A New Control and Design of PEM Fuel Cell Powered Air Diffused Aeration System

Aeration of water by using PEM fuel cell power is not only a new application of the renewable energy, but also, it provides an affordable method to promote biodiversity in stagnant ponds and lakes. This paper presents a new design and control of PEM fuel cell powered by diffused air aeration system for a shrimp farm in Mersa Matruh in Egypt. Also Artificial intelligence (AI) techniques control is used to control the fuel cell output power by controlling input gases flow rate. Moreover the mathematical modeling and simulation of PEM fuel cell is introduced. A comparison study is applied between the performance of fuzzy logic control (FLC) and neural network control (NNC). The results show the effectiveness of NNC over FLC

고분자 전해질막 연료전지 시스템 고장 반응 및 심각도 기반 고장진단 방법

학위논문(박사) -- 서울대학교대학원 : 공과대학 기계항공공학부(멀티스케일 기계설계전공), 2021.8. 박진영.최근 들어 지속 가능하며 오염 없는 수소 사회에 대한 관심이 증가하고 있다. 수소는 우주에 가장 많은 물질이며 또한 쉽게 제조할 수 있다. 친환경 기술 개발과 더불어 수소 사회가 실현 된다는 가정하에, 수소에너지를 전기에너지로 변환시켜 주는 장치가 반드시 필요하다. 고분자 전해질막 연료전지 시스템은 산소와 수소의 전기화학반응을 이용하여 전기를 발전시키는 시스템이며, 다른 변환 장치에 비해 많은 장점을 가지고 있다. 또한, 가장 널리 사용되고 있는 장치이기도 하다. 다만, 연료전지의 상용화와 보급에 있어 내구성과 신뢰성은 아직 부족하여 극복해야 할 문제로 언급되고 있다. 이러한 내구성과 신뢰성 증진을 위해서는 고장 진단 기술이 반드시 필요하다. 연료전지는 운전 조건에 따라 그 성능과 내구성이 크게 영향을 받기 때문에 시스템에 발생한 문제를 빠르게 진단하여 장치를 보호하는 것이 중요하기 때문이다. 본 연구에서는 먼저 연료전지 시스템에 고장 발생시 그 영향을 관찰하였다. 일차적으로는 연료전지 스택에 반응의 공급 혹은 냉각이 원활히 이루어지지 않는 상황에서의 변화를 실험적으로 관찰하였다. 이어, 연료전지 시스템을 제작하여 연료 공급 시스템, 공기 공급 시스템, 열 관리 시스템에서 발생할 수 잇는 고장 시나리오를 설정하였다. 고장 시나리오는 연료전지 스택 혹은 시스템 전체에 미칠 수 있는 영향을 그 심각도에 따라 분류하였다. 마지막으로 고장을 인가하고 제어 및 계측 신호의 변화 양상을 관찰 및 분석하였다. 다음으로, 본 연구에서는 이러한 연료전지 시스템 고장을 진단할 수 있는 방법을 제안하였다. 고장의 심각도에 따라 변화 반응의 크기와 속도가 다르다는 점에 착안하여, 치명적 고장, 심각한 고장, 사소한 고장을 각각 진단하는 뉴럴 네트워크 기반 알고리즘을 개발하고, 이를 심각도 기반 고장 진단 알고리즘이라 명명하였다. 각각의 뉴럴 네트워크에 입력하는 계측 잔차 값의 이동 평균 시간과 이를 나누는 분산의 배수 값을 조절함으로 서, 진단 알고리즘의 민감도와 강건성을 동시에 달성할 수 있다는 장점을 갖는다. 또한 고장 실험 없이 고장 시 예상되는 제어 및 계측 신호 값의 증감을 테이블화 하는 것만으로도 본 알고리즘을 개발할 수 있다는 장점을 갖는다. 이러한 방법으로 개발 된 심각도 기반 고장 진단 알고리즘에 고장실험 데이터를 입력한 결과 고장을 성공적으로 진단하는 것을 확인하였다. 이어서, 본 연구에서는 내부 전류 분포를 예측할 수 있는 모델 개발법을 제안하였다. 지금까지의 연료전지 내부 전류 분포 연구는 실험 기반으로, 혹은 모델기반으로 각각 이루어져 왔다. 다만 두가지 접근 방법 모두 필연적으로 한계점을 가진다. 이러한 한계를 뉴럴 네트워크를 도입하여 극복하고자 하였다. 분할 연료전지를 이용하여 압력, 온도, 유량 및 가습도가 변하는 다양한 운전 조건에서의 전류 분포 정보를 습득하였고, 이를 뉴럴 네트워크 모델에 학습시켰다. 그 결과 제한된 데이터만으로 모델을 개발하고, 다양한 운전조건에서 전류 밀도 분포를 예측 할 수 있음을 확인하였다. 이러한 접근법은 상용 연료전지의 개발 과정에서 효율적으로 활용될 것이라 생각한다. 마지막으로, 본 연구에서는 열화 및 고장 발생에 따른 내부 전류 분포를 예측할 수 있는 모델 개발법을 제안하고 검증하였다. 연료전지는 시간이 지나면 필연적으로 열화 한다는 특성을 가지고 있다. 따라서 열화에 따른 전류 분포 변화 특성을 이해하고 예측하는 작업은 중요하다. 하여, 가속 열화 기법을 도입하여 열화에 따른 내부 전류 분포 변화를 먼저 관찰하였다. 또한 가속 열화 시험 중간에 운전 온도 상승, 당량비 증감, 가습도 저하와 같은 고장을 인가하여 전류 분포 변화 정보를 추가적으로 습득하였다. 이러한 정보를 바탕으로 열화 및 열화 진행 상태에서의 고장 발생 시, 전류밀도 분포를 예측하는 뉴럴 네트워크 기반 모델을 개발하였다. 