基于UGF的光伏发电系统可靠性及容量置信度研究

为计算光伏发电系统可靠性及置信容量,首先通过通用生成函数法建立辐照强度及各元件的多状态u-函数模型,综合辐照强度的波动性和元件的随机故障特性建立光伏电站输出功率概率模型;其次运用有效载荷容量法求解光伏电站置信容量,并对影响光伏电站置信容量的各因素,如光伏装机容量、光伏电站出力状态数、组件故障特性及组件额定功率进行灵敏度分析;最后,IEEE-RTS79算例验证了该方法的有效性。     

诊断键合图在动态系统故障诊断中的应用

基于解析冗余关系故障诊断方法的关键是建立解析冗余关系。系统键合图模型经过转换可以得到系统的诊断键合图模型,利用该模型中的虚拟传感器与系统组件的关系可以方便地建立系统解析冗余关系和具有残差方向的故障特征矩阵。然后,通过观测特征与故障特征的比较进行故障检测和隔离。通过在五箱系统的仿真验证,证明该方法是非常有效的。     

基于I-V特性分析的晶硅光伏组件故障诊断

该文针对实际电站中的光伏组件故障,实地调研并收集多晶硅光伏组件中的一些常见故障类型,建立光伏电池的反偏模型,分析光伏组件失配下I-V输出特性的原因,测试不同故障类型光伏组件的I-V特性曲线,重点分析了玻璃碎裂组件I-V特性出现凸函数特征的原因,提取不同故障组件的故障特征,提出一种基于I-V特性的光伏组件故障在线诊断方法...     

高速柴油机气阀组件振动监测诊断技术试验研究

介绍了利用气缸盖表面振动信号对高速柴油机气阀组件等故障进行的振动监测诊断试验研究。分析了引起缸盖振动的激励源特征;对单缸熄火和气阀组件等故障进行了模拟试验;对不同故障状态的气缸盖表面振动信号进行了测量分析,提取用于故障诊断的特征参数,建立了不同类型及不同程度故障与特征参数间的相互关系。     

考虑旁路二极管故障的光伏组件数学建模及功率特性分析研究

在光伏组件中引入旁路二极管是目前解决组件中电流失配问题的主要手段,但是当旁路二极管故障时,不仅会导致光伏组件的功率损失,极端情况下还会引发火灾。考虑到目前针对旁路二极管故障尚缺乏有效的检测手段,本文根据光伏组件中旁路二极管的工作原理和热特性,建立了一种考虑旁路二极管的光伏组件数学模型,分析了旁路二极管故障时光伏组件的输出特性;最后,搭建了并网光伏系统模型,分析了旁路二极管损坏对光伏系统最大功率跟踪控制的影响,为光伏系统故障诊断提供了理论依据。     

循环流化床锅炉风烟系统的多模态建模与时序分析

由于循环流化床锅炉结构复杂、运行模态多变,为对其动静态特性进行准确描述和有效分析,提出一种基于组件的风烟系统多模态建模与时序分析方法:首先,根据模态切换过程中各相关设备和物理量之间的关联关系,建立系统的模态感知模型;然后,通过从系统点火准备至点火完成中多模态切换过程的时间统计,实现关键设备及参数的时序分析。以宁夏宁东330 MW循环流化床锅炉机组为例,采用该方法对引风机启动过程中的故障进行了模拟与诊断,诊断结果证明了所提方法的适用性和有效性。     

遮挡状态下光伏组件多峰输出特性的参数计算与分析

基于太阳电池正反向输出特性,建立光伏组件输出特性模型,针对遮挡状态下的多峰输出特性,提出一种模型参数计算方法,研究不同遮挡状态对I-V特性曲线和模型参数的影响作用。通过仿真和实验,分析组件中各单元所受遮挡光强和电池片遮挡数量的变化对模型参数的影响规律。研究结果表明：模型参数计算结果和基于模型参数获得的I-V特性曲线,有较高精度;所建立的组件输出特性模型和参数计算方法,对于实现光伏组件和组串的故障诊断,具有良好的工程应用前景。     

CMI发动机燃油喷射系统工作原理及故障诊断技术分析

基于CMI发动机燃油喷射系统的系统构造,通过对该型发动机燃油喷射系统的驱动燃油泵、燃油计量组件、燃油分配器和燃油喷嘴等主要部件的系统构造和工作原理进行分析,深入阐述了该燃油喷射系统各部件的故障机制及故障表征现象,提供了该燃油喷射系统常见故障的诊断方法及故障排除措施,为该型发动机燃油喷射系统的日常维护、故障诊断及排除和故障预防提供了有力依据。     

