高压变频器在华能曲阜电厂凝结水泵上的应用

本文首先阐述了变频调速技术的基本节能原理,然后通过对凝结水泵变频改造方案、项目实施的介绍及改造后节能效果的比较分析,证明了凝结水泵变频改造节能效果显著、具有较高的经济效益。     

高压变频器在电厂循环水泵上的应用

本文介绍了高压变频器在广西信发铝电集团电厂循环水泵机组中的应用情况,通过对水泵变频改造方案的介绍及改造后运行效果的比较分析,表明电厂循环水泵机组变频改造节能效果显著,具有较高的经济效益。     

变频技术在空分装置循环水系统中的应用

介绍了循环水泵改造前的运行情况和变频技术节能的理论依据以及在循环水泵上进行改造的方法,并对变频改造的效益进行了分析。     

临河热电厂凝结水泵变频调速改造实例

针对临河热电厂#2机组凝结水泵设计裕量偏大,电机长期低效运行的实际问题,选用ZINVERT系列高压变频器进行一拖二接线方式的变频调速改造。项目完成了变频器安装、调试和DCS系统接入等工作。通过对改造前、后的现场参数对比和电量统计得出凝结水泵变频运行节能效果显著的结论。     

浅析火力发电厂凝结水泵变频节能改造

火力发电厂的电机节能一直受到电厂的高度重视。随着经济的增长,我国正面临能源危机,因此加强能源的有效利用,是节约资源、促进可持续发展的重要手段。针对采用变频的方式对凝结水泵进行节能的技术改造,介绍了改造的必要性、改造前的情况、改造的方案、及改造后节能、节电的分析计算方法,阐述了变频改造后产生的直接经济效益和间接经济效益,说明了凝结水泵变频技术改造的必要性。     

信发铝电氧化铝循环水泵变频调速改造

本文介绍了高压变频器在广西信发铝电集团氧化铝循环水泵机组中的应用情况,通过对水泵变频改造方案的介绍及改造后节能效果的比较分析,表明氧化铝企业循环水泵机组变频改造节能效果显著,具有较高的经济效益。     

高压变频在600MW火电厂10kV凝结泵上的应用

本文介绍了级联多单元高压变频调速装置在600MW空冷发电机组凝结水泵节能改造中的应用，简述了装置的工作原理和“一拖二”连接方法，并进行了节能经济分析。     

高压变频器在600MW发电机组凝结水泵上的应用

本文阐述了国产高压变频装置在上海吴泾第二发电有限责任公司600MW机组凝结水泵中的应用情况。着重介绍凝结水泵采用变频装置的改造方法和设备选型，分析变频改造后的经济效益和社会综合效益。[编者按]     

浅谈火电厂凝结水泵高压变频改造应注意的问题

针对当前火电厂凝结水泵高压变频改造现状,从"电气改造方案"、"保护功能"、"控制策略"三个方面,阐述了改造应注意的问题。并以广安电厂600MW机组凝结水高压变频改造为例,论证了注意这三方面问题的必要性和可行性。     

高压变频器一拖二自动旁路系统在凝结水泵上的应用

本文着重介绍了国产高压变频器一拖二自动旁路系统的控制方式和基本逻辑,通过比较凝结水泵改造前后的运行情况,分析变频改造给电厂带来的方便和直观的经济效益。     

高压变频器在华电贵州大方电厂300MW火电机组凝结水泵上的应用

随着高压变频装置应用领域不断扩大,300MW机组凝结水泵上也开始应用。300MW机组配套的凝结水泵采用变频装置后,流量的调节不再依靠传统的阀门或回流方式。本文结合华电贵州大方电厂的变频改造项目,介绍了凝泵变频系统的特点,使用变频调速装置不仅可以达到明显的节能目的,更主要是调节性能好,同时也改善了水泵和电动机起动问题,延长了设备的使用寿命,降低了现场设备的维护量。     

机组循环水变频节能优化系统的应用研究

通过对循环水系统的运行方式进行剖析,结合高压变频调速技术在循环泵变工况运行方式中的应用,从另外角度分析实现机组经济性优化运行的方式方法。阐述循环水系统进行变频节能优化的可行性,为循环水变频系统的优化运行提供可借鉴的依据。     

Wavelength conversions in quasi-phase matched LiNbO/sub 3/ waveguide based on double-pass cascaded /spl chi//sup (2)/ SFG+DFG interactions

Based on the cascaded nonlinear interactions (/spl chi//sup (2)/:/spl chi//sup (2)/) of sum- and difference-frequency generation (SFG+DFG), a novel all-optical wavelength conversion scheme is proposed for the first time in periodically poled LiNbO/sub 3/ (PPLN) waveguide, in which a double-pass configuration is introduced. The performance of this scheme is thus different from the previous single-pass SFG+DFG scheme. The concept of the "balance condition" is presented to optimize the power and frequencies of the two pump sources. Under this condition, the energy is transferred irreversibly from the pump waves to the SF wave during the forward propagation. The equations describing the SFG can be solved analytically under this condition. Subsequently, the DFG equations are solved under the assumption that the SF wave would be constant during the backward propagation. Theoretical expressions are derived and are found to be consistent with numerical calculations. Compared with the conventional converter based on the cascaded /spl chi//sup (2)/:/spl chi//sup (2)/ interactions of second-harmonic generation and difference frequency generation SHG+DFG, the same conversion efficiency can be achieved in our scheme by employing two pump sources with lower power, or conversely higher conversion efficiency can be reached using two pump sources similar to that used in SFG+DFG scheme. The profile of the conversion efficiency can be further improved by adjusting the wavelengths of the two pump sources. In addition, compared with the single-pass SFG+DFG scheme, the main advantage of this new scheme rests on the fact that the conversion efficiency can be enhanced significantly. The advantages of the double-pass SHG+DFG scheme and the single-pass SFG+DFG scheme are combined in this new design to a great extent.     

