Dynamic Behavior and Management Strategy of Hybrid Wind/Fuel Cell System

Abstract: hybrid generation system is considered as a solution for the uncontrolled energy production from such dispersed sources as wind generation. In this paper, modeling and control of wind/FC system is proposed. Dynamics models for the main system components, namely, wind energy conversion system (WECS), fuel cell, electrolyses, power electronic interfacing circuits, hydrogen storage tank and ultra-capacitor are developed. Also, a variable speed wind generation maximum power point tracking (MPPT) based on Adaptative Neuro-Fuzzy Inference system (ANFIS) is presented. Based on the dynamic component model, a simulation model for the proposed hybrid energy system has been developed using Matlab/Simulink and the power flows management strategy are proposed. The result shows that this system can tolerate the rapid changes in wind speed and/or power demand. This results shows also that, the overall power management strategy is effective and the power flows among the different energy sources and the load demand is balanced successfully

MODELLING AND FAULT DIAGNOSIS APPROACH FOR PROTON EXCHANGE MEMBRANE FUEL CELL SYSTEMS INCORPORATING AMBIENT CONDITIONS

Proton exchange membrane fuel cell (PEMFC), as a source of electrical power, provides numerous benefits such as zero carbon emission and high reliability as compared to wind and solar energy. PEMFC operates at very low temperature, high power density, and has very high durability as compared to other fuel cells. Being a non-linear power source with high sensitivity to ambient conditions variation, the prediction of PEMFC voltage and temperature is a complicated issue. The most common PEMFC models are classified as mechanistic models, semi-empirical models, and purely empirical methods. The mechanistic models are complex and require differential equations to predict the voltage and temperature of PEMFC. However, the semi-empirical models are less complicated and can be used easily for the online prediction of PEMFC outputs. Therefore, the first part of this thesis attempt to model the voltage of PEMFC using simple and effective semi-empirical equations. The initial feature of the proposed technique is to incorporate the features of a mechanistic model with less complex equations. The model considers the internal currents and the internal voltage drop associated with the PEMFC. Besides, activation and concentration voltage drops are addressed based on theoretical functions. Thus, the proposed model provides an additional benefit that not only does the output voltage model satisfy the voltage for both loaded and unloaded conditions but also the component voltage drops waveforms match with the theoretical waveforms given in the mechanistic models. The second part of the thesis focuses on modelling the PEMFC temperature. Previously most temperature models use complex equations incorporating PEMFC output voltage which is not a good option as the temperature must be predicted using only load current and ambient temperature. The model proposed in this thesis is developed through an algorithm that tracks the online changes in the load current and ambient temperature. It provides the accurate temperature of PEMFC by using a simple first-order equation with the help of a tracking algorithm. Quantum lig tening search algorithm (QLSA) is used for the optimization of constant parameters for both voltage and temperature models. The PEMFC performance is affected by factors such as variations in ambient temperature, pressure, and air relative humidity and thus they are vital for predicting PEMFC performance. The thesis also attempts to directly predict the variations in PEMFC voltage under varying ambient conditions at different load resistance. For this purpose, statistical analysis is used to propose empirical equations that can predict the variations in PEMFC voltage for varying ambient conditions. In this context of the model development, the parameters which are significantly varying with ambient changes are identified with the help of statistical regression analysis and represented as ambient temperature and air relative humidity dependent parameters. The enhanced semi-empirical voltage model is verified by performing experiments on both the Horizon and NEXA PEMFC systems under different conditions of ambient temperature and relative humidity with root mean square error (RMSE) less than 0.5. Results obtained using the enhanced model are found to closely approximate those obtained using PEMFCs under various operating conditions, and in both cases, the PEMFC voltage is observed to vary with changes in the ambient and load conditions. Inherent advantages of the proposed PEMFC model include its ability to determine membrane-water content and water pressure inside PEMFCs. The membrane-water content provides clear indications regarding the occurrence of drying and flooding faults. For normal conditions, this membrane water content ranges between 12.5 to 6.5 for the Horizon PEMFC system. Based on simulation results, a threshold membrane water- content level is suggested as a possible indicator of fault occurrence under extreme ambient conditions. Limits of the said threshold are observed to be useful for fault diagnosis within the PEMFC systems

