基于PC104的DCS冗余软件设计与实现

介绍DCS中冗余组态软件和冗余运行软件的设计与实现,包括冗余系统硬件结构、冗余系统软件结构、冗余参数组态、组态信息的存储、组态信息的下传通信、冗余运行软件切换控制逻辑、错误表管理、冗余运行软件与I/O模块的数据交换。这一软件实现能有效提高DCS在工业应用中的可靠性和安全性。     

工业生产中别样的冗余控制

针对工业生产中的工艺控制要求,介绍一种有别于常规意义上的冗余控制方案,该方案利用继电器切换冗余回路并与DCS程序冗余控制相结合,实现在同一控制系统中或不同控制系统中两个控制单元间的热备冗余控制,为工业生产中的重要受控设备提供了一种切实可行的控制方案.     

基于导向钻井工具的双冗余控制器设计

为了提高导向钻井工具在复杂地质环境下对井下姿态测量的可靠性,设计一套基于导向钻井的双冗余控制器。首先对双冗余控制器技术进行研究建立双冗余控制器模型,然后提出双冗余控制器方案。实验表明双冗余控制器不但能够检测出系统的故障,能够准确的切换主备控制器,极大的提高了系统的可靠性。     

WinCC在SBR污水处理监控系统中的应用

设计了一套较为先进的污水处理监控系统,介绍其硬件组成及WinCC在监控系统设计中的冗余组态、画面中设备动态功能的实现、操作小窗口及画面切换等。该系统能够完成序列间歇式活性污泥法(SBR)污水处理的监控功能。     

Application of WinCC in Shenmu SBR Wastewater Treatment System

设计了一套较为先进的污水处理监控系统,介绍其硬件组成及WinCC在监控系统设计中的冗余组态、画面中设备动态功能的实现、操作小窗口及画面切换等.该系统能够完成序列间歇式活性污泥法(SBR)污水处理的监控功能.     

ControlLogix控制器冗余故障诊断与分析

介绍ControlLogix冗余系统的组成与工作原理,针对系统控制器冗余故障进行了分析,通过对冗余系统软、硬件的排查,分析了冗余故障产生的原因,并应用软件优化方法解决了系统冗余故障,提高了控制系统的可靠性和安全性。     

天然气处理厂火气报警系统的研究与应用

苏里格第四天然气处理厂火气报警系统(简称FGS站)自动采集各个区域的可燃气体探测器、火焰探测器的输出信号和手动防爆火灾按钮信号,完成可燃气体泄漏浓度监测报警、火灾监视报警和声光报警。FGS系统与PCS系统进行数据连接,建立动态数据库。当有报警信号时,能准确地切换到相应画面,显示出报警部位,同时FGS系统向ESD系统发出火灾报警信号,ESD系统做相应的紧急停车控制。FGS系统采用UPS供电,采用冗余控制器完成数据采集、处理和控制;FGS系统设置工程师站/服务器/操作员站,完成组态和实时监视。     

DCS系统应用中的抗干扰措施

为提高DCS系统的抗干扰能力,我公司DCS系统通信结构设计为2层:第一层为现场控制层,连接现场设备到控制器,采用标准的Prifbus DP双绞线;第二层为中央监控层,实现各现场控制站之间及与操作员站、工程师站的通信,采用塑料光缆进行传输信号,它具有较强的抗干扰能力,适于工业现场。由于各站之间距离较长(最大约400m),系统通信采用TCP/IP协议以太网l∶l冗余设置,导轨安装型光纤中继器通信模件,该中继器提供双冗余供电、双路光纤接口,可以将光缆接成环形,当环路任何一处出现故障可以在30ms内自动切换到另外一条备用线路上,提高了DCS系统的可靠性。本文总结了影响DCS系统运行的干扰和采取的措施。     

浅谈安全保护系统在香港终端的应用

海洋采油平台广泛应用自动化仪表和控制系统进行生产,安全保护系统是确保自动化系统在安全条件下进行油气田自动生产和管理的重要部分。安全保护系统统由设施保护系统和火气探测系统组成。火气探测系统采用冗余控制器的热备,通过高速串行链路(HSSL)不断更新处理器I/O数据和内部逻辑状态,实现主备控制器之间的数据传递和故障时的自动无扰动切换;采用双系统的设施保护系统,其硬件配置成一个双冗余系统,PLC都有单独的I/O模块和通讯模块,采用CRI监测系统监测设施保护系统PLC的输入与输出,通过输入系统支持模块ISSM、输出系统支持模块OSSM和电流检测模块的监测来完成对系统的监测,采用周期测试、输出持续测试和输入状态改变测试等方式完成对设施保护系统的监测,通过检测两个PLC输出对比检测是否同步,提供系统报警和自我修复,提供设施保护系统更高的可靠性和安全性。     

焦炉加热DCS系统改造及故障处理

宣钢焦化厂第二炼焦车间焦炉加热DCS系统采用ABB公司的AC800现场控制器,控制系统采用CPU冗余、Ethernet冗余、PROFIBUS总线冗余、CI840冗余、RLM01冗余等,系统包括焦炉自动加热、除尘测点监控、3#与4#炉CO报警监控、低水分熄焦控制、荒煤气自动点火放散控制等,从近几年的使用情况发现系统存在许多不足,因此,需要对原DCS系统进行改造完善.     

