ger-3658d-speedtronic-mark-v-gas-turbine-control-system.pdf

GER-3658DSPEEDTRONIC™ MARK V GAS TURBINE CONTROL SYSTEM D. Johnson and R.W. Miller T. Ashley GE Drive Systems GE Power Systems Salem, VA Schenectady, NY INTRODUCTION Dry Low NOx techniques, fuel staging and com- The SPEEDTRONIC Mark V Gas Turbine ™ bustion mode are controlled by the Mark V sys- Control System is the latest derivative in the tem, which also monitors the process. highly successful SPEEDTRONIC ™ series. Sequencing of the auxiliaries to allow fully auto- Preceding systems were based on automated tur- mated startup, shutdown and cooldown are also bine control, protection and sequencing tech- handled by the Mark V Control System. Turbine niques dating back to the late 1940s, and have protection against adverse operating situations grown and developed with the available technol- and annunciation of abnormal conditions are ogy. Implementation of electronic turbine con- incorporated into the basic system. trol, protection and sequencing originated with The operator interface consists of a color the Mark I system in 1968. The Mark V system is graphic monitor and keyboard to provide feed- a digital implementation of the turbine automa- back regarding current operating conditions. tion techniques learned and refined in more Input commands from the operator are entered than 40 years of successful experience, over 80% using a cursor positioning device. An arm/exe- of which has been through the use of electronic cute sequence is used to prevent inadvertent tur- control technology. bine operation. Communication between the The SPEEDTRONIC ™ Mark V Gas Turbine operator interface and the turbine control is Control System employs current state-of-the-art through the Common Data Processor, or <C>, to technology, including triple-redundant 16-bit the three control processors called <R>, <S> and microprocessor controllers, two-out-of-three vot- <T>. The operator interface also handles com- ing redundancy on critical control and protec- munication functions with remote and external tion parameters and Software-Implemented devices. An optional arrangement, using a Fault Tolerance (SIFT). Critical control and pro- redundant operator interface, is available for tection sensors are triple redundant and voted those applications where integrity of the exter- by all three control processors. System output nal data link is considered essential to contin- signals are voted at the contact level for critical ued plant operations. SIFT technology protects solenoids, at the logic level for the remaining against module failure and propagation of data contact outputs and at three coil servo valves for errors. A panel mounted back-up operator dis- analog control signals, thus maximizing both play, directly connected to the control proces- protective and running reliability. An indepen- sors, allows continued gas turbine operation in dent protective module provides triple redun- the unlikely event of a failure of the primary dant hardwired detection and shutdown on operator interface or the <C> module. overspeed along with detecting flame. This mod- Built-in diagnostics for troubleshooting pur- ule also synchronizes the turbine generator to poses are extensive and include “power-up,” the power system. Synchronization is backed up background and manually initiated diagnostic by a check function in the three control proces- routines capable of identifying both control sors. panel and sensor faults. These faults are identi- The Mark V Control System is designed to ful- fied down to the board level for the panel and fill all gas turbine control requirements. These to the circuit level for the sensor or actuator include control of liquid, gas or both fuels in components. The ability for on-line replacement accordance with the requirements of the speed, of boards is built into the panel design and is load control under part-load conditions, tem- available for those turbine sensors where physi- perature control under maximum capability cal access and system isolation are feasible. Set points, tuning parameters and control constants conditions or during startup conditions. In addi- are adjustable during operation using a security tion, inlet guide vanes and water or steam injec- password system to prevent unauthorized access. tion are controlled to meet emissions and oper- Minor modifications to sequencing and the ating requirements. If emissions control uses addition of relatively simple algorithms can be 1 FUNCTIONS al and utility prime mover in the late 1940s with The SPEEDTRONIC™ Gas Turbine Control initial applications in gas pipeline pumping and System performs many functions including fuel. The automatic relay sequencing. matically logs time-tagged alarms. The ence has been centered on more than 4. emphasis was placed on Improvements in the new design have been integrity of the power supply system. replaced the fuel regulator. in combination plays is an operator configurable demand dis. there were 424 gas tur. exceeds 99. utility peaking. Once the changeover to electronics was trol is achieving greater reliability.400 units. also play that can be automatically printed at a allowed interfacing with SCADA (Supervisory selectable interval. This philosophy hours. SIFT DC-based system with AC. the rapid advances in electronic sys- time-to repair and improved control system tem technology resulted in similar advances in availability than the SPEEDTRONIC™ Mark IV gas turbine control technology (Table 1). monitoring of and manual sequencing. The printer auto. display shown on the monitor. These early electronic systems provid- operator information. almost 264 Mark V systems experience has involved more than 5. Note applications. trip. cally dependent nature. continuous remote control operation. Independent devices all turbine. It provides an easy means to Control and Data Acquisition) systems for true obtain periodic and shift logs. reliability.000 ties of the existing technology. rapid growth in the field of control technology. with rudimentary annunciator monitoring. shutdown and cooldown printer is capable of copying any alpha-numeric where appropriate for unattended installations. lents where appropriate. loss of flame. SPEEDTRONIC™ Mark V con. In addition. I/O capacity. The hydro-mechanical design culminated in the A printer is included in the control system “fuel regulator” and automatic relay sequencing and is connected via the operator interface. As of May 1994. maintainability. gas achieve the previously described philosophy in turbine control designs benefited from the 2 .4 million hours. loss of lube oil and conditions. control and auxiliary functions. in an integrated manner that is tailored to Through the early years of the industry. mechanical starting fuel control with an elec- The statistical measures of reliability and avail. bine installations. the printer will electronic gas turbine control in 1968.and shaft-powered technology. in that Mark V systems shipped or on order. All of these functions are performed high vibration.9 the control philosophy shown in Table 2 has percent. The log assists in identifying the cause of a pneumatic temperature control and electro- trip for trouble shooting purposes.GER-3658D accomplished when the turbine is not operating. developed and matured