SCADA in Thermal Power Plant Dept. of Electrical Engg.Page 1 Project reportOnSCADA in Thermal Power Plant Chapter 1 INTRODUCTION ThischapterprovidesanintroductionabouttheSCADAbasedsystem,the significanceoftheSCADAimplementationinthermalpowerplant.Itprovides application in real time and configuration, control and managing the SCADA system to improve the efficiency and reducing the cost of the power plant. 1.1.What is SCADA? SCADAisusedformonitoringandcontrollingoftheindustrialprocesses. SCADA stands for supervisory control and data acquisition. The processes which can control using SCADA can be industrial, Infrastructural or Public Utilities. SCADA is used around the world to control all kind of industrial processes.Industrial processes includemanufacturing,Production,Developments,andFabrication.Infrastructural SCADA in Thermal Power Plant Dept. of Electrical Engg.Page 2 processesincludegasandoildistribution,Electricalpowerandwaterdistribution. Public utilities include light rail, airport, bus transit systems, Shopping malls. SCADA application has two major components. 1.Thesystemorprocessyouwanttocontrol/monitor.Itcanbeelectricalpower distribution, manufacturing plant, power plant or production plant. 2.Agroupoftheintelligentdeviceswhichcontrolthesystemorprocess.These devices include sensors and control input/output to monitor and control the system or processes. 1.2 Overview of the SCADA based Thermal Power Plant TheSCADAbasedthermalpowerplantwhichusesminimalof hardware/softwareinterfacesandprovidethehigherefficiency.Italsoprovideslow costsolutionandreducingthenumberoflosesduringprocessflow.SCADA implementationhelpstoprovidehigherefficiencyaswellasmonitoringand controlling of the process parameters like generated power, turbine speed and quality ofthegeneratedpower.SCADAimplementationprovidesthehighercontrollability duetosensors,valvesandmetersincorporatedwithinthepathoftheprocessflow. The same techniques can also applicable for various other processing flows like water purification, Oil purification and manufacturing of the products. SCADA in Thermal Power Plant Dept. of Electrical Engg.Page 3 Chapter 2 SCADA SYSTEM ThischapterdescribesbasicapplicationsandusesofSCADAsystem.This alsocoversbasicdesignaspectsoftheSCADAsystem.Itclearlyexplainshowto select the particular SCADA system for specific requirements. It also gives details on the monitoring and control of the Real time systems. 2.1 SCADA as a System SCADAisonekindofapplicationwhichcollectsdatafromthefactory through various sensors and sends this information to the computer system or remote locations. SCADA is control and management solutions for the most of the industries. SCADA is a central control system which consists of controllers, Network interfaces, Input/Output, communication equipments and software. All together SCADA system collectsimportantinformationandsendsittothecomputerorremotelocations.The SCADA in Thermal Power Plant Dept. of Electrical Engg.Page 4 mostimportantpartoftheSCADAisremoteterminalunitwhichisalsoknownas RTU.RTUconsistofprogrammablelogicconverterwhichcanbesettospecific requirementsoritcanalsoallowhumaninterventionduringtheoperation.For example, in thermal power plant the water flow can be set to specific value or it can bechangeaccordingtotherequirements.RTUalsodisplaystheerrororanycritical warningsatcontrolstationsousermaybeawareofthedevelopments.SCADA system takes the reading of the meters and checks the status of the sensors in a regular intervalsothatitrequiresminimalinterferenceofhuman.SCADAsystemmadeof many data points which include monitor points or software/hardware points. SCADA systemcreatesthelogoftheallnecessaryeventsandsavethehistoryforfuture references. 2.2 SCADA Applications SCADAisusedforallkindofcomplexsystemwherehumaninteractionis impractical. SCADA isused in theapplicationswhere there are more control factors difficult to mange with the short time frame. 1.Power generation, transmission and distributionPower stations use SCADA system to monitor the current flow, voltage level, checking the status of the transmission line and circuit breakers. Also, sometimes it is used to power off or shutdown particular sections. 2.Water distribution and Reservoir system SCADA in Thermal Power Plant Dept. of Electrical Engg.Page 5 SCADA is used for municipal water distribution system to monitor the flow of thewaterduringthedistribution.Also,reservoirwaterlevelandpressurecanbe measure using the SCADA system. 