华能上安电厂2×350MW机组2号机给水泵汽轮机电液调节控制系统改造

介绍华能上安电厂一期工程 2× 35 0MW机组 2号机 2台给水泵汽轮机电液调节控制系统(MEH)改造背景、系统配置、主要功能及其评价。应用结果表明 ,采用分散控制系统硬件对GE公司的给水泵汽轮机控制系统进行改造 ,能够提高机组效益和自动化水平 ,为同类型机组MEH改造提供了经验     

华能上安电厂300 MW机组给水泵汽轮机控制系统的改造开发及应用

介绍华能上安电厂１号机组给水泵汽轮机控制系统（ＭＥＨ）改造背景、系统配置、主要功能及其软件结构。实践表明,采用ＩＮＦＩ９０硬件对ＧＥ公司的给水泵汽轮机控制系统进行改造,能够提高机组运行经济性和自动化水平,为同为型机组ＭＥＨ改造提供了经验。     

给水泵汽轮机的提效改造

结合300 MW机组给水泵汽轮机的提效改造实例,对比通流改造与整机更换两种方案,提出整机更换方案在给水泵汽轮机提效改造项目中的优势,为小型汽轮机的提效改造工作提供了新的方法和经验。     

300 MW机组汽动给水泵控制系统改造

针对沙角A电厂二期300 MW机组汽动给水泵控制系统润滑油和保安调节系统结构比较复杂,运行过程经常出现漏油及转速波动调节不稳等现象,分别对2台300 MW机组的给水泵汽轮机控制系统及润滑系统进行了改造,在新润滑油系统隔膜阀前加装蓄能器,调节保安系统采用电液转换器,由电-液调节改为纯电调控制.系统改造后,其可控性、稳定性均得到提高.     

给水泵组顺序控制及调节控制设计和调试分析

对西塞山发电厂1号机组N330-17．75／540／540型汽轮机所配电动给水泵组的顺序控制和调节控制系统的组态设计特点和工程调试要点进行了深入分析,为今后实现大型火电机组同类配置的电动给水泵组控制的工程化具有借鉴意义。     

200 MW机组汽轮机控制系统自动化改造

结合邢台发电厂６号机组热控自动化改造工程,详细叙述了国产２００ＭＷ机组原汽轮机控制系统存在的问题,汽轮机控制系统的自动化改造的必要性,以及汽轮机控制系统改造的方案。通过自动化改造能够改善机组性能,提高可靠性和经济效益,实现ＡＧＣ控制。     

300 MW直接空冷机组给水泵电泵改汽泵方案分析

早期直接空冷机组大多数使用电动机来驱动给水泵,厂用电率较高,其驱动方式改造可以降低厂用电率。对山西某300 MW直接空冷机组给水泵驱动方式改造方案的技术、经济性进行了分析,计算了给水泵驱动方式改造前后厂用电率、给水泵及其配件的总效率和电厂运行效益的变化。结果表明:给水泵改为小汽轮机驱动后,机组的厂用电率降低约2.7%,年运行收益可达2097万元。     

给水泵汽轮机排汽方式的优化及其热经济性分析

分析给水泵汽轮机排汽排入主凝汽器对汽轮机真空的影响,提出在凝结水泵与轴封加热器间加装小型凝汽器来回收部分给水泵汽轮机的排汽热量的改造设想。以600 MW机组为例,计算改造后机组效率的变化。计算结果表明,改造后主凝汽器蒸汽负荷减少,机组做功及效率提高,能有效地降低标准煤耗率,经济效益显著。     

CC60-8.83/4.12/1.47型汽轮机推力轴承改造

分析了CC60－8．83／4．12／1．47型汽轮机现有推力轴承各瓦块载荷不均，个别瓦块温度偏高等缺陷产生的原因，介绍了LEG均衡载荷推力轴承的工作原理和技术特点，以及推力轴承改造的技术方案，改造后运行显示：推力轴承的瓦块温度大幅下降，且性能稳定，长期来困扰机组运行安全的推力轴承瓦温偏高问题得以解决。     