to match the capabili- forced-outages (MTBFO) stands at 28. overtem. order. The for automatic startup. along with continued ed an order of magnitude increase in running application flexibility and careful design for reliability and maintainability. synchronization and voltage match- temperature control. tronic equivalent. emphasizes safety of operation. as well as the This was the basis for introduction of the first clearance of alarms. The automatic relay sequenc- ability for SPEEDTRONIC™ Mark V systems have ing was retained and the independent protective quickly established the effectiveness of the new functions were upgraded with electronic equiva- control because it builds on the highly success. flexi- bine Mark V systems and 106 steam turbine bility. This sys- print the historical trip log that is frozen in tem. and provided protection against overspeed. ultimately known as the SPEEDTRONIC™ memory in the unlikely event of a protective Mark I Control. diagnostics. and the fleet mean-time-between. The early control systems were air and emissions control. had entered commercial ser vice and system while the 26 years of electronic control experi- operation has exceeded 1. protection against unsafe and adverse operating perature. One of these dis. including sensors and actuators. maintainability and ease of use. supplemented by a pneumatic cooldown. preset startup fuel limiting ing of the generator and system. standardization and back-ups. that more than 40 years of gas turbine control As of May 1994. leading to a made in microprocessors. achieved. They are also protected by a security password. faster mean. Because of its electri- ful SPEEDTRONIC ™ Mark IV system. sequencing of turbine based on hydro-mechanical steam turbine gov. shutdown and erning practice. fire. Throughout this time period.400 tur- established Mark V level of system reliability. CONTROL SYSTEM HISTORY CONTROL SYSTEM The gas turbine was introduced as an industri. fuel and auxiliaries for startup. (when separated from the grid) or load (when The speed and load control function acts to connected). A in accordance with the operator’s fuel selection. the control functionality required by the gas tur- peratures and controls air flow via the inlet bine may be found in Reference 1. Figure 1. GER-3658D Table 1 ADVANCES IN ELECTRONIC CONTROL CONCEPTS the stated priority. The input to the system is the operator command for speed Table 2 GAS TURBINE CONTROL PHILOSOPHY • Single control failure alarms when running or during startup • Protection backs up control.Gas turbine generator controls and bility while maintaining flexibility limits 3 . guide vane positioning system and the emissions Temperature control limits fuel flow to a maxi. The outputs are the commands to control the fuel flow under part-load conditions the gas and liquid fuel control systems. guide vanes to optimize part-load heat rates on The fuel command signal is passed to the gas heat recovery applications. thus independent • Two independent means of shutdown will be available • Double failure may cause shutdown. block diagram of the fuel. but will always result in safe shutdown • Generator-drive turbines will tolerate full-load rejection without overspeeding • Critical sensors are redundant • Control is redundant • Alarm any control system problems GT17610B • Standardize hardware and software to enhance relia. Startup can be on either fuel and transfers trol systems is shown in Figure 2. The operating limits and liquid fuel systems via the fuel signal divider of the fuel control are shown in Figure 1. control system. the inlet to satisfy the needs of the gover nor. air and emissions con. A more detailed discussion of mum consistent with achieving rated firing tem. as well as maximum flow from one system to the other after an appropri. porating a pressure control proportional to The liquid fuel control system is shown speed and a flow control proportional to fuel schematically in Figure 5. independent stop valve. signals to the servo valve. The stop/speed ratio valve also acts as an characteristics during a transfer from gas to liq. Two stages provide a stable turn. position on loss of either signal or hydraulic out operator intervention. zles in the multiple combustors is accomplished The gas fuel control system is shown schemat. which will be single-acting valves that will fail to the closed alarmed. Gas turbine fuel control under load are accomplished by transitioning warm-up conditions. can trip the valve closed independent of control ly monitored to ensure proper operation. Fuel distribution to the gas fuel noz- nal fuel is manually initiated. by a ring manifold in conjunction with careful ically in Figure 4. incor. Both the stop ratio Transfer can be automatically initiated on loss of and control valves are hydraulically actuated. hydraulically-actuated trip relay that the idle fuel system is automatic and continuous. and will proceed to completion with. Purging of interposed. System ture. It is a two-stage system. Since the fuel pump is command. control of fuel nozzle flow areas. pressure. It is equipped with an uid fuel are illustrated in Figure 3. Return to the origi. supply of the r unning fuel.GER-3658D GT17603B Figure 2. for peak output at minimum ambient tempera- ate fill time to minimize load excursions. the system down ratio in excess of 100:1. Gas fuel control system 4 . a positive displacement pump. Dual fuel transfer characteristics gas to liquid Figure 4. which is more achieves flow control by recirculating excess fuel than adequate for control under starting and GT20703B GT17599 Figure 3. lube oil pressure established. as appropriate to make the actual fuel extra cranking power is used for gas path purg- flow. and then attempt type. allowed proven mechanical device that consists of care. equal the product of turbine speed ing. as measured by the speed of the liquid fuel ing prior to ignition. the turbine den load rejection. The control sys- tem also monitors actual combustion system operation to ensure compliance with the required schedule. like any internal combustion engine. force at the turbine site. is used on some of the larger gas tur- The required turndown ratio is achieved by mul. Purge times will vary from one minute to as long fast-acting shutoff valve is provided to ensure as 10 minutes in some heat recovery applica- against loss of flame from over-watering on sud. The amount of water controls will automatically enter a purge required is a function of the fuel flow. gas path purging equivalent water flow. After automatic system mands are essentially equal. Liquid fuel control system steam or gas supplies are available. Accuracy of es purge speed. Special provisions are incor- porated to accommodate off-normal situations such as load rejection. The resultant signal speed. supplies. emissions levels required by the regulations in However. This is usually a diesel engine or electric motor com- bined with a torque converter. or bypass even though ignition speed is 10% to 15%. The ignition sequence consists of turning on 5 . reliable ignition and cross firing of the combus- nations. GER-3658D ulates the division of fuel among the multiple- combustion stages according to a schedule that is determined by a calculated value of the com- bustion reference temperature. depending