3. Generators and Turbines Monitor and control the temperature and flow in heat exchanger unit and heat recovery unit. 2.3Human Machine Interface (HMI) SCADAsystemusesinterfacewhichisknownashumanmachineinterface (HMI). HMI is the place where the information is displayed and monitored to process byhuman.Theinterfaceprovidesthecontrolssohumancaninterfacewiththe system.HMIprovidestheaccessofmultiplecontrolunitswhichcanbePLCs (programmable logic unit) or RTUs. Usually RTU and PLC is pre program according to the requirements but monitoring of them is difficult for the users. SCADA system communicates with the PLCs throughout the system and provides the information to the user using network interfaces. TheHMIprovidesthegraphicalpresentationofthesystem.Forexample,it provides the graphics picture of the pump connected to the tank. User can see the flow of the water and pressure of the water. Also, User can on/off the supply of the water withintheparticularpipes.HMIalsoprovidesthemultipledisplayssousercan control more equipment at a time. The important part of the HMI is an alarm system whichisactivatedaccordingtothepredefinedvalues.Forexample,thetankwater SCADA in Thermal Power Plant Dept. of Electrical Engg.Page 6 levelalarmissetto80%and90%values.Ifthewaterlevelreachesabovethe80% thealarmgivesnormalwarningandifwaterlevelreaches90%thealarmgives criticalwarnings.Accordingtothewarningusercancontroltheflowofthewater from reservoir to the tank. 2.4SCADA Animation SCADA animation consists of different color bars, text, rotating/sliding parts, level indicator and position of the parts using different colors. Basic animation of the SCADA system is shown below. Figure 2.1 Standard SCADA Animation SCADA in Thermal Power Plant Dept. of Electrical Engg.Page 7 Chapter 3 WORKING OF SCADA SYSTEM The SCADA system mainly performs the following functions. 3.1 Data Acquisitions 3.2Data Communication3.3Information/Data Presentation 3.4Monitoring/Control Thesefunctionsareperformedbysensors,RTUs,MasterUnitsand Communicationnetworks.Sensorsareusedtocollecttheimportantinformationand RTUsusesthisinformationtodisplaythestatusofthesystematthecontrol equipments. According to the status of the system user can give command to the other systemcomponents.Theoperationssendtheimportantcommandthroughthe communication network. SCADA in Thermal Power Plant Dept. of Electrical Engg.Page 8 3.1Data Acquisitions TheRealtimesystemconsistsofthousandofcomponentsandsensors.Itis very important to measure the status of the particular components. For example, some sensorsmeasurethewaterflowfromthereservoirtothetankwhichisinputtothe system.Somesensorsmeasurethevalvepressureasthewaterisreleasefromthe reservoir. Somesensorsindicatethenormaleventofthesystem.Forexample,in production environment sensor counts the number of produced product or the number ofdefectedproducts.Somesensorsindicatethecondition(on/off)oftheparticular systemcomponents.Furthermore,somesensorsprovideverycriticalinformation whichshouldgivetheaccurateresults.Forinstance,itisimportanttomeasurethe temperatureofthesystemasitcandamagethesystem.Temperaturevaluesare predefinedinthesystemsothatitsoundsalarmwhensystemreachesabovethe threshold value. 3.2Data Communication Simple electronic control system uses wired network to communicate between user and devices but in Real time application there are lots of sensors and components which should be control remotely. It is important to have strong network between all the components and user. Early, SCADA network used to communicate through radio andmodem.Today,SCADAusesinternetasacommunicationmedium.All SCADA in Thermal Power Plant Dept. of Electrical Engg.Page 9 informationistransmittedthroughinternetusingspecificprotocols.Sensorsand relaysarenotabletocommunicatewiththenetworkinterfacesoRTU(Remote TelemetryUnit)isneededtoestablishthecommunicationbetweensensorsand network interface. The RTU converts the input from the sensors into specific protocol andsendittothemasters.AccordingtothemastersfeedbackRTUreceivedthe protocol formatted command and apply the electrical signal to the relays. 