scholarly journals Transient Analysis of Simultaneous Multivariable Signals on Fuel Cell/Gas Turbine Hybrid to Define Control Strategies for Cathode Parameters and Compressor Stall

2017 ◽  
Author(s):  
Bernardo Restrepo ◽  
David Tucker
Keyword(s):  
Fuel Cell ◽  
Gas Turbine ◽  
Transient Analysis ◽  
Control Strategies ◽  
System Failure ◽  
Electric Load ◽  
Energy Technology ◽  
Process Variables ◽  
Simultaneous Operation ◽  
Performance Project

Transients in a hybrid system composed of a solid oxide fuel cell (SOFC) and a gas turbine (GT) were evaluated during simultaneous manipulation of system airflow bypasses and turbine electric load. The three airflow bypass valves selected for study were chosen for their potential application in controlling dynamic excursions of the main fuel cell and gas turbine parameters in the system. The objective of this work was to understand the physical behavior by the simultaneous operation of the bypass valves along with the turbine electric load in order to formulate scenarios of control on the key parameters relevant to system failure, specifically from compressor stall and surge. Empirical data was collected using the National Energy Technology Laboratory Hybrid Performance project hardware simulation of a SOFC/GT hybrid. Step changes were implemented in all three valves for various open/close valve commands and increase/decrease of the turbine electric load simultaneously. The transient response of process variables was analyzed to determine the potential for mitigating or aggravating compressor stall and surge during load excursions.

Emergency Shutdown Management in Fuel Cell Gas Turbine Hybrid Systems

2014 ◽  
Author(s):  
Fabio Lambruschini ◽  
Mario L. Ferrari ◽  
Alberto Traverso ◽  
Luca Larosa
Keyword(s):  
Fuel Cell ◽  
Gas Turbine ◽  
Control Strategies ◽  
University Campus ◽  
Time Dynamic ◽  
Micro Gas Turbine ◽  
Emergency Shutdown ◽  
Start Up ◽  
Pressure Stress ◽  
The University

A real-time dynamic model representing the pressurized fuel cell gas turbine hybrid system emulator test rig at Thermochemical Power Group (TPG) laboratories of the University of Genoa has been developed to study the fuel cell behavior during different critical operative situations like, for example, load changes (ramp and step), start-up and shut-down and, moreover, to implement an emergency shutdown strategy in order to avoid any damage to the fuel cell and to the whole system: focus has been on cathode/anode differential pressure, which model was validated against experimental data. The real emulator plant (located in Savona University campus) is composed of a 100 kW recuperated micro gas turbine, a modular cathodic vessel (4 modules of 0.8 m3 each) located between recuperator outlet and combustor inlet, and an anodic circuit (1 module of 0.8m3) based on the coupling of a single stage ejector with an anodic vessel. Different simulation tests were carried out to assess the behavior of cathode-anode pressure difference, identifying the best control strategies to minimize the pressure stress on fuel cell stack.

Performance Evaluation of Solid Oxide Fuel Cell Engines Integrated With Single/Dual-Spool Turbochargers

2011 ◽  
Vol 8 (6) ◽  
Author(s):  
So-Ryeok Oh ◽  
Jing Sun ◽  
Herb Dobbs ◽  
Joel King
Keyword(s):  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Control Strategies ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Operating Characteristics ◽  
Load Following ◽  
Fuel Flow

This study investigates the performance and operating characteristics of 5kW-class solid oxide fuel cell and gas turbine (SOFC/GT) hybrid systems for two different configurations, namely single- and dual- spool gas turbines. Both single and dual spool turbo-chargers are widely used in the gas turbine industry. Even though their operation is based on the same physical principles, their performance characteristics and operation parameters vary considerably due to different designs. The implications of the differences on the performance of the hybrid SOFC/GT have not been discussed in literature, and will be the topic of this paper. Operating envelops of single and dual shaft systems are identified and compared. Performance in terms of system efficiency and load following is analyzed. Sensitivities of key variables such as power, SOFC temperature, and GT shaft speed to the control inputs (namely, fuel flow, SOFC current, generator load) are characterized, all in an attempt to gain insights on the design implication for the single and dual shaft SOFC/GT systems. Dynamic analysis are also performed for part load operation and load transitions, which shed lights for the development of safe and optimal control strategies.

