Structured approach in PLC (programmable logic controller) programming for water/wastewater applications

This paper describes a methodology for efficient implementation of PLC programming for water/wastewater applications. The PLC was interfaced with a supervisory host computer which used touch screen equipped color monitors as operator interfaces. PLC ladder logic had to be designed to process real-world hardwired I/O as well as the I/O received from the host computer and/or touch screens, via a communications link. Standard "templates" of PLC networks were developed for (a) pump controls including provision for touch screen I/O; (b) PID control; (c) alarms; (d) motor run times; (e) square root extraction; (f) signal conversion, and (g) flow totalization. All logic was implemented using the standard templates. This structured approach led to efficient implementation, easy debugging/start-up, and easy to read uniform ladder logic.     

基于PLC和变频器的恒压供水控制系统

介绍了一种基于PLC和变频器的恒压供水控制系统,阐述了系统组成、系统功能、工作原理和安全措施.该控制系统性能稳定可靠,已成功用于某电厂供水系统,取得了恒压供水的效果.     

基于PLC和GSM的水监测系统设计与实现

针对目前国内灌溉系统落后的现状,提出了基于PLC与GSM的水监测系统设计方案,采用GSM组网技术和模糊PID控制,实现了对张掖盈科灌区干渠和支渠4扇闸门的自动控制.该系统具有通信速度高、实时性好、可靠性高等特点,目前已投入实际应用.     

基于 PLC和iFIX的乙腈变压精馏实验装置控制系统设计

根据共沸物组成随压力改变而变化的特性,设计了单塔可进行减压与加压两种操作方式的精馏装置,用于变压精馏分离乙腈-水的共沸物,以获得高纯乙腈。同时,应用西门子S7-300系列PLC及工业自动化监控组态软件iFIX,实现对乙腈变压精馏实验装置的实时监测和自动控制,控制系统运行稳定,实时性强,进一步提高了该精馏装置操作的安全性与便利性。装置及系统应用于化学工程与工艺专业本科生的实验教学及化学工程专业研究生的理论研究,效果优良。     

基于DSP和PLC的污水处理控制系统的通信设计与实现

介绍了基于DSP和PLC的污水处理控制系统的通信设计方案与实现方法,详细阐述了DSP和PLC之间、PLC与上位机组态王之间通信协议的建立和程序设计.实际应用表明该设计是成功的.     

Design and experimental evaluation of a simple and robust control setup for measurement optimization in industrial applications

Theoretical and experimental aspects are discussed concerning design and experimental setup of a simple and robust controller for optimization of on-line measurement of coating thickness, using a PC-based approach. Solutions assumed for a feedback control system are described in order to satisfy the main requirements set by this application: accuracy of operation, dynamic bandwidth, modularity of settings depending on the specific coating, handiness of using and modifying when necessary, robustness of control, and global operating reliability. Experimental results confirm that an acceptable measurement uncertainty can be achieved in tin plate coating thickness measurements by this simple displacement control system of the fiber optic measuring head.     

Design and implementation of a gain scheduling controller for a water level control system

The design of a gain-scheduled proportional plus integral (PI) controller for a nonlinear water-tank level control system is presented. A novel approach of determining operating points in terms of interpolation error is also given. The controller is implemented in LABVIEW in the laboratory. The field test results of the system response at different operating conditions clearly illustrate the controller's improved performance over a fixed PI controller.     

选煤厂PLC应用系统设计选型浅析

以近几年实践经验为基础,对选煤厂基于PLC的控制系统进行了分析和研究,探讨了选煤行业PLC应用系统的设计选型原则,期望能推动行业自动化系统设计整体水平再上新台阶.     

A novel optimized hybrid fuzzy logic intelligent PID controller for an interconnected multi-area power system with physical constraints and boiler dynamics