on the ambient temperature. depending on desired operating tem. but have a more benefi. or if the exhaust ducting has pockets where ments are generally about 40% higher than the combustibles can collect. This approach ensures a sys. usually sufficient to ensure tem monitoring meets or exceeds both EPA and three to five volume changes in the gas path. the ambient humidity and nitrogen oxide to refire. as described later. A typical automatic starting sequence is tem in which both the liquid and gas fuel com. control system and sys. bines. This speed has been found to be optimum from bustion techniques relies on multiple-combus. but could also be GT17604 a steam turbine or gas expander if external Figure 5. This is a device is started and. to warm up. the cranking tors is achieved via the flow divider. Steam flow require. the standpoint of both thermal fatigue duty on tion staging to optimize fuel/air ratios and the hot gas path components. can proceed as the rotor speed passes through Control of nitrogen oxide emissions may be firing speed. for compressor water wash- flow divider. Sufficient cranking power is provided to tiplying the fuel command by a signal propor. if there is heat recovery equipment. When the turbine reach- cial effect on turbine performance. as well as offering achieve thorough premixing in various combi. When purging is completed. and fuel command. Startup via the generator. shown in Figure 6. Simple-cycle gas turbines with con- fully matched gear pumps for each combustor. sary purge period. ventional upward exhausts do not require purg- all of which are mechanically connected to run ing prior to ignition and the ignition sequence at the same speed. The gas turbine. Emissions control using Dry Low NOx com. If ignition does not occur before accomplished by the injection of water or steam the 60 second cross-firing timer times out. tions. all local code requirements. Fuel distribution to checks have been successfully completed and the liquid fuel nozzles in the multiple combus. crank the unfired gas turbine at 25% to 30% tional to turbine speed. An independent. and for accelerated cooldown. ensures a safe light-off. This valve. is not self-starting and requires an out- side source of cranking power for startup. rotor is allowed to decelerate to ignition speed. the into the combustors. this speed is held for the neces- the flow measurement. perature. The emissions fuel control system reg. using variable frequency power from the discharge back to the pump suction. the fuel sequence. positions the pump recirculation. tors. for diesel engines. and then closing the breaker at the point side of the turbine from the spark plugs. If successful ignition and cross firing are the generator breaker from tripping on reverse not achieved within an appropriate period of power at breaker closure. In the protective mod- time. As the turbine approaches running speed. are opened to the full-speed. which are on the opposite bus. Acceptable synchronizing conditions tion monitor as a high exhaust temperature are independently verified by the triple-redun- spread prior to loading the gas turbine. At a speed of about step in the starting sequence consists of auto- 30% to 50%. where the two are in phase within predeter- tion and cross-firing are complete. reduced to the warm-up value for one minute Turbine speed is matched to the line frequen- and the starting device power is brought to max. igni. the compressor inlet guide vanes. triple-redundant microprocessor-based syn- back to the purge sequence. The shutdown sequence begins with automatic synchronizing is initiated. At about 80% NOx systems. the gas turbine enters a predeter. and faster just before reaching running lected intermediate load. The final begins to accelerate faster. step process that consists of matching turbine ting firing fuel flow. When flame is detected by generator speed. After completion of the warm-up period. fuel At the completion of synchronizing. The purpose of this is to reduce the ther.GER-3658D GT17606D Figure 6. dant control processors as a check function. bines. turbine efficien. and will attempt a chronizing methods are used to predict zero- second firing sequence without operator inter. Fuel is mined limits. In the unlikely event of incomplete breaker closing time to provide true zero angle cross firing. Typical starting times to base load are mal-fatigue duty associated with startup. either the normal or fast rate. and sometimes voltage. the control system automatically reverts ule. Typical gas turbine starting characteristics ignition power to the spark plugs and then set. shown in Table 3. base load or peak speed. matic loading of the gas turbine generator. to the the flame detectors. the turbine operating speed falls below 95%. which were closed during startup to prevent Normal shutdown is initiated by the operator compressor surge. phase angle difference and compensate for vention. This is a two or three unloading of the unit. to either a prese- tially. load. slower ini. the tur- flow is allowed to increase and the gas turbine bine will be at a spinning reserve load. speed no-load applies to all simple cycle gas tur- cy has increased sufficiently so that the gas tur. closure. Although the time to full- At about 40% to 85% speed. cy with a small positive differential to prevent imum. at mined program of acceleration rates. and is reversible until the breaker is opened and no-load position. the loading rates shown are for standard bine becomes self sustaining and external crank- combustion and may var y for some Dr y Low ing power is no longer required. to 90% speed. The main generator breaker is opened by the reverse power relay at 6 . it will be detected by the combus. multiple control computer faults and compres- Gas turbines are capable of faster loading in sor surge for the aircraft-derivative gas turbines. instant. microprocessors. high lube oil header the larger units. some mal fatigue duty for these fast load starts is sub. or by operation of a conventional turning ning reliability due to the redundancy of the gear on some larger gas turbines. triple-redundant protective mod- load start is by operator action with the normal ule. loss of flame or sequent startups. low hydraulic supply pressure. the with diesel engine starting devices are optionally manual emergency trip buttons. The rotor should be turned trip the gas turbine independently from the fuel periodically to prevent bowing from uneven control in the event of overspeed. overtempera- cooldown. the pro- without outside electrical power. the gas turbine coasts start capability. where fuel is completely shut off. sensors and signal processing. A ing pump for black starts on distillate. The black start option uses a sequence is to reduce the thermal fatigue duty DC batter y-powered turning device for rotor imposed on the hot gas path parts. which would cause vibration on sub. The added functions include combustion and er turbines to as much as 48 hours on some of thermocouple monitoring. Lubricating oil tection model performs the synchronization for starting is supplied by the DC emergency function to close the breaker at the proper pump powered from the unit battery. hydraulic supply. Because of their nature or criticality. loss of lube oil pressure. which drives the gas plies