Research On Hardware In The Loop Simulation Of Molten Carbonate Fuel Cell And Micro Gas Turbine Hybrid Power System

With the traditional energy resources consuming and the serious environmental problems increasing,it is imperative to save energy,reduce emission,and prevent climate warming.The efficiency of the distributed energy system has attracted worldwide attention.Molten Carbonate Fuel Cell(MCFC)is an efficient energy conversion device that directly converts chemical energy into electrical energy,does not involve combustion during the reaction process,and is not restricted by the Carnot cycles.A distributed energy system that couples the MCFC with the Micro Gas Turbine(MGT)is benefit to the efficiency,flexibility and stability of the system.For the MCFC-MGT hybrid system,the transient characteristics caused by the interdependence of different subsystems have not been well revealed.The Hardware In the Loop Simulation(HILS)method,which can take advantage of numerical simulation and experimental research,can increase the degree of freedom of the system dynamics under the condition of ensuring the accuracy of simulation results.Therefore,the HILS method is a very effective tool for the research of the MCFC-MGT hybrid system.Moreover,the HILS method gives new meaning to the research of hybrid power system with complex objects.However,it brings new challenges.The HILS method involves the interaction between the physical part and the virtual part,which faces many complex technical problems.In the hybrid power system,there are a lot of exchange of mass flow and energy flow between different subsystems.The key of building MCFC-MGT hybrid power system based on HILS method is to keep the mass,energy and momentum of the HILS system consistent with the prototype system.In this thesis,a MCFC-MGT HILS hybrid power system based on the MGT and the zero-dimensional and one-dimensional MCFC model is built.The HILS architecture and the dynamic characteristics of complex non-linear hybrid power system,and the influence of temperature and gas composition distribution in fuel cell are studied from the perspective of engineering thermophysics.The research results can provide the theoretical and practical support for the general HILS system of the distributed energy systems.The research contents of this thesis are as follows:1)The safe and efficient operation of distributed energy system is related to the performance of each subsystems.Understanding the performance of fuel cell is the basis of performance analysis of MCFC-MGT hybrid power system.Fully understanding the heat transfer and electrochemical reaction process inside the fuel cell,and accurately describing the energy conversion process inside the fuel cell is benefit to develop the mathematical model to analyze the performance of fuel cell.In this thesis,the real-time lumped parameters model and the one-dimensional distribution parameters model of the direct internal reforming MCFC is developed by Fortran language.Moreover,the MCFC model is embedded in the APROS simulation platform through dynamic linked library.The dynamic characteristics of fuel cell stack and the temperature,voltage,and gas distribution characteristics of the MCFC are studied.2)It is obviously different that the physical structure between the HILS system and the prototype system.The key to ensure the consistency of HILS system and prototype system is to ensure the consistency of mass flow and energy flow.Therefore,a new Simulation-Stimulation(Sim-Stim)interface model for the MCFC-MGT HILS hybrid power system that includes a model to calculate energy compensation,a model to calculate pressure compensation,and the actual actuator is proposed.Furthermore,in order to validate the Sim-Stim interface model,the overall model of the HILS hybrid system based on the Sim-Stim interface model and the overall model of the prototype system are developed.The comparison of the dynamic responses of the two system shows that the Sim-Stim interface model can keep the charcteristics of the HILS system consistent with the prototype system.It provides a reference for solving the problem of energy flow and mass flow transmission between various subsystems in the construction of a HILS system for general distributed energy systems.3)During the start-up process of the MCFC-MGT HILS hybrid power system,the response speed between the two subsystems is very different,and the mechanism of the interaction between the two subsystems is complex.The control strategy switching is involved in the start-up process of the MCFC-MGT HILS hybrid power system that easily affect the physical system.Therefore,the start-up process of the MCFC-MGT HILS hybrid power system based on Sim-Stim interface model is simulated.The start-up process includes starting-up the MGT,reading micro gas turbine data to initialize MCFC model subsystem and switching control signals.The simulation results show that the impact on the physical system is slight under this start-up scheme and the speed is fast.The reasonable start-up strategy can provide a theoretical basis for the start-up process of the real MCFC-MGT HILS hybrid power system.4)With the commercial MGT as the physical core,APROS as the operating platform of MCFC model subsystem,and OPC as the main data transmission protocol between various software and hardware,a MCFC-MGT HILS hybrid power system is established.This research laid the foundation for the development of a general HILS method for studying distributed energy systems.The effects of different fuel utilization rates on the performance of the system are investigated on the one-dimensional MCFC-MGT HILS hybrid power system.The range of fuel utilization varies from 65% to 85%.The research shows that the working conditions of each part of the system are more suitable under the fuel utilization ratio of about 75%.Based on the lumped parameter MCFC-MGT HILS hybrid power system,the experiments of load step changing are carried out,and the rapid response of the hybrid system to load is studied.The linear load change transient analysis are carried out and the stability of the hybrid system for load tracking is studied.The results show that the MCFC-MGT hybrid power system has the advantages of flexibility and stability in load response.