GER-3687C - SPEEDTRONIC Mark V Steam Turbine Control System
GER-3687CSPEEDTRONIC MARK V STEAM TURBINECONTROL SYSTEMJ. Kure-JensenGE Power SystemsSchenectady, NYW. BarkerGE Power SystemsSchenectady, NYINTRODUCTION1987, with the DCM2. GE has an installed base ofover 1,000 running triple-redundant, steam and gasturbine control systems. The Mark V family of turbine controls for the 1990s, offers a common controlarchitecture for small, medium, and large steam turbines, turbine-generator monitoring systems, generator excitation systems, and gas turbine controls.Some of the features are: Common Architecture, Maintenance, and SpareParts between steam turbine, gas turbine,and other controls Very flexible, PC-based operator interfacewith Color Monitor and Logging Printer withalarm log, event log, historical trip log, etc. Common operator training and controls for steamand gas turbines in combined-cycle STAGTMplants Full Turbine-Generator Monitoring for all sizesof turbines can be included High Resolution Time Tags including 1 ms timetags of contact inputs New Communication Links to plant controls Distributed Multiprocessor Control in each controller for maximum processing capability Enhanced Diagnostics that can isolate a fault tothe card level in any of the triple-redundantcontrollers On-Line Repair of the triple-redundant controllers Standard built-in Synchronizing CheckProtection Fully Digital Valve Positioning to provide amore linear response of the steam turbine Direct Interface to Turbine Devices, includingproximity monitoring equipment Compact Packaging in half the cabinet size ofthe previous control systemThe SPEEDTRONIC Mark V is the latest version of GE’s long series of highly reliable electrohydraulic control (EHC) systems for steam turbines. Its heritage consists of a long list ofsuccessful control systems, including the first EHCMark I steam turbine control built in the 1960s,and the SPEEDTRONIC Mark I-IV gas turbinecontrol. The Mark V continues to combine thebest turbine and generator design engineeringwith the latest electronic controls engineering toprovide a modern, yet experienced controls package (Figure 1).The Mark V is the third generation of triple-redundant microprocessor-based turbine controls that originated in 1982, with the Mark IV1 and was followed inCONTROL SYSTEM HISTORYFrom their introduction in the late 1800s,steam turbines were governed by mechanicalhydraulic control (MHC) systems. Speed was controlled by a flyweight governor of James Watt heritage, signals were transmitted by levers and linksor hydraulic pressure signals, and motive power tocontrol steam valves was provided by low-pressureRDC26449-2-11Figure 1.SPEEDTRONIC Mark V steamturbine control cabinet1
GER-3687Chydraulics. Refined to the utmost, this technologywas used through the mid-1960s, to control suchsophisticated units as double-extraction industrialturbines, large double-reheat fossil units, and thefirst nuclear units incorporating pressure controlsfor BWRs. The complexity of these later controlsclearly showed that a new technology was needed.component count with a resultant increase in reliability. The EHC Mark II version for large steam turbines, in addition to integrated circuits, also introduced triple-redundant protection systems for thefunctions that can cause a turbine trip, resulting infurther improvement in running reliability by virtually eliminating spurious forced outages.The associated high-pressure hydraulic system,using 1600 psig (110 bar) fire-resistant fluid, hasundergone gradual improvement through theyears. The basic technology is still in use for thenew electro- hydraulic controls.The history of analog controls, as well as thenew digital controls, is summarized in Table 1.The reliability of EHC systems developedaccording to a classic learning curve shown inFigure 2. The step change in reliability realizedwith the EHC Mark II is attributed to two factors:the superior reliability of integrated electronicsand the introduction of triple-redundant protection logic described above.ANALOG CONTROLSGE introduced the electro-hydraulic control(EHC) system for steam turbines in the 1960s.The first medium-size unit went into service in1961, and the first large reheat unit in 1968. Theproportional controls used analog circuitry withdual redundancy for speed control and singlechannel for other controls. The logic and protective system was implemented with relays.The original Mark I system consisted of discretecomponent analog circuitry. In the 1970s, thesecircuits were modernized to take advantage of integrated circuitry (IC) technology as well as solidstate logic circuits for some of the protection andlogic. This resulted in the EHC Mark II, which hadmany IC components and a new cabinet arrangement, while the subsequent Mark III, used only onsmall- and medium-sized turbines, employed ICsthroughout and also included electronic speedsensing and microprocessors for automation.A major improvement for both medium andlarge steam turbine controls was a reduction inDIGITAL CONTROLSWhile GE steam turbines were being shippedwith these EHC systems through the mid-1980s, inthe early 1980s, GE’s Gas Turbine Division introduced the very successful triple-redundant digitalcontrol system – the SPEEDTRONIC Mark IV.The first triple-redundant steam turbine controlsystem for utility turbines, the DCM system, wasTable 1PROGRESS OF STEAM TURBINE ELECTRONIC CONTROLSSystemIntroducedEHC MK I1961ECH MK II1970EHC MK III*1980DCM/MK III 1986ST MK V1991Total id StateIntegratedCircuits &DiscreteIntregratedCircuits &TMR elaysRelaysRelaysDisplayAnalog Meters& LightsDigital Meters& LightsDigital Meters& LightsOperator InputsPushbuttons and DialsTMR Micro-Processors/singleColor CRTTouch PanelFault ToleranceDual RedundantSpeed ControlDual RedundantSpeed ControlSingle ChannelControl ro-Processor*Used only for small and medium size steam turbines2Cursor or TouchTMR (2/3 Voting) with Sift(Software Implemented FaultTolerance)/SingleMicro-processors
