Demonstration of Simultaneous Temperature and Power Control in a Simulation Facility for a SOFC Hybrid System

2012 ◽  
Author(s):  
Francesco Caratozzolo ◽  
Mario L. Ferrari ◽  
Alberto Traverso ◽  
Aristide F. Massardo
Keyword(s):  
Control System ◽  
Fuel Cell ◽  
Real Time ◽  
Hybrid System ◽  
Thermal Response ◽  
Experimental Plant ◽  
Outlet Temperature ◽  
Test Rig ◽  
Time Model ◽  
The University

This study is based on a complete hybrid system emulator test rig developed at the University of Genoa (Savona laboratory) by the Thermochemical Power Group (TPG). The plant is mainly composed of a 100 kW recuperated micro gas turbine coupled with both anodic and cathodic vessels for high temperature fuel cell emulation. The test rig was recently equipped with a real-time model for emulating components not physically present in the laboratory (SOFC block, reformer, anodic circuit, off-gas burner, cathodic blower). This model is used to fully evaluate thermodynamic and electrochemical performance related to solid oxide fuel cell systems. Using a UDP based connection with the test rig control and acquisition software, it generates a real-time hardware-in-the-loop (HIL) facility for hybrid system emulation. Temperature, pressure and air mass flow rate at the recuperator outlet (downstream of the compressor) and rotational speed of the machine are inputs from the plant to the model. The turbine outlet temperature (TOT) calculated by the model is fed into the machine control system and the turbine electric load is moved to match the model TOT values. In this study various tests were carried out to characterize the interaction between the experimental plant and the real-time model; double step and double ramp tests of current and fuel provided the dynamic response of the system. The control system proved to be fast, compared to the slow thermal response of the SOFC stack, and also reliable. The hybrid systems operated at 90% of nominal power with electrical efficiency of about 56% based on natural gas LHV.

Real-Time Hardware-in-the-Loop Tool for a Fuel Cell Hybrid System Emulator Test Rig

2011 ◽  
Author(s):  
Francesco Caratozzolo ◽  
Mario L. Ferrari ◽  
Alberto Traverso ◽  
Aristide F. Massardo
Keyword(s):  
Control System ◽  
Fuel Cell ◽  
Real Time ◽  
Hybrid Systems ◽  
Hybrid System ◽  
Solid Oxide ◽  
Outlet Temperature ◽  
Hardware In The Loop ◽  
Test Rig ◽  
Time Model

The Thermochemical Power Group of the University of Genoa built a complete Hybrid System emulator test rig constituted by a 100 kW recuperated micro gas turbine, an anodic circuit (based on the coupling of a single stage ejector with a stainless steel vessel) and a cathodic modular volume (located between the recuperator outlet and combustor inlet). The system is sized to consider the coupling of the commercial micro turbine, operated at 62 kW load, and a planar Solid Oxide Fuel Cell (SOFC) to reach the overall electrical power output of 450 kW. The emulator test rig has been recently linked with a real-time model of the SOFC block. The model is used to simulate the complete thermodynamic and electrochemical behavior of a high temperature fuel cell based on solid oxide technology. The test rig coupled with the model generates a real-time hardware-in-the-loop (HIL) facility for hybrid systems emulation. The model is constituted by a SOFC module, an anodic circuit with an ejector, a cathodic loop with a blower (for the recirculation) and a turbine module. Temperature, pressure and air mass flow rate at recuperator outlet (downstream of the compressor) and rotational speed of the machine are inputs from the plant to the model. The turbine outlet temperature (TOT) calculated by the model is fed to the machine control system and the turbine electric load is moved to match the model TOT value. In this work different tests were carried out to characterize the interaction between the experimental plant and the real-time model; double step and double ramp tests of current and fuel characterized the dynamic response of the system. The mGT power control system proved to be fast enough, compared to the slow thermal response of the SOFC stack, and reliable. The hybrid systems was operated at 90% of nominal power with about 56% of electrical efficiency based on natural gas LHV.

Hybrid System Test Rig: Start-up and Shutdown Physical Emulation

2010 ◽  
Vol 7 (2) ◽  
Author(s):  
Mario L. Ferrari ◽  
Matteo Pascenti ◽  
Loredana Magistri ◽  
Aristide F. Massardo
Keyword(s):  
Control System ◽  
Thermal Stress ◽  
High Temperature ◽  
Fuel Cell ◽  
Hybrid System ◽  
Cell Hybrid ◽  
Test Rig ◽  
Start Up ◽  
Outlet Flow ◽  
Integrated Project