그 결과 모델을 이용하여 효율적이면서도 정확한 전류 밀도 분포 예측이 가능함을 확인하였다.In recent years, interest in hydrogen society has grown from the viewpoint of a sustainable clean energy society. Hydrogen is the most abundant element in the universe and can be easily produced. When hydrogen becomes a commonly used fuel, an energy conversion device is needed. A polymer electrolyte membrane fuel cell (PEMFC) system is the most widely distributed device so far, with many advantages among many devices. However, there still are some barriers to overcome for the commercialization of the PEMFC system; reliability and durability. In order to improve the reliability and durability of the fuel cell system, fault diagnosis technology is essentially required. Since the performance and durability of the PFMFC highly depend on operating conditions, faults in the system should be correctly detected in the early stage for its protection. Firstly, fault responses of a PEMFC stack and PEMFC system are investigated in this study. A response of 1 kW PEMFC stack under insufficient reactant supply or failure thermal management is investigated. Next, probable fault scenarios in a 1 kW class PEMFC system are established. The fault scenarios in air providing system, fuel providing system and thermal management system are classified depending on their fault severity to the stack or the entire system. Responses of control and sensing signals are investigated and analyzed under each fault scenario. Secondly, a fault diagnostic method for the PEMFC system is suggested in this study. Considering that response time and magnitude differ depending on fault severity, three neural networks that diagnose the critical fault, significant fault and minor fault, respectively, are developed. The neural networks together work as a severity-based fault diagnosis algorithm. The algorithm can achieve both sensitivity and robustness by adjusting the moving average time and standard deviation multiplication value that divides the residual data. The residual data is acquired from the control and sensing signals during the system operation. The severity-based fault diagnosis algorithm can be developed using a tabularized expected fault response without experimental data. As a result, the developed algorithm successfully diagnosed all the considered fault scenarios. Thirdly, a local current distribution prediction method is suggested in this study. Local current distribution studies have been conducted experimentally or numerically. Both approaches had limitations. In order to overcome the limitations, a neural network-based local current distribution prediction model is developed. Current distribution data is collected under various pressure, temperature, reactant stoichiometric ratio and relative humidity conditions. The model is developed with the data and successfully predicted local current distribution. Using the model, the effect of the operating parameters is investigated. Lastly, a local current distribution prediction model under degradation and fault is suggested in this study. The performance of the fuel cell inevitably decreases over time. With the degradation, local current distribution