In the fast developing world nowadays, load frequency control (LFC) is considered to be a most significant role for providing the power supply with good quality in the power system. To deliver a reliable power, LFC system requires highly competent and intelligent control technique. Hence, in this article, a novel hybrid fuzzy logic intelligent proportional-integral-derivative (FLiPID) controller has been proposed for LFC of interconnected multi-area power systems. A four-area interconnected thermal power system incorporated with physical constraints and boiler dynamics is considered and the adjustable parameters of the FLiPID controller are optimized using particle swarm optimization (PSO) scheme employing an integral square error (ISE) criterion. The proposed method has been established to enhance the power system performances as well as to reduce the oscillations of uncertainties due to variations in the system parameters and load perturbations. The supremacy of the suggested method is demonstrated by comparing the simulation results with some recently reported heuristic methods such as fuzzy logic proportional-integral (FLPI) and intelligent proportional-integral-derivative (PID) controllers for the same electrical power system. the investigations showed that the FLiPID controller provides a better dynamic performance and outperform compared to the other approaches in terms of the settling time, and minimum undershoots of the frequency as well as tie-line power flow deviations following a perturbation, in addition to perform appropriate settlement of integral absolute error (IAE). Finally, the sensitivity analysis of the plant is inspected by varying the system parameters and operating load conditions from their nominal values. It is observed that the suggested controller based optimization algorithm is robust and perform satisfactorily with the variations in operating load condition, system parameters and load pattern.     

热连轧液压泵站控制系统设计与应用

根据热连轧精轧机组HAGC(液压自动厚度控制系统)液压泵站控制系统连续工作时间长、可靠性要求高、信号复杂的特点,以ABB公司AC800M型PLC为基础,对液压泵站的硬件构成、工作过程和程序结构进行设计.该液压泵站控制系统控制精度高、可靠性强,完全满足连轧机液压泵站控制要求,已经成功通过模拟调试,并将应用于生产实际.     

功率分流式无级变速器电子控制系统设计与试验研究

从工程化及实用性的角度研究和分析了功率分流式无级变速器电子控制系统的功能要求以及设计原则;根据该型变速器的工作原理及其应用对象的实际需求对电子控制系统中的各类传感器、执行器及控制单元等进行了选型和设计;制定了汽车起步过程中执行器磁粉离合器的控制策略和控制流程,并综合燃油经济性和动力性最优原则设计了变速器的换挡控制规律作为电子控制系统的控制依据;最后通过台架试验,验证了电子控制系统的合理性及控制策略的正确性。     

An experimental test system for the generation,control and analysis of sinusoidal pulsatile pipe flows (An application case for time dependent flow measurements)

The hardware and software of an experimental test system which has been designed, constructed and operated for the analysis of transitional characteristics of a laminar time-dependent flow field into turbulence with comprehensive uncertainty analysis are the major contents of the paper. Therefore presentation herein aims to offer an application case in terms of time-dependent measurement and data acquisition technology using an electronic digital mass flow control (MFC) unit at laboratory site instead of previously used pressure driven mechanisms. The flow field is a sinusoidal pulsatile one in order to simulate the real practice and to utilize the simplicity in production, control and analysis of oscillation. The previous background and the updated portrait on the transitional pulsatile flow [1], [2] are outlined to determine the relevant flow parameters and their critical ranges, the details of the measurement and data acquisition systems and the proposed methodologies. The production of the controlled pulsatile flow and the generated flow characteristics, the methodology for the analysis, accuracy and sensitivity of the measurement and data acquisition chains are given for the purpose. The overall uncertainties of the velocity and pressure measurement chains are found to be ±3.2% and ±1.3%, respectively. The range of the experimental research devised to investigate the interactive influences of oscillation frequency, f and velocity amplitude ratio, A₁ in the intermediate and the inertia dominant regions of pulsatile flow field with an emphasis on transition to turbulence is presented via sample measurements of mean velocity and pressure waveforms as solid outputs without going into details on physical aspects of flow dynamics.     

Development of a new lapping method for high precision ball screw (2nd report): Design and experimental study of an automatic lapping machine with in-process torque monitoring system

This paper presents a new approach in lapping process in making appropriate condition to improve the manufacturing operations for ball screw. After grinding, high precision ball screw is lapped by highly skilled operators. These operators have the ability to control and maintain the lapping conditions by sensing the lapping torque manually. Prior to lapping process, the effective diameter must be measured to find out the effective threaded profile along the screw shaft. The section which has a large effective diameter will be primarily lapped wherein the lapping torque is high. The aim of this study is to establish a control scheme on the automatic lapping machine for high precision ball screw in both measuring and finishing process. A prototyped horizontal lapping machine with in-process torque monitoring system has been designed, built, and tested. This is to determine the relationship among lapping torque, effective diameter, and error on travel to establish the measurement system to control the finishing operations efficiently and eventually improve and eliminate the various sorts of error components in a ball screw. The experimental results showed that the new lapping method could adequately predict the effective diameter and error on travel by observing the lapping torque.