Browsing by Author "Merino, Julia"
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Item Algorithm development for night charging electric vehicles optimization in big data applications(2017) Alvaro-Hermana, Roberto; Fraile-Ardanuy, Jesús; Merino, Julia; Tecnalia Research & InnovationIn this paper a night charging method that optimizes the recharging process of electric vehicles (EVs) depending on hourly energy price in a peer to peer (P2P) energy trading system is presented. This algorithm determines how much energy should be recharged in the battery of each EV and the corresponding time slot to do it, avoiding the discontinuities in the charging process and considering the users’ personal mobility constraints.Item Analysis of the applicability of the IEEE 2030.8 standard for testing a microgrid control system(CIGRE, 2021) Jimeno, Joseba; Merino, Julia; Perez-Basante, Angel; Gil-de-Muro, AsierTo coordinate the operation of the different generating units, storage systems and loads belonging to a microgrid, typically a Microgrid Control System (MGCS) is needed. This MGCS defines the set points to be delivered to the controllable devices to guarantee the appropriate operation of the microgrid both from the technical and the economic perspectives. The MGCS must be able to operate the microgrid in islanded mode, grid-connected, and withstand the transitions between the two operatingmodes. Recently two international standards have been approved dealing with microgrid con-trollers, “IEEE 2030.7-2017 – IEEE Standard for the Specification of Microgrid Control-ler” and “IEEE 2030.8-2018 - IEEE Standard for the Testing of Microgrid Controllers”.Item Assessment of distribution grid losses depending on storage location for residential PV systems in three grids in the region of Murcia(CIGRE, 2020) Rubio-Miguel, D.; Merino, Julia; Eguia-Lopez, P.; Torres-Iglesias, E.This paper shows the results of the studies carried out to determine which system, batteries installed behind the meter (BTM) or batteries installed in front of the meter (FTM), shows the best performance in terms of minimal power losses and energy storage capacity that would have the Battery Energy Storage Systems (BESS) to be installed. The analysis has been carried out over real networks in the region of Murcia (Spain) with different topologies and a variable number and location of customers along the grid. In addition, real consumption profiles of random customers, as well as real measurements of the transformer loading curves recorded at the Secondary Substation (SS), have been considered in the analysis. In this way, it can be ensured that the results represent real situations that can be found nowadays.Item Carbon-Free Electricity Generation in Spain with PV–Storage Hybrid Systems(2022-06-29) Fraile Ardanuy, Jesús; Alvaro-Hermana, Roberto; Castano-Solis, Sandra; Merino, Julia; Tecnalia Research & InnovationClimate change motivated by human activities constitutes one of the main challenges of this century. To cut carbon emissions in order to mitigate carbon’s dangerous effects, the current energy generation mix should be shifted to renewable sources. The main drawback of these technologies is their intermittency, which will require energy storage systems to be fully integrated into the generation mix, allowing them to be more controllable. In recent years, great progress to develop an effective and economically feasible energy storage systems, particularly motivated by the recent rise of demand for electric transportation, has been made. Lithium-ion (Li-ion) battery prices have fallen near 90% over the past decade, making possible the affordability of electric vehicles and transforming the economics of renewable energy. In this work, a study on storage capacity demand previously presented as conference paper is expanded, including a deep analysis of the Spanish generation mix, the evaluation of the energy storage requirements for different low-carbon and carbon-free scenarios in Mainland Spain, and the calculation of the CO2 emissions’ reduction and the associated storage costs.Item Control Room Requirements for Voltage Control in Future Power Systems(2018) Coelho, António; Soares, Filipe; Merino, Julia; Riaño, Sandra; Peças Lopes, João; Tecnalia Research & Innovation; SISTEMAS FOTOVOLTAICOSIn future power grids, a large integration of renewable energy sources is foreseen, which will impose serious technical challenges to system operators. To mitigate some of the problems that renewable energy sources may bring, new voltage and frequency control strategies must be developed. Given the expected evolution of technologies