also changes. Therefore, understanding and predicting the current distribution changes are important. An accelerated stress test (AST) is applied to the fuel cell for fast degradation. With the AST, current distribution data is collected. Also, fault data under elevated temperature, reduced humidity and varying cathode stoichiometric ratio condition are collected. With the collected data, local current distribution model based on a neural network is developed. As a result, the model predicted the current distribution under degradation and fault with high accuracy. In summary, a fault response of PEMFC is investigated from the viewpoint of the system and local current distribution. A severity-based fault diagnosis algorithm is suggested and validated with the PEMFC system fault experimental data. Also, local current distribution prediction algorithm is suggested and successively predicted the current distribution under PEMFC degradation and faults.Chapter 1. Introduction 1 1.1 Background of study 1 1.2 Literature survey 7 1.2.1 PEMFC fault diagnosis technology 7 1.2.2 PEMFC local current distribution 11 1.3 Objective and scopes 19 Chapter 2. Fault response of PEMFC system 22 2.1 Introduction 22 2.2 Fault response of 1 kW stack 23 2.2.1 Experimental setup description 23 2.2.2 Fault response of stack 29 2.3 Fault response of 1 kW PEMFC system 34 2.3.1 PEMFC system description 34 2.3.2 Fault scenarios 44 2.3.3 Fault response of PEMFC system 52 2.4 Summary 63 Chapter 3. Severity-based fault diagnostic method for PEMFC system 64 3.1 Introduction 64 3.2 Fault residual patterns 68 3.2.1 Input values 68 3.2.2 Normal state 69 3.2.3 Faul residual pattern table 72 3.3 Fault diagnosis algorithm development 79 3.3.1 Severity-based fault diagnosis concept 79 3.3.2 Algorithm development 82 3.4 Results and discussion 88 3.5 Summary 105 Chapter 4. Current distribution prediction with neural network 106 4.1 Introduction 106 4.2 Experimental setup 108 4.2.1 Experimental apparatus 108 4.2.2 Experimental conditions 113 4.3 Model development 116 4.3.1 Neural network model 116 4.3.2 Data conditioning 119 4.3.3 Model training 122 4.4 Results and discussion 127 4.4.1 Model accuracy 127 4.4.2 Effects of parameters on current distribution 129 4.4.3 Effects of parameters on standard deviations 133 4.4.3 Uniform current distribution 134 4.5 Summary 138 Chapter 5. Current distribution prediction under degradation and fault 139 5.1 Introduction 139 5.2 Accelerated stress test 140 5.3 Experimental setup 143 5.3.1 Experimental apparatus 143 5.3.2 Experimental conditions 148 5.4 Current distribution characteristics 152 5.4.1 Local current distribution change with accelerated stress test 152 5.4.2 Local current distribution change under faults 156 5.5 Model development 161 5.5.1 Neural network models 161 5.5.2 Data conditioning 166 5.5.3 Model training 169 5.6 Prediction results 171 5.7 Summary 176 Chapter 6. Concluding remarks 177 References 180 Abstract (in Korean) 197박

