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侯典来 《世界仪表与自动化》2005,9(11):36-38
随着机组容量的不断增加和市场经济的进一步深入,电网的供电质量要求也越来越高,要求电网频率非常稳定,满足各用户的要求,根据山东电力调度中心对机组参与电网一次调频的要求,验证DCS、DEH的一次调频逻辑、参数设置,考察300MW机组参与电网的一次调频特性。 相似文献
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浅析汽轮机DEH一次调频 总被引:1,自引:0,他引:1
汽轮机DEH系统的大量应用,不仅增强了汽轮机的可控性。提高了机组的安全性和热效率,其它许多优越性也越来越突出的表现出来。但是大量新建电厂不愿投入一次调频,而陈旧的液调机组一次调频速度又太慢,电网周波的稳定性日渐受到影响,甚至可能威胁到整个电网的安全运行。文中根据汽轮机DEH系统的特点,分析了国内一次调频的必要性和对机组的影响,以及其实现方法。 相似文献
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主要介绍了台山电厂5号机组一次调频控制原理,根据广东电网提出的一次调频要求,对一次调频控制逻辑进行优化,并通过一次调频试验验证优化结果。 相似文献
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在电力提灌多梯级泵站的运行中,泵站前池水位的平衡调节是工程运行管理特别是运行调度管理的难点。实现泵站前池水位科学合理调节,将对节约能源,保证工程设施及机电设备的安全运行,提高干渠水利用系数,充分发挥工程经济效益均具有十分重要的作用。笔者就景电工程泵站前池水位调节控制的必要性、依据和调节控制的模式进行阐述。 相似文献
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V. A. Grechikhin T. A. Khrennikova 《Optoelectronics, Instrumentation and Data Processing》2018,54(1):13-18
This paper describes the analysis of the potential accuracy of estimation of the signal modulation index of a homodyne laser Doppler vibrometer with frequency modulation and known and unknown non-information parameters of the signal. The Rao — Cramer inequality is used to obtain expressions for calculating the lower bound of variance of the modulation index estimate and study its relationship with a signal/noise mixture. Recommendations on the choice of conditions for measuring the amplitude of vibro-displacement by the homodyne Doppler laser vibrometer are given. 相似文献
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DPSK调制方式在S模式数据链通信系统中的应用研究 总被引:1,自引:0,他引:1
S模式询问信号包括前同步脉冲与有效数据两部分,它经过DPSK调制之后被发送出去。在研究S模式询问信号的特点、格式和DPSK调制解调原理的基础上,论述了DPSK调制解调原理,并在FPGA中用Verilog语言编程实现了S模式询问信号的产生和提取,给出了位同步实现方法,得到了正确的仿真结果。 相似文献
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通过施加调制磁场降低测量1/f噪声、实现矢量化测量,是原子磁力仪中常用的方法。根据调制磁场频率与弛豫率的相对大小,可以分为低频调制和高频调制两大类。本文对高频调制原子磁力仪进行了总结和分类,按照调制磁场方向与抽运光方向的相对位置分为平行调制与垂直调制两大类,之后再按照主磁场方向细分为七类不同的配置。详细分析了其中四类较为常见的配置,分别是垂直调制X型、垂直调制零场型、平行调制Z型和平行调制零场型。从Bloch方程出发,推导了这4类配置的测量解析模型,除了梳理和验证现有文献的理论分析之外,也得到一些现有文献没有提及的测量模型。采用MATLAB Simulink模块进行了数值仿真,验证了解析模型推导过程一些简化处理的合理性。给出了Bloch方程的通用Simulink模型,可用于任意配置原子磁力仪的数值仿真。 相似文献
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Active suppression of chatter in peripheral milling Part 1. A statistical indicator to evaluate the spindle speed modulation method 总被引:1,自引:1,他引:0
Professor F. Ismail E. G. Kubica 《The International Journal of Advanced Manufacturing Technology》1995,10(5):299-310
This work investigates the potential of employing the spindle speed modulation method for real-time control of chatter in peripheral milling. The first part of the study concentrates on developing a measurable chatter indicator which can quantify the relative vibration suppression properties of various speed modulation parameters. Experimental and simulation runs have shown that this indicator provides a well-behaved estimate of the relative cutting condition. The simulation and the experimental set-up for implementing spindle speed modulation are described. Different amplitude-frequency combinations of sinusoidal fluctuations were tested at 20% and 50% beyond the limit of stability both numerically and experimentally with steel workpieces. They showed higher vibration suppression with increased values of speed modulation parameters, which is a general trend that was also reported in other works conducted under different environments. 相似文献
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We discuss here the principles of a novel optical method in which the scanning of a laser spot around a fluorescent object is used to determine its shape, orientation, and fluorophore distribution. The scanning pattern is adapted to the shape of the object according to a feedback principle based on intensity modulation measurements. The modulation of the intensity with respect to the angular coordinate is used to keep the orbit centered on the object. The modulation induced by rapid oscillations of the orbit radius is used to measure the local distance from the surface with nanometer precision. We provide a model to describe the fundamental relationship between modulation and distance and discuss the range of validity of several approximate expressions. According to this model, the distance can be measured with a precision dependent on the steepness of the point spread function and the total number of detected photons. To test our findings, we performed experiments with one or two channels on fluorescent spheres of known size and characterized the modulation function of our microscope setup. We conclude that the method can be used to measure distances in the range 10–200 nm between two surfaces labeled with two different probes. Microsc. Res. Tech. 75:1253–1264, 2012. © 2012 Wiley Periodicals, Inc. 相似文献
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A Study of the Influence of Superimposed Low-Frequency Modulation on the Drilling Process 总被引:1,自引:0,他引:1
A preliminary investigation of the effects of low-frequency modulation of the force in drilling has been completed. Important changes occur in the drilling of aluminum with the imposition of modulation at frequencies below 200 Hz. The effects depend on the amplitude of the modulation and the relationship of the frequency of modulation fp to the frequency of rotation of the drill fd. When fp/fd is an even integer, the modulation introduces no significant effects in the force, torque, or chip morphology. When fp/fd is an odd integer, the average drilling force decreases, and a large dynamic component of force and torque is seen with a frequency dependence fp. For peak-to-peak amplitudes of vibration that are greater than one-half of the drill feed/rev, the chips are broken. A simple explanation of these effects is provided. 相似文献