and information systems, these new strategies will benefit from increasing system observability and resources controllability, enabling a more efficient grid operation. The ELECTRA IRP project addressed the new challenges that future power systems will face and developed new grid management and control functionalities to overcome the identified problems. This work, implemented in the framework of ELECTRA, presents an innovative functionality for the control room of the cell operator and its application in assistance with the voltage control designed for the Web-of-Cells. The voltage control method developed uses a proactive mode to calculate the set-points to be sent to the flexible resources, each minute, for a following 15-min period. This way, the voltage control method developed is able to mitigate voltage problems that may occur, while, at the same time, contributes to reduce the energy losses. To enable a straightforward utilization of this functionality, a user interface was created for system operators so they can observe the network state and control resources in a forthright manner accordingly.Item Coordinación entre TSO y DSO para aprovechar el potencial de flexibilidad de los recursos distribuidos conectados en las redes de distribución(CIGRE, 2018-11) Madina, Carlos; Sanchez, J.; Jimeno, Joseba; Pardo, M.; Merino, Julia; Duarte, M.; Marroquin, M.; Estrade, E.Los sistemas eléctricos se enfrenan a numerosos desafíos a medida que la generación basada en energías renovables sustituye en gran parte a la que emplea combustibles fósiles. El carácter estocástico de muchas fuentes de generación renovable aumenta el volumen de reservas necesarias para asegurar la estabilidad del sistema, tanto en lo que se refiere a la tensión como a la frecuencia. Igualmente, el creciente número de sistemas de generación y almacenamiento de pequeño tamaño y consumidores con capacidad de flexibilizar su demanda aumenta la cantidad de potenciales proveedores de servicios a los que los operadores de transporte y distribución pueden acudir para optimizar la gestión de sus redes. El proyecto SmartNet (http://smartnet-project.eu/) compara cinco posibles esquemas de coordinación entre TSO y DSO, con diferentes arquitecturas de mercado en tiempo real (5 minutos), a fin de determinar qué soluciones son mejores desde una perspectiva tecno-económica para el sistema eléctrico. Para ello, se ha desarrollado una metodología de coste-beneficio específica, que se ha aplicado a los distintos esquemas de coordinación en los tres países considerados en el proyecto: España, Italia y Dinamarca. En paralelo, se han desarrollado tres pilotos de demostración, en esos mismos tres países, con el objetivo de demostrar la viabilidad tecnológica de las soluciones propuestas. Cada piloto tiene una arquitectura, un esquema de coordinación y unos proveedores de flexibilidad diferentes. En concreto, el piloto español, desplegado en Barcelona, utiliza la flexibilidad de las baterías de respaldo de estaciones base de telefonía móvil para mejorar la operación de la red de distribución, mediante la creación de un mercado local gestionado por la distribuidora. Este artículo presenta las conclusiones preliminares del estudio de coste-beneficio para los diferentes esquemas de coordinación en los tres países, así como los resultados de los pilotos y, en particular, del desarrollado en España.Item Electra IRP voltage control strategy for enhancing power system stability in future grid architectures(2017-10-01) Merino, Julia; Rodríguez-Seco, J.E.; García-Villalba, Íñigo; Temiz, Armağan; Caerts, Chris; Schwalbe, Roman; Strasser, Thomas I.; Temiz, Armaǧan; Tecnalia Research & Innovation; POWER SYSTEMSThis study is intended to show the future voltage control strategy designed in the framework of the ELECTRA Integrated Research Programme (IRP) project for the web-of-cells (WoC) concept. This scheme, called post-primary voltage control, aims to keep the node voltages at any time within the bands defined by the regulations and to minimise the power losses in the system by calculating the optimal voltage set-points for the different nodes. The reactive power will mainly be used to restore the voltages but also active power could be delivered in some cells depending on their voltage levels. Different operating modes of the voltage control will be discussed taking both planning and the real-time operation phases into account. The application of the voltage control strategy to one test grid considered as representative of the WoC structure will also be shown in this study.Item Electrical machines-based multi-disturbance device for