外文文献：Design and Implementation of Heat Exchange Station Control SystemKeywords:Heat exchange station, Control system, PLC, Inverter, Configuration software.Abstract.This paper introduces a design and implementation of heat exchange station control systembased on PLC and industrial configuration software, which includes the contr ol scheme and principle,hardware selection and software design, etc. The circulating pumps and re plenishing pumps in thesystem can all be driven automatically by PLC and inverter. Main process parameters, such as steampressure and measurement temperature and so on,can all be shown on the industrial PC runningconfiguration software, and instructions could be sent by the engineer and operator on-the-spot via theHuman Machine Interface as well. The automatic pressures adjustment of stea m supply of the heaterby advanced PID algorithm has been realized finally. It is verified that the system is highly reliableand stable, and it greatly enhances the level of automation and pressure control accuracy of the heatexchange station and meets all the equipments running demands well. IntroductionWith the rapid development of economy and society, heat supply systems are the key power source inthe communities and plants in China. As a media between heat sources and heat loads in the systems,a heat exchange stations plays a very important role for the heat supplyquality. Traditionally, most ofthe pumps in the heat supply systems are operated by valves manually, s o it could bring about thepower energy consuming, high labor intensity and low operation automation. I n this paper a design ofcontrol system for heat exchange station based on PLC, inverter and indust rial configuration softwarewas proposed,accordingly the aim for power energy saving,high heat efficiency and operationautomation has been achieved.Process outline and Control demandsProcess outline.The process outline and control demands were put forward at first before the schemeand design of heat exchange station control system were proposed.Heat exchange station consists of a steam-driven heater,plus3ci rculating pumps,2replenishingpumps and electric control valve. By adjusting the steam flux into the mixture of water and steamaccording to the temperature sensors mounted indoors and outdoors, the pr ocess of heat exchangecould be completed. Among these equipments, the steam-driven heater, a heat exchanger containingmixture of steam-and-water, is the key appliance for heat supply system.Control demands.Major control demands for the control system were listed a s follows [1]:(a)Pumps driving.Pumps include3circulating pumps(2in operation,1for backup)and2replenishing pumps (1 in operation, 1 for backup). Among circulating ones one is driven by powerfrequency, the others are driven by variable frequency, with 75KW power ea ch; among replenishingones one is driven by power frequency, the other is driven by variable frequency, with 3KW powereach. The control signal should be originated from the pressure difference between the supply waterand return water.Pumps could be driven in stepless speed regulating when connecting variablepower;(b)Parameters Showing.The showing parameters contain temperatureshowing-temperature ofsupply water, return water, the indoor, the outdoor and steam - and pre ssure showing - pressure ofsupply water, return water and pre-valve and post-valve of the steam etc;(c) Butterfly valves driving.Two butterfly valves can be on or of f automatically when the wholesystem start or stop;(d) Motor-driven valves control. By continuously adjusting the opening of t he valves according to thesignal from the temperature sensors indoors and outdoors, the supply wate r temperature should bestabilized in the presetting values;(e) HMI (Human Machine Interface) Demands. The process flow chart of heatexchange station andmain process parameter can be shown in HMI, and instructions can be trans mitted via this interface;(f) Safeguard Function. The circulating pumps should be out of running when heat exchange system isin water needing, and steam should be kept out of the heater when the pumps are not revolving.Hardware Selection of the Control SystemFrom the control demands mentioned above, the controller of the control s ystem can process signalsboth relay and analog, having the ability of loop adjustment of analog q uantity. At the meantime thepumps could run in the working condition of variable frequency, so the hardware selection of thecontrol system for heat exchange station should be made deliberately.PLC Serving as Main Controller.As some experienced electrica l engineers known,PLC/PC(Program Controller) is a kind of popular industrial computer, and it can not only accomplish logiccontrol, but also complete many advanced functions, such as analog quanti ty loop adjustment, andmotion control, etc. According to the component amounts of input and outpu t and the needs of controlsystem, FX1N-60MR micro PLC of MITSUBISHI FX series is selected, which hav ing 36 inputs and24 outputs, and doing analog adjustment by using advanced instruction likePID instruction [2].Because of the sampling and driving of the analog signal necessarily, P LC should be extended toanalog input/output function module like FX2N-4AD (4AD) and FX2N-4DA (4DA) or somethinglike.On one hand,4AD adopted is an analog input module having4channels with12bit highresolution, which could receive 0~+10V voltage signal, 0~20mA or 4~20mA cu