压力匹配器用于大型机组汽动给水系统经济性分析

针对大型机组汽动给水泵在低负荷下,仅靠改变主汽轮机抽汽点来满足小汽轮机进汽参数的方法经济性不够好,提出了在原汽动系统中加装压力匹配器,并利用主机高压抽汽引射低级抽汽的改造方案。以某300 MW机组为例,分析其不同方案下各引射系数及相关理论,通过改造前后的能耗比较,加装压力匹配器可节能10%~15%,为工程应用提供理论依据。     

PAS/DMS/DMIS/TMR一体化系统的研究与设计

统一筹划电力监控自动化系统的一体化建设是国内外电力行业和技术标准组织普遍提出的思想.阐述了配套自动化子系统在电网建设初期在信息交换上的实际需要和复杂性,提出了基于IEC 61970标准和CIM/XML的无缝连接一体化自动化系统的目标.在数据库、网络和通信技术的基础上构建了能对各个配套自动化子系统实现相对高度统一的数据和信息共享的平台.最后论述了该系统建设中需要注意的技术特点和系统所具有的显著优点.     

PAS/ DMS/ DMIS/ TMR 一体化系统的研究与设计

统一筹划电力监控自动化系统的一体化建设是国内外电力行业和技术标准组织普遍提出的思想。阐述了配套自动化子系统在电网建设初期在信息交换上的实际需要和复杂性,提出了基于IEC61970标准和CIM/XML的无缝连接一体化自动化系统的目标。在数据库、网络和通信技术的基础上构建了能对各个配套自动化子系统实现相对高度统一的数据和信息共享的平台。最后论述了该系统建设中需要注意的技术特点和系统所具有的显著优点。     

欧洲共同体指令94/9/EC的重要性

概要现在在整个欧共体范围内对防爆进行了新的规定。欧洲共同体指令 94/9/EC为防爆设备、元件、保护系统投放市场提供了新的法律框架 ,并且已经生效。电气设备、非电气设备和自动保护系统第一次同时被收进指令中。增补的欧洲指令1 999/92 /EC包含有对潜在的爆炸进行人身的保护条款提供给用户 ,最近已被采用。对于化学工业中有潜在爆炸性环境的多数工厂的操作者来说 ,明确新指令的重要性 ,并按照新指令进行操作非常重要。最重要的是执行EC指令的方式、EC指令的实际解释和应用。防爆领域内统一要求的目的是消除产品自由贸易的壁垒。扩大市场、为欧洲提供更多的经济贸易机会 ,减少竞争的不利因素。合理应用EC指令规定的准则是 ,必须防止使制造商和用户在安全方面没有收获却增加了额外费用。现在对新指令提供的机会和风险予以讨论     

Breakdown voltages of polymers in the temperature range 23/spl deg/-250/spl deg/C

The direct voltage electric strengths of several polymers are measured using a new type of environmental chamber in which a new specimen of the material can be introduced without the necessity of cooling and reheating after every voltage application. The range of temperatures at which investigations are carried out is 23/spl deg/C-250/spl deg/C. The plots of the dielectric strength on Weibull paper demonstrates departure from the two parameter Weibull distribution, particularly at low field strengths. In each case the method of determining the more favorable distributions are discussed with the view of obtaining consistent results for the dielectric strength. The lower voltage breakdown cannot be ignored if high reliability is desired and the evaluated dielectric strengths on this basis are also presented. The polymers studied are aromatic polyamide, PTFE, aromatic polyimide and polyamide-polyester-polyamide composites. Thickness effects are presented for selected polymers.     

Effect of nitrogen on the band structure and material gain of In/sub y/Ga/sub 1-y/As/sub 1-x/N/sub x/-GaAs quantum wells

The conduction subband structure of InGaAsN-GaAs quantum wells (QWs) is calculated using the band anticrossing model, and its influence on the design of long-wavelength InGaAsN-GaAs QW lasers is analyzed. A good agreement with experimental values is found for the QW zone center transition energies. In particular, a different dependence of the effective bandgap with temperature when compared to the equivalent N-free structure is predicted by the model and experimentally observed. A detailed analysis of the conduction subband structure shows that nitrogen strongly decreases the electron energies and increases the effective masses. A very small N incorporation is also found to increase the nonparabolicity, but this effect saturates for higher nitrogen contents. Both the In content and well width decrease the effective masses and nonparabolicity of the conduction subbands. Material gain as a function of the injection level is calculated for InGaAsN-GaAs QWs for moderate carrier densities. The peak gain at a fixed carrier density is found to be reduced, compared to InGaAs, for a small N content, but this reduction tends to saturate when the N content is further increased. For the gain peak energy, a monotonous strong shift to lower energies is obtained for increasing N content, supporting the feasibility of 1.55-/spl mu/m emission from InGaAsN-GaAs QW laser diodes.     