testing distribution grid technologies(2018-07) Merino, Julia; Veganzones, Carlos; Alvaro-Hermana, Roberto; Fraile-Ardanuy, Jesús; Tecnalia Research & InnovationThe growth of distributed energy resources in power systems, mainly converter-coupled generators, has forced the evolution of grid codes, increasing the requirements to be fulfilled by the generators before their connection to the mains. Solving this problem is crucial to guarantee the reliability and stability of the power system. Current standards force the generators to remain connected when facing voltage and/or frequency disturbances and, in some advanced grid codes, also when the generators are facing transient phase jumps produced as a consequence of those disturbances. If considering that the increment of the distributed generation is mainly done at a distribution level, it is unrealistic to consider voltage and frequency events as decoupled phenomena in the testing and certification procedures, as it is currently done. The testing device proposed in this paper is able to reproduce voltage, frequency and phase jumps disturbances of a controlled value simultaneously, being able to reproduce the real grid behavior reliably. Its design is based on standard components with a simple control system, which makes it easily replicable and scalable up to the power of the device to be tested. Therefore, the proposed device is an interesting commercially competitive testing equipment suitable for certification.Item ERIGrid Holistic Test Description for Validating Cyber-Physical Energy Systems(2019-07-16) Heussen, Kai; Steinbrink, Cornelius; Abdulhadi, Ibrahim F.; Nguyen, Van Hoa; Degefa, Merkebu Z.; Merino, Julia; Jensen, Tue V.; Guo, Hao; Gehrke, Oliver; Bondy, Daniel Esteban Morales; Babazadeh, Davood; Pröstl Andrén, Filip; Strasser, Thomas I.; Van Hoa, Nguyen; Tecnalia Research & InnovationSmart energy solutions aim to modify and optimise the operation of existing energy infrastructure. Such cyber-physical technology must be mature before deployment to the actual infrastructure, and competitive solutions will have to be compliant to standards still under development. Achieving this technology readiness and harmonisation requires reproducible experiments and appropriately realistic testing environments. Such testbeds for multi-domain cyber-physical experiments are complex in and of themselves. This work addresses a method for the scoping and design of experiments where both testbed and solution each require detailed expertise. This empirical work first revisited present test description approaches, developed a newdescription method for cyber-physical energy systems testing, and matured it by means of user involvement. The new Holistic Test Description (HTD) method facilitates the conception, deconstruction and reproduction of complex experimental designs in the domains of cyber-physical energy systems. This work develops the background and motivation, offers a guideline and examples to the proposed approach, and summarises experience from three years of its application.Item Impact of self-consumption and electric vehicle recharging policies on energy communities(2021) Alvaro-Hermana, Roberto; Fraile-Ardanuy, Jesús; Merino, Julia; Castano-Solis, Sandra; Tecnalia Research & InnovationSelf-consumption is a key element to integrate renewable energies and foster consumer participation in the energy sector. To expand it, self-consumption regulation needs to incorporate policies such as shared self-consumption, energy communities, storage and electric vehicles. In this article, an optimization problem for the total cost of an energy community considering different self-consumption and electric vehicle management policies is presented. The problem is applied to a set of electric vehicle usage scenarios with diverse work schedules and daily consumptions. Results show that the involved policies have a greater impact on the community’s energy cost than the usage of the electric vehicles.