scholarly journals Development of Controls for Dynamic Operation of Carbonate Fuel Cell-Gas Turbine Hybrid Systems

2005 ◽  
Author(s):  
Rory A. Roberts ◽  
Jack Brouwer ◽  
Eric Liese ◽  
Randall S. Gemmen
Keyword(s):  
Fuel Cell ◽  
Gas Turbine ◽  
Control Strategies ◽  
Cell Voltage ◽  
Modeling Tools ◽  
Dynamic Operation ◽  
Fuel Flow ◽  
Low Emission ◽  
Hybrid Power Plant ◽  
Demand Fluctuations

Hybrid fuel cell/gas turbine (FC/GT) systems have been shown through experiment and simulation to be highly efficient technologies with low emissions. Maintaining efficient, low emission, and safe operation, whether during disturbances or regular operational transients, is a challenge to both understand and address. Some likely disturbances can arise from changes in ambient temperature, fuel flow variations induced by supply pressure disturbances, fuel composition variability, and power demand fluctuations. To gain insight into the dynamic operation of such cycles and address operating challenges, dynamic modeling tools have been developed at two different laboratories. In this paper these models are used to simulate the dynamic operation of an integrated MCFC/GT hybrid system and to subsequently develop and test control strategies for the hybrid power plant. Two control strategies are developed and tested for their ability to control the system during various perturbations. Predicted fuel cell operating temperature, fuel utilization, fuel cell and GT power, shaft speed, compressor mass flow and temperatures throughout the FC/GT system are presented for the controlled response to a fuel cell voltage increase in order to show the effect of a load decrease.

Simulation of Model Predictive Control for a Fuel Cell/Gas Turbine Power System Based on Experimental Data and the Recursive Identification Method

2016 ◽  
Author(s):  
Bernardo Restrepo ◽  
Larry E. Banta ◽  
David Tucker
Keyword(s):  
Fuel Cell ◽  
Model Predictive Control ◽  
State Space ◽  
Gas Turbine ◽  
Predictive Control ◽  
Measured Data ◽  
The State ◽  
Electric Load ◽  
Dynamic Data ◽  
Turbine Speed

A Model Predictive Control (MPC) strategy has been suggested and simulated with the empirical dynamic data collected on the Hybrid Performance (HyPer) project facility installed at the National Energy Technology Laboratory (NETL), U.S. Department of Energy, in Morgantown, WV. The HyPer facility is able to simulate gasifier/fuel cell power systems and uses hardware-based simulation approach that couples a modified recuperated gas turbine cycle with hardware driven by a solid oxide fuel cell model. Dynamic data was collected by operating the HyPer facility continuously during five days. Bypass valves along with electric load of the system were manipulated and variables such as mass flow, turbine speed, temperature, pressure, among others were recorded for analysis. This work was developed by focusing on a multivariable recursive system identification structure fitting measured transient data. The results showed that real-time or online data is a viable means to provide a dynamic model for controller design. The excursion dynamic data collected between the setup changes of the experiments was processed off-line to determine the feasibility of applying an adaptive Model Predictive Control strategy. One of the strengths of MPC is that it can allow the designer to impose strict limits on inputs and outputs in order to keep the system within known safe bounds. Two identification structures, ARX and a State-Space model, were used to fit the measured data to dynamic models of the HyPer facility. The State-Space identification was very accurate with a second order model. Visual inspection of the tracking accuracy shows that the ARX approach was approximately as accurate as the State-Space structure in its ability to reproduce measured data. However, by comparing the Loss Function and the FPE parameters, the State-Space approach gives better results. The MPC proved to be a good strategy to control the HyPer facility. The airflow valves and the electric load were used to control the turbine speed and the cathode airflow. For the ARX/State Space models, the MPC was very robust in tracking set-point variations. The anticipation feature of the MPC was revealed to be a good tool to compensate time delays in the output variables of the facility or to anticipate eventual set-point moves in order to achieve the objectives very quickly. The MPC also displayed good disturbance rejection on the output variables when the fuel flow was set to simulate FC heat effluent disturbances. Different off-design scenarios of operation have been tested to confirm the estimated implementation behavior of the plant-controller dynamics.

