对于电厂电能质量的改善分析

结合实际阐述电能质量的几种改善方法与措施;无源滤波器、有源滤波器、静止型无功补偿装置,介绍了它们的基本组成和原理,这些方法可以有效地解决稳态时的电压质量问题;文章还就电能质量技术的改进与提高,提出系统化综合补偿技术是解决电能质量问题的＂治本＂途径,以解决动态电能质量问题。     

无功补偿技术在矿井供电系统中的应用

本文以某矿井工程为例,首先,对煤矿区的电能质量进行了电能质量测试设备的测量。测量结果显示,在三相区域内,矿区出现了相对稳定的状态。同时发现整个系统存在着功率因数偏低、无功波动变化幅度大以及谐波电流含量较高等问题。其次,对煤矿的无功补偿需求进行了分析,并设计了相关的无功补偿装置。最后,对比TCR型SVC和MCR型SVC的测试,以评估其在煤矿无功补偿中的效果。研究结果表明,无功补偿技术在煤矿电力系统中具有重要的应用价值。     

石化企业电网无功补偿分析

石化企业电网中感性负载较多,功率因数较低,因此电网中通常装有无功补偿装置改善电能质量、降低网络损耗。介绍了石化企业常用的无功补偿方方法、原则以及补偿量的计算方法,通过仿真计算,分析无功补偿地点以及补偿量对电网损耗的影响,为石化企业无功补偿提供理论基础。     

10KV配电网电能质量分析及改善措施研究

电能质量已经逐渐成为全世界共同关注的重要问题,电能质量关系着电网的安全经济运行,本文分析了无功对线损和电压的影响,采取配电变压器随器补偿以及配电线路分散补偿相结合的方式,提出对10KV配电网的电能质量改善措施。     

有源电力滤波器在化工企业中的应用

本文介绍了在改善电能质量,提升功率因数方面,低压无功电力补偿器和有源电力滤波器主要特点和使用效果。作者从自身工作经验,对两种电能质量提升设备分析和对比。使用电容器作为补偿设备时,提升功率因数效果明显,消除谐波效果不理想;使用有源电力滤波器,能够主动补偿无功功率,把检测的谐波抵消,并向电网系统注入相反的电流,达到既提供无功补偿,又消除谐波,改善正弦波形。     

无功补偿装置对提高电能利用率的影响

介绍了无功补偿对供配电系统电能质量的影响,为了提高电能的利用率,在此研究了如何减少感性负荷的无功储能。详细介绍了两种提高功率因数的方法：传统法和补偿法。传统法是对感性负荷自身进行改造或运行状态的改变来减少无功损耗;补偿法是通过给感性负荷并联电容器纽进行无功补偿的一种新型方法。目的都是为了提高电能的利用率和减少有色金属的浪费。研究结果证明,补偿法运行与维护方便,而且能够很方便地进行增加或减少容量的工作,安装也简单,在工厂广泛使用补偿法来提高功率因数。     

基于无功补偿的电力系统电压稳定控制分析与仿真

电压是电能质量的重要指标之一,而无功补偿是控制电力系统电压稳定性的有效手段.在电网中的适当位置装设无功补偿装置成为满足电网无功需求的必要手段.通过介绍电力系统电压稳定性的重要意义,引出无功功率对电压稳定性影响的理论性分析,并进一步分析了无功补偿对电压稳定性影响的原理.基于无功补偿的应用,介绍了主要的无功补偿装置及其发展.最后对装设了静止同步补偿器的电力系统进行了仿真,简明的反映了无功补偿对电压稳定性的影响及其重要性.     

