Energy Management Strategies in hydrogen Smart-Grids: A laboratory experience

As microgrids gain reputation, nations are making decisions towards a new energetic paradigm where the centralized model is being abandoned in favor of a more sophisticated, reliable, environmentally friendly and decentralized one. The implementation of such sophisticated systems drive to find out new control techniques that make the system “smart”, bringing the Smart-Grid concept. This paper studies the role of Energy Management Strategies (EMSs) in hydrogen microgrids, covering both theoretical and experimental sides. It first describes the commissioning of a new labscale microgrid system to analyze a set of different EMS performance in real-life. This is followed by a summary of the approach used towards obtaining dynamic models to study and refine the different controllers implemented within this work. Then the implementation and validation of the developed EMSs using the new labscale microgrid are discussed. Experimental results are shown comparing the response of simple strategies (hysteresis band) against complex on-line optimization techniques, such as the Model Predictive Control. The difference between both approaches is extensively discussed. Results evidence how different control techniques can greatly influence the plant performance and finally we provide a set of guidelines for designing and operating Smart Grids.Ministerio de Economía y Competitividad DPI2013-46912-C2-1-

On the Comparison of Stochastic Model Predictive Control Strategies Applied to a Hydrogen-based Microgrid

In this paper, a performance comparison among three well-known stochastic model predictive control approaches, namely, multi-scenario, tree-based, and chance-constrained model predictive control is presented. To this end, three predictive controllers have been designed and implemented in a real renewable-hydrogen-based microgrid. The experimental set-up includes a PEM electrolyzer, lead-acid batteries, and a PEM fuel cell as main equipment. The real experimental results show significant differences from the plant components, mainly in terms of use of energy, for each implemented technique. Effectiveness, performance, advantages, and disadvantages of these techniques are extensively discussed and analyzed to give some valid criteria when selecting an appropriate stochastic predictive controller.Ministerio de Economía y Competitividad DPI2013-46912-C2-1-RMinisterio de Economía y Competitividad DPI2013-482443-C2-1-

Integration of Fuel Cell Technologies in Renewable-Energy-Based Microgrids Optimizing Operational Costs and Durability

In this paper, a Model Predictive Control (MPC) approach is proposed to manage a grid-tied hydrogen microgrid (μG) . The μG testbed is equipped with a 1-kW polymer electrolyte membrane (PEM) electrolyzer and a 1.5-kW PEM fuel cell as main equipment. In particular, we present a formulation that includes the cost of the electricity exported/imported, the aging of the components, and the operational constraints. The control objective is to satisfy user demand, as well as extend the lifespan of expensive equipment, as is the case of the fuel cell or the electrolyzer. μG performance is investigated under realistic scenarios in three experiments. The experimental results illustrate how the proposed control system is able to manage the fuel cell and the electrolyzer through smooth power references, as well as to satisfy the power demanded. Finally, benchmarking is carried out between hysteresis band (HB) control and the proposed MPC in regard to efficiency and cost of the operation. The results obtained show that the MPC approach is more effective than HB for this type of μG , with a reduction in operation cost of up to 30%

On the comparison of stochastic model predictive control strategies applied to a hydrogen-based microgrid

© . This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/In this paper, a performance comparison among three well-known stochastic model predictive control approaches, namely, multi-scenario, tree-based, and chance-constrained model predictive control is presented. To this end, three predictive controllers have been designed and implemented in a real renewable-hydrogen-based microgrid. The experimental set-up includes a PEM electrolyzer, lead-acid batteries, and a PEM fuel cell as main equipment. The real experimental results show significant differences from the plant components, mainly in terms of use of energy, for each implemented technique. Effectiveness, performance, advantages, and disadvantages of these techniques are extensively discussed and analyzed to give some valid criteria when selecting an appropriate stochastic predictive controller.Peer ReviewedPostprint (author's final draft

Hydrogen as energy storage for wind energy

Nowadays, problems associated with greenhouse gases emission and fuel ending, makes that renewable energy sources and hydrogen technology have high interest for governments and researchers, and become an option for an environmentaly sustainable world. Renewable energy sources, like solar energy and wind energy, have been used for the last three decades to produce electricity. Researchers and companies have improved the efficiency of this kind of systems, but they have a problem due to energy source temporality that does a fluctuation in systems power output. This fluctuation makes sometimes energy demand is higher than energy produced by the system and vice versa. Hydrogen Technology, actuating as energy storage, may solve this problem. In this paper, a wind-hydrogen installation will be described. Also, its behavior in relation to different electric demand will be analysed

Gestión de energía en sistemas con fuentes renovables y almacenamiento de energía basado en hidrógeno mediante control predictivo

