运算周期和算法块时序对机组超速保护逻辑的影响

火力发电厂汽轮机控制系统中的超速103%保护控制和超速110%保护跳机是机组紧急跳闸回路中一条重要分支,针对国华电力某台600MW机组发生超速保护误发事故,分析了汽轮机控制系统中逻辑运算功能块的排序问题以及运算周期对超速保护的影响,通过试验验证了运算周期和时序对选择功能块的影响.制定了改进措施,总结了事故教训,提出了逻辑设计中要注意的事项.     

联合循环汽轮机DCS直流油泵保护缺陷处理方案

针对印度尼西亚某电厂联合循环机组汽轮机DCS直流事故油泵低油压保护逻辑存在的问题,提出了有针对性的解决方法,并在机组停运期间对设备系统进行改造,新增硬接线联锁启动功能,经过试验及试运行达到了预期效果,确保汽轮机直流事故油泵能够可靠启动,降低汽轮机断油烧轴瓦的风险.     

汽轮机超速保护系统优化

本文结合高安屯燃气热电厂300MW汽轮机实际情况,对超速保护系统线路的设计进行总结和分析,并对超速保护系统供电和负载回路提出优化方案。     

DCS中顺序控制功能块应用及综合设计

在集散控制系统中,控制功能的实现是依靠控制功能块正确使用和控制回路图的正确连接.文中分析研究了常用的顺序控制功能块即定时器和计数器.对连续控制中选择开关SW-33与顺序控制的综合应用进行了设计分析.编写了顺序控制表.并对集散控制系统中应用实例进行了控制方案实现和运算块程序设计.     

汽轮机控制的相关问题及优化措施

汽轮机控制是燃煤电厂核心控制系统,直接关系整个机组的安全稳定运行。本文收集了某电厂汽轮机从调试至机组稳定运行期间暴露的各种典型问题和缺陷,并对其进行了详细分析,优化了汽轮机控制的运行逻辑、控制逻辑、保护逻辑等,针对可能影响机组安全运行的缺陷,提出了解决方案。     

maxDNA大型分散控制系统在1000MW超超临界机组DEH和ETS中的应用

针对1000MW超超临界汽轮机特点和控制、保护要求,采用国产maxDNA大型分散控制系统,通过合理的硬件配置和控制算法软件设计,实现国产分散控制系统在百万机组汽轮机数字电液控制系统和危急保护系统上的首次一体化成功应用,打破了国外系统在此领域的垄断地位,最终实现国产系统在百万机组锅炉、汽轮机和电气一体化监视、控制与保护....     

DCS中顺序控制功能块应用及综合设计

在集散控制系统中,控制功能的实现是依靠控制功能块正确使用和控制回路图的正确连接。文中分析研究了常用的顺序控制功能块即定时器和计数器。对连续控制中选择开关SW-33与顺序控制的综合应用进行了设计分析。编写了顺序控制表。并对集散控制系统中应用实例进行了控制方案实现和运算块程序设计。     

控制逻辑中功能块的处理时序对DEH控制品质的影响

以广东粤电湛江生物质发电项目工程2×50MW机组为例,对DEH仿真试验过程中出现的并网后调阀振荡问题进行分析研究,得出控制逻辑中功能块的处理时序错乱会对DEH控制品质造成严重影响的结论。并对国电智深DEH控制逻辑中的功能块进行重新排序,达到理想的控制品质。     

PLC在汽轮机保护ETS中的应用

1引言大型单元机组的特点是机、炉、电在生产过程中组成一个有机的整体,加之有大量复杂的控制系统及装置,其相互间的关系又都非常密切。当其中某些环节发生故障后将会影响整个机组的安全运行,严重的故障可能导致停炉停机,甚至危及设备和人身安全。汽轮机是高速旋转的机械,机组在危急情况下,完全依靠人工操作是不安全的。因此,在装设机械的危机保安器(超速及手动)之外,还装设自动停机的紧急停机系统(ETS)。ETS的任务是对机组的一些重要参数进行监视,并在其中之一超过规定危险值时,发出遮断信号给汽轮机调节系统去关闭汽轮机的全部进汽阀门…     

PROFIBUS-DP在轧钢厂双边剪控制系统中的应用

PROFIBUS-DP最主要的应用就是工业现场级主从站之间周期的数据交换,从而实现工业控制网络的实时通讯;针对一个兼有高度实时性和快速性的多机械联动的复杂机组传动系统,提出了基于PROFIBUS-DP的现场总线控制系统;根据系统的实际应用,分析了不同情况下总线循环周期的变化,总结了影响控制系统实时性的几个因素,最后给出了提高系统实时性的几个建议.     