NASA Tech Briefs, May 2008

Topics covered inclde: Deployable Wireless Camera Penetrators; Hand-Held Units for Short-Range Wireless Biotelemetry; Wearable Wireless Telemetry System for Implantable BioMEMS Sensors; Electronic Escape Trails for Firefighters; Architecture for a High-to-Medium-Voltage Power Converter; 24-Way Radial Power Combiner/Divider for 31 to 36 GHz; Three-Stage InP Submillimeter-Wave MMIC Amplifier; Fast Electromechanical Switches Based on Carbon Nanotubes; Solid-State High-Temperature Power Cells; Fast Offset Laser Phase-Locking System; Fabricating High-Resolution X-Ray Collimators; Embossed Teflon AF Laminate Membrane Microfluidic Diaphragm Valves; Flipperons for Improved Aerodynamic Performance; System Estimates Radius of Curvature of a Segmented Mirror; Refractory Ceramic Foams for Novel Applications; Self-Deploying Trusses Containing Shape-Memory Polymers; Fuel-Cell Electrolytes Based on Organosilica Hybrid Proton Conductors; Molecules for Fluorescence Detection of Specific Chemicals; Cell-Detection Technique for Automated Patch Clamping; Redesigned Human Metabolic Simulator; Compact, Highly Stable Ion Atomic Clock; LiGa(OTf)(sub 4) as an Electrolyte Salt for Li-Ion Cells; Compact Dielectric-Rod White-Light Delay Lines; Single-Mode WGM Resonators Fabricated by Diamond Turning; Mitigating Photon Jitter in Optical PPM Communication; MACOS Version 3.31; Fiber-Optic Determination of N2, O2, and Fuel Vapor in the Ullage of Liquid-Fuel Tanks; Spiking Neurons for Analysis of Patterns; Symmetric Phase-Only Filtering in Particle-Image Velocimetry; Efficient Coupler for a Bessel Beam Dispersive Element; and Attitude and Translation Control of a Solar Sail Vehicle

Development of neuro-fuzzy strategies for prediction and management of hybrid PV-PEMFC-battery systems.

Doctor of Philosophy in Electrical Engineering. University of KwaZulu-Natal, Durban 2017.Abstract available in PDF file

NASA SBIR abstracts of 1990 phase 1 projects

The research objectives of the 280 projects placed under contract in the National Aeronautics and Space Administration (NASA) 1990 Small Business Innovation Research (SBIR) Phase 1 program are described. The basic document consists of edited, non-proprietary abstracts of the winning proposals submitted by small businesses in response to NASA's 1990 SBIR Phase 1 Program Solicitation. The abstracts are presented under the 15 technical topics within which Phase 1 proposals were solicited. Each project was assigned a sequential identifying number from 001 to 280, in order of its appearance in the body of the report. The document also includes Appendixes to provide additional information about the SBIR program and permit cross-reference in the 1990 Phase 1 projects by company name, location by state, principal investigator, NASA field center responsible for management of each project, and NASA contract number

Mathematical Modeling Of Pre And Post Combustion Processes In Coal Power Plant

Coal is a brownish-black sedimentary rock with organic and inorganic constituents. It has been a vital energy resource for humans for millennia. Coal accounts for approximately one quarter of the world’s energy consumption, with 65% of this is energy utilized by residential consumers, and 35% by industrial consumers. Coal operated power stations provide 42% of U.S. electricity supply. The United States hold 96% of coal reserves in North America region, out of which 26% are known for commercial usage. The coal combusted in these power generating facilities requires certain pre-combustion processing, while by-products of coal combustion go through certain post-combustion processing. The application of hydrometallurgical extraction of Rare Earth Elements (REE) from North Dakota Lignite coal feedstock can assist coal value amplification. Extraction of REE from lignite coals liberates REEs and CMs that are vital to electronics, power storage, aviation, and magnets industries. The REE extraction process also reduces the sulfur content of ND lignite coal, along with ash components that foul heat exchange surfaces and can have benefits for post-combustion scrubbing units. When coal is combusted, the exhaust gasses contain carbon dioxide (CO2), sulfur dioxide (SO2), oxides of nitrogen (NOx), water (H2O) and nitrogen (N2). Carbon dioxide comprises approximately 8-10 vol% of the flue gas and is reported to contribute to the greenhouse effect, a primary reason for climate change. Carbon Capture and Storage (CCS) involves of CO2 by use of liquid or solid absorbents to separate CO2 from combustion flue gas. Little data is available on gas-liquid interfacial area correlations in the literature for use of second generation solvents, such as MonoEthanolAmine (MEA), in structured packing absorber columns consisting of thin corrugated metal plates or gauzes, designed to force fluids on complicated paths. While mathematical model development for existing post-combustion carbon capture (PCCC) technologies, such as carbon capture simulations using computational fluid dynamics (CFD) for prediction of mass transfer coefficients is well developed, models describing the behavior of third generation solvents is lacking. Two main research opportunities exist: (i) due to the complex chemistry of coal, there is a requirement for a modeling tool that can account for the coal composition and complex hydrometallurgical extraction processes to assist in designing and sizing pre-combustion REE extraction plants; and (ii) CFD models are required that can capture the mass transfer coefficients of third generation CO2 solvents using structured packing. Two primary hypotheses have been developed to address the research opportunities: (1.) Process modeling of hydrometallurgical extraction of REE provides some theory-based understanding that is complementary to experimental validation and, with the help of chemical kinetics and percentage carboxylation existing in feedstocks, can forecast the efficiency and leachability of other feedstocks, and (2.) A detailed Volume of Fluid (VOF) simulation of coupled mass and momentum transfer problems in small intricate regions of corrugated structured and packed panels placed at 45° angle can be used to predict mass transfer coefficients for third generation solvents by using open-source numerical C/C++ based framework called Open Fields-Operations-And-Manipulations (OpenFOAM). The hydrometallurgical process modeling is developed using METSIM, a leading hydrometallurgical process modeling software tool. The steady state process model provides an overview of REE production along with equipment inventory sizing. The model also has functions to define percentage of organic carboxylic acid bonds present in coal, since, the prior research has identified that the primary association of REE in lignite coal is as weakly-bonded complexes of carboxyl groups, which are targets of the extraction technology. The CFD modeling work is expected to determine critical mass transfer coefficients for CO2 capture using structured packing columns. Further, the developed CFD model and its validity will be tested against experimental data from various industrial and literature sources