有源电力滤波器的几种谐波软测量方法

对并联型有源电力滤波器的几种软测量方法进行了分析,谐波检测方法研究集中在瞬时无功功率理论和单位功率因数法上,并且指出了这几种方法的优、缺点,对电流平均值法提出了相应的改进方法并采用仿真软件Matlab进行了仿真。     

基于同步旋转坐标变换的三相锁相环设计

本文分析了有源电力滤波器需要实时检测正序基波电压的相位,作为计算和补偿标准。着重研究了基于同步旋转坐标变换的三相锁相环软件技术,分析了连续和离散数学模型,提出实现全数字化相位跟踪检测的方法。最后采用MATLAB的定点符号工具箱和Simulink进行仿真。理论推导和仿真验证了所提方法在电压波形畸变时仍实时可有效检测出正序基波相位。     

采用最小二乘支持向量机的PVC汽提温度逆补偿控制方法

基于最小二乘支持向量机(LSSVM)构建聚氯乙烯树脂(PVC)汽提过程的温度预测逆模型,将逆模型作为前馈控制器置于PVC汽提过程的前馈通道,以补偿汽提过程的非线性问题。在逆补偿控制的基础上加入PID控制器作为反馈控制器,对PVC汽提过程进行复合控制。通过汽提塔温度进行逆建模和仿真实验,仿真结果表明所提控制方法的控制效果更好。     

基于核主角的故障检测方法

基于主元分析（PCA）的统计检测方法已经被广泛应用于各种化工过程的故障检测和识别.移动主元分析（moving principal component analysis,简称MPCA）算法基于PCA,根据主元子空间的变化来判断故障是否发生.然而,基于主元分析的统计检测方法是线性方法,无法有效应用于非线性系统.因此,提出一种适合于非线性系统的故障检测方法——基于核主角(kernel principal angle,简称KPA)的故障检测方法,其基本思想与MPCA相似,主要内容包括构建特征子空间和核主角测量两部分.TE过程故障检测仿真实验证明,基于核主角的故障检测方法优于传统的多元统计检测方法（cMSPC）和MPCA.     

Colour metrics for image edge detection

Image edge detection based on low-level feature is usually performed on gray-scale images. Some methods have been developed for edge detection on colour images based on low-level feature, but they are not consistent with human colour perception. This research provides a new algorithm for edge detection based on the “HyAB” large-colour-difference formula. This algorithm uses Sobel operators for gradient-magnitude calculations and Canny methods for localizing edge points. The performance of the new algorithm is qualitatively compared with Sobal and Canny methods using some challenging colour images. The results indicate that gradient magnitudes are best calculated using the HyAB colour-difference formula, and that CIELAB and CIEDE2000 differences are not suitable for this purpose. Definition of gradient magnitudes according human perception is essential in applications such as quality control of fabric printing, calculation of disruptive colouration, and so on. The new algorithm is successful in accuracy and fine edge detection in comparison with the Sobel and Canny methods. The new method is quantitatively compared with state-of-the-art methods using three datasets including BSDS500, MBDD, and BIPED. The correctness and accuracy of annotations of images in datasets have an important effect on results. The new method does not reach scores better than deep-learning-based methods, but it is simple and does not need training. It could probably have better results with improving noise-suppression.     

3D打印混凝土可塑造性能的评价方法研究

本文就3D打印混凝土的可塑造性能的评价工作展开研究,包括成型时间、承载力、变形和失稳控制.成型时间是打印混凝土试体硬化特征的判别依据,本文提出和设计了可塑造时间比的评价及测试方法;针对于打印混凝土承载力的评价,给出了统一流变模型的实验方法与参数获取手段;分析了打印混凝土材料在可塑造性能研究中的变形控制问题,提出了两项变形控制的评价方法,还给出了打印混凝土失稳破坏的控制指标;最后,通过控制打印行程时间与混凝土材料硬化强度增长关系及试体载重特征值的关系,推导出了3D打印混凝土结构总攀升高度的计算方法.     

Closed‐loop Fault Detection Using the Local Approach

Fault detection and isolation (FDI) has become a crucial issue for industrial process monitoring in order to increase availability, reliability and production safety. Model‐based FDI methods rely on a mathematical model and input‐output data of a process to perform detection. The local approach is a new model‐based FDI method that aims to detect slight changes of a system's parametric properties. Closed‐loop detection is an important issue for the local approach since all control systems work under closed‐loop conditions. A new algorithm was proposed to revise the original detection algorithm in order to make it work for closed‐loop data. Simulation results show that the proposed method can detect the changes of parameters of a system that can affect closed‐loop performance.     

