Advanced Control for Clusters of SOFC/GT Hybrid Systems

Author(s):  
Iacopo Rossi ◽  
Valentina Zaccaria ◽  
Alberto Traverso

The use of model predictive control (MPC) in advanced power systems can be advantageous in controlling highly coupled variables and optimizing system operations. Solid oxide fuel cell/ gas turbine (SOFC/GT) hybrids are an example where advanced control techniques can be effectively applied. For example, to manage load distribution among several identical generation units characterized by different temperature distributions due to different degradation paths of the fuel cell stacks. When implementing a MPC, a critical aspect is the trade-off between model accuracy and simplicity, the latter related to a fast computational time. In this work, a hybrid physical and numerical approach was used to reduce the number of states necessary to describe such complex target system. The reduced number of states in the model and the simple framework allow real-time performance and potential extension to a wide range of power plants for industrial application, at the expense of accuracy losses, discussed in the paper.

Author(s):  
Iacopo Rossi ◽  
Valentina Zaccaria ◽  
Alberto Traverso

The use of model predictive control (MPC) in advanced power systems can be advantageous in controlling highly coupled variables and optimizing system operations. Solid oxide fuel cell/gas turbine (SOFC/GT) hybrids are an example where advanced control techniques can be effectively applied. For example, to manage load distribution among several identical generation units characterized by different temperature distributions due to different degradation paths of the fuel cell stacks. When implementing an MPC, a critical aspect is the trade-off between model accuracy and simplicity, the latter related to a fast computational time. In this work, a hybrid physical and numerical approach was used to reduce the number of states necessary to describe such complex target system. The reduced number of states in the model and the simple framework allow real-time performance and potential extension to a wide range of power plants for industrial application, at the expense of accuracy losses, discussed in the paper.


Electronics ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 1762
Author(s):  
Adel Merabet

In the Special Issue “Advanced Control for Electric Drives”, the objective is to address a variety of issues related to advances in control techniques for electric drives, implementation challenges, and applications in emerging fields such as electric vehicles, unmanned aerial vehicles, maglev trains and motion applications. This issue includes 15 selected and peer-reviewed articles discussing a wide range of topics, where intelligent control, estimation and observation schemes were applied to electric drives for various applications. Different drives were studied such as induction motors, permanent magnet synchronous motors and brushless direct current motors.


Author(s):  
Hossein Ghezel-Ayagh ◽  
Joseph M. Daly ◽  
Zhao-Hui Wang

This paper summarizes the recent progress in the development of hybrid power systems based on Direct FuelCell/Turbine® (DFC/T®). The DFC/T system is capable of achieving efficiencies well in excess of state-of-the-art gas turbine combined cycle power plants but in much smaller size plants. The advances include the execution of proof-of-concept tests of a fuel cell stack integrated with a microturbine. The DFC/T design concept has also been extended to include the existing gas turbine technologies as well as more advanced ones. This paper presents the results of successful sub-MW proof-of-concept testing, sub-MW field demonstration plans, and parametric analysis of multi-MW DFC/T power plant cycle.


2016 ◽  
Vol 842 ◽  
pp. 200-207 ◽  
Author(s):  
Vu Minh Thanh ◽  
Sigit P. Santosa ◽  
Djarot Widagdo ◽  
Ichsan Setya Putra

Plate is one of the most common structural elements, which appears in a wide range of applications: steel bridges, blast-resistance door, and armored vehicles. In this paper, the behavior of steel plates under blast loading was studied through numerical approaches using LS DYNA and then the results were compared with the experiment results obtained from existing literatures. The study of a clamped square plate exposed to blast loading in three distinct stand-off distances. Three different methods of modeling blast loading were used, namely: empirical blast method, arbitrary Lagrangian Eulerian (ALE) method, and coupling of Lagrangian and Eulerian method. The empirical blast method was deployed by using key card *LOAD_BLAST in LS-DYNA. In ALE method, Langrangian and Eulerian solution were combined in the same model and the fluid-structure interaction (FSI) handled by coupling algorithm. In coupling method, the engineering load blast in LS-DYNA (*LOAD_BLAST_ENHANCED) was coupled with the ALE solver. In terms of central deflection and computational time, the coupling method appeared to be the best method which is very time-effective and showed a good correlation with the experiment data.


Geophysics ◽  
2019 ◽  
Vol 85 (1) ◽  
pp. J1-J13 ◽  
Author(s):  
Fang Ouyang ◽  
Longwei Chen

Self-demagnetization due to strongly magnetic bodies can seriously affect the interpretation of magnetic anomalies. Conventional numerical methods often neglect the self-demagnetization effects and limit their use to low susceptibilities ([Formula: see text]). We have developed a novel iterative method based on the integral equation and the Gauss-fast Fourier transform (FFT) technique for calculating the magnetic field from finite bodies of high magnetic susceptibility and arbitrary shapes. The method uses a segmented model consisting of prismatic voxels to approximate a complex target region. In each voxel, the magnetization is assumed to be constant, so that the integral equation in the spatial domain can reduce to a simple form with lots of merit in numerical calculation after the 2D Fourier transform. Moreover, a contraction operator is derived to ensure the convergence of the iterative calculation, and the Gauss-FFT technique is applied to reduce numerical errors due to edge effects. Our modeling results indicate that this new iterative scheme performs well in a wide range of magnetic susceptibilities (1–1000 SI). For lower susceptibilities ([Formula: see text]), the iterative algorithm converges rapidly and indicates very good correlation with the analytical solutions. At higher susceptibilities ([Formula: see text]), our method still performs well, but the numerical accuracy improves with a relatively slow speed. In the extreme case ([Formula: see text]), an acceptable result is also obtained after sufficient iterative computation. A further improvement in the numerical precision can be achieved by increasing the number of prismatic voxels, but at the same time, the computational time increases linearly with the size of the voxels.