Control Strategies for Start-Up and Part-Load Operation of Solid Oxide Fuel Cell/Gas Turbine Hybrid System

2009 ◽  
Vol 7 (1) ◽  
Author(s):  
Wei Jiang ◽  
Ruixian Fang ◽  
Jamil Khan ◽  
Roger Dougal
Keyword(s):  
Fuel Cell ◽  
Gas Turbine ◽  
Hybrid System ◽  
Control Strategies ◽  
Operating Conditions ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Electrical Characteristics ◽  
Part Load ◽  
Start Up

Control strategy plays a significant role in ensuring system stability and performance as well as equipment protection for maximum service life. This work is aimed at investigating the control strategies for start-up and part-load operating conditions of the solid oxide fuel cell/gas turbine (SOFC/GT) hybrid system. First, a dynamic SOFC/GT hybrid cycle, based on the thermodynamic modeling of system components, has been successfully developed and simulated in the virtual test bed simulation environment. The one-dimensional tubular SOFC model is based on the electrochemical and thermal modeling, accounting for voltage losses and temperature dynamics. The single cell is discretized using a finite volume method where all the governing equations are solved for each finite volume. Two operating conditions, start-up and part load, are employed to investigate the control strategies of the SOFC/GT hybrid cycle. In particular, start-up control is adopted to ensure the initial rotation speed of a compressor and a turbine for a system-level operation. The control objective for the part-load operation regardless of load changes, as proposed, is to maintain constant fuel utilization and a fairly constant SOFC temperature within a small range by manipulating the fuel mass flow and air mass flow. To this end, the dynamic electrical characteristics such as cell voltage, current density, and temperature under the part load are simulated and analyzed. Several feedback control cycles are designed from the dynamic responses of electrical characteristics. Control cycles combined with control related variables are introduced and discussed.

Part-Load Performance Analysis of Pressurized Molten Carbonate Fuel Cell/Micro-Gas Turbine Hybrid System Using a Commercially Available Micro-Gas Turbine

2009 ◽  
Author(s):  
Ai-guo Liu ◽  
Yi-wu Weng
Keyword(s):  
Fuel Cell ◽  
Gas Turbine ◽  
Hybrid System ◽  
Control Strategies ◽  
Molten Carbonate Fuel Cell ◽  
Inlet Temperature ◽  
Molten Carbonate ◽  
Part Load ◽  
Micro Gas Turbine ◽  
Carbonate Fuel Cell

This paper presented the work on the design and part-load operation of a power generation system composed of a pressurized molten carbonate fuel cell and a micro-gas turbine (MCFC/MGT). The gas turbine was based on the commercially available one and the MCFC was assumed to be newly designed for the hybrid system. The effect of different control strategies on the performance of system during part-load operation has been analyzed. Performance of system and gas turbine was compared at the same part-load considering the different control strategies. The results show that the system efficiency is lower compared with the same systems analyzed by the other authors. The system has good performance when both the turbine inlet temperature and cell temperature are maintained close to the design-point condition, but it is difficult for gas turbine to obtain the original power.

Evaluation of Electric Load Following Capability on Fuel Cell System Fueled by High-Purity Hydrogen

2011 ◽  
Vol 131 (12) ◽  
pp. 927-935
Author(s):  
Yusuke Doi ◽  
Deaheum Park ◽  
Masayoshi Ishida ◽  
Akitoshi Fujisawa ◽  
Shinichi Miura
Keyword(s):  
Fuel Cell ◽  
High Purity ◽  
Cell System ◽  
Electric Load ◽  
Fuel Cell System ◽  
Load Following ◽  
High Purity Hydrogen
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