Modelling of hydrogen blending into the UK natural gas network driven by a solid oxide fuel cell for electricity and district heating system

A thorough investigation of the thermodynamics and economic performance of a cogeneration system based on solid oxide fuel cells that provides heat and power to homes has been carried out in this study. Additionally, different percentages of green hydrogen have been blended with natural gas to examine the techno-economic performance of the suggested cogeneration system. The energy and exergy efficiency of the system rises steadily as the hydrogen blending percentage rises from 0% to 20%, then slightly drops at 50% H2 blending, and then rises steadily again until 100% H2 supply. The system's minimal levelised cost of energy was calculated to be 4.64 £/kWh for 100% H2. Artificial Neural Network (ANN) model was also used to further train a sizable quantity of data that was received from the simulation model. Heat, power, and levelised cost of energy estimates using the ANN model were found to be extremely accurate, with coefficients of determination of 0.99918, 0.99999, and 0.99888, respectively

Machine Learning Approach for Modeling and Control of a Commercial Heliocentris FC50 PEM Fuel Cell System

In recent years, machine learning (ML) has received growing attention and it has been used in a wide range of applications. However, the ML application in renewable energies systems such as fuel cells is still limited. In this paper, a prognostic framework based on artificial neural network (ANN) is designed to predict the performance of proton exchange membrane (PEM) fuel cell system, aiming to investigate the effect of temperature and humidity on the stack characteristics and on tracking control improvements. A large part of the experimental database for various operating conditions has been used in the training operation to achieve an accurate model. Extensive tests with various ANN parameters such as number of neurons, number of hidden layers, selection of training dataset, etc., are performed to obtain the best fit in terms of prediction accuracy. The effect of temperature and humidity based on the predicted model are investigated and compared to the ones obtained from real-time experiments. The control design based on the predicted model is performed to keep the stack operating point at an adequate power stage with high-performance tracking. Experimental results have demonstrated the effectiveness of the proposed model for performance improvements of PEM fuel cell system.This research was funded by the Basque Government, Diputación Foral de Álava and UPV/EHU, respectively, through the projects EKOHEGAZ (ELKARTEK KK-2021/00092), CONAVANTER and GIU20/063

Impact of sensorless neural direct torque control in a fuel cell traction system

Due to the reliability and relatively low cost and modest maintenance requirement of the induction machine make it one of the most widely used machines in industrial applications. The speed control is one of many problems in the traction system, researchers went to new paths instead the classical controllers as PI controller, they integrated the artificial intelligent for its yield. The classical DTC is a method of speed control by using speed sensor and PI controller, it achieves a decoupled control of the electromagnetic torque and the stator flux in the stationary frame, besides, the use of speed sensors has several drawbacks such as the fragility and the high cost, for this reason, the specialists went to propose an estimators as Kalman filter. The fuel cell is a new renewable energy, it has many applications in the traction systems as train, bus. This paper presents an improved control using DTC by integrate the neural network strategy without use speed sensor (sensorless control) to reduce overtaking and current ripple and static error in the system because the PI controller has some problems like this; and reduce the cost with use a renewable energy as fuel cell