||El autoconsumo es una herramienta fundamental para integrar energías renovables y fomentar la participación activa de los consumidores en el sector energético. Para ello, la regulación del autoconsumo debe expandirse, incorporando figuras como el autoconsumo compartido, las comunidades energéticas, el almacenamiento y los vehículos eléctricos. En este artículo se presenta un problema de optimización del coste energético de una comunidad que considera diferentes políticas de autoconsumo compartido y gestión del vehículo eléctrico. El problema se aplica a una comunidad de energía compuesta por cinco consumidores domésticos para escenarios de uso del vehículo eléctrico con diferentes horarios de trabajo y consumos diarios. Los resultados muestran que las políticas involucradas tienen mayor impacto en el precio de la comunidad que el uso dado a los vehículos eléctricos.Item New energy bound-based model for optimal charging of electric vehicles with solar photovoltaic considering low-voltage network's constraints(2021-07) Felipe Cortés Borray, Andrés; Garcés, Alejandro; Merino, Julia; Torres, Esther; Mazón, Javier; Tecnalia Research & InnovationThis paper introduces a linear programming (LP)-based optimisation method of charging electric vehicles (EVs) in a decentralised fashion. It exploits the available photovoltaic (PV) power to charge EV batteries while maintaining the low-voltage (LV) network within its operational limits. A new energy-bound model is implemented in order to meet the connected EVs energy requirements. This model highlights two main aspects: first, the proposed formulation seeks to compute both the upper and lower energy boundaries from the arrival energy and no from zero. Second, the charging power is dynamically adjusted by combining a fixed and variable charging rate to assure the technical limits of the network. This means maximising power delivered to all EVs for a given period by optimising the charging rate of each EV connected. Besides, a network sensitivity analysis technique is developed to manage voltage and loading constraints. The accuracy of the proposed linear approximation was tested simulating two cases (moderate and high penetration level of PVs and EVs) on a real LV feeder. Results over a set of simulations for winter and summer seasons demonstrate that this method can be effectively implemented as a charging strategy and for energy planning studies.Item Optimal coordination of PV active power curtailment and evs charging among aggregators(2020-10-15) Borray, Andrés Felipe Cortés; Merino, Julia; Torres, Esther; Mazón, Javier; Tecnalia Research & InnovationWith the growing adoption of electric vehicles (EVs) and residential photovoltaic (PV) systems around the world, the distribution system operators (DSOs) are facing several technical challenges on their network planning and operation, particularly on low-voltage grids. As the aggregators are intermediary actors at that system level, they are a promising figure to coordinate these devices in an aggregated manner to help to mitigate adverse effects like overloading of network assets. However, to do so, proper coordination techniques among these entities and the DSO should be developed to avoid further investments in new network assets. In this context, a centralised coordination strategy among aggregators at the DSO level is proposed. By employing a linear programming model, the optimal export limit of PV and charging profile for each aggregator is dictated by the DSO, maintaining the operational limits of the network assets. A case study on two aggregators with moderate and critical penetration levels was carried out. Results show that, by controlling the aggregated export limit of PV power and the aggregated charging rate of EVs, high penetration levels can be integrated into current networks with minor or no need for reinforcing network infrastructure.Item PowerDynamics.jl—An experimentally validated open-source package for the dynamical analysis of power grids(2022-01) Plietzsch, Anton; Kogler, Raphael; Auer, Sabine; Merino, Julia; Gil-de-Muro, Asier; Liße, Jan; Vogel, Christina; Hellmann, Frank; Tecnalia Research & Innovation; POWER ELECTRONICS AND SYSTEM EQUIPMENTPowerDynamics.jl is a Julia package for time-domain modeling of power grids that is specifically designed for the stability analysis of systems with high shares of renewable energies. It makes use of Julia’s state-of-the-art differential equation solvers and is highly performant even for systems with a large number of components. Further, it is compatible with Julia’s machine learning libraries and allows for the utilization of these methods for dynamical optimization and parameter fitting. The package comes with a number of predefined models for synchronous machines, transmission lines and inverter systems. However, the strict open-source approach and a macro-based user-interface also allows for an easy implementation of custom-built models which makes it especially interesting for the design and testing of new control strategies for distributed generation units. This paper presents how the modeling concept, implemented component models and fault scenarios have been experimentally tested against measurements in the microgrid lab of TECNALIA.Item REDUCCIÓN DEL