Comprehensive summary of solid oxide fuel cell control : a state-of-the-art review

Hydrogen energy is a promising renewable resource for the sustainable development of society. As a key member of the fuel cell (FC) family, the solid oxide fuel cell (SOFC) has attracted a lot of attention because of characteristics such as having various sources as fuel and high energy conversion efficiency, and being pollution-free. SOFC is a highly coupled, nonlinear, and multivariable complex system, and thus it is very important to design an appropriate control strategy for an SOFC system to ensure its safe, reliable, and efficient operation. This paper undertakes a comprehensive review and detailed summary of the state-of-the-art control approaches of SOFC. These approaches are divided into eight categories of control: proportional integral differential (PID), adaptive (APC), robust, model predictive (MPC), fuzzy logic (FLC), fault-tolerant (FTC), intelligent and observer-based. The SOFC control approaches are carefully evaluated in terms of objective, design, application/scenario, robustness, complexity, and accuracy. Finally, five perspectives are proposed for future research directions

Modeling and dynamic stability of distributed generations

The objective of this dissertation is to develop dynamic models for distributed generations (DG), to investigate their impacts on dynamic stability of power distribution systems, and to design controllers for DGs to improve the dynamic stability of the integrated power distribution system.;A two-year distributed generation (DG) project at West Virginia University (WVU) evaluated the impact of various DG sources on actual distribution systems by performing computer simulations. The data is supplied by two regional electric utilities of two actual distribution systems each. In this project several important issues were investigated, including the availability of simulation tools and impacts of DGs connected to a distribution line under a variety of line operating conditions. Based on this preliminary research the further most interesting topics for continued research were raised.;The continued research has focused on deeper investigation, such as, modeling DG sources, evaluating their interaction and impacts, and improving the dynamic stability of the integrated power distribution system. Four specific DGs are studied in this dissertation: fuel cell power plant, wind turbine induction generator, gas turbine synchronous generator and diesel engine synchronous generator.;A full-order synchronous generator model represents the generator models of gas turbine generator and diesel engine generator. A simplified gas turbine model has been chosen to be implemented. A practical diesel engine for emergency use is modeled. The generator model of wind turbine induction generator is represented by a full-order induction generator. The rated power operating regime is considered for impacts evaluations and controller design. Two types of fuel cell models are developed. The first one is a model of already operational phosphoric acid fuel cell (PAFC) obtained through data fitting and the second one is dynamic model of solid oxide fuel cell (SOFC). Since fuel cells are connected to the electric power network via inverters, an inverter model has been developed.;Multi-DG controls are investigated in this dissertation. One DG control is fuel cell control, the other one is wind-turbine control. The control of fuel cell (SOFC) plant is through the inverter to adjust active power injection to the network during the transient time. The control of wind turbine generator is through the parallel connected SVC by adjusting reactive power injection to the system. Both control schemes are centralized.;Linear analysis methodologies are utilized in designing the controller. In the fuel cell control design, two pairs of critical modes are screened out using eigenvalue analysis. The participation factors of DGs with respect to the modes are calculated. Two specific lead-lag compensation units are designed to damp each mode separately. The gains of the two compensation units were then obtained via optimal control methodology. In wind turbine DG control design procedure, three rotor speed deviations are used as input signals while the controller outputs are the firing angle for the SVC and the pitch angle for the wind-turbine DG. An output feedback controller is designed. The dynamic load characteristic is also considered by modeling it as a structured uncertainty. mu-analysis is used to evaluate the robust stability of the controllers with respect to the uncertain parameters in the dynamic loads. The IEEE-13 node radial feeder with existing gas turbine and diesel engine DGs is used as a test system to evaluate the multi-DG control. The simulation results demonstrate the effectiveness of the control strategies.;Coordinated operation of all the DGs is investigated. Simulation results show that good configurations within DGs along the system can improve the system stability. Furthermore, the fast acting SVC is very effective in improving damping. Among the DGs investigated in this research, the fuel cell plant control is the best choice for the coordinated operation.;Finally, the approach to model a complete three-phase power distribution system is implemented. The impact of the developed DGs models is evaluated on a three-phase unbalanced distribution system. The three-phase 13-node IEEE system with gas turbine and diesel engine DGs is simulated using MATLAB/Simulink\u27s Power System Blockset (PSB). In the simulation, a three-phase thyristor controlled braking resistor (TCBR) is connected to absorb the surplus energy when the system is subjected to a disturbance. The three-phase dynamic simulation demonstrates the effectiveness of the proposed strategy