고분자 전해질막 연료전지 내부 국소 전류 분포에 관한 연구

학위논문 (석사) -- 서울대학교 대학원 : 공과대학 기계공학부, 2020. 8. 김민수.As fuel cell technology is in the commercialization stage, reliability and durability of the technology are constantly in the spotlight. In this regard, numerous studies are conducted to focus on the uniformity of current distribution to increase durability. In this study, operating condition s and degradation are mainly experimented to observe the change in current distribution by the segmented fuel cell. The tested operation conditions have different characteristic s of distribution and it is also varied when it is experienced degradation. In addition, a new neural network-based modelling method has been newly proposed to predict the current density distribution under various operating conditions and suggest the optimum operating condition to improve uniformity.연료전지는 다른 친환경 에너지에 비해 상대적으로 높은 에너지 변환 효율 및 저장성으로 인해 차세대 에너지원으로 각광받는 기술이다. 또한 자가발전을 위한 SOFC, 상대적으로 작동 온도가 낮아 운송 및 교통수단에 사용되는 PEMFC 등 다양한 종류의 연료전지가 여러 산업에서 응용 될 수도 있을 것으로 기대되어 많은 연구가 이루어 지고 있다. 또한 이미 상용화 단계에 들어선 연료전지의 내구성 문제가 중요시 되고 있기 때문에 본 연구에서는 연료전지 사형유로에서 상이한 전류 밀도로 인해 발생한 국소 온도구배에 의한 열화를 방지하기 위하여 전류밀도분포에 관한 연구를 진행하였다. 첫번째로는 연료전지가 운전 시 핵심적인 실험변수를 조정해 가며 실험을 진행하였다. 변수로는 작동 온도, 습도 및 수소 와 산소의 유량을 조정하며 실험을 진행하였다. 실험방법으로는 가로 세로 5cm, 넓이 25cm2의 반응 면적을 25 구간으로 나누어 전류밀도 분포의 변화를 살펴보았다. 두번째로는 인공신경망을 이용하여 연료전지의 운전 상태 분석 및 운전조건을 예측 및 조절 가능한 모델을 개발하였다. 이를 위해, 연료전지에 특화된 다양한 데이터 전처리 기법들이 적용 및 제안되었으며, 수치해석법으로는 어느정도 한계가 있는 전류밀도분포 예측 모델도 개발되었다. 뿐만 아니라 역방향 인공신경망을 이용하여 전류 밀도를 균일하게 맞추기 위한 운전조건을 제시하는 방법을 새롭게 도입하였고, 이를 모델링을 통해 검증하였다. 세번째로는 연료전지가 열화 되었을 때 발생할 수 있는 전류밀도분포 변화에 대해 연구하였다. 이를 위해 가속열화기법이 도입되었고, 습도에 따라 열화 정도가 변화하는 현상을 관찰하였다. 습도에 따라 출구부근에서 더 큰 열화가 일어나는 것을 관찰하고 EIS, SEM 및 EDS 등을 사용하여 이를 증명하였다. 또한 이를 통해 열화가 일어났을 시 국부적인 열화의 가속을 줄이고자 운전 조건의 조절을 두번째 챕터의 인공신경망을 통해 제어하는 방식도 새롭게 제안되었다.1.0 Introduction 1 1.1 Background of study 1 1.2 Literature review 8 1.3 Objectives and scopes 12 2.0 Characteristics of current density distribution under various conditions 15 2.1 Introduction 15 2.2 Experimental setup 16 2.3 Process of experiment 24 2.4 Results and discussions 27 2.5 Summary 44 3.0 Neural network-based prediction model for PEMFC 3.1 Introduction 45 3.2 Process of modelling 46 3.3 Results and discussions 55 3.4 Summary 70 4.0 MEA degradation and current distribution with an accelerated stress test (AST) 72 4.1 Intruduction 74 4.2 Experimental setup 80 4.3 Results and discussions 97 4.4 Summary 98 5.0 Conclusions 99 References 102 Abstract (in Korean) 108Maste

Fuel cell-based CHP system modelling using Artificial Neural Networks aimed at developing techno-economic efficiency maximization control systems

This paper focuses on the modelling of the performance of a Polymer Electrolyte Membrane Fuel Cell (PEMFC)-based cogeneration system to integrate it in hybrid and/or connected to grid systems and enable the optimization of the techno-economic efficiency of the system in which it is integrated. To this end, experimental tests on a PEMFC-based cogeneration system of 600 Wof electrical power have been performed to train an Artificial Neural Network (ANN). Once the learning of the ANN, it has been able to emulate real operating conditions, such as the cooling water out temperature and the hydrogen consumption of the PEMFC depending on several variables, such as the electric power demanded, temperature of the inlet water flow to the cooling circuit, cooling water flow and the heat demanded to the CHP system. After analysing the results, it is concluded that the presented model reproduces with enough accuracy and precision the performance of the experimented PEMFC, thus enabling the use of the model and the ANN learning methodology to model other PEMFC-based cogeneration systems and integrate them in techno-economic efficiency optimization control systems

Model predictive control using machine learning for voltage control of a PEM fuel cell stack