M701F4型燃机单轴联合循环机组汽轮机主汽门控制分析

汽轮机的主汽门在机组启停过程中起着重要的作用,本文通过分析M701F4型燃气—蒸汽联合循环机组汽轮机主汽门的控制逻辑,使运行人员更好的掌握机组运行中主汽门的动作过程和动态特性,以优化特殊工况下的操作并给事故处理和分析提供理论依据.     

Analysis of novel cascaded /spl chi//sup (2)/ (SFG+DFG) wavelength conversions in quasi-phase-matched waveguides

A novel cascaded second-order nonlinear interaction (/spl chi//sup (2)/), which is simultaneously based on sum frequency generation (SFG) and difference frequency generation (DFG) processes, is proposed and analyzed in quasi-phase-matched wavelength converters. Analytical expressions with clear physical insights are derived for the converted light. It is shown that the same conversion efficiency can be achieved by employing two pump sources with lower output power (P/sub p1/,P/sub p2/) in this novel scheme as compared with the conventional cascaded wavelength conversion technique based on second-harmonic generation and difference frequency generation (SHG+DFG) with a single higher power pump beam (P/sub p/=P/sub p1/+P/sub p2/). The theoretical results are consistent with the experimental ones. It is found that the pump wavelength difference can be separated by a span as large as 75 nm, while large 3-dB signal conversion bandwidth is retained. The results show that the novel cascaded /spl chi//sup (2)/ wavelength conversion scheme is very attractive for practical applications.     

Optical parametric oscillation with intracavity sum-frequencygeneration

Theoretical calculations of an optical parametric oscillator containing an intracavity sum-frequency crystal are presented for the case in which only the signal beam from the parametric generation process oscillates in the cavity. The pump beam that is not converted in the parametric generation process is summed with the signal beam to produce a beam at the desired frequency. The stable steady-state configurations that completely deplete the incident pump radiation are determined. When the sum-frequency crystal precedes the parametric-oscillator crystal, steady states with nearly complete pump depletion can occur for over a factor of twelve variation in the pump intensity. Other regimes of operation display period-doubling routes leading to chaotic solutions. A numerical calculation for conversion of 1.064-μm radiation to 589-nm light yields an intensity conversion efficiency of 86.6%     

Optical frequency conversion in quasi-phase-matched stacks of nonlinear crystals

We present a quantitative theory of nonlinear frequency conversion in stacks of crystals where the phase mismatch due to dispersion is compensated by changing the sign of the nonlinear coupling coefficient in successive crystals-a method first proposed by Armstrong et al. We include pump depletion in our calculations of the second harmonic generation and sum and difference frequency generation. We start with ideal stacks in which the crystal lengths are tailored to achieve perfect phase compensation. When the conversion in each coherence length is small, all crystal lengths tend to equal the coherence lengthpi/Deltak. Frequency conversion in such stacks is well approximated by that in an equivalent phase-matched crystal with the nonlinear coupling coefficient reduced by a factor of2/pi. The effect of systematic as well as random departures in crystal lengths are studied with special attention to the evolution of the relative phase. We show that with appropriate choice of the signs of the nonlinear coupling coefficient in various crystals, high efficiency frequency conversion should be possible using practically any sufficiently large set of nonlinear crystals. The theory of second harmonic generation in periodic stacks and in rotationally twinned crystals of zinc-blend structure is described in detail.     

飞秒级超短脉冲光参量转换效率及脉冲特征计算

建立了超短脉冲光参量产生过程的理论模型,数值求解耦合波方程组,研究了在飞秒 级超短脉冲的光参量产生过程中,泵浦光的强度和脉宽对转换效率、输出脉冲的宽度和不对称度的影响。结果表明:泵浦光越强,光参量产生的转换效率越高,同时脉宽的压窄效应越明显;泵浦光的脉宽越窄, GVM参数和IGVD参数就越大,导致转换效率下降,同时引起输出脉冲的脉宽变大和波形的对称性变差。     

基于铌酸锂晶体电光效应的差频转换效率调制

为了在差频过程中得到较高的转换效率,利用铌酸锂晶体的电光效应来改变晶体的折射率,进而在非线性过程中调整位相失配量来实现差频转换效率的调制,模拟了外加电场对差频转换效率的影响。结果表明,利用铌酸锂晶体的电光效应,可以在任意给定抽运光强的情况下,获得较高的差频转换效率。这一结果对于获得新的中红外光源是非常有益的。