The University of Genoa (TPG) has designed and developed an innovative test rig for high temperature fuel cell hybrid system physical emulation. It is based on the coupling of a modified commercial 100 kW recuperated micro gas turbine to a special modular volume designed for the experimental analysis of the interaction between different dimension fuel cell stacks and turbomachines. This new experimental approach that generates reliable results as a complete test rig also allows investigation of high risk situations with more flexibility without serious and expensive consequences to the equipment and at a very low cost compared with real hybrid configurations. The rig, developed with the support of the European Integrated Project “FELICITAS,” is under exploitation and improvement in the framework of the new European Integrated Project “LARGE-SOFC” started in January 2007. The layout of the system (connecting pipes, valves, and instrumentation) was carefully designed to minimize the pressure loss between compressor outlet and turbine inlet to have the highest plant flexibility. Furthermore, the servocontrolled valves are useful for performing tests at different operative conditions (i.e., pressures, temperatures, and pressure losses), focusing the attention on surge and thermal stress prevention. This work shows the preliminary data obtained with the machine connected to the volume for the test rig safe management to avoid surge or excessive stress, especially during the critical operative phases (i.e., start-up and shutdown). Finally, the attention is focused on the valve control system developed to emulate the start-up and shutdown phases for high temperature fuel cell hybrid systems. It is necessary to manage the flows in the connecting pipes, including an apt recuperator bypass, to perform a gradual heating up and cooling down as requested during these phases. It is an essential requirement to avoid thermal stress for the fuel cell stack. For this reason, during the start-up, the volume is gradually heated by the compressor outlet flow followed by a well managed recuperator outlet flow and vice versa for the shutdown. Furthermore, operating with a constant rotational speed control system, the machine load is used to reach higher temperature values typical of these kinds of systems.

scholarly journals Advanced Control System for Grid-Connected SOFC Hybrid Plants: Experimental Verification in Cyber-Physical Mode

2019 ◽  
Author(s):  
Mario L. Ferrari ◽  
Iacopo Rossi ◽  
Alessandro Sorce ◽  
Aristide F. Massardo
Keyword(s):  
Control System ◽  
Fuel Cell ◽  
Real Time ◽  
Pid Control ◽  
Controller Design ◽  
Experimental Tests ◽  
Cell System ◽  
Hybrid Plant ◽  
Time Model ◽  
Point Data

Abstract This paper presents a Model Predictive Controller (MPC) operating an SOFC Gas Turbine hybrid plant at end-of-life performance condition. Its performance was assessed with experimental tests showing a comparison with a Proportional Integral Derivative (PID) control system. The hybrid system operates in grid-connected mode, i.e. at variable speed condition of the turbine. The control system faces a multivariable constrained problem, as it must operate the plant into safety conditions while pursuing its objectives. The goal is to test whether a linearized controller design for normal operating condition is able to govern a system which is affected by strong performance degradation. The control performance was demonstrated in a cyber-physical emulator test rig designed for experimental analyses on such hybrid systems. This laboratory facility is based on the coupling of a 100 kW recuperated microturbine with a fuel cell emulation system based on vessels for both anodic and cathodic sides. The components not physically present in the rig were studied with a real-time model running in parallel with the plant. Model output values were used as set-point data for obtaining in the rig (in real-time mode) the effect of the fuel cell system. The result comparison of the MPC tool against a PID control system was carried out considering several plant properties and the related constraints. Both systems succeeded in managing the plant, still the MPC performed better in terms of smoothing temperature gradient and peaks.

Pressurized SOFC System Fuelled by Biogas: Control Approaches and Degradation Impact

2020 ◽  
Author(s):  
Mario L. Ferrari ◽  
Valentina Zaccaria ◽  
Konstantinos Kyprianidis
Keyword(s):  
Thermal Stress ◽  
Fuel Cell ◽  
Real Time ◽  
High Efficiency ◽  
Cell System ◽  
System Response ◽  
Outlet Temperature ◽  
Time Model ◽  
Set Point ◽  
Additional Tool

Abstract This paper shows control approaches for managing a pressurized Solid Oxide Fuel Cell (SOFC) system fuelled by biogas. This is an advanced solution to integrate the high efficiency benefits of a pressurized SOFC with a renewable source. The operative conditions of these analyses are based on the matching with an emulator rig including a T100 machine for tests in cyber-physical mode (a real-time model including components emulated in the rig, operating in parallel with the experimental facility and used to manage some properties in the plant, such as the turbine outlet temperature set-point and the air flow injected in the anodic circuit). The T100 machine is a microturbine able to produce a nominal electric power output of 100 kW. So, the paper presents a real-time model including the fuel cell, the off-gas burner, and the recirculation lines. Although the microturbine components are planned to be evaluated with the hardware devices, the model includes also the T100 expander for machine control reasons, as detailed presented in the devoted section. The simulations shown in this paper regard the assessment of an innovative control tool based on the Model Predictive Control (MPC) technology. This controller and an additional tool based on the coupling of MPC and PID approaches were assessed against the application of Proportional Integral Derivative (PID) controllers. The control targets consider both steady-state (e.g. high efficiency solutions) and dynamic aspects (stress smoothing in the cell). Moreover, different control solutions are presented to operate the system during fuel cell degradation. The results include the system response to load variations, and SOFC voltage decrease. Special attention is devoted to the fuel cell system constraints, such as temperature and time-dependent thermal gradient. Considering the simulations including SOFC degradation, the MPC was able to decrease the thermal stress, but it was not able to compensate the degradation. On the other hand, the tool based on the coupling of the MPC and the PID approaches produced the best results in terms of set-point matching, and SOFC thermal stress containment.