Abstract: In this paper, a Nonlinear Model Predictive Control (NMPC) is designed using a data-based model of Proton Exchange Membrane Fuel cell (PEMFC) for output voltage control. To capture PEMFC complex dynamics and non-linearities, Machine Learning (ML) algorithms are utilized to model the behavior of the system. This model is then embedded inside the NMPC controller to provide the predictions required for solving the optimization problem. The NMPC not only provides precise output voltage tracking, but also can simultaneously reduce the fuel consumption of the stack as one additional term in the cost function. Moreover, the possible upper and lower bounds of the control effort generated by actuators are set as the hard constraints of NMPC. The simulation results show that while these constraints are not violated, the desired output voltage is generated with less fuel being consumed comparing to the case that fuel consumption is not controlled.Communication présentée lors du congrès international tenu conjointement par Canadian Society for Mechanical Engineering (CSME) et Computational Fluid Dynamics Society of Canada (CFD Canada), à l’Université de Sherbrooke (Québec), du 28 au 31 mai 2023

Optimisation of stand-alone hydrogen-based renewable energy systems using intelligent techniques

Wind and solar irradiance are promising renewable alternatives to fossil fuels due to their availability and topological advantages for local power generation. However, their intermittent and unpredictable nature limits their integration into energy markets. Fortunately, these disadvantages can be partially overcome by using them in combination with energy storage and back-up units. However, the increased complexity of such systems relative to single energy systems makes an optimal sizing method and appropriate Power Management Strategy (PMS) research priorities. This thesis contributes to the design and integration of stand-alone hybrid renewable energy systems by proposing methodologies to optimise the sizing and operation of hydrogen-based systems. These include using intelligent techniques such as Genetic Algorithm (GA), Particle Swarm Optimisation (PSO) and Neural Networks (NNs). Three design aspects: component sizing, renewables forecasting, and operation coordination, have been investigated. The thesis includes a series of four journal articles. The first article introduced a multi-objective sizing methodology to optimise standalone, hydrogen-based systems using GA. The sizing method was developed to calculate the optimum capacities of system components that underpin appropriate compromise between investment, renewables penetration and environmental footprint. The system reliability was assessed using the Loss of Power Supply Probability (LPSP) for which a novel modification was introduced to account for load losses during transient start-up times for the back-ups. The second article investigated the factors that may influence the accuracy of NNs when applied to forecasting short-term renewable energy. That study involved two NNs: Feedforward, and Radial Basis Function in an investigation of the effect of the type, span and resolution of training data, and the length of training pattern, on shortterm wind speed prediction accuracy. The impact of forecasting error on estimating the available wind power was also evaluated for a commercially available wind turbine. The third article experimentally validated the concept of a NN-based (predictive) PMS. A lab-scale (stand-alone) hybrid energy system, which consisted of: an emulated renewable power source, battery bank, and hydrogen fuel cell coupled with metal hydride storage, satisfied the dynamic load demand. The overall power flow of the constructed system was controlled by a NN-based PMS which was implemented using MATLAB and LabVIEW software. The effects of several control parameters, which are either hardware dependent or affect the predictive algorithm, on system performance was investigated under the predictive PMS, this was benchmarked against a rulebased (non-intelligent) strategy. The fourth article investigated the potential impact of NN-based PMS on the economic and operational characteristics of such hybrid systems. That study benchmarked a rule-based PMS to its (predictive) counterpart. In addition, the effect of real-time fuel cell optimisation using PSO, when applied in the context of predictive PMS was also investigated. The comparative analysis was based on deriving the cost of energy, life cycle emissions, renewables penetration, and duty cycles of fuel cell and electrolyser units. The effects of other parameters such the LPSP level, prediction accuracy were also investigated. The developed techniques outperformed traditional approaches by drawing upon complex artificial intelligence models. The research could underpin cost-effective, reliable power supplies to remote communities as well as reducing the dependence on fossil fuels and the associated environmental footprint