2006 ◽  
Vol 3 (3) ◽  
pp. 234-241 ◽  
Author(s):  
Rodolfo Taccani ◽  
Diego Micheli

Pressurized high temperature fuel cells and gas turbine integrated power systems are receiving growing attention as capable of reaching very high electrical conversion efficiency even in small size power plants. In this system the fuel and the oxidant (air) enter the cell after being compressed. The fuel oxidation reaction occurs predominantly within the fuel cell. The reaction is completed in a combustion chamber and the pressurized combustion products are exhausted through a turbine. The dynamic interdependences related to the integration of the fuel cell and the gas turbine are not completely understood and unexpected complications and dangers might arise. In fact as a consequence of both the relatively large volume of the pressurized portion of the plant and the shape of the stalled characteristic of available compressors, the plant could be affected by the inception of fluid-dynamic instabilities. In particular, surge could be detected in the transient off-design operational conditions occurring during plant regulation, start up and shut down. The paper presents a new experimental fuel cell gas turbine simulation facility that has been constructed at the Mechanical Engineering Department of the University of Trieste, Italy. The facility was designed to examine the effects of transient events on the dynamics of these systems. The theoretical analysis of the plant is completed using a dynamic model of the system purposely developed.


1966 ◽  
Vol 88 (4) ◽  
pp. 323-333 ◽  
Author(s):  
B. Sternlicht ◽  
J. W. Bjerklie

The paper discusses a modular approach to power and total-energy systems for undersea missions. Vehicular, portable, and stationary power plants of various power levels (1–100 kwe) and duration (10–1000 and > 1000 hr) are considered. Both dynamic (open and closed Brayton and Rankine cycles) and static (battery, fuel cell, and thermoelectric) systems utilizing chemical and nuclear heat sources are compared. The comparison is based on a rating of a number of criteria for which weighing factors have been selected, e.g., weight, size, reliability, serviceability, applicability, development time, and cost. The paper indicates that several types of power systems will be necessary for undersea missions. Isotope-thermoelectrics are well suited for extremely low-power-level, long-duration missions. Batteries appear satisfactory power sources for low kilowatt hours, chemical-dynamic and fuel cell for intermediate kilowatt hours, and isotope-dynamic for high kilowatt hours. The dynamic systems have the advantage that they can be used with several heat sources, (e.g., chemical, isotope, and reactor). Recommendations are made for component development to allow early availability of power sources for undersea missions.


2019 ◽  
Vol 42 (1) ◽  
pp. 285-290
Author(s):  
Michael D. Lukas ◽  
Hossein Ghezel-Ayagh

2014 ◽  
Vol 622-623 ◽  
pp. 625-631
Author(s):  
Ugo Ripert ◽  
Lionel Fourment

The 3D finite element simulations of processes like multi-pass rolling or drawing often result into exorbitant computational times that make the numerical approach almost infeasible while only the “stationary” step of the process is actually of interest for the industry. Therefore, it can be advantageously simulated by resorting to steady-state formulations which allows reducing the calculation time by, at least, an order of magnitude with respect to more conventional methods where the steady regime is incrementally calculated. A general and robust formulation is developed; it is suitable for parallel computing, compatible with unstructured meshes and general enough to apply to a wide range of forming processes. It consists in alternatively resolving the “simple” steady-state material forming problem for a given domain geometry and then computing the domain corrections that allow satisfying the free surface condition. Within the “simple forming problem”, a Streamline Upwind Petrov Galerkin (SUPG) method is used to integrate the state variables along the streamlines. For the domain geometry correction, a Least Squares formulation with an Upwind shift is introduced. The two resolutions are coupled by the contact equations. This method is applied to several metal forming problems such as 3D rolling and drawing. Results show the high efficiency of the method with respect to an incremental resolution. Computational time is reduced by a factor ranging between 20 and 30. Results are as accurate as with an incremental method. Convergence is always reached whatever the initial geometry of the domain at the beginning of the iterative algorithm.


Author(s):  
Hossein Ghezel-Ayagh ◽  
Robert Sanderson ◽  
Jim Walzak

FuelCell Energy Inc. (FCE) is developing ultra high efficiency Direct FuelCell/Turbine® (DFC/T®) hybrid power plants. Present activities are focused both on the demonstration of the DFC/T concept in small packaged hybrid power generation units for distributed generation, and the design of multi-megawatt (Multi-MW) hybrid systems for the wholesale electric power market. The development of Multi-MW DFC/T systems has been focused on the on the design of power plants with efficiencies approaching 75% (LHV of natural gas). The design efforts included thermodynamic cycle analysis of key gas turbine parameters such as compression ratio. The power plant designs were studied for near-term deployment utilizing the existing commercially available gas turbines and long-term deployment requiring advanced gas turbine technologies. A new fuel cell cluster concept was developed for mechanical design of Multi-MW systems. The concept utilizes the existing one-MW fuel cell modules as the building block for the Multi-MW hybrid systems.


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