GER-3687CGT21457BFigure 2.Control system reliability, PH is forced outage rate based on period hours; MWW is megawattweightedshipped in 1987, building on gas turbine experience, including the use of many of its electronicsmodules, and developing it further with SoftwareImplemented Fault Tolerance (SIFT). A companion single-channel system, the Mark III Plus,aimed at the smaller industrial units, was firstshipped in 1988.Some of the benefits from the new digital systems are flexibility and greater precision of ofthe benefits from the new digital systems are flexibility and greater precision of controls becausefunctions are determined by software rather thanhardware, CRT operator interface, data linkinterface to plant level control systems, and online repair capability for triple-redundant systems, providing further improvement in reliability.The new SPEEDTRONIC Mark V SteamTurbine Control System is developed from thislong evolution of electronic steam turbine controls. It is available in both triple-redundant MarkV TMR and single-channel Mark V Simplex control systems, the only difference being the twoadditional controllers in the TMR design.STEAM TURBINEUNIT CONTROLSThe main functions of a modern steam turbinecontrol system are: Speed and acceleration control during start-up Initialization of generator excitation Synchronization and application of load inresponse to local or area generation dispatchcommands Pressure control of various forms: inlet,extraction, back pressure, etc. Unloading and securing of the turbine Sequencing of the above functions underconstraint of thermal stress Overspeed protection during load rejectionand emergencies Protection against serious hazards, e.g., lossof lube oil pressure, high exhaust temperature, high bearing vibration Testing of steam valves and other importantprotective functionsAdditional control and monitoring functionsare also required in most applications, such as: Monitoring and supervision of a large num3
GER-3687Cber of pressures, temperatures, etc., to provide guidance and alarms for operators Start-up and monitoring of turbine-generator auxiliaries such as lube oil, hydraulic, andsteam seal systems Display, alarm, and recording of the abovefunctions and data Diagnosis of turbine or generator problems Health check and diagnostics of the electronic system itselfIt is characteristic of the first group of functionsthat they must be performed with high controlbandwidth, or with very high reliability, or both, toensure long-term reliable operation and service ofthe turbine. It is for these reasons that GE has,from the very beginning of turbine technology,designed and provided the controls and protection for its units, starting with the MHC systems acentur y ago and continuing with the newSPEEDTRONIC Mark V control system.For the new all-digital systems, GE has definedthe first group of functions as a “Turbine UnitControl System." These functions, together withthe input and output devices (I/O) required, areincluded in all control systems which are an integral part of steam turbines supplied by GE.A characteristic of the unit control system isthat all essential turbine control and protectionfunctions are included to allow a unit to operatesafely even if other supporting systems should fail.Another characteristic is that the “control point”interface (i.e., the interface between the turbineand the control system) remains in GE’s scope,while interface to plant controls can be made at“data point” level, which does not include criticaland rapidly varying commands and feedback signals, and therefore, is a more suitable point ofinterface to possible non-GE controls. Yet anothercharacteristic of unit control functions is that theymust be performed either continuously or veryfrequently to provide satisfactory control. Datasampling and processing of control algorithms upto ten times per second are used for many unitcontrol functions.The second group of functions can be performed less frequently (i.e., every few seconds ormore), and turbine operation may be continued,in most cases, during short-term interruptions inthe monitoring functions as long as the “unit control” is performing correctly.The second group of functions includes mostof what used to be called “TSI,” for TurbineSupervisory Instrumentation, which we now pre-Table 2STEAM TURBINE CONTROL PHILOSOPHY1. Clear separation between control and protection shall be provided.2. Controls comply with IEEE 122 standard.