the AC power required for ignition and the turbine fuel flow to a minimum value sufficient local operator interface. selection of a fast the hardwired. high rotor vibration. Cool down sequences may be temperature. have been added with minimum impact on run- bines. which replaces the Gas turbine generators that are equipped mechanical overspeed bolt on some units. However. An inverter sup. Turning of the rotor for cool. This bat. GER-3658D Table 3 SIMPLE CYCLE PACKAGE POWER PLANT STARTING TIMES about 5% negative power. additional protective features ratcheting mechanism on the smaller gas tur. the purpose of this “fired shutdown” about 50% speed. but not turbine speed. It also receives signals from the flame tery also provides power to the DC fuel forward. ture. It shows how loss of lube oil. cooldown to ensure the integrity of the black After fuel is shut off. These functions are the hardwired over- start being the default case. or manual hydraulic trip will 7 . the protective function acts to can be effective. With the advent of down or maintenance is accomplished by a microprocessors. and “customer capable of starting in a blacked out condition process” trips. detectors and determines if flame is on or off. the event of a system emergency. are powered from the battery. fire. ther. down periods vary from five hours on the small. down to a point where the rotor turning system As mentioned. protective functions trip the stop valve through stantially higher. The tur. The system fans is obtained from the main generator gas turbine then decelerates to about 40% to through the power potential transformer after 25% speed. Normal cool. speed detection system. As the generator field is flashed from the battery at before. Therefore. As previously mentioned. block diagram of the turbine protective system is bine and generator control panels on all units shown in Figure 7. Power for the cooling to maintain flame. interrupted at any point for a restart if desired. reliability and ease Other protective coordination is provided as of on-line maintenance. a new tive purposes and combined-cycle coordination triple-redundant protective module and a signif- with heat recovery steam generators and single. The latter is Standardized modular construction enhances hydraulically integrated as shown in Figure 7. It include turbine shutdown for generator protec. uses SIFT technology for the control. Interfacing to other application-specific trip CONTROL CONFIGURATION functions is provided through the three control The SPEEDTRONIC™ Mark V control system processors. Protective system block diagram. These trip functions and has an enhanced system configuration. and standardized links to remote operator sta- GT20781B Figure 8. SPEEDTRONIC™ Mark V turbine control result in direct hydraulic actuation of the stop SPEEDTRONIC™ MARK V valves. shaft STAG ™ steam turbines. Standard control configuration 8 . the hardwired protection module or makes increased use of modern microprocessors the hydraulic trip system. has been improved with color graphic displays tions. The operator interface required to meet the needs of specific applica.GER-3658D GT20784B Figure 7. quality. icant increase in hardware diagnostics. speed of installation. Dry Low NOx has four flame detectors in each of two zones 9 . Table 4 lists typical Processor called <I>. or <C>.O. Generator output are redundant only for “constant settable droop” systems 6. <I> also availability is significantly increased. Voted sensor values are computed by each ments the common I/O for non-critical signals of the control processors. This value rithms. It includes a monitor. Switch Protection Shared 3 Notes: 1. and printer. the overall control system cess and handling operator commands. frame blwr. as with ing operator displays. Dedicated sensors: one-third are connected to each processor 2. maintains the alarm buffers. redundant sensor arrangements. vidual exhaust temperature measurements are The Common Data Processor. Figure 8 shows the standard SPEEDTRONIC™ The three control processors accept input Mark V control system configuration. LVDTs (Linear Variable Dif ferential ticipating on the voting link. Redundant gathers data from the control processors by par. All critical control algo. Its main functions are driv. Vibration and fire detectors are related to the physical arrangement 5. The <I> processor communicates with One key output goes to the servo valves used <C> using a peer-to-peer communication link in position loops as shown in Figure 9.O. These voted values are and control actions. Pickup CTL & PROT Dedicated 3 to 6 Exhaust temperature T. Transformers. pickup Control Dedicated 3 Gas fuel flow Transducer Control Dedicated 3 Water flow Mag. turbine sequencing and primary protec.C. Some sen- does system configuration and download. The signal is compared with the position Table 4 CRITICAL REDUNDANT SENSORS Parameter Type Function Usage Number Speed Mag. like exhaust thermocouples. Switch Protection Shared 2 Filter delta p. ly to <C>. the fault tolerance to include sensors. chooses the higher of the two signals. produce the required control actions. a position sensor) produce a sig- At the core of SPEEDTRONIC™ Mark V con. is chosen because the LVDT is designed to have tive functions are handled by these processors. alarms. temperature Switch Protection Shared 3 Exh. pickup Control Dedicated 3 Actuator stroke LVDT Control Shared 2/Actuator Steam flow Transducer Control Shared 1 Vibration Seismic probe Protection Shared 8 to 11 Flame Scanner Protection Shared 4 to 8 Fire Switch Protection Shared 17 to 21 Control oil pressure Switch Protection Shared 3 L. Shared sensors are shared by processors 3. The top from various arrangements of redundant tur- block in the diagram is the Inter face Data bine and generator sensors. nal proportional to actuator position. CTL & PROT Dedicated 13 to 27 Generator output Transducer Control Dedicated 3 Liquid fuel flow Mag. By extending board. and imple. ues. off. are ments interfaces to remote operator stations divided among the control processors. but many. collects exchanged on the voter link so that each control data for display. managing the alarm pro. processor knows all exhaust thermocouple val- generates and keeps diagnostic data. the Mark IV system. key. Each con- trol are the three identical control processors trol processor measures both LVDT signals and called <R> <S> and <T>. sors are brought in to all three control proces- line diagnostics for maintenance. <C> position loops are closed digitally. GER-3658D tions and distributed control systems (DCS). The indi- and plant distributed control systems. pressure Switch Protection Shared 3 L. These which permits one or more <I> processors. and imple. a strong failure preference for low voltage out- They also gather data and generate most of the put. Turbine supervisory sensors used in control and sequencing algorithms that such as wheelspace thermocouples come direct. sors. Thee number of exhaust thermocouples is related to the number of combustors 4. which reduces the probability of result is that the turbine continues running machine overspeed or out of phase synchroniz- under control. almost all single failures will the <I> processor. tions. A hardwired that on-line repair can be initiated quickly. the Overspeed