential, the authors suggest categorization of the methods in three dimensions: study scale, data collection and approach/perspective (bottom up vs. top down). Following this schematic, previous regional waste heat studies are reviewed. Studies focusing on single sectors or companies are not considered in this review, as well as studies estimating the heat demand. As a result it can be seen that the available data are the driving force in the choice for the used estimation method. For general factors, the resulting waste heat potential ranges between 5 and 30% of the energy demand of the industrial sector of a region. Once derived, key figures are often reused in other studies for other countries. Therefore, more data and a thorough meta study of the available figures are desirable.