基于频率解调方法的柴油机瞬时转速信号计算

运用磁电传感器测量柴油机转速时,对所得电压信号进行处理可得到瞬时转速。分别采用计数法和频率解调法得到了柴油机的瞬时转速,比较了结果的差异。不考虑齿轮的齿形和分度误差,计数法的幅值误差主要取决于采样频率,采样频率越大误差越小,因此需要很高的采样频率;而频率解调法误差主要来源于采样噪声和信号处理过程,该方法不需要很高的采样频率,从而降低了瞬时转速测量的硬件要求,具有很强的现实推广意义。     

励磁系统PSS频率采样故障案例分析

平遥耀光电厂200 MW发电机发生内部振荡,通过故障录波器记录曲线和调试软件的测试信号波形分析,查找到原因为励磁系统PSS频率采样故障,阐述了电力系统稳定器PSS的工作原理和UNITROL5000励磁系统频率采样信号的软件传输流程,分析得出PSS频率采样异常引发机组功率振荡的故障机理和诊断结论,并针对测量单元板更换后进行了PSS性能校核试验.     

基于功率谱的一种新型燃烧器燃烧状况识别

为有效地对新型燃烧器火焰燃烧状况进行识别,通过光电传感器获得一系列火焰光强信号,然后利用快速傅里叶变换(FFT)对火焰光强信号采样时间序列进行分析得出功率谱曲线,判断出非接触式的辐射式燃烧器燃烧状况稳定,进而得出了该种燃烧器燃烧孔开口大小及位置合理的结论.应用结果表明,燃烧火焰时域信号的采样频率至少要1 000 Hz,稳定的火焰信号功率谱低频部分波动小,不稳定的火焰信号功率谱波动相对于稳定的要大很多.     

A／D系统采样频率的精确测定及设置

介绍了一种测量及设置Ａ／Ｄ系统采样频率的方法，通过对Ａ／Ｄ系统采集的已各标准正弦信号的数据进行频谱分析，反推出系统所用的采样频率，并用此原理，求出时间延迟循环的时间常数，达到设置系统采样频率的目的。     

高压共轨柴油机电控系统信号采集处理模块的设计与研究

本文论述了信号采集处理模块在高压共轨柴油机电控系统中的重要性，分析了电控系统对各类传感器、处理电路、采样点和采样频率的要求，并研究了针对各类传感器的失效处理策略。在上述基础上，设计了高压共轨电控系统的信号采集处理模块。试验结果表明：设计模块功能完整、性能优越可靠，达到了系统的要求。     

发动机曲轴系扭振测量的谐次提取及精度分析

发动机曲轴系扭转振动的准确测量对研究其扭转振动及振动控制具有重要意义。针对发动机特点,对电磁传感器输出转速信号的处理算法和精度进行研究,给出了一种实用的扭振信号处理方法。采用标准信号进行监测并结合扭振测量台架,分析了平均转速、采样密度对测量精度的影响。     

应用相关技术测量炉内高温烟气流速的研究

应用抗干扰能力强和适应恶劣环境的相关测量技术，研制了一套相关流速测量系统，对管道内的高温烟气流速进行了在线测量。该系统利用微压传感器烟气压力脉动信号，高性能数据采集卡进行数据采集和Ａ／Ｄ转换，在ＰＣ机上编制软件，对高温烟气的压力脉动信号进行互相关处理，求得高烟气流经上，下游传感器的渡越时间，从而计算出烟气流速值。实验结果证明，该系统能较准确地连续到测量锅炉内高温烟气的流速，有可能开发成为一种实用的     

电容式煤粉浓度传感器的实验研究

针对输送管道中煤粉浓度测量存在的问题,通过试验找出了双极板结构电容式传感器测量准确性差的原因,并试制出了一种8极板结构的电容式传感器,测量时每次采样单向向前转动1个电极位置,每采样4次取其算术平均值作为传感器本次测量输出值.实验表明,这种方法能够有效地消除流型及相分布对浓度测量的影响,使测量准确度和线性度显著提高.     