and synchronization functions are maximum current that one failed amplifier can independently performed in both the triple- deliver is overridden by the combined signals redundant control and triple-redundant protec- from the remaining two good amplifiers. turns. LVDT outputs that disagree. are Modbus Slave Station and a standard ether- trolled turbine parameter. Digital servo position loops command and the error signal passed through a is accomplished on a trip card associated with transfer function and a D/A converter to a cur. the main control processor drives one of the three coils. such as SCADA remote dispatch terminal units. Hardware voting for <P> solenoid outputs The wires are connected to the I/O module 10 . The two interfaces available not cause an appreciable bump in the con. interface is also available. manual trip push buttons The servo valve acts on the sum of the ampere and other hardwired customer trips. specification for the physical and medium access and current not equalling the commanded control (MAC) layers. The table includes an sors. An independent protective module <P> is Table 5 lists signals and commands available internally triple redundant. ing to the lowest achievable values. on the interfacing links. A GE protocol is available value make it easy to find a system problem. The current amplifier from each signals from the emergency overspeed.GER-3658D GT20782A Figure 9.3 excitation voltage. It accepts speed sen. control processors. The SIFT system ensures that the output fuel SPEEDTRONIC ™ Mark V control provides command signals to the digital ser vo stay in interfaces to DCS systems for plant control from step. flame detectors and potential transformer option for hard-wired contacts and 4-20 ma sig- inputs to perform emergency electronic over. As a result. which complies with the IEEE-802. the module. flame detection and synchronizing func. If one of the three channels fails. nals intended to interface with older systems speed. so for use over the ethernet link. Diagnostics of LVDT net link. The tive hardware. The trip card merges trip contact rent amplifier. The <I> processor. or a single <I> – Turbine fast load processor can control multiple gas and steam – Governor set point raise/lower turbines. the <I> – Base/Peak load selection processor can be equipped with plant load con- – Gas/Distillate fuel selection trol capability that will allow plant level manage- – Generator voltage (VARS) raise/lower ment of all units for both real and reactive – Generator synchronizing inhibit/release power. – Watts. and events – All allowable remote commands are available and alarms are captured when they occur. Compliance with recognized standards is an important aspect of SPEEDTRONIC™ Mark V controls. two <I> processors are used to obtain – Flame indication redundant links to the DCS system. cross-plotting and histogram screens. and provisions are included for both archiving and restoring older data. Analog data is stored when the values • Commands available change beyond a settable deadband.” or <H> processor.4 Gas Turbine Control and GT22904 Protection System Figure 10. Display options include a full range of trending. with ETL labeling of complete control cabs • CSA/UL — Approval has been obtained for the complete SPEEDTRONIC™ Mark V control panel • UBC — Seismic Code Section 2312 Zone 4 • ANSI — B133.90A Surge Withstand 11 . VARS and volts (analog for meters) In process plants where maintaining the link – Breaker status to the DCS is essential to keeping the plant on- – Starting sequence status line. For critical – On temperature control indication installations. or Operator • Feedback from turbine control Interface. For multi-unit configurations.200 a “historian. is available that – RS232C data transmission only. for the gas tur- baud bine installation. All data available in the Mark V • Connects to interface processor (I) data base can be captured and stored by the his- • RS232C link layer torian. • Alarm management referred to as the <D> processor. • Turbine control is Modbus slave station A specially configured PC is available to act as • Transmission on request by master. data can be requested periodically or • Feedback from turbine control on demand in user definable lists. a redundant <C> processor option. Mark V operator interface • ANSI — C37. INTERFACING OPTIONS The “stage link” that interconnects the <C> processor with the <I> processor is an Hardwired extendible Arcnet link that allows daisy chaining • Connects to common “C” processor I/O multiple gas turbines with multiple <I> proces- • Commands to turbine control sors. Thus a single gas turbine can be controlled – Turbine start/stop from multiple <I> processors. from <1> ensures that no single hardware failure can interrupt communications between the gas tur- Modbus link bine and the DCS system. GER-3658D Table 5 associated with <C>. It is designed to comply with several standards including: • ETL — Approval has been obtained for labeling of the Mark V control panel. 300 to 19. The historian – Most turbine data available in the I data base is sized so that about a month’s worth of data for a typical four unit plant can be stored on line. In – Alarm management addition. is shown in Figure 10. Mark V turbine control panel The Interface Data Processor. al black start inverter from the battery. and humidity between 5 and 95%. Figure 11. panel interior is shown in Figure 12. used for the Considerable thought has been given to the ignition transformer and the <I> processor. such as those caused by starting a diesel cranking motor. The routing of incoming wires to minimize noise typical standard panel will require 900 watts of and crosstalk. and the Ambient air at the panel inlet vents should be modules are identified by location in Figure 13. non-condensing. can be individually accessed. Cards are connect- and weighs approximately 1. minimize power dissipation and maximize func. AC for the local <I> pro- control system is specifically designed for GE gas cessor will normally be supplied via a cable from and steam turbines. cover locks the cards in place. By having 12 . the standard panel runs on the card rack back in place and closing the front 125 volt DC unit battery power.GER-3658D RDC26449-2-8 Figure 12. These can accept an extremely wide range of incoming DC. neat. They feature card racks that tilt out so cards 90 inches high. only thor- oughly tested panels leave the factory. iary input at 120 volt. Figure ed by front-mounted ribbon cables which can be 11 shows the panel with doors closed. The new design dissipates less power ion and is quite standardized. between 32 F and 72 F (0 C and 40 C) with a Each of these modules is also standardized. a typical processor module is shown in Figure The standard panel is a NEMA 1A panel that is 14. can be powered by house power. the auxiliary power can be 240 volt easily identified and the resulting installation is AC 50 Hz. The wiring has been made more DC and 300 watts of auxiliar y AC power. Each control module supplies its own regulated DC busses via AC/DC converters. Quality control is an the power and distributes it to the individual integral part of the manufacturing. Tilting For gas turbines. particularly a remote <I>. 