IMPACTO DE VEHÍCULOS ELÉCTRICOS A TRAVÉS DE UNA PLATAFORMA DE ECONOMÍA COLABORATIVA(Grupo Tecma Red S.L., 2016) Alvaro-Hermana, Roberto; Merino, Julia; Fraile-Ardanuy, José Jesús; Castaño, SandraEn este trabajo se presenta una nueva forma de reducir el impacto de la recarga de vehículos eléctricos (VE), basado en aplicaciones de economía colaborativa. La propuesta consiste en que VEs con excedente de energía almacenada en sus baterías puedan vender energía a aquellos VEs que requieran recargar sus baterías durante el día y que estén aparcados en la misma zona y a la misma hora. A través del mercado propuesto, es posible reducir significativamente el coste de la recarga a aquellos usuarios que necesitan recargar fuera del horario nocturno (hasta un 70% dependiendo de la situación) y reducir también el impacto de la recarga sobre la red, puesto que dicha recarga se realiza intercambiando la energía entre vehículos aparcados en la misma zona, sin necesidad de estar conectados a la red eléctrica.Item A review of the population-based and individual-based approaches for electric vehicles in network energy studies(2020-12) Cortés Borray, Andrés Felipe; Merino, Julia; Torres, Esther; Mazón, Javier; Tecnalia Research & InnovationThe growing trend of introducing electric vehicles (EVs) into power systems to reduce the environmental emissions in the transport sector is gaining significant attention among electrical power system agents for two reasons: the potential grid services the EVs can offer in an aggregated manner and the possible undesirable effects of massive integration in grid operation that can increase the requirement for investment in new assets. In this context, the aggregator is the representative entity that needs to maximise the benefits in the management of these sizeable quantities of vehicles while fulfilling the requirements of grid services requested by the distribution system operator. In this study, we review the concept of EV aggregators and their potential services to the distribution network. Several studies related to EVs aggregation modelling have been analysed and classified into three groups: individual-based, population-based, and hybrid approaches. We present the current status of EVs aggregation modelling as well as future research trends. Furthermore, we discussed the performance comparison of EVs models from several manufacturers utilised in network integration studies, likewise the most relevant databases and surveys. Finally, we arranged and annexed the most relevant mathematical expressions of the reviewed approaches, thereby simplifying the comprehension of the methods.Item Scenario Analysis(Springer, Cham, 2019-10-25) Rossi, Marco; Merino, Julia; Madina, Carlos; Turienzo, Elena; Svendsen, Harald; Kuusela, Pirkko; Koponen, Pekka; Tecnalia Research & Innovation; POWER SYSTEMS; ADAPTACIÓN AL CAMBIO CLIMÁTICOThe performance of TSO-DSO coordination schemes depends on the characteristics of the electricity systems in which regulation reserves can be provided by both transmission and distribution resources. In order to investigate the main aspects influencing TSO-DSO interactions, three detailed electricity scenarios (related to the expected 2030 evolution of Denmark, Italy and Spain) are defined. In particular, these scenarios are designed by assuming various distribution network conditions, determining different volumes of flexibility requested by the DSO in order to carry out local services. Then, the structure of a simulation platform, aimed at testing TSO-DSO coordination schemes, is proposed. It is based on three main blocks, integrating actual market clearing, bidding and dispatching algorithms, together with a simulator for the network and all the physical power resources. Finally, the simulation results are processed by means of a cost-benefit analysis which identified the market architectures providing the highest economic benefits to the system and the main factors that influence the profitability of one TSO-DSO coordination scheme among the others.Item Scenario-based approach adopted in the ELECTRA project for deriving innovative control room functionality(2017-10-01) Marinelli, Mattia; Heussen, Kai; Prostejovsky, Alexander; Bindner, Henrik W.; Catterson, Victoria M.; Merino, Julia; Tornelli, Carlo; Tecnalia Research & InnovationHere, the authors analyse the operator point of view of the Web-of-Cells concept defined in the EU project ELECTRA, by identifying operator tasks into the supervision of a highly automated power system, and the information requirements to facilitate appropriate operator situation awareness. The study outlines the