发电机励磁系统参数辨识扰动信号与辨识精度分析

为提高发电机励磁系统参数辨识精度,以MEC3300T型励磁系统为例,提出分别采用伪随机信号和阶跃信号作为扰动信号,利用混沌遗传算法对励磁系统的参数进行辨识,分析了不同的采样频率下不同扰动信号与参数辨识精度的关系及在相同的采样频率下不同信噪比的扰动信号对参数辨识精度的影响。结果表明,采用PRBS信号作为扰动信号时,辨识结果的相对误差随着采样频率的改变有一定的波动,而STEP信号为扰动信号时辨识结果的相对误差相对稳定;同一采样频率下,采样PRBS与STEP信号辨识结果的相对误差均随信噪比的增加呈指数增长。     

电力系统中非同步采样误差的研究

由于实际电网信号的频率通常会在额定频率附近波动,很难保证对信号的同步采样,FFT算法的泄漏现象和栅栏效应将会导致较大的测量误差。从软、硬件两个方面综合分析了几种常用的预防、补偿措施的优缺点,表明这些方法提高了信号的分析精度和测量参数的可信度。     

基于扩展证据理论的信息融合方法在传感器故障诊断中的应用

电厂传感器的网络结构提供了在空间或时间上的冗余或互补的信息，为传感器故障的检测和分离提供依据。证据理论的组合运算是在同一个识别框架下进行的，而电厂的传感器是来自不同层次上的信息源，其识别框架是不同的。为此提出一种在不同识别框架下的证据组合规则，采用精细和粗化两种算予，可以充分利用来自不同层次传感器的所有信息，减小传感器状态判断的模糊性。仿真结果表明，该方法可以对传感器的多故障进行有效准确的诊断。图2表2参6     

New noise rejection techniques on pulse-by-pulse basis for on-linepartial discharge measurement of turbine generators

On-line partial discharge tests for turbine generators are useful for recognizing abnormal or deteriorated stator winding insulation without a machine outage. One problem related to such a test is additional installation of sensors. We propose that wires of a resistance temperature detector (RTD) embedded in a stator slot are applied as a partial discharge sensor in the form of an RF coupler. The other problem is electrical noise that is a pulse similar to partial discharge in frequency characteristic and has higher amplitude than partial discharge. The sensors in two steam turbine generators showed enough sensitivity and broad frequency bandwidth to facilitate the elimination of noise from the partial discharge measurement. Two new techniques of noise rejection on a pulse-by-pulse basis are investigated with the multiple sensors. One is founded on the correlation between pulse height in two frequency bands. The other is based on the correlation between pulse height from the two partial discharge sensors. It was found that each noise rejection technique was successful in a trial testing     

Continuously distributed sensors for steady-state temperature profile measurements: main principles and numerical algorithm

Principally new method for measurements of steady-state temperature field is suggested. This method is based on the use of so-called continuously distributed sensors (CDS). The basic CDS function is the measurement of temperature profile along the sensor length.The CDS can be manufactured my means of microfilm technologies in the form of a rod, flexible thread, or thin film. Only three electrical cables are needed for connection of CDS and measuring equipment. Nevertheless, it is possible to obtain simultaneously the information about temperature profile at several tens space points along the CDS. So, the CDS is equivalent to several tens of conventional discrete sensors, for example, thermocouples.The measuring process with the use of CDS can be described by the following scheme. A temperature field acts on the CDS causing space non-homogeneity of the electrical parameters of thermo-sensitive films. The space distribution of electrical parameters along CDS can be measured by means of electrical signals of different frequencies. Indeed, the distance to which the electrical signal penetrates the sensor depends on the frequency. So, the measuring impedance of the sensor contains information about space distribution of electrical parameters, which are directly related with the temperature profile.Restoration of the space distribution of electrical parameters from frequency characteristics of the measuring impedance is non-trivial task. From the mathematical point of view it is inverse problem. Some algorithms for solving of this inverse problem are developed and are presented in the paper. Numerical simulations demonstrate possibilities to measure temperature fields by means of CDS.     