A review on prognostics and health monitoring of proton exchange membrane fuel cell

Fuel cell technology can be traced back to 1839 when British scientist Sir William Grove discovered that it was possible to generate electricity by the reaction between hydrogen and oxygen gases. However, fuel cell still cannot compete with internal combustion engines although they have many advantages including zero carbon emissions. Fossil fuels are cheaper and present very high volumetric energy densities compared with the hydrogen gas. Furthermore, hydrogen storage as a liquid is still a huge challenge. Another important disadvantage is the lifespan of the fuel cell because of their durability, reliability and maintainability. Prognostics is an emerging technology in sustainability of engineering systems through failure prevention, reliability assessment and remaining useful lifetime estimation. Prognostics and health monitoring can play a critical role in enhancing the durability, reliability and maintainability of the fuel cell system. This paper presents a review on the current state-of-the-art in prognostics and health monitoring of Proton Exchange Membrane Fuel Cell (PEMFC), aiming at identifying research and development opportunities in these fields. This paper also highlights the importance of incorporating prognostics and failure modes, mechanisms and effects analysis (FMMEA) in PEMFC to give them sustainable competitive advantage when compared with other non-clean energy solutions

Impacts of renewable energy resources on effectiveness of grid‐integrated systems: succinct review of current challenges and potential solution strategies

This study is aimed at a succinct review of practical impacts of grid integration of renewable energy systems on effectiveness of power networks, as well as often employed state‐of-the‐art solution strategies. The renewable energy resources focused on include solar energy, wind energy, biomass energy and geothermal energy, as well as renewable hydrogen/fuel cells, which, although not classified purely as renewable resources, are a famous energy carrier vital for future energy sustainability. Although several world energy outlooks have suggested that the renewable resources available worldwide are sufficient to satisfy global energy needs in multiples of thousands, the different challenges often associated with practical exploitation have made this assertion an illusion to date. Thus, more research efforts are required to synthesize the nature of these challenges as well as viable solution strategies, hence, the need for this review study. First, brief overviews are provided for each of the studied renewable energy sources. Next, challenges and solution strategies associated with each of them at generation phase are discussed, with reference to power grid integration. Thereafter, challenges and common solution strategies at the grid/electrical interface are discussed for each of the renewable resources. Finally, expert opinions are provided, comprising a number of aphorisms deducible from the review study, which reveal knowledge gaps in the field and potential roadmap for future research. In particular, these opinions include the essential roles that renewable hydrogen will play in future energy systems; the need for multi‐sectoral coupling, specifically by promoting electric vehicle usage and integration with renewable‐based power grids; the need for cheaper energy storage devices, attainable possibly by using abandoned electric vehicle batteries for electrical storage, and by further development of advanced thermal energy storage systems (overviews of state‐of‐the‐art thermal and electrochemical energy storage are also provided); amongst others