FAULT DETECTION AND DIAGNOSIS IN BATCH AND SEMI-BATCH PROCESSES USING ARTIFICIAL NEURAL NETWORKS

The objective of this work is to assess the feasibility of adopting artificial neural networks (ANNs) in fault detection and diagnosis for batch and semi-batch processes. Although there is a large volume of related publications available, most of them used steady-state data to train ANNs and, as such, the task of fault diagnosis can only be implemented in continuous operations. Based upon the concept of analytical redundancy, the framework of a two-stage fault monitoring system is proposed in this paper. In the first stage, a hybrid ANN is adopted to predict the long-term dynamic behaviors of the output variables under normal condition. The occurrence of fault(s) can be detected by inspecting the residuals, i.e. the differences between the measured and the predicted values of outputs. A second feedforward neural network is then used for the purpose of differentiating the residual patterns caused by various faults. In addition to the fact the results of pilot tests are quite satisfactory, it is also demonstrated in our experimental studies that the proposed fault-monitoring system is capable of detecting and diagnosing faults that cannot be described by traditional mathematical models.     

多传感器故障检测与隔离算法

在系统状态、执行器及传感器故障检测与隔离的问题研究过程中,对传感器故障的检测与隔离难度最大,而针对欠量测系统和传感器冗余系统中传感器故障检测与隔离问题难度更大。为此,首先建立了包含卡死、增益时变和偏差时变3种典型传感器故障的数学模型;其次,借助输出方程,将待检测的传感器故障转换到系统状态方程中进行处理,对欠量测系统转换结果不唯一这一问题,分别采用最小二乘和基础解系的方法进行处理,对传感器冗余系统,通过两次利用系统状态,分别构造两个并行运行的残差产生器;然后,设计出既能检测出故障,又能将各个故障进行有效隔离的残差产生器;最后,用算例对上述设计结果的有效性进行计算机仿真验证。     

焚硫炉火管废热锅炉的副线设计—兼论废热锅炉面积富裕系数

推导出火管废热锅炉的面积富裕系数,系统生产负荷率、主线率3者之间的解析关系式,利用该公式可以确定废热锅炉副线设计的气量范围,认为现有的焚硫废热锅炉的面积富裕系数取值普遍偏大,提出1种测定火管废热锅炉实际面积富裕系数的具体计算方法。     

Decentralized fault-tolerant control system design for unstable processes

Fault-tolerant control is an important issue in control of mission critical processes. In this paper, a new approach to fault-tolerant control of unstable processes is proposed based on the Passivity Theorem. The control system is designed in two sequential steps: A multi-loop proportional controller is used to stabilize the unstable process; a passivity-based decentralized unconditionally stabilizing (DUS) controller is then applied to the stabilized process. While the multi-loop stabilizing controllers need to be built with redundancy, the DUS controller is inherently fault tolerant and can maintain closed-loop stability when any of its loops fail. By using a stabilizing proportional controller with the fewest loops, control redundancy can be reduced to the minimum level.     

Robust fault detection and monitoring of hybrid process systems with uncertain mode transitions

A methodology for fault detection and monitoring of a class of hybrid process systems modeled by switched nonlinear systems with control actuator faults, uncertain continuous dynamics, and uncertain mode transitions is presented. A robust hybrid monitoring scheme that distinguishes reliably between faults, mode transitions, and uncertainty is developed using tools from unknown input observer theory and results from Lyapunov stability theory. The monitoring scheme consists of (1) a family of dedicated mode observers that locate the active operating mode at any given time and detect mode switches, (2) a family of robust Lyapunov‐based fault detection schemes that detect the faults within the continuous modes, and (3) a supervisor that synchronizes the switching between different controllers and different fault detectors as the process transitions from one mode to another. A key idea of the developed framework is to design the mode observers in a way that facilitates the identification of the active mode without information from the controllers and renders the residuals insensitive to the faults and uncertainties in the constituent subsystems. The implementation of the developed monitoring scheme is demonstrated using a simulated model of a chemical reactor that switches between multiple operating modes. © 2010 American Institute of Chemical Engineers AIChE J, 2011     

MUX-DEMUX using a Spatial Wave-Function Switched Field Effect Transistor (SWSFET)

A spatial wave-function switched field effect transistor (SWSFET) conducts through different channels within its structure. The switching of charge carriers between different channels can be controlled by the gate voltage. The self-consistent Schrodinger and Poisson equation solution can explain the switching of charge population in different channels of a SWSFET. A circuit model is developed by modifying the BSIM 3.2.2 IGFET (Insulated Gate Field Effect Transistor) model. Different circuits can be designed for a SWSFET with less circuit elements than conventional CMOS. The innovative circuit design using the SWSFET can make only electrons participate in the circuit operation with better performance. This work discusses the design of an ultrafast 3-in-1 multiplexer and 1-to-3 demultiplexer using the SWSFET where only one SWSFET is used to design the circuit.     

FF现场总线控制系统的质量要求及其实现技术

通过对临界实时安全系统质量要求的分析，提出了FF现场总线控制系统的质量要求，并结合FF的特点给出了满足质量要求的实现技术。利用FF的冗余技术实现了FF现场总线控制系统的系统级、回路级和仪表级的容错。利用FF的失效安全机制，使FF在出现不可避免的错误时仍然能够提供最低限度功能，从而实现了更深层次的容错。     

Device and SPICE modeling of RRAM devices

We report the development of physics based models for resistive random-access memory (RRAM) devices. The models are based on a generalized memristive system framework and can explain the dynamic resistive switching phenomena observed in a broad range of devices. Furthermore, by constructing a simple subcircuit, we can incorporate the device models into standard circuit simulators such as SPICE. The SPICE models can accurately capture the dynamic effects of the RRAM devices such as the apparent threshold effect, the voltage dependence of the switching time, and multi-level effects under complex circuit conditions. The device and SPICE models can also be readily expanded to include additional effects related to internal state changes, and will be valuable to help in the design and simulation of memory and logic circuits based on resistive switching devices.