scholarly journals Advanced Control System for Grid-Connected SOFC Hybrid Plants: Experimental Verification in Cyber-Physical Mode

2019 ◽  
Vol 141 (9) ◽  
Author(s):  
Mario L. Ferrari ◽  
Iacopo Rossi ◽  
Alessandro Sorce ◽  
Aristide F. Massardo
Keyword(s):  
Control System ◽  
Fuel Cell ◽  
Real Time ◽  
Pid Control ◽  
Controller Design ◽  
Experimental Tests ◽  
Cell System ◽  
Hybrid Plant ◽  
Time Model ◽  
Point Data

This paper presents a model predictive controller (MPC) operating a solid oxide fuel cell (SOFC) gas turbine hybrid plant at end-of-life performance condition. Its performance was assessed with experimental tests showing a comparison with a proportional integral derivative (PID) control system. The hybrid system (HS) operates in grid-connected mode, i.e., at variable speed condition of the turbine. The control system faces a multivariable constrained problem, as it must operate the plant into safety conditions while pursuing its objectives. The goal is to test whether a linearized controller design for normal operating condition is able to govern a system which is affected by strong performance degradation. The control performance was demonstrated in a cyber-physical emulator test rig designed for experimental analyses on such HSs. This laboratory facility is based on the coupling of a 100 kW recuperated microturbine with a fuel cell emulation system based on vessels for both anodic and cathodic sides. The components not physically present in the rig were studied with a real-time model running in parallel with the plant. Model output values were used as set-point data for obtaining in the rig (in real-time mode) the effect of the fuel cell system. The result comparison of the MPC tool against a PID control system was carried out considering several plant properties and the related constraints. Both systems succeeded in managing the plant, still the MPC performed better in terms of smoothing temperature gradient and peaks.

Physical Simulator of Start-Up for Hybrid System Cathode Side

2006 ◽  
Author(s):  
A. Traverso ◽  
M. L. Ferrari ◽  
M. Pascenti ◽  
A. F. Massardo
Keyword(s):  
High Temperature ◽  
Fuel Cell ◽  
Hybrid Systems ◽  
Hybrid System ◽  
Cell Hybrid ◽  
Cathode Side ◽  
Outlet Temperature ◽  
Test Rig ◽  
Start Up ◽  
Fuel Cell Hybrid

A start-up test rig at TPG laboratory at the University of Genoa, Italy, has been designed and built for two main purposes: physically simulating different early start-up layout and procedures of high temperature fuel cell hybrid systems, and validating time-dependent hybrid system models based on TRANSEO software. Since start-up is a critical operating phase for high temperature fuel cell hybrid systems, and it may require specific modifications to the hybrid system layout, the start-up test rig is meant to be very flexible for testing several start-up layouts as well as the coupling of different turbomachines and stacks. Results for cold test, 700°C and 950°C start-up combustor outlet temperature tests are reported. Such results show the pressure and temperature quick rise during the early phase of start-up, which could represent an issue for the mechanical and thermal stress to the stack. A dynamic model of the test rig was built up and validated showing good agreement with the experimental results. This achievement was very useful to increase the confidence with predictive dynamic simulation tools during the start-up phase, where experimental data are hardly available and where the fuel cell materials may undergo risky thermal shocks.

Micro Gas Turbine Real-Time Modeling: Test Rig Verification

2009 ◽  
Author(s):  
Francesco Ghigliazza ◽  
Alberto Traverso ◽  
Matteo Pascenti ◽  
Aristide F. Massardo
Keyword(s):  
Fuel Cell ◽  
Real Time ◽  
Gas Turbine ◽  
Simulation Models ◽  
Time Dependent ◽  
Test Rig ◽  
Time Model ◽  
The Real ◽  
Micro Gas Turbine ◽  
Time Modeling

This paper reports on the latest application of a generic time-dependent real-time simulation tool, originally developed for fuel cell gas turbine hybrid systems, and now applied to an actual micro gas turbine test rig. Real-time modeling is a recognized approach for monitoring advanced systems and improving control capabilities: applications of real-time models are commonly used in the automotive and aircraft fields. The overall objective is improving of calculation time in existing time-dependent simulation models, while retaining acceptable accuracy of results. The real-time modeling approach already applied to fuel cell gas turbine systems has here been validated against the experimental data from the micro gas turbine Turbec T100 test rig in Savona, Italy. The real-time model of the microturbine recuperator has been newly developed to fit such an application. Two representative transient operations have been selected for verification: the heating and cooling phases of the connected volume. The results already show an acceptable agreement with measurements, and they have contributed to a better insight into performance prediction for the entire plant.