(e.g., can reject rated load without causinga turbine trip.)3. A protection system backup is provided forall control functions.4. A double set of steam valves is provided forall major admissions; one set for controlsand one set for protection.5. Protection (trips) are classified accordingto criticality: vital to have conceptual redundancy and for triple redundant systems.6. Controls use two out of three redundancyfrom sensor to actuator for all vital andimportant functions.7. A single failure in the controls will notcause a shutdown. It will cause a diagnosticalarm, and it is repairable on-line.fer to call TGM, for Turbine Generator Monitoring. The TGM functions can be included in theMark V systems, or they may be integrated intothe plant control system. For small- and mediumsized units, the TGM functions can be incorporated without significant extra hardware, and forlarge units, additional cabinets are needed. Thesecabinets can be mounted either at the turbineand generator or in an equipment room, and theycan interface with a common Mark V operatorinterface.The philosophy applied to steam turbine control systems has developed over time, and it issummarized in Table 2.A block diagram of the protective system of theMark V is shown in Figure 3. The left-hand sideshows the various trip inputs entering throughredundant paths. At the extreme right is the output to the emergency trip system (ETS), ahydraulic pressure signal, which will cause rapidclosure of all steam admission valves when depressurized. The critical inputs to the ETS can be tested on-line, one at a time, with the help of the lockout valves located immediately to the left of thefinal output to the ETS. This diagram shows thestandard offering with an all-electronic overspeedtrip. Optionally, a system with a mechanical overspeed governor can be supplied.4
GER-3687CGT24371Figure 3. Turbine protection system5
GER-3687CCGRI219AFigure 4. Mark V controller modulecontrol systems is due in considerable measure tothe use of triple sensors for all critical parameters,as it was first demonstrated with the triple-redundant protection system of the EHC Mark II.SPEEDTRONIC MARK VCONTROL CONFIGURATIONFigure 5 shows the configuration for theSPEEDTRONIC Mark V triple modular redundant (TMR) control system for a medium to largesteam turbine with redundant operator interfaces.The core of this system is the three identical controllers called R , S , and T . All critical control algorithms, protective functions, and sequencing are performed by these processors. In sodoing, they also acquire the data needed and generate outputs to the turbine. Protective outputsare routed through the P module consisting oftriple redundant processors X , Y , and Z ,which also provide independent protection forcertain critical functions such as overspeed.The three control processors, R , S , and T , acquire data from the triple-redundant sensors as well as from dual or single sensors. Ageneric complement of sensors is described inTable 3. The actual number of sensors willdepend on turbine type. All critical sensors forcontinuous controls, as well as protection, aretriple-redundant. Other sensors are dual or singledevices fanned out to all three control processors.The extremely high reliability achieved by TMRMARK V ELECTRONICSAll of the microprocessor-based controls have amodular design for ease of maintenance. Eachmodule or controller contains up to five cards,including a power supply. Multiple processorsreside in each controller which distribute the processing for maximum performance. Individualprocessors are dedicated to specific I/O assignments, application software, communications, etc.,and the processing is performed in a real-time,multi-tasking operating system. Communicationbetween the controller’s five cards is accomplishedwith ribbon cables and gas-tight connectors. Thiseliminates the traditional computer backplane.Communication between individual controllers isperformed on high-speed Arcnet links.Figure 4 shows the standard microprocessormodule.6
GER-3687CTable 3DIGITAL CONTROLS REDUNDANCYAnalogUseDigitalUse2/3Speed pickupsEOS pickupsMain steam pressureHot or cold reheat pressureControland/ortrip2/3Low bearing oil pressureLow shaft pump pressureLow vacuum, each hoodLow hydraulic fluid pressureTripTripTripTripThrust bearing wearTripLVDT CV #1-4 IV #1/2ControlExhaust thermostat each hoodL-1 thermostat (for units w/bypass)TripTripHP 1st stage temperatureHP last stage temperatureAlarm/tripAlarm/trip2/2Thrust bearing wear(or 2/3 if practical)Trip2/2Low ETS pressureLow lube oil level (option)Cross tripTrip1/2Differential expansionAll ATS temperatures & pressBearing oil temperature1/1EccentricityBearing vibrationShell expansionCT and PT’s (3)1/2NoneAut. Turb. Start(ATS)ATS1/1Numerous contacts fanned out to R, S, & Tfor testing and plant interface.Preroll checkTripMonitor/alarmControl/PLU/load holdBearing oil pressureSS header pressure & tempHydr. fluid pressure & tempPrerollcheckFirst stage pressureControlLine frequencyH2 pressureGenerator field I & VH2 cooler inlet tempH2 cooler outlet tempSCW outlet tempL-1 tempUnit load demandControlATS loadholdPreroll checkLoad holdLoad holdMonitor/alarmCoord. cont. inputNumerous contact inputs to C for alarm,monitoring, and ATS checks and holds.Customer trips.three controllers is automatically diagnosed to thecard level and displayed as an alarm message.Maintenance personnel can power down theappropriate controller and replace the defectivecard while the turbine is on-line. Redundant sensors are used in control and trip protection systemsPRIMARY CONTROLLERS R S T The three controllers R , S , and T , shownin Figure 5, are physically separate and independent modules that contain all control and protection hardware and software. A failure in any of the7