Effective solution of certain problems of theory of schedulings of nets

Cybernetics and Systems Analysis -     

Complexity of families of learning algorithms and estimation of the nonrandomness of extraction of empirical regularities

The paper presents a general approach to the evaluation of the complexity of classes of algorithms, so-called pVCD-method. To develop this method, all the examined families of models of empiric generalization were restricted to classes implementable on computers and, wider, by examining their partially recursive representations. Within the framework of the algorithmic approach, the concept of Kolmogorov’ complexity of algorithms for the recognition of properties or the extraction of regularities is proposed. The method proposed to evaluate the nonrandomness of the extraction of empirical regularities is based on this concept.     

Analysis of microdensitometric data in terms of probability of cleavage of DNA

Computer-aided analysis of autoradiographic films of DNA fragments is presented. The Powell least-squares procedure is used for optimization of parameters for components of complex densitometric curves. Since each densitometric spectrum may be divided for several non-overlapped blocks of bands, there is no upper limit on the number of parameters which must be optimized. Eight shapes for the component bands are utilized: symmetric and asymmetric Gauss and Cauchy functions, direct, symmetric and asymmetric product of Gauss function and inverse of Cauchy function, and log-normal function. The probability of DNA cleavage is calculated with correction for multiple cuts. The methods presented was applied to detailed analysis of densitometric spectra of a 21-bp DNA restriction fragment and allowed for direct correlation between structural microheterogeneity of DNA and the resulting cutting pattern. This method should facilitate the analysis of densitometric data from antibiotic-induced cleavage of DNA and footprinting experiments.     

联合收割机脱粒滚筒恒速智能控制器设计

研究了轴流式联合收割机的控制问题,给出了联合收割机脱粒滚筒的数学模型,介绍了基于模式识别的智能控制原理,建立了联合收割机脱粒滚筒恒速控制模型,设计了基于模式识别的智能恒速控制器.应用Matlab/Simulink进行了控制器仿真,其结果表明,将基于模式识别的智能控制应用于联合收割机脱粒滚筒的恒速控制,其过渡过程平稳、响应速度快、无超调、无振荡并且无稳态误差.     

An estimate of numbers of terms of semicycles of delay difference equations

In this paper, we study the semicycles of oscillatory solutions of the delay difference equation y_n+1 − y_n + p_ny_n-k = 0, where p_n is a sequence of nonnegative real numbers and k is a positive integer. Upper bound of numbers of terms of semicycles are determined in the case when

Our results improve and complement known results in literature.     

Complexity of approximation of 3-edge-coloring of graphs

The problem to find a 4-edge-coloring of a 3-regular graph is solvable in polynomial time but an analogous problem for 3-edge-coloring is NP-hard. To make the gap more precise, we study complexity of approximation algorithms for invariants measuring how far is a 3-regular graph from having a 3-edge-coloring. We show that it is an NP-hard problem to approximate such invariants with an error O(n1−ε), where n denotes the order of the graph and 0<ε<1 is a constant.     

Modifications of the method of variation of parameters

In spite of being a classical method for solving differential equations, the method of variation of parameters continues having a great interest in theoretical and practical applications, as in astrodynamics. In this paper we analyse this method providing some modifications and generalised theoretical results. Finally, we present an application to the determination of the ephemeris of an artificial satellite, showing the benefits of the method of variation of parameters for this kind of problems.     

计算机辅助课表编排技术的研究

讨论了几种实用的计算机辅助课表编排技术及在实际编排中的应用。应用分析表明，采用分批与或图搜索和分批优化的匈牙利算法相结合的方法，在计算机辅助课表编排中是行之有效的。