3.3Information/Data Presentation Normalcircuitnetworkhavesomeindicatorwhichcanbevisibletothe operatorbutinRealtimeSCADAsystemtherearethousandsofsensorsandalarm whicharenearlyimpossibletohandlesimultaneously.SCADAsystemusesHuman systeminterfacetoprovidetheallinformationgatheredfromthevarioussensors. SCADAmasterworksasahumaninterface.Ithasmanydifferentfunctions.Master collecttheinformationfromthedifferentsensoralsoprocesstheaccumulated information and provide the necessary suggestion to improve the efficiency as well as indication of the alarms. 3.4Monitoring/Control SCADAsystemprovidesthedifferentswitchesanddisplaysatthecontrol center.Anypartoftheprocesscanbeturnedon/offfromthecontrolstationusing these switches. SCADA in Thermal Power Plant Dept. of Electrical Engg.Page 10 Forexample,ifthepartfollowingthewaterdistributionsystembrokeupor malfunctioning then water control can be stopped or slowing down directly from the controlstation.Mostly,SCADAsystemisimplementedtoworkautomatically withouthumaninterventionbutitisalsopossibletooverridetheautomaticcontrol from the control station. Most of the monitoring and control operations are performed by RTUs or PLCs. As we can see from the figure that SCADA system RTU Reads the flow level and flow control form the sensors and sends the set points to the PLCs. PLC1 compared the flow with the set point and according to that it manages the speed pump.PLC2observestheflowandcompareitwiththesetpointsandaccordingto that it manages the flow. Figure 3.1 Schematic Diagram of SCADA System SCADA in Thermal Power Plant Dept. of Electrical Engg.Page 11 Chapter 4 SCADA SYSTEM OF A THERMAL POWER PLANT 4.1Functionality of SCADA Based Thermal Power Plant Thermal power plant uses steam as a primaryrequirement to move the wings oftheturbine.Afterthepassingthroughtheturbinethissteamiscondenseina condenser. Steam is generated by different type of fuel depends on the availability and requirements.Differenttypesofthermalpowerplantareclassifiedaccordingtothe typeoffuelandtheprimarymoverintheplant.Thefunctionalityofthethermal power plant can be understood by the following diagram. The overall efficiency of the power plant can be measured by the ratio of the temperatureofthesteaminputandoutput.Higherefficiencyrequiresthehigher pressureandhighertemperature.Theoverheatedsteamisrotatesthewingsofthe turbine and then return back to the MP body and BP body of the turbine. Most of the thermal power plants can automatically operate but it still allows the access to human SCADA in Thermal Power Plant Dept. of Electrical Engg.Page 12 interventiontotakesomecriticaldecision.Mostofthepowerplanthavealertand monitor system which can be easily operated from the control room. Figure 4.1 Functionality of Thermal Power Plant

4.2Architecture of SCADA Based Thermal Power Plant ThearchitectureoftheSCADAbasedthermalpowerplantisshowninthe followingfigure.ThepowerplantisconnectedusingthenetworkEthernet.The network Ethernet allows the file transfer between the different stations. Also, it avoids SCADA in Thermal Power Plant Dept. of Electrical Engg.Page 13 theburdenofthenodebusnetwork.TherearethreelevelsinSCADAsystem: acquisition,processingandmonitoring.TheSCADAsystemismadeofdifferent components which transfer information using the interface. Figure 4.2 Architecture of SCADA SystemI/A: Intelligent / Automation FBM: Field bus modules FCM: Field bus Communication module AW: Application work station WP: work station processor SCADA in Thermal Power Plant Dept. of Electrical Engg.Page 14 Chapter 5 THERMAL POWER PLANT 5.1 Introduction The coal is used to generate the steam and through this steam it can generate theelectricity.Asthepopulationincreasestherequirementofthepoweralso increases.Nuclearpowerplantisalsoasolutiontothisdemandbutitisnotsafeas thermal power plant. Thermal power plant uses water as a primary resource and water isheatedtogeneratesteam.Thissteamisusedtospintheturbineandgeneratethe electricity. The steam which passed through the turbine is condensed using condenser. SCADA in Thermal Power Plant Dept. of Electrical Engg.Page 15 Figure 5.1 General Layout of Thermal Power Plant 5.2 Coal Fired Thermal Power Plant More than half of the energy is generated using the coal based thermal power plant.Thebasicconceptistoproducetheelectricityfromtheenergystoredinthe coal.Theenergystoredwithinthecoalisusedtogeneratetheelectricityandthis electricity is used in industrial, commercial and residential. 