US3928972A - System and method for improved steam turbine operation - Google Patents

System and method for improved steam turbine operation Download PDF

Info

Publication number
US3928972A
US3928972A US331738A US33173873A US3928972A US 3928972 A US3928972 A US 3928972A US 331738 A US331738 A US 331738A US 33173873 A US33173873 A US 33173873A US 3928972 A US3928972 A US 3928972A
Authority
US
United States
Prior art keywords
turbine
steam
rotor
representation
heat flow
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US331738A
Other languages
English (en)
Inventor
Robert L Osborne
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Westinghouse Electric Corp
Original Assignee
Westinghouse Electric Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Westinghouse Electric Corp filed Critical Westinghouse Electric Corp
Priority to US331738A priority Critical patent/US3928972A/en
Priority to CA191,029A priority patent/CA1029456A/en
Priority to JP1688174A priority patent/JPS5543084B2/ja
Priority to IT20718/74A priority patent/IT1007719B/it
Application granted granted Critical
Publication of US3928972A publication Critical patent/US3928972A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D19/00—Starting of machines or engines; Regulating, controlling, or safety means in connection therewith
    • F01D19/02—Starting of machines or engines; Regulating, controlling, or safety means in connection therewith dependent on temperature of component parts, e.g. of turbine-casing
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
    • F01K7/00—Steam engine plants characterised by the use of specific types of engine; Plants or engines characterised by their use of special steam systems, cycles or processes; Control means specially adapted for such systems, cycles or processes; Use of withdrawn or exhaust steam for feed-water heating
    • F01K7/16—Steam engine plants characterised by the use of specific types of engine; Plants or engines characterised by their use of special steam systems, cycles or processes; Control means specially adapted for such systems, cycles or processes; Use of withdrawn or exhaust steam for feed-water heating the engines being only of turbine type
    • F01K7/22—Steam engine plants characterised by the use of specific types of engine; Plants or engines characterised by their use of special steam systems, cycles or processes; Control means specially adapted for such systems, cycles or processes; Use of withdrawn or exhaust steam for feed-water heating the engines being only of turbine type the turbines having inter-stage steam heating
    • F01K7/24—Control or safety means specially adapted therefor

Definitions

  • the present invention relates to elastic fluid turbine systems and more particularly to systems and methods for controlling the dynamic operation of steam turbines as a function of heat flow.
  • the Berry patent discloses an improved method of determining present rotor stress as a function of monitored tu'rbine impulse chamber steam temperature, comparing the present stress with a predetermined stress limit, and deriving a control signal from such comparison, by which inlet steam flow is controlled.
  • limits of impulse chamber steam temperature maybe further controlled by considerations of bore loading or casing strain. The effects of thermal expansion and contraction on respective regions of the turbine are thus controlled as a function of calculated present stress at such regions, which calculations are based upon the monitored inlet steam condition, centrifugal force loadings, and other input variables.
  • a limit which may be a predetermined limit or a future predicted stress limit calculated on the basis of the turbines temperature history.
  • Such prior art techniques provide feedback control directed to dynamic loading and/or speed changing without exceeding allowable stress conditions. They are premised on present calculations of stress and not on any variable which is determinative of future stress