54 inches wide. or it can be supplied from an option.200 pounds. with AC auxil. which makes the control tolerant of significant battery voltage dips. HARDWARE This will normally be the case when the central CONFIGURATION control room has an Uninterruptible Power The SPEEDTRONIC ™ Mark V gas turbine Supply (UPS) system. Each wire is Alternatively. Individual power supplies can be RDC26449-2-5 replaced while the turbine is running. The panels are made in a highly standardized The power distribution module conditions manufacturing process. easily disconnected for service purposes. and uses a considerable the SPEEDTRONIC™ Mark V panel or alterna- number of CMOS and VLSI chips selected to tively from house power. A picture of the than previous generations for equivalent panels. All power sources and regulated busses are monitored. accessible for ease of installation. Panel internal arrangement power supplies for the redundant processors through replaceable fuses. 50/60 Hz. 20 inches deep. The panel is constructed in a modular fash- tionality. The basic SIFT concept brings one sensor of each kind into each of <R>. If a sensor fails. No special hardware or software link and receives tables from the other proces. Each of the running processors so no bump in fuel control processor sends its table out on the voter flow will occur. Module map of panel interior ferent kind of transducer on another controller could cause a turbine trip. Consider the <R> controller: it outputs its Since only one turbine is connected to each table to and receives the tables from the <S> and panel. GER-3658D median value for each sensor and integrator output. This recombination is will be in the <R> processor. <C> is also connected to the voter link. Typical processor module Voting is also performed on the outputs of all integrators and other state variables. a SIFT-based system can tolerate one failed transducer of each kind. In previous sys- tems. <T> and exchange the fuel command and vote and all <C> controllers. is needed to keep integrated outputs in step. If there are any significant disagreements. If one computer technology and result in a more robust control. <S> and <T> follow the same procedure. calculates an erroneously high fuel command. an integrator compares the frequency of the SOFTWARE CONFIGURATION generator with the nominal frequency reference Improved methods of implementing the (50 Hz or 60 Hz). one failed transducer was likely to cause GT20783A one processor to vote to trip. sors. <C> will then diagnose that the transducer or parts immediately associated with it have failed and GT21533A will post an alarm to <I>. Any error is integrated to pro- triple-modular redundant system center on SIFT duce the fuel command signal. if a turbine is set to run on isochronous speed control with an isolated load. which selects the done in software or. its fuel command will initially be set to troller. the resulting mod. place. <S>. The values of all on the voter link. its output will not be correct and there will be a dis- agreement with the two correct values. But it exchanges data with the other processors and when the vot- ing takes place. the controller with the failed trans- ducer initially has a bad value. The sensor numbers to be voted are zero. Now all three controller tables must be recombined. fewer bumps in out- ules and panels are very consistent and repeat. the repaired control processor state outputs. for example. will output the voted value that will be from one the load setpoint. the bad value is rejected. Therefore. For instance. exchanging these variables. SIFT involves exchanging information on the nothing happens because the processors will voter link directly between <R>. This does not hap- pen with SIFT because the input data is exchanged and voted. <C> reports them to <I> for operator attention and maintenance action. are added to the table. in 13 . will use the correct value of fuel command. <S> and <T>. Figure14. such as integrators. If one of the transducers has failed. sures all of its input sensors so that each sensor When the processor is repaired and put back in signal is represented by a number in the con. the triple-redundant control information <T> controllers. It eavesdrops while all three sets of variables are transmitted by the control processors and calcu- lates the voted values for itself. for more critical signals. put are caused when a failure or a repair takes able. But as soon as the first data is exchanged gathered in a table of values. Each control processor mea. service. and uses these voted outputs in all sub- sequent calculations. By a highly controlled process. A failure of a dif- Figure 13. display list. The software is quite flexi. The information for the control proces- such as the fuel command. output. If tain the correct output.GER-3658D dedicated voting hardware. Security codes The exception is setpoint incrementing com- limit access to the programs used to change con. and whether the requires that the new software be compiled in alarm is still active. <I> also keeps a complete list of vari- ware relay driver circuits that require two or ables that can be displayed and printed. They are tuned and control processors and. The most critical algorithms for protection. they can be software voted and output by the I/O associated uploaded for storage in <I> where they will be with <C>. new ones can be estab. retained for use in any subsequent software Logic outputs are voted by dedicated hard. dently by the Protective Module <P> as well. It shows the status of the other side of the trip solenoid and indepen. the alarm does 14 . major selections and presents key turbine dently cause the trip solenoid to drop out on parameters in a table that includes the variable detection of overspeed. It takes control power for the electronics Changes in control constants can be accom- and the actual output current from all three sec. The driver signals are sent OPERATION AND to the trip card in the protective model where MAINTENANCE independent relays are actuated. is complete. generated by the primary overspeed pro- tective function in the control processors. keyboard and printer. Once the download bine itself as previously explained. has been acknowledged or not. three “on” signals to pick up the output relay. on site by qualified personnel. These basic Protective functions are accomplished by the algorithms are in EPROM. By protecting these critical algorithms from Primary speed pickups are wired to the control inadvertent change. where the operator can For most upgrades. A list of the The <I> processor is equipped with a hard oldest three unacknowledged alarms appears on disk which keeps the records that define the site this screen. do logic forcing. name. are voted to cause the trip solenoid to drop out. up to four critical 4 ma to 20 ma turbine will continue to run properly. The most recent alarm is added to the top of the lished on site. user defined display. It comes from GE with an operator-entered list of variables. the recombination of sors is passed through <C> and stored in EEP- the signals is done by the servo valve on the tur. a new set of tuning constants can be tried. value and engineering units. the basic software configura. The line shows whether the alarm such as an upgrade to turbine capability. These codes are under the Alarm management screens list all the alarms