5.3Basic Layout of a Thermal Power Plant SCADA in Thermal Power Plant Dept. of Electrical Engg.Page 16 Thermalpowerplantsaremostlyusedtogeneratetheelectricity.Thermal powerplantreleaseslargeamountofgreenhousegasesinouratmosphere.The general layout of the thermal power plant includes the following main components. Coal and Ash circuitCoalandashcircuitisusedtosupplyingthecoaltotheboilerandcollecting theashthatisproducedafterburningofthecoal.Thisincludesthe components used to transfer and storage of the coal and ash. Air and Gas Circuit Airisthemostimportantfactorforcombustionofthecoal.Hence,itis required to supply the sufficient amount of air for the combustion of the coal. The exhausted gases used to heat the air before releasing to the environment. Feed water and steam circuit Thesecomponentsareusedtosupplythegeneratedsteamtotheturbineand alsoforcoolingthesteamwhichispassedthroughtheturbine.Thissteamis condensed to form the water. This water is used again for the same process. Cooling water circuit Thispartisusedtocondensethesteamusingwater.Itrequireslargeamount ofwaterforcoolingtheheatedsteam.Thewaterisgenerallytakenfromthe river or reservoir.SCADA in Thermal Power Plant Dept. of Electrical Engg.Page 17 Figure 5.2 Basic Layout of Thermal Power Plant 5.4Working of Thermal Power Plant Thermalpowerplantusescoalornaturalgasestogeneratetheheatwhichis usedtoboilthewater.Thisboiledwatergeneratesthesteam,whichfeedstothe turbines.Theturbineisconnectedtothegenerator.Thisgeneratorprovidesthe electricity to the consumers. The following are the steps for the process of generating electricity 1.Water Intake SCADA in Thermal Power Plant Dept. of Electrical Engg.Page 18 Thewaterisfeedtotheboilerforgeneratingthesteam.Thewaterisdriven fromtheriver,pondorreservoir.Ifthewaterisnotpurethenitisfiltered using various techniques. Also, this water can be used again and again for the next cycle. 2.Boiler heating Theboilerisheatedusingthecoalornaturalgases.Thehightemperature causesthewatertotransformintothesteam.Thissteamisfeedtothenext stage for the generation of electricity. 3.Steam turbine The steam generated using boiler is feed to the steam turbine. The pressure of the steam applied on the blades of the turbine. Hence, the wings of the turbine rotate according to the pressure of the steam. 4.Generator Thegeneratorisnormallyconnectedwiththeturbineanditproducesthe electricity.Thisproducedelectricityispassedtotheconsumersusingother circuits. SCADA in Thermal Power Plant Dept. of Electrical Engg.Page 19 Chapter 6 SCADA MODELING There are few steps which is necessary for proper implementation of the power plant. 6.1Important Steps for SCADA Modeling Screening Thewaterfromthereservoir,riverorlakeisnot100percentpure.Water includesimpuritieslikerocks,sand,woodandmanyotherparticleswhich need to remove before using this water for the plant. These materials are sent to landfill. Pumping Mostlywaste water treatment plants are locatedbelow the level of the power plant. So it is required to send this water to the plant using motors. The plant is mostly above the level of the river or lake therefore the water needs to pumped up to the reservoir tank. SCADA in Thermal Power Plant Dept. of Electrical Engg.Page 20 Aerating The water treatment plant shake up the mess and expose it to air.This step is necessary to remove dissolved gases from the water. Water is passed through theseriesoftanks.Firsttankfeedstheairintothewater.Duetoorganic matterdecays,itusesupoxygen.Bubblepassedthroughtheoxygenallows the organic particles to settle. Removing sludge & Scum Heavy particles from the water are settled down at the bottom of the tank and theseparticlesareremovedinastepcalledthickeningandthenthesludgeis processedinlargetankknownasdigesters.Also,someimpuritiesarelight weight.Forexample,oil,plasticandgreasewhichcaneasilyfloatonthe surfaceofthewater.Theseimpuritiesareremovedbyslowmovingrakes.Some plant also uses filtration in sewage treatment.Water is passed through thesandwhichcanremovethebacteria,unpleasantodorsandreducesthe amount of iron. Sometime water is also passed through the carbon particles to removeorganicparticles.Thisfilteredwaterisstillhavesomegaseslike oxygenwhichformsoxides.Theseoxidesrustandcrackstheboilersalong with the time so whole boiler system needs to be replaced after some period of time. This can lead to very high amount of cost to the company. To avoid this extracostthiswatersendtotheelectrodialysisunitwherethegasesare removed using some sort of techniques.