Emulation of Hybrid System Start-Up and Shutdown Phases With a Micro Gas Turbine Based Test Rig

2008 ◽  
Author(s):  
Mario L. Ferrari ◽  
Matteo Pascenti ◽  
Loredana Magistri ◽  
Aristide F. Massardo
Keyword(s):  
Control System ◽  
High Temperature ◽  
Fuel Cell ◽  
Power Systems ◽  
Gas Turbine ◽  
Hybrid System ◽  
Test Rig ◽  
Micro Gas Turbine ◽  
Start Up ◽  
Critical Phases

The aim of this work, focused on natural gas fired distributed power systems, is the experimental analysis of the start-up and shutdown for high temperature fuel cell hybrid systems. These critical phases have been emulated using the micro gas turbine test rig developed by TPG at the University of Genoa, Italy. The rig is based on the coupling of a modified commercial 100 kWe recuperated gas turbine with a modular volume designed to emulate fuel cell stacks of different dimensions. It is essential to test the dynamic interaction between the machine and the fuel cell, and to develop different operative procedures and control systems without any risk to the expensive stack. This paper shows the preliminary experimental results obtained with the machine connected to the volume. The attention is mainly focused on avoiding surge and excessive stress on the machine components during the tests. Finally, after the presentation of the valve control system, this paper reports the emulation of the hybrid system start-up and shutdown phases. They have been performed to produce a gradual heating up and cooling down of the fuel cell volume, using the cold bypass line, three high temperature valves, and the machine load control system. This approach is necessary to avoid high thermal stress on the cell material, extremely dangerous for the plant life.

scholarly journals Hardware-in-the-Loop Operations With an Emulator Rig for SOFC Hybrid Systems

2017 ◽  
Author(s):  
Mario L. Ferrari ◽  
Alessandro Sorce ◽  
Aristide F. Massardo
Keyword(s):  
Fuel Cell ◽  
Real Time ◽  
Hybrid Systems ◽  
Control Strategies ◽  
Experimental Tests ◽  
Outlet Temperature ◽  
Hardware In The Loop ◽  
Set Point ◽  
The Real ◽  
System Components

This paper shows the Hardware-In-the-Loop (HIL) technique developed for the complete emulation of Solid Oxide Fuel Cell (SOFC) based hybrid systems. This approach is based on the coupling of an emulator test rig with a real-time software for components which are not included in the plant. The experimental facility is composed of a T100 microturbine (100 kW electrical power size) modified for the connection to an SOFC emulator device. This component is composed of both anodic and cathodic vessels including also the anodic recirculation system which is carried out with a single stage ejector, driven by an air flow in the primary duct. However, no real stack material was installed in the plant. For this reason, a real-time dynamic software was developed in the Matlab-Simulink environment including all the SOFC system components (the fuel cell stack with the calculation of the electrochemical aspects considering also the real losses, the reformer, and a cathodic recirculation based on a blower, etc.). This tool was coupled with the real system utilizing a User Datagram Protocol (UDP) data exchange approach (the model receives flow data from the plant at the inlet duct of the cathodic vessel, while it is able to operate on the turbine changing its set-point of electrical load or turbine outlet temperature). So, the software is operated to control plant properties to generate the effect of a real SOFC in the rig. In stand-alone mode the turbine load is changed with the objective of matching the measured Turbine Outlet Temperature (TOT) value with the calculated one by the model. In grid-connected mode the software/hardware matching is obtained through a direct manipulation of the TOT set-point. This approach was essential to analyze the matching issues between the SOFC and the micro gas turbine devoting several tests on critical operations, such as start-up, shutdown and load changes. Special attention was focused on tests carried out to solve the control system issues for the entire real hybrid plant emulated with this HIL approach. Hence, the innovative control strategies were developed and successfully tested considering both the Proportional Integral Derivative and advanced approaches. Thanks to the experimental tests carried out with this HIL system, a comparison between different control strategies was performed including a statistic analysis on the results The positive performance obtainable with a Model Predictive Control based technique was shown and discussed. So, the HIL system presented in this paper was essential to perform the experimental tests successfully (for real hybrid system development) without the risks of destroying the stack in case of failures. Mainly surge (especially during transient operations, such as load changes) and other critical conditions (e.g. carbon deposition, high pressure difference between the fuel cell sides, high thermal gradients in the stack, excessive thermal stress in the SOFC system components, etc.) have to be carefully avoided in complete plants.

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