control of the owner so that if there is a need to in the chronological order of their time tags. Control power for the circuit and output relay is control and sequencing have evolved over many taken from all three control sections. Their relay Displays for normal operation center around contacts are wired in a voting arrangement to the unit control display. clears. The functions available on the operator inter- Separate overspeed pickups are brought to the face are shown in Table 6. change access codes. control and so forth. there. plished on-line in working memory. Non-critical outputs are they are found to be satisfactory. each activate a relay driver. years of GE gas turbine experience. more secure. adapted with constants that are field adjustable. called a the site-specific software properly configured. ROM in <R>. The operator interface also supports software configuration. the alarm can be reset. For critical outputs. When the alarm condition <I> and downloaded to the processor modules. commands from the local backup display while cuit. The trip com. for overspeed. ple. accepting outputs are voted in a dedicated electronic cir. which are processed immediately and do stants and sequencing. mands. download. Contacts from The operator interface is comprised of a VGA each of these three primary protective trip relays color graphics monitor. change the state of the turbine require an arm ble and most required alterations can be made activate sequence to avoid accidental operation. Commands that from the GE factory. The circuit selects the median signal for <I> is being repaired. mands. type in any turbine-generator variable and it will tion on the disk is replaced with new software be added to the variable list. Basic changes in configuration. If reset is selected The information for <C> is stored in EEPROM and the alarm has not cleared. manual not require an arm-activate sequence. <S> and <T>. indepen. For exam- tions such that any two control sections will sus. the <I> processor can fail and the For example. independent protective module. the performance and safety processors and used for both speed control and of the complete fleet of GE gas turbines is made primary overspeed protection. This is particu- – Emission control data larly useful in identifying the original source of – Logical status trouble if a spurious signal manages to cause • Contracts in one of the control processors to call for a trip • Relay out and does not leave a normal diagnostic trail. These displays will include the selec- • Fuel stroke reference tion of engineering units and allow changing • Auxiliary control between English and metric units. blown fuse. or open sensor circuit. Examination of these – Tuning tools records can reveal what has gone wrong with the • Constant change routines system. A partial list • Data (examples) of the diagnostics available is presented in Table – Exhaust temperatures 7. contact inputs are • Administrative– resolved to one millisecond. This – Wheelspace temperatures display gives detailed information about the – Generator temperatures actual logic signal path that caused any trip. – Select scale units The previously mentioned comparison of vot- – Display identification numbers ing values is another powerful diagnostic tool. dedicating one to the alarm log. print the complete list and form feed – Unit control again. The trip diagnostic screen traps the actual sig- – Lube oil temperatures nal condition that caused a turbine trip. • Preselected load setpoint Administrative displays help with various tasks • Inlet guide vane control such as setting processor real time clocks and • Isochronous control the date. • Water wash There are a number of diagnostic displays • Mechanical overspeed test that provide information on the turbine and on the condition of the control system. it will form • Control feed. In • Internal logic SPEEDTRONIC™ Mark V controls. Any alarms that happened during the – Generator control (or load control) time of printing were stored and are now print- – Alarm management ed. showing the time tags which are sent put from the flame detectors which shows the from the control modules with each alarm. which makes this – Set time/date sequence of events information more valuable. An optional alternative is to add a second – Manual control (examples) printer. effective ultraviolet light level is another new Software is provided to allow printing of other diagnostic routine. time of the breaker is an excellent diagnostic on The alarm log prints alarms in their arrival the health of the synchronizing system. or 15 . – Control reference Diagnostic alarms are generated whenever there – Configuration tools is such a disagreement. An out- sequence. all trips are – Demand display annunciated and information about the actual • Periodic logging logic path that caused the trip is captured. • On-line Some of the diagnostics are intended to – System memory access enhance turbine-generator monitoring. GER-3658D Table 6 making a listing of the full text of all alarms or OPERATOR INTERFACE FUNCTIONS turbine variables. such as copying of text screens. When the printer has been requested to make such an output. Many of these combinations have specif- – Actuator auto-calibrate ic diagnostics associated with them and the soft- – Trip display ware has many algorithms that infer what has – Rung display gone wrong from a pattern of incoming diag- – Logic forcing nostic signals. In this way the diagnostic alarm – Diagnostic alarms will identify as nearly as possible what is wrong. failed • Off-line card. For instance. It is – Vibration accomplished by freezing information about the – Timers and event counters logic path when the trip occurs. In addition to this information. – Change security code Normally these values will agree and significant • Maintenance/Diagnostics disagreement means that something is wrong. – Diagnostic displays such as a failed power supply. reading and saving the actual closing not clear and the original time tag is retained. It is an indicator of degrada- information. The gas tur- • Sensors and actuators bine control is completely automatic and needs – Contact inputs circuits can force and interrogate little human intervention for starting. non-interfering with other ground redundant <I> processors make the use of the detectors back-up display even more unlikely. product line shipments of the Mark V System on fication could lead to powering down a good new unit production commenced early in 1993. the contact input circuits units.4 million powered opera- 16 . almost 80 ed. A back- up display is provided to handle this situation. UV light level count output alarms with their internal alarm numbers. Reliability of the in service fleet. The SPEEDTRONIC ™ Mark V Turbine tenance easier and faster so that the control sys. sequently put into utility service on two peaking Once the diagnostic routines have located a gas turbines to obtain experience in daily start- failed part. The system was sub- starting and running reliability approach 100%. and repair of the – Incoming power sources normal operator interface will usually be accom- – Power distribution – All control voltages plished in less than three hours. voting current monitor and lower load. This is due to the floor space available in retrofit sor. This