SCADA in Thermal Power Plant Dept. of Electrical Engg.Page 21 6.2Components of the Plant 6.2.1Valves Avalveisusedtocontroltheflowofthefluidorwater.Itcanbeoperated manually or automatically. A valve can be operated manually using wheel, paddle or handle.Anautomaticvalveoperatesbasedonthepressurechanges.TheChangein the pressure operates the piston and activates the valve.Also, some highly controlled systemusesactuatorforcontrollingthevalve.Dependingonthecontrolledinput valve can be positioned accurately according to the requirement.Generally two types of valves are used in thermal power plant 1.One port valves One port valves used to allow or obstruct the flow of the fluid, water or gases. It can allow fluid to flow along the pipes or It can stop moving the fluid.2.Two port valves Two port valves are also known as regulating valves because they can beopen,closeorpartiallyopen.Somevalvesaredesignedtoregulatethe certain amount of flow. Here are some operations of the valves Control : force or flow speed closing at over speed run over pressure prevention back flow protection SCADA in Thermal Power Plant Dept. of Electrical Engg.Page 22 6.2.2Sensors Generally sensors are used for following purpose measure the water heightmeasure the pressure measure the temperature Measure the flow speed Thesesensorsdirectlygiveoutputtothecontrolstationoritcansupplythe information to the next stage. Also, sensors can be analog or digital depend on the plant design. 6.2.3Motors Motorsareusedtosupplythewaterfromonestagetothenextstage.For example, Water needs to be transferred from mesh tank to the nest tank. These heavy duty motors needs proper supervision to avoid any mishap.

6.3Step by Step Functionality of Thermal Power Plant Firststepofthepowerplantistoselectthepropersourceofthewater.The watershouldbeeasilyavailable.Theplantshouldbeneartheriverorlakesoit requireslessefforttomovewatertotheplant.Also,watershouldbecontinuously available to gain more advantage out of the plant.SCADA in Thermal Power Plant Dept. of Electrical Engg.Page 23 Next step is the proper storage of the water. Water can be stored in a tank or reservoir. The water is kept for some amount of time at this stage to settle down most off the impurities. Now the water is moved to the tank using motors and valves. The waterisalsokepthereforsomeamountoftimetoremovesmallparticlepresentin the water. These tanks have some set of sensors. These sensors are used to control the flow of incoming water. For example, if the amount of water in the tank is high then highersensordeactivatesthevalvewhichinturnstopsthewaterflowingintothe tank.Ifthewaterinthetankistoolowthenlowersensoractivatesthevalveand allows the water to flow into the tank. Then next step is to remove the impurities from thewater.Thisstepisrequiredtoremovethebigparticleswhichescapefromthe initial tank. These particles can clog in pipe or it can damage the motor in next stage. Themeshgenerallyhastwostages.Firststageisusedtoremovethelargeparticles and second stage is used to remove the smaller particles.Motors are used to flow water coming from the mesh. Motors send this water to the next tank in which is used for removal of the sludge. This tank has two mode of operation.Duringnormalmodeofoperationsludgeisscreenedfromthetankbyan outlet at the bottom of the tank. During self cleaning mode the incoming and outgoing ofthewaterisshutdownandthewaterinsidethetankismovedwithfullspeedto remove the sludge which can be clog over the wall of the tank. This water is now sent tothescumremovaltank.Thistankalsohastwomodesofoperation.Innormal mode,thescumisscreenedfromthetankbyanoutletatthebottom.Thiswateris nowsenttotheelectrodialysisunitusing motors.Inselfcleaningmode,thenormal supplyofwaterisshutdownandanotherhighspeedsupplyofwaterisfedintothe SCADA in Thermal Power Plant Dept. of Electrical Engg.Page 24 tank.Thewaterbeingsuppliedismixedwithsomechemicalstokillthemicro organism in the tank. SCADA in Thermal Power Plant Dept. of Electrical Engg.Page 25 Chapter 7 CONCLUSION The SCADA for thermal power plant allows the owner of the plant not only to control and supervise the plant which is its features but also operates the plant in the economical way. SCADA for thermal power plant overrides all the drawbacks of the conventional DCS basedthermalpowerplant.Itdoesnotentertainmoremanualoperationsinstead operatesautomaticallyhenceoverridingthehumanerrorsandminimizingtheerrors in the power plant operation. SCADA in Thermal Power Plant Dept. of Electrical Engg.Page 26 REFERENCE [1] SCADA http://en.wikipedia.org/wiki/SCADA [2] http://www.integraxor.com pioneering web SCADA [3] Sandia National Laboratories http://www.sandia.gov/scada [4] Thermal power station http://en.wikipedia.org/wiki/Thermal_power_station [5] International Journal of the Physical Sciences Vol. 5(6), pp. 1175-1182, June 2010 Available online at http://www.academicjournals.org/IJPS ISSN 1992 - 1950 2010 Academic Journals [6] International Journal of Emerging Technology and Advanced Engineering Website: www.ijetae.com (ISSN 2250-2459, Volume 2, Issue 5, May 2012)