Our civilization, dependent on fossil fuels, has a peculiarity, namely a centralized and deterministic character of the energy system. The highly centralized nature means the overall energy control in a small number of institutions, of which depends the welfare of much of humankind. The commitment of many scientists and engineers and many other people and institutions in the world, is by the use of hydrogen as an energy carrier (Raimund Bleischwitz, 2009), resulting in what has been termed as The Hydrogen Economy. Hydrogen is a fuel that does not pollute and can be found potentially everywhere. However, it is rarely found in nature Free State, so it must be produced. The various forms of producing, which although may involve the use of energy from oil, lean towards the use of renewable energies, such as photovoltaic, wind, hydro and geothermal. These energies can generate the electricity consumed to split water into hydrogen and oxygen in the electrolysis process. But the most interesting aspect of hydrogen is a new economy less centralized, more self-sufficient, and linked to the consumer (Suzanne Shaw, 2009). Distributed generation refers to a set of small power plants, located close to the end user, or just in the same location, and it may well be integrated into a network or operate autonomously. Users can be factories, commercial enterprises, public buildings or private residences neighbourhoods. These small power plants have been called "Microgrids". Microgrids have gained great reputation recently, nations are making decisions towards a new electrical system while the old centralized system is being abandoned in favour of a new one, more sophisticated, efficient and environmentally friendly. Therefore, the energy system is facing a major transformation. This document reflects the initiative of contribution to the development of hydrogen technology in the field of hydrogen-based microgrid control systems. The implementation of such complex systems such as microgrids, drove to find out improved control systems for efficiently and safely handle these microgrids. This thesis is about microgrid control system, covering both theoretical and experimental study from simple strategies to the more complex. In addition, this thesis presents a new approach in microgrid control applying the Model Predictive Control (MPC) methodology. In order to reach the mentioned objectives, in this thesis we have started from a detailed study of these systems. The first section, Chapters 1 to 3, review the state of the art of energy storage systems, integrated system types, configurations and existing control strategies. One chapter was devoted to the description of the experimental test bench, including tests performed for the component characterization. For the control system study and design it was necessary to obtain suitable models. Modelling and validation tasks are framed in a second block (Chapter 4 and 7) which develops a complete control oriented model. In this model, most relevant dynamics were implemented, covering the gap in the literature. The models were validated experimentally with good results. Additionally, chapter 7 attends to apply the proposed modelling methodology to a real operational plant: "The Hydrogen Office" located in UK. A plant model was obtained using the same methodology applied to laboratory scale. The models were experimentally validated with data gathered from real operating conditions. The validation results show a very good fit with model predictions. This chapter demonstrated that the modelling methodology, which is the basis of the theoretical and experimental study of the MPC and operation modes, is a valid approach. The last block of the thesis is dedicated to the theoretical and experimental study of operation modes (Chapter 5) and MPC strategies (Chapter 6). The design, simulation and implementation is showed along with experimental results. The plant operation obtained in the laboratory showed a good system performance, depending on the control strategy used, in concordance with the theoretical results obtained formerly. MPC control achieved smooth operation along high efficiency. In contrast, operation modes got different results in terms of efficiency and cost depending on the operation mode used. Finally a benchmark between classical control (heuristic hysteresis band) and MPC is presented. The MPC achieved outstanding results, especially in economic cost, in comparison with non-optimization strategies despite slightly neglecting the system efficiency. This contrast is discussed extensively in the thesis and finally some future work is proposed

On the comparison of stochastic model predictive control strategies applied to a hydrogen-based microgrid

© . This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/In this paper, a performance comparison among three well-known stochastic model predictive control approaches, namely, multi-scenario, tree-based, and chance-constrained model predictive control is presented. To this end, three predictive controllers have been designed and implemented in a real renewable-hydrogen-based microgrid. The experimental set-up includes a PEM electrolyzer, lead-acid batteries, and a PEM fuel cell as main equipment. The real experimental results show significant differences from the plant components, mainly in terms of use of energy, for each implemented technique. Effectiveness, performance, advantages, and disadvantages of these techniques are extensively discussed and analyzed to give some valid criteria when selecting an appropriate stochastic predictive controller.Peer Reviewe

Experimental and numerical investigation of a PEMFC single cell and stack analysis

The present paper describes the work being done by INTA and University of Seville – AICIA in the framework of a joint research project in the field of Proton Exchange Membrane Fuel Cells (PEMFC). The main objective of the project is to develop a novel methodology for the characterization and investigation of fuel cell stacks, that combines experimental and Computational Fluid Dynamics (CFD) analysis. A CFD model based on the PEMFC Module implemented in FLUENT software is being developed for a single cell, and the polarization curve obtained is being validated against experimental results obtained at INTA facilities. At a second stage of the investigation, a method for the extrapolation of CFD single cell results to the complete stack is developed. The extrapolation method is being validated against experimental results obtained for the fuel cell stack with different numbers of cells. This paper describes the results of the early stages of the investigation and presents the methodology developed for the project. The developed model would allow researchers to use CFD for the complete fuel cell stack with reasonable computing facilities

Experimental and numerical investigaton of a pem fuel cell. Single cell and stack analysis

The present paper describes the work being done by INTA and University of Seville – AICIA in the framework of a joint research project in the field of Proton Exchange Membrane Fuel Cells (PEMFC). The main objective of the project is to develop a novel methodology for the characterization and investigation of fuel cell stacks, that combines experimental and Computational Fluid Dynamics (CFD) analysis. A CFD model based on the PEMFC Module implemented in FLUENT software is being developed for a single cell, and the polarization curve obtained is being validated against experimental results obtained at INTA facilities. At a second stage of the investigation, a method for the extrapolation of CFD single cell results to the complete stack is developed. The extrapolation method is being validated against experimental results obtained for the fuel cell stack with different numbers of cells. This paper describes the results of the early stages of the investigation and presents the methodology developed for the project. The developed model would allow researchers to use CFD for the complete fuel cell stack with reasonable computing facilities

Energetic analysis of a hydrogen refuelling station in Seville province district project Hercules

In 2006, HERCULES Project was launched with two objectives. First, design and build the first hydrogen refuelling station at South of Spain, in Seville province. Hydrogen will be produced via an electrolyser connected to a Photovoltaic Field. Second, change internal combustion engine of a SUV vehicle into an electric engine fed using a PEM Fuel Cell. Hydrogen produced at station will be consumed by the electric vehicle. Project Hercules is promoted by several partners: Santana, Hynergreen, Abengoa Solar, INTA, AICIA, Carburos Metalicos, GreenPower and Agencia Andaluza de la Energía. The objectives of this article are: describing the hydrogen refuelling station and analyse it, taking into account solar radiation, hydrogen production and estimated consumption by vehicle, and electric consumption of auxiliaries (compressor and dispenser)