Sensors fault diagnosis and fault tolerant control for grid connected PV system

This paper discusses a Sensors Fault Detection and Isolation (FDI) and Fault Tolerant Control (FTC) of three phase inverter for PV system application. All sensors used in the inverter control strategy are addressed in this work. The developed FDI algorithm focuses on residuals generation; it is defined by the different between measurement and reconstituted signal. So, estimators block are investigated, such as, two Models References Adaptive Systems (MRAS) are developed to reconstitute the information of three phase line currents and dc link voltage sensors. The reconstituted information is injected to the corresponding FDI algorithm. Grid voltage sensors FDI is presented in this contribution trough the use of scaled virtual flux estimator, based on Second Order Generalized Integrator and Frequency Looked Loop. When a fault detected, FTC is ensured by replacing the erroneous measurement by its corresponding estimator. Theoretical study and simulations results are presented to validate the effectiveness of the proposed method.     

基于频率和模态的变电构架损伤识别研究

变电构架是变电站配电装置场地的重要构筑物,其安全可靠性与变电站密切相关。文章基于频率和模态推导了变电构架结构损失识别理论模型,且通过部分频率和模态片段来进行损伤识别,提高了灵敏度;利用传感器的先验信息,发展了一种测量点优化选择算法,以保证损伤参数识别过程的适定性。用交替进行测量点优化选择、参数识别和误差更新操作来最大限度地减少先验信息不准确所带来的识别误差对损伤识别结果的影响,尽量提高损伤识别的精度。     

电控汽油发动机传感器故障的综合分析与检修

介绍了电控汽油发动机通过传感器所需获取的主要信息,重点阐述了电控汽油发动机主要传感器的故障及检修方法。     

Reducing sensor complexity for monitoring wind turbine performance using principal component analysis

Availability and reliability are among the priority concerns for deployment of distributed generation (DG) systems, particularly when operating in a harsh environment. Condition monitoring (CM) can meet the requirement but has been challenged by large amounts of data needing to be processed in real time due to the large number of sensors being deployed. This paper proposes an optimal sensor selection method based on principal component analysis (PCA) for condition monitoring of a DG system oriented to wind turbines. The research was motivated by the fact that salient patterns in multivariable datasets can be extracted by PCA in order to identify monitoring parameters that contribute the most to the system variation. The proposed method is able to correlate the particular principal component to the corresponding monitoring variable, and hence facilitate the right sensor selection for the first time for the condition monitoring of wind turbines. The algorithms are examined with simulation data from PSCAD/EMTDC and SCADA data from an operational wind farm in the time, frequency, and instantaneous frequency domains. The results have shown that the proposed technique can reduce the number of monitoring variables whilst still maintaining sufficient information to detect the faults and hence assess the system’s conditions.     

输变电工程工频电场实时智能监测系统设计

针对目前输变电工程工频电场监测工作的实际需求,提出了一种输变电工程工频电场智能实时监测系统,从工频电场参数、信号处理电路、非磁性支架三方面进行设计,采用拉格朗日插值法对传感器进行线性度校正,设计的工频电场传感器的灵敏度和线性度均能满足工频电场的测量要求,并通过现场数据与工频电场限值运行对照。结果表明,该监测系统能够实现无气象条件制约的工频电场实时监测,且数据远低于限制值,为输变电工程环评、竣工验收等提供有力的数据支撑。     

Design and reliability assessment of control systems for a nuclear-based hydrogen production plant with copper–chlorine thermochemical cycle

The thermochemical Copper–Chlorine (Cu–Cl) cycle is an emerging new method of nuclear-based hydrogen production. In the process, water is decomposed into hydrogen and oxygen through several physical and chemical processes. In this paper, a Distributed Control System (DCS) is designed for the thermochemical Cu–Cl cycle. The architecture and the communication networks of the DCS are discussed. Reliability of the DCS is assessed using fault trees. In the assessment, the impact of the malfunction of the actuators, sensors, controllers and communication networks on the overall system reliability is investigated. This provides key information for the selection of control system components, and determination of their inspection frequency and maintenance strategy. The hydrogen reactor unit, which is one of the major components in the thermochemical Cu–Cl cycle, is used to demonstrate the detailed design and analysis.     

光电和机压混合方式的水轮机频率测量

分析了使用光电传感器和发电机电压测量水轮机频率时各自的利弊，提出了优势互补的混合方式进行测量，介绍了该方式的原则及实现方法，以及加强可靠性的若干措施，实现表明该方法是有效的