rrent signal. On theother hand, 4DA chosen could send standard voltage signal and/or current signal, having 4 channelswith 12 bit high resolution also. It is something to be mentioned here , the wiring form of currentinput/output (4~20mA) must be adopted in order to avoiding the strong elec tromagnetism disturbancein the working field [3].Inverter completing Stepless Speed Regulating.At present, inverter, as an im port power electronicconverter, can convert constantly power frequency into continually variable frequency. Thus, energysaving, cost consuming and noise reduction can be easily reached by this equipment.In this control system inverter of ACS510 series of ABB Corporation were elaborately chosen, whichhas many advantages, such as Direct Torque Control (DTC) and advanced appl ying macro and so on.Its main good points and characteristics are illustrated as follows: it can acquire maximum startingtorque (200% normal torque) by using direct excitation; it can be applied to multiple driving systemsby using master-slave function;input and output programmable function;high precision of speedregulating, perfect safeguard and alarming steps. Owing to these highlights of this inverter, pumpsdriving of stepless speed regulating can be easily obtained.There are many applying macro inACS510 series, but we should only choose manual/automatic macro here as we need.IPC Acting as Monitor&Control Interface.IPC(Industrial Personal Computer)has strongcompatibility,extensibility and reliability,which can connect PLC by RS-232serial portconveniently. In the hardware configuration we select IPC H610 series of A DVANTECH as HMI.MCGS(Monitor Control Generated System),fashionable home-mad e industrial configurationsoftware, is running on the ADVANTECH IPC. Using this HMI, the visualizati on process of Monitorand Control is realized easily, intuitively and vividly.With the sensor/transducer,analog input/output modules,PLC a nd actuators,.inverter andmotor-driven valve, the loop adjustment of steam pressure can be precisely attained, and temperatureof all measure points could be measured also[4].The overall hardware configuration of heatexchange station control system see Fig. 1.Fig. 1 The overall hardware configuration of heat exchange station control systemSoftware Design of the Control SystemLAD Diagram Programming.Out of the thoughts of modular programming, the whole programstructure can be divided into such several modules as Initialization Function,upper IPCCommunication Function, Relay Control Function, Analog Sampling, Fuzzy PID Adjust Functionand Safeguard Function, etc. The flow chart of LAD diagram programming of PLC is shown in Fig. 2.Among these modular functions, it is something worthy to mention of Fuzzy PID Adjust Function.Under some circumstances the using of PID instruction of PLC was not so good at what we expected;therefore, the self-made program of Fuzzy PID adjustment of steam pressure was done from deviationand deviation acceleration of temperature between the indoor and the outdoo r in accordance with theFuzzy Control Theory and its application [5].HMI Configuration.For the sake of the appearance beauty and personalizati on between machineand human, the MCGS- Monitor Control Generated Software of Beijing MCGS Tech Co. Ltd wasadopted. This industrial configuration software has very quick, easy devel opment of configurationprocess, which can build bi-directional and high speed communication betwee n PLC and upper IPCthru RS422/232 serial port.In the development environment of MCGS, all needed windows and pictures we re created, includingMain Window of Process Flow, Process Parameters Showing Window, and Key P arameters SettingWindow, etc. Vivid and readily interaction between human and machine can be completed by suchbeautiful pictures and animations when IPC running MCGS.ConclusionsThis design of heat exchange station control system based onFX series PLC,MCGS,and ABBinverter has been realized the pressure automatic adjustment of steam-driven heater as originallyexpected.More over,design demands of power energy savi ng,high heat efficiency and lowequipments noise can all be well met. Finally, the practical operation ver ifies that the system is highlyreliable and stable, and it greatly enhances the level of automation and pressure control accuracy ofheat exchange station and meets equipments requirements of energy saving an d green driving.BEGINInitializationFuzzy PIDAdjust FunctionCommunicationFunctionAnalog OutputNoRelay ControlFunctionAnalog FilteringFunctionCall AnalogSample FunctionSample OverYesAnalog InputLinear TransferLinear TransferAnalog OutputDrivingSafeguard FunctionFailure OccurNoYesFailure HandlingRelated MemoryResetENDFig. 2 The flow chat of LAD diagram programming of PLCAcknowledgementComposition of this paper was with the help and under the direction ofSenior Engineer Nian-huiZhang of Qingdao Wellborn Automation Corporation.References[1]Information on H. Zhang, . Li:The Principle of PLC with itsApplications to Process Control(China PowerPress, Beijing 2008).[3]H. Zhang:The Design and Development of MITSUBISHI FX Series PLC( China Machine Press,Beijing 2009).[4]H. Zhang: Process Automation Instrumentation, Vol. 31(4) (2010), p. 34-36, in Chinese.[5]. Zadeh:Fuzzy Sets and their Applications(Academic Press, New Yor k 1975).Progress in Civil Engineeringand Implementation of Heat Exchange Station Control System外文翻译：换热站控制系统的设计和实现关键词:换热站、控制系统、PLC、变频器、配置软件。