典型故障条件下光伏阵列建模与仿真

为实现光伏阵列在典型故障条件下的仿真模拟和数据分析,利用Simulink搭建了局部遮阴、开路、短路和老化条件下的光伏阵列仿真模型。构建2种光伏组件模型,通过实验数据分析,得到精度较高的光伏组件模型;根据光伏阵列故障原理,通过搭建物理接口电路实现优选的光伏组件模型和电阻器之间的串并联,建立光伏阵列故障模型。对光伏阵列故障输出特性进行仿真分析,结果表明,该光伏阵列故障仿真平台便于故障模拟和特性分析,能够直观看出光伏阵列电气参数变化趋势,为研究如何有效地选取电气参数作为故障诊断模型的输入特征变量提供了理论依据。     

基于运行参数特征的风力机叶片覆冰诊断方法

为更好地解决工程实际中的叶片覆冰问题,通过建立叶片覆冰状态特征参数处理模型,提取出能反映叶片覆冰状态的6种故障特征指标,并将其作为输入,将叶片覆冰状态作为输出,建立风电机组叶片覆冰诊断的BP神经网络模型,利用实际风电机组数据采集与监视控制(SCADA)系统数据构造BP神经网络的训练样本和测试样本。结果表明:所构建的叶片覆冰诊断模型能准确地诊断出叶片覆冰状态。     

Diagnosis of a hydrogen-fueled 1-kW PEMFC system based on exergy analysis

In this study, a model based diagnosis of a hydrogen-fueled 1-kW proton exchange membrane fuel cell (PEMFC) system was conducted based on exergy analysis to identify faulty components. Faulty components of balance of plant (BOP) were experimentally simulated by reducing the rpm signals of the pump, fan, and air and fuel blowers; reducing the output signals of the air and fuel flow meters; increasing the output signal of the temperature sensor; opening the valve between the air blower and the air flow meter; and blocking the heat exchange area during the operation of the PEMFC system. The irreversibility rate, malfunction (MF) and dysfunction (DYS) of each component were calculated for the case under normal condition and simulated failure conditions using the observed data. The residuals of the MF and relative malfunction (RMF) between the normal and failure conditions were the fault indicators used to identify the faulty components in the system. The proposed diagnosis method employing both the MF and the RMF was found to be not only simple but also effective.     

Expert diagnosis of polymer electrolyte fuel cells

Diagnosing faulty conditions of engineering systems is a highly desirable process within control structures, such that control systems may operate effectively and degrading operational states may be mitigated. The goal herein is to enhance lifetime performance and extend system availability. Difficulty arises in developing a mathematical model which can describe all working and failure modes of complex systems. However the expert's knowledge of correct and faulty operation is powerful for detecting degradation, and such knowledge can be represented through fuzzy logic. This paper presents a diagnostic system based on fuzzy logic and expert knowledge, attained from experts and experimental findings. The diagnosis is applied specifically to degradation modes in a polymer electrolyte fuel cell. The defined rules produced for the fuzzy logic model connect observed operational modes and symptoms to component degradation. The diagnosis is then tested against common automotive stress conditions to assess functionality.     

Fault-tolerant control for steam fluctuation in SOFC system with reforming units

Faults of solid oxide fuel cell (SOFC) systems can affect the characteristics of the stack and inhibit SOFC system commercialization. It has been found that the temperature fluctuation of the burner caused by fluctuation of steam flow rate would greatly affect the temperature of SOFC system and even exceed the safe operation range. Firstly, this paper introduces a mathematical model for the process of steam and natural gas reforming in a real SOFC system. Secondly, the cause of the burner temperature fluctuation is analyzed, and the model to simulate this faulty situation is established. Then, the Bayesian regularization neural network is used for fault diagnosis and good test results are obtained. Finally, fuzzy fault-tolerant control strategy is designed for the thermal safety problem of SOFC system. The simulation results validate the effectiveness of the proposed fault-tolerant control strategy.     

基于液态金属朗肯循环的空间双模式核热推进系统性能分析

随着深空探测技术的进步,空间核动力越来越成为载人航天任务的理想选择,将双模式空间核动力推进系统应用于航天推进系统已成为一种新的趋势。基于空间核能液态金属朗肯循环,提出一种新型的双模式核热推进系统,并对该推进系统发电模式下的液态金属朗肯循环进行了性能分析。利用能量分析和?分析的方法对双模式核热推进系统下的朗肯循环进行热力计算,得出各部件的能量损失和?损,找出损失最大的部件并分析原因,取不同的空间环境温度研究其对?损和?效率的影响,为系统的进一步优化提供理论依据。     

Design of an integrated propulsion, guidance, and levitation system by magnetically excited transverse flux linear motor (TFM-LM)

A magnetically levitated vehicle dedicated for transportation systems requires propulsion, guidance, and levitation forces. The components used to generate these forces, such as linear motors and magnets, must have less mass especially because the magnetically levitated vehicle has to carry its own linear motor and magnet. In this paper, an integrated propulsion, guidance, and levitation system by magnetically excited transverse flux linear motor (TFM-LM) with high force and high efficiency is introduced. Analytical equations with one-dimensional magnetic equivalent circuit are developed to predict the propulsion force and to guide the design of TFM-LM. A three-dimensional (3-D) finite-element (FE) program calculates the propulsion force, the guidance force, and the levitation force of TFM-LM also, in order to verify the given specification. To verify the results of 3-D FE calculation, the computed propulsion force, guidance force, and levitation force are compared with the experimentally measured forces detected on the experimental setup. The calculated and measured performances of TFM-LM reveal a high potential of mass reduction for magnetic-levitated vehicles.     

Hybrid fuel cell and battery propulsion system modelling and multi-objective optimisation for a coastal ferry

Efforts from all sectors of society including the shipping industry are needed to limit the overall global temperature rise to within 2°C of pre-industrial levels by 2050. The hybridisation of Proton Exchange Membrane Fuel Cells (PEMFC) and Lithium-ion batteries for coastal ship propulsion systems may potentially offer beneficial emission performance. However, such hybrid systems are constrained by power and energy density limitations, lifetime; and costs as well as life-cycle emissions of alternative fuel/energy. There is a lack of holistic design methodology dealing with these uncertainties in the literature. This paper proposes a holistic design methodology for coastal hybrid ships based upon a developed model. The power source sizing problem is solved using constrained mixed-integer multi-objective optimisation in the external layer. The global optimum energy management strategies for an averaged operating profile are obtained from deterministic dynamic programming in the inner layer, while considering power source degradations in the sizing algorithm. The proposed methodology was applied to a coastal ferry to investigate the feasibility and benefit potential of adopting the hybrid PEMFC and battery propulsion system in Matlab. The case studies indicate that the proposed propulsion system can achieve at least a 65% life-cycle greenhouse gas reduction for the considered two cases.     

Introducing and evaluation of a new propulsion system composed of solid oxide fuel cell and downstream cycles; usage in Unmanned Aerial Vehicles

Recently, Unmanned Aerial Vehicles (UAVs) with propulsion systems based on fuel cells have led to increased flight endurance and fuel economy. However, due to the limited operation of propulsion systems designed with alone fuel cells, the integration of fuel cells with other power generators can be used. This article attempts to provide a conceptual model of a new solid oxide fuel cell based-propulsion system that is cascaded with thermionic and thermoelectric generators. The fuel cell produces power and heat by receiving hydrogen fuel and oxidant. The required heat of thermionic and thermoelectric generators is supplied by the dissipative heat of the fuel cell and the dissipated heat of thermionic, respectively. The objective of this article is to determine the necessary electricity of a small UAV under mission profile. The conceptual design and structure of the proposed propulsion system (for use in a small drone) is new. In addition, the results presented do not correspond to the same literature. Results showed that the proposed propulsion system is capable of producing 481.3 W of power with an overall efficiency of 46.7%. In addition, UAV needs 1110.3 W of electricity under the desired mission profile. Five various sizing of the propulsion system to provide the necessary electricity of an UAV are discussed.     

柴-柴联合动力装置单调速器并车控制法的数学建模和仿真

柴-柴联合动力装置(CODAD)是一种符合国情的推进装置。在建立单调速器法负荷控制器的数学模型后,利用仿真应用软件Matlab/Simulink将其转化为仿真模型,并进行仿真研究。仿真结果表明:单调速器法可以很好地解决柴油机双机并车运行过程中的关键性问题———负荷合理分配问题,保证了双柴油机运行时(稳态或动态过程)柴油机输出转速的稳定性和负荷分配的合理性。     

基于马氏距离算法的配电网故障定位系统研究

为了满足智能配电网故障定位的实时性、可靠性、准确性等需求,提出了基于马氏距离算法的配电网故障定位系统。以IDT智能配电终端作为系统运行状态电气量实时采集核心模块,按F检验获得元件电气量变化显著性概率P值初判故障元件和故障类型后,通过马氏距离算法准确定位故障区域和故障元件,并采用IEEE9节点系统的三相短路故障对配电网故障定位系统进行测试分析。仿真结果表明,该系统能真实地反映配电网故障后故障区域和故障元件的电气量变化,可满足智能配电网在线故障定位需求。     

Transient pattern analysis for fault detection and diagnosis of HVAC systems

Modern building HVAC systems are complex and consist of a large number of interconnected sub-systems and components. In the event of a fault, it becomes very difficult for the operator to locate and isolate the faulty component in such large systems using conventional fault detection methods. In this study, transient pattern analysis is explored as a tool for fault detection and diagnosis of an HVAC system. Several tests involving different fault replications were conducted in an environmental chamber test facility. The results show that the evolution of fault residuals forms clear and distinct patterns that can be used to isolate faults. It was found that the time needed to reach steady state for a typical building HVAC system is at least 50–60 min. This means incorrect diagnosis of faults can happen during online monitoring if the transient pattern responses are not considered in the fault detection and diagnosis analysis.