Influence of Cr/sub 2/O/sub 3/ and MnO additives on the surface properties of alumina insulators

Alumina insulators containing 95wt% Al/sub 2/O/sub 3/ were doped with Cr/sub 2/O/sub 3/ and MnO(MnCO/sub 3/). The properties of the doped samples were measured and compared with those of the original alumina insulators. Better surface performances of the samples doped with proper Cr/sub 2/O/sub 3/ and MnO were obtained while the bulk properties have hardly been changed. After doping the sample showed a lower SEE (secondary electron emission) coefficient, a lower surface resistivity and a higher surface flashover voltage in vacuum. Meanwhile, some points regarding the effects of manganese and chromium doping on the properties of alumina insulators were also briefly discussed.     

双马来酰亚胺/烯丙基苯基化合物/环氧化合物共聚树脂的研究与应用

介绍和评述了双马来酰亚胺(BMI)/烯丙基苯基化合物(APC)/环氧化合物(EP)高性能多元共聚树脂的化学结构与固化反应,以及在耐热电绝缘材料、高性能覆铜板、半导体封装材料和耐热胶粘剂等领域的研究与应用进展情况。     

Effects of Ar post-annealing on the electrical properties of Pt/YMnO3/p-Si and Pt/YMnO3/Y2O3/p-Si

Abstract

YMnO₃ thin films were prepared on p-Si(111) and Y₂O₃/p-Si(111) substrates by chemical solution deposition and annealed at 800°C for 1 hour under the oxygen pressure of 2 Torr. The YMnO₃ thin films showed good crystallinity and c-axis preferred orientation. Effects of Ar post-annealing on electrical properties were examined in Pt/YMnO₃/p-Si and Pt/YMnO₃/Y₂O₃/p-Si structures. Leakage current densities decreased considerably by Ar post-annealing. The Pt/YMnO₃/p-Si and Pt/YMnO₃/Y₂O₃/p-Si showed clockwise C-V hysteresis induced by ferroelectric polarization after Ar post-annealing and memory windows of MFS and MFIS structure were 1.1V and 0.6V, respectively.     

零电流Buck/Boost双向DC/DC变换器的研究

针对中大功率双向DC/DC变换器软开关难以实现的问题,基于耦合电感(变压器)设计了一种无源低损软开关方案.实现了开关管的零电流开通并回馈缓冲能量.详细分析了变换器的工作原理并设计了主要元件参数,据此推导出主要开关器件的开通损耗估算表达式.实验表明,零电流开通效果良好,缓冲电感能量回收效果明显,60kW变换器装置在较宽的功率范围内效率达90%以上.     

The influence of the dielectric strength of the N/sub 2//SF/sub 6/-insulation by conducting particle on the spacer surface

This paper investigates the dielectric properties of various N/sub 2//SF/sub 6/ gas mixtures based upon a cylindrical spacer model with adhering particle on the surface tinder homogeneous field conditions. The investigation involves a comparison with pure SF/sub 6/. The flashover field strength for clean and particle contaminated spacer surface under AC and LI stress is determined. The results of the investigations show the sensitivity of N/sub 2//SF/sub 6/ gas mixtures to conducting particles on spacer surfaces for gas pressures up to 800 kPa. Moreover, the correspondence between pure SF/sub 6/ at pressure range from 100 to 400 kPa and N/sub 2//SF/sub 6/ gas mixtures for AC and lightning impulse (LI) flashover field strength range from 50 to 178 kV/cm is determined. Conclusions are drawn about the ability of SF/sub 6/ gas mixtures to serve as technically efficient media for GIS/GITL. The results shed light on the issue of the SF/sub 6/ reduction and particle detectability in GIS/GITL.