GER-3687CGT21460Figure 5.TMR system with redundant communicationsto provide a “total system” fault-tolerant design. Asa result, diagnostics are able to distinguish betweenredundant sensor failures and electronics failures.Three basic forms of voting are used in the control. Figure 6 shows how the first form of voting,the software implemented fault tolerance (SIFT),works. At the beginning of each computing timeframe, each controller independently reads its sensors and exchanges this data with the data fromthe other two controllers. The median value ofeach analog input is calculated in each controllerand then used as the resultant control parameterfor that controller. Diagnostic algorithms monitora predefined deadband for each analog input toeach controller, and if one of the analog inputsdeviates from this deadband, a diagnostic alarm isinitiated to advise maintenance personnel.Contact inputs are voted in a similar manner.Each contact input connects to a single terminalpoint and is parallel wired to three contact inputcards in the voted contact input module. Eachcard optically isolates the 125 V dc input, and thena dedicated 80196 processor in each card timestamps the input to within 1 ms resolution. Thesesignals are then transmitted to the R , S , and T controllers for voting and execution of theapplication software. This technique eliminatesany single point failure in the software voting system. Redundant contact inputs for certain functions such as low lube oil pressure are connectedto three separate terminal points and then individually voted. With this SIFT technique, multiplefailures of contact or analog inputs can be accepted by the control system without causing an erroneous analog or trip command from any of thethree controllers as long as the failures are notfrom the same circuit.GT21459Figure 6. Software implemented fault tolerance(SIFT)8
GER-3687CGT21461Figure 7. Hardware voting of analog outputsGT21462AFigure 8. Hardware voting of logic outputs9
GER-3687CA second form of voting is hardware voting ofanalog outputs. As illustrated in Figure 7, threecoil servo valves on the steam valve actuators areseparately driven from each controller, and theposition feedback is provided by three LVDRs.The normal position of each steam valve is theaverage of the three commands from R , S ,and T , respectively. The resultant averaging circuit has sufficient gain to override a gross failureof any controller, such as a controller outputbeing driven to saturation. Diagnostics monitorthe servo coil currents and the D/A converters inaddition to the LVDRs.The third form of voting for the trip solenoidsis discussed under OVERSPEED.instead of using the traditional synchroscope onthe generator protective cabinet. Operators canchoose one additional mode of operation by selecting the monitor mode, which automatically matches speed and voltage, but waits for the operator toreview all pertinent data on the CRT display beforeissuing a breaker close command.POWER LOADUNBALANCE – PLULarge steam turbine applications use anothermodule similar to P which is designated PLU for power load unbalance. This provides powerload unbalance protection and interface to thefast closing feature on control and intercept valvesvia three independent cards U , V , and W .OVERSPEEDThe P protective controller contains threeindependent cards X , Y , and Z with theirown processors and power supplies. This separateset of triple-redundant electronics with its associat
control system – the SPEEDTRONIC Mark IV. The first triple-redundant steam turbine control system for utility turbines, the DCM system, was Table 1 PROGRESS OF STEAM TURBINE ELECTRONIC CONTROLS System EHC MK I ECH MK II EHC MK III* DCM/MK III ST MK V Introduced 1961 1970 1980 1986 1991 Total Shipped 190 290 120 27/44 55 (Approx.)
GE Mark IV Speedtronic Driver Manual 4 1 Description The GE mark IV Speedtronic driver allows the FieldServer to receive status data from Speedtronic devices over either RS-232 or RS-485 using GE Mark IV Speedtronic protocol. The Driver acts as a Passive Client and receives status data from Speedtronic devices.
The GE mark IV Speedtronic driver allows the FieldServer to receive status data from Speedtronic devices over either RS-232 or RS-485 using GE Mark IV Speedtronic protocol. The Driver acts as a Passive Client and receives status data from Speedtronic devices. Note that only Digital values are
GE Mark IV Speedtronic Description The GE Mark IV Speedtronic driver allows the FieldServer to receive status data from GE Mark IV Speedtronic devices. The driver can receive data over a RS-232 or RS-485 serial communications line. The driver can only receive status data and therefore acts as a passive client. Fieldserver Mode Nodes Comments Client
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additif alimentaire ainsi que d’une nouvelle utilisation pour un additif alimentaire déjà permis. Les dispositions réglementaires pour les additifs alimentaires figurent à la partie B du titre 16 du RAD. L’article B.16.001 énumère les exigences relatives à l’étiquetage des additifs alimentaires. En particulier, l’article B.16.002 énumère la liste des critères qui doivent .