methodology adopted, which is based on the cognitive work analysis framework, to provide an overview of the most interesting scenarios and to summarise the requirements analysis results. In order to derive required control room functionality, a set of relevant control room scenarios have been identified based on the Web-of-Cells control concept. The authors considered scenarios that challenge traditional control schemes, scenarios that caused major failures (i.e. blackouts), and scenarios that can be expected to appear in the future. For each scenario, information concerning network layout, triggering events, physical constraints, manually/automatic operations, operators' tasks, and relevant analytics have been analysed.Item Shared Self-Consumption Economic Analysis for a Residential Energy Community(IEEE, 2019-09) Alvaro-Hermana, Roberto; Merino, Julia; Fraile-Ardanuy, Jesus; Castano-Solis, Sandra; Jimenez, David; Tecnalia Research & InnovationSelf-consumption is a growing public demand in an energy environment with growing electricity costs and decreasing photovoltaic installation costs. Shared self-consumption is an imperative aspect for bringing self-consumption into Multi-Family Residential Buildings (MRB), where most families live. Nevertheless, current legislation in most countries does not consider shared self-consumption or does not exploit its full potential; such is the case of Spain or Portugal. This paper will present a novel optimization problem for studying the economics of a shared self-consumption installation in a MRB (composed of five family demands, a PV installation and a battery) with the aim of reducing the total bill of the MRB during an entire year. The impact on energy communities of two different types of energy policies is analysed: the remuneration scheme for the surplus energy (net metering, net billing, and exclusive self-consumption policies) and the regulation for shared self-generated energy (demand-dependent, proportional output and no sharing). It is found that the regulation for the sharing energy can be more important that the remuneration scheme, which has been the traditional target of the self-consumption policy.Item Strategy of management of storage systems integrated with photovoltaic systems for mitigating the impact on LV distribution network(2018-12) Cortés, Andrés; Mazón, Javier; Merino, Julia; Tecnalia Research & InnovationThis article presents an integrated storage management strategy with photovoltaic systems connected to the grid, to provide voltage regulation and losses reduction in the low voltage feeder, minimising the power supplied by the network upstream of the main transformer. A new control algorithm for battery energy storage systems (BESS) is presented embedding as a battery management algorithm for charging and discharging process. The charging of the storage system is defined by the optimization of the αk coefficient to establish the value of charging threshold power, in a distributed manner, to maximise the use of photovoltaic systems. The discharging process occurs by a given σ coefficient. A standard network model from CIGRE was used for the validation of the management strategy. It was modified with real profiles of load and irradiance with a minute resolution to adapt it to the using of the quasi-static load flow in MATLAB/Simulink. As a result, by integrating 67% of PV along with 442 kWh of BESS with its management algorithm, power import from the grid decreases up to 49.3%.Item Using Dynamic Neural Networks for Battery State of Charge Estimation in Electric Vehicles(2018) Jiménez-Bermejo, David; Fraile-Ardanuy, Jesús; Castaño-Solis, Sandra; Merino, Julia; Alvaro-Hermana, Roberto; Tecnalia Research & InnovationDue to urban pollution, transport electrification is being currently promoted in different countries. Electric Vehicles (EVs) sales are growing all over the world, but there are still some challenges to be solved before a mass adoption of this type of vehicles occurs. One of the main drawbacks of EVs are their limited range, for that reason an accurate estimation of the state-of-charge (SOC) is required. The main contribution of this work is the design of a Nonlinear Autoregressive with External Input (NARX) artificial neural network to estimate the SOC of an EV using real data extracted from the car during its daily trips. The network is trained using voltage, current and four different battery pack temperatures as input and SOC as output. This network has been tested using 54 different real driving cycles, obtaining highly accurate results, with a mean squared error lower than 1e-6 in all situations