EXPERIENCE level of monitoring and diagnostics makes main. rectly without disturbing their normal opera- tion. Wrong identi. raise load – 4/20 MA control outputs — loopback testing – Relay driver. The same is true for data points. A properly maintained May 1992 on one of three industrial generator panel is highly fault-tolerant and makes systems drive MS9001B gas turbines. shipped or on order. the second half of that year. value and engineering In another example. the turbine will trip. – LVDT excitation voltage The back-up display provides for a minimum – Servovalve current feedback loopback test set of control commands: start. Today. the short symbol name. the bulk of these are will then join in with the others to control the designed as Simplex rather than the triple- turbine and the fault tolerance is restored. it may be replaced while the turbine ing service in order to develop a starting reliabil- continues to run. It • Power happens ver y infrequently. The rack is closed and retrofitted SPEEDTRONIC™ Mark V Turbine power is reapplied to the module. section and result in a vote to trip. Should the fault be in the <I> or <C> proces. This – Synchronizer — phase angle at closure list is used to look up the alarm name from the – Trip contact status monitor alarm number. or go blank and commands can no longer be subsequent to commissioning and after accumu- sent by the operator to the turbine from <I>.GER-3658D Table 7 This upsets the operator much more than it dis- MONITORING AND DIAGNOSTICS turbs the control processors or turbine. – Open thermocouple stopping or tripping once a sequence is initiat- – Open and short on seismic vibration transducers ed. The module is gas turbines and 106 new steam turbines either opened and tilted out. this limited list of key parameters established for rogated to ensure that the circuit functions cor. The module Control Systems. cables disconnected. a preselected list of key data points are programmed into the back-up panel that display tion in the ultraviolet flame detection system. Optional – Battery ground. To affect the repair. lating more than 1. General section where the problem exists. however. This includes 424 new correct section is powered down. the Mark V Turbine Controls. redundant systems associated with new units. card replaced and existing units have been committed to cables reconnected. It reports all process alarms by – RTD open and short number. virtually all turbine shipments include ing the correct section. The extent of this kind of diagnostics has been greatly increased in SPEEDTRONIC ™ CONTROL SYSTEM Mark V control over previous generations. it is likely that the operator display will stop applications. the offending card locat. A great deal of effort has been put into identify. • Voted data however. If the failed with new installations starting up throughout section is also voting to trip. In addition. The most critical function of ity assessment in addition to the continuous the diagnostics is to identify the proper control duty running reliability assessment. a provision is included to print the – Flame detector. The control ships from the factory with can be forced to either state and then be inter. Control System was initially put into service in tem stays in better repair. the back-up display. running. Since the alarm text can be altered on • Protective site in <I>. stop. over the Mark IV system. which includes control panel. are also less likely to cause a tur. actu. it is fully expected Why is the Mark V system so much better than the Mark V system will further advance the con- its predecessors? First. SUMMARY nents ensures that failures. Control system reliability 17 . tinuing growth of gas turbine control system nents to fail and fewer types of components in starting and running reliability. but flexibility has also been increased. GER-3658D tional hours on 264 units. which are less likely The SPEEDTRONIC ™ Mark V Gas Turbine to begin with. and in The Mark V system is a further improvement both peaking and base load service. Flexibility of application and ease of manufacturing and testing. has been as expected. and testing have been complimented by greater ators and all intervening wiring and connectors. there are fewer compo. operation will also grow to meet the needs of ing the potential for human error. system availability will be achieved by logical evo- is highest. Extensive built-in diagnostics and the cessful gas turbine control experience. and increas. Although the two-out- of-three voting philosophy is retained.) Two-out-of-three redundancy on critical functions and compo. sensors. lution of the unique architectural features devel- ized.000 hours for the sys. its imple- mentation is improved and made more robust through use of SIFT techniques. Standardization of hard- GT21537B Figure 15. Thus. ware and software has been carried several steps Indicated MTBFO (mean time between force further. (This also means that there are fewer spares to stock. cess and utility operating environments. Further advancements in running with a failed component when the the goals of starting and running reliability and potential to trip resulting from a double failure. in pro- ing the repeatability of the process. yet still flexible. Greater degrees of automated manufacturing tem. while processor techniques. use of computer-aided engineering to standard- This performance is shown relative to the rest of ize the generation and testing of software and the electronic control history in Figure 15. Finally. substantially lower. the control panel. software and hardware oped and initially put into service with the Mark allowed a much greater degree of automated IV system. system configuration. the high degree of standard. Components and types of components have been further reduced in number. generator and mechanical drive systems. outages) is in excess of 28. Control System is based on a long history of suc- bine trip. with a ability to replace almost any component while substantial portion using electronic and micro- running further minimize exposure time. W. Rowen.” ASME Paper No.GER-3658D REFERENCES 1. presented at the Gas Turbine and Aeroengine Congress. Amsterdam.. June 6-9.I. © 1996 GE Company 18 . Netherlands. 88-GT-150. “Operating Characteristics of Heavy-Duty Gas Turbines in Utility Service. 1988. Operator interface functions Table 7. Monitoring and diagnostics . Standard control configuration Figure 9. Simple cycle package power plant starting times Table 4. Advances in electronic control concepts Table 2. Gas turbine control philosophy Table 3. Gas turbine fuel control Figure 3.Typical processor module Figure 15.Panel internal arrangement Figure 13. Interfacing options Table 6.Mark V turbine control panel Figure 12. Protective system block diagram.Mark V operator interface Figure 11. Gas turbine generator controls and limits Figure 2.Control system reliability LIST OF TABLES Table 1. Liquid fuel control system Figure 6. Gas fuel control system Figure 5. Typical gas turbine starting characteristics Figure 7.Module map of panel interior Figure 14. Digital servo position loops Figure 10. GER-3658D LIST OF FIGURES Figure 1. Critical redundant sensors Table 5. SPEEDTRONIC™ Mark V turbine control Figure 8. Dual fuel transfer characteristics gas to liquid Figure 4.