基于一阶滞后传递函数的换热器模型预测控制

针对换热器本身具有较强的纯滞性、约束性等特性,提出将模型预测控制应用于换热器控制中。首先将换热器近似处理为一阶惯性环节,推导出其传递函数作为预测模型;而后以输出误差与控制量加权之和的二次型性能指标为目标函数对其进行滚动优化,使全过程达到最优;最后,通过反馈校正构成系统的闭环优化,提高控制的鲁棒性。通过仿真实例证明:模型预测控制能够较好地处理换热器控制上的纯滞后等问题,具有较好的鲁棒性。     

Improved process monitoring using the CUSUM and EWMA-based multiscale PCA fault detection framework

Process monitoring techniques are of paramount importance in the chemical industry to improve both the product quality and plant safety. Small or incipient irregularities may lead to severe degradation in complex chemical processes, and the conventional process monitoring techniques cannot detect these irregularities. In this study to improve the performance of monitoring, an online multiscale fault detection approach is proposed by integrating multiscale principal component analysis (MSPCA) with cumulative sum (CUSUM) and exponentially weighted moving average (EWMA) control charts. The new Hotelling's T² and square prediction error (SPE) based fault detection indices are proposed to detect the incipient irregularities in the process data. The performance of the proposed fault detection methods was tested for simulated data obtained from the CSTR system and compared to that of conventional PCA and MSPCA based methods. The results demonstrate that the proposed EWMA based MSPCA fault detection method was successful in detecting the faults. Moreover, a comparative study shows that the SPE-EWMA monitoring index exhibits a better performance with lower values of missed detections ranging from 0% to 0.80% and false alarms ranging from 0% to 21.20%.     

DEVELOPMENT OF AN ISOTOPE-DILUTION GAS CHROMATOGRAPHIC-MASS SPECTROMETRIC METHOD FOR THE ANALYSIS OF POLYCYCLIC AROMATIC COMPOUNDS IN ENVIRONMENTAL MATRICES

An isotope-dilution GC-MS (GC-IDMS) method for the analysis of polycyclic aromatic hydrocarbons (PAHs) in various environmental matrices, including soils, sediments and an extended application to air particulate, has been developed. This method allows for the quantification of each target analyte against its isotope-labelled analogue as well as for the correction of analyte recovery during sample preparation and analysis. Using isotope-dilution mass spectrometric analysis, the isotope-labelled internal standards can significantly reduce systematic error (bias) from several sources including sample stability prior to analysis, analyte loss during both the extraction procedure and post-extraction sample workup and from the calibration procedure. Sample analysis and quantification was carried out using a multi-point calibration technique with continuing single-point calibration (daily single-point checks of the calibration) in order to assess daily instrumental performance; various other new quality control measures have also been employed. Faster methods of gas chromatographic analysis were evaluated using different types of GC columns, stationary phases and methods of detection. Overall, this method has improved the quality and accuracy of PAH data produced and has significantly reduced the time required for sample preparation.     

一种软测量模型性能监测评价及其自适应校正方法

工业过程对象特性变化会导致软测量的测量精度下降甚至失真,需要对软测量模型进行校正。首先构建软测量模型性能评价指标用于对模型性能进行监测。当性能评价指标超过统计限时,对过程特性变化类型进行诊断：若过程特性渐变,则对模型进行递推校正;若过程特性发生突变,则对模型进行重构校正。通过对连续搅拌釜式反应器和DAISY（database for identification of systems）数据库提供的蒸发器实际生产数据进行仿真实验,验证了本文方法的有效性。实验结果表明,该方法避免了传统校正方法存在的盲目校正、受离线分析噪声影响严重等问题,有效地提高了软测量模型对对象特性变化的适应能力。     

利用U形管测量低压环雾状流与液束环状流体积含气率

由能量方程出发,根据U形管垂直上升段与下降段的重位压降与摩阻压降的大小及方向之间的关系求得体积含气率测量模型,并通过实验研究了体积含气率测量误差的影响因素,利用体积含气率测量误差与流动密度测量值之间的线性关系对体积含气率进行了修正,使测量精度明显提高,并通过独立实验进行了验证。最后分析了U形管测量低压气液两相流体积含气率的适用范围。