The impact of high-energy proton irradiation on the low-frequency 1/f noise in FZ-silicon diodes

In this paper, the impact of high-energy proton irradiation on the low-frequency 1/f noise in p-type float-zone Si diodes is described and analysed in detail. More in particular, the effect on the noise magnitude, the current index β and on the frequency index γ is reported. It is shown that for large-square diodes, the irradiations cause a significant increase in the current noise spectral density S_I in forward operation, for not too high forward current I_F. This is accompanied by a reduction of the current index from 2 before to 1.5 after irradiation, which indicates a change in the underlying flicker noise mechanism. In order to trace back the origin of the excess 1/f noise, a comparison is made with the microscopic damage — coefficients for the ionisation damage the linear energy transfer function (LET) — and the non-ionising energy loss (NIEL) parameter, as a function of the proton energy in the range 10–100 MeV. The results strongly suggest that the source of the additional 1/f noise after proton exposure is located at the diode periphery rather than in the bulk.     

Analysis and optimization of high temperature proton exchange membrane (HT-PEM) fuel cell based on surrogate model

The stoichiometric ratio and flow channel geometry play a vital role in the performance of high temperature proton exchange membrane (HT-PEM) fuel cells. Because of the high cost of experiments or simulations, most analyses and optimization of the stoichiometric ratio and flow channel geometry are limited to several points in the entire design domain. In this study, an analysis and optimization method for HT-PEM fuel cells based on the surrogate model was proposed. Surrogate models were constructed using some of the available budgets of samples to analyze and optimize the entire design domain. With this method, it was indicated that the effect of the cathode stoichiometric ratio is more significant to the cell performance than the anode stoichiometric ratio and there are significant nonlinear interactions among the flow channel geometry parameters. At the fixed operating voltage, the flow channel geometry with the maximum current density and that with the maximum real power were obtained. Compared with the base design, the designs obtained by the surrogate model improve the current density and real power by 10.54% and 3.93%, respectively. Thus, this analysis and optimization method is demonstrated to be helpful and deserves attention in future research.     

考虑系统负荷规模的 CPS1 标准修正方法

CPS1( Control Performance Standard 1) 标准在应用于负荷规模悬殊控制区域中,存在适用性问题,故有必要对 CPS1 标准进行分析以便改进。通过对 CPS1 标准频率调节责任分配本质内涵的剖析,和负荷波动幅度与负荷规模之间关系的探究,指出 CPS1 标准是依据系统的负荷规模分配频率调节责任。由于负荷波动的平滑效应,负荷规模较大控制区域的负荷随机波动与负荷规模( 与发电规模相当) 的比值较小,因此,在实际运行中大区域获得较好的评价结果是一个必然现象。在明确了这两种模式下( 分别按照系统负荷规模和波动幅度分配频率调节责任) 评价标准适用条件的基础上,提出了适用于我国电网运行现状标准的改进方法,即: 无需进行 B系数分配原则的改动,直接对标准中的 B 系数进行相关修正即可解决其适应性问题。仿真算例结果分析表明,按照原有标准进行评价,大区域将获得较好的评价结果,而所提出 CPS1 标准调整方法可有效解决该问题。     

基于两段式水煤浆气化的气化参数对气化性能的影响

利用Thermoflex建立基于两段式水煤浆气化的气化岛流程模型,对影响两段式水煤浆气化性能的气化参数进行分析,研究二段给煤比对气化性能的影响。结果表明,随着二段给煤比的增加,合成气的有效气含量降低,而冷煤气效率先升后降。二段给煤比存在最佳值,综合考虑气化温度和冷煤气效率,最佳二段给煤比为0.1~0.15。     

1000MW超超临界机组小汽机瓦温高的原因分析及治理

1 000 MW超超临界机组小汽机为东方汽轮机厂设计制造,轴瓦采用可倾瓦设计,机组运行过程中,出现了2号轴瓦温度高问题。介绍了小汽机可倾瓦的结构特点和轴瓦温度高的事件经过等,针对可倾瓦温度高进行原因分析,并利用机组停运机会进行了有效治理,为其它机组在处理类似问题时提供参考。     

1000MW机组凝结水泵配置方案优化探讨

对国内1 000 MW火电机组所采用的凝结水泵配置方案进行介绍,着重分析了富川项目初步设计阶段凝结水泵配置方案可能出现的问题,并提出了优化对策。阐述了影响凝结水泵配置选型的几个重要因素,以及在选择配置方案过程中应该注意的问题,为同类机组提供参考。     

基于改进Apriori算法的直流闭锁受端断面越限调整策略

当发生特高压直流闭锁故障时,会实施一系列调控措施填补受端电网的功率缺额。针对一、二次调频之后存在的断面越限问题,提出了一种基于改进Apriori算法的断面越限调整策略。首先,采用动态潮流算法进行闭锁故障仿真,根据灵敏度方法对断面越限进行调整,再提取调整信息,经过数据处理,形成机组、负荷调整策略和断面状态变化情况数据库。然后,对Apriori算法进行改进,将前项约束为机组、负荷调整策略,后项约束为断面状态变化情况,通过关联分析得到调整策略与断面状态变化情况之间的强关联规则。最后,对锦苏直流闭锁故障进行仿真及关联分析来验证所提方法的有效性,结果表明,改进后的Apriori算法大大减少了无效规则的产生,通过关联分析可得到对断面调整有效的强关联规则,为电网的断面越限调整提供决策依据。     

大型燃煤电站锅炉能效评价与节能分析

为了分析燃煤发电能量转化与传递过程中的能效情况,挖掘燃煤发电机组的节能减排潜力,利用热平衡和㶲平衡的对比分析,揭示燃煤发电过程热损失和㶲损失的内在联系,进而揭示燃煤发电过程节能潜力的分布情况。基于节能潜力分布情况,深入讨论采用空气分级提高热风温度、富氧燃烧、降低过量空气系数和提高主蒸汽/再热蒸汽参数等节能技术方案,以确定分别降低燃烧㶲损失、传热㶲损失以及其他主要㶲损失的效果。研究表明,提高热风温度、提高空气含氧量、提高主蒸汽/再热蒸汽温度、提高主蒸汽压力等方案,可分别降低燃煤发电机组供电煤耗6~9、6~10、11和5~12g/(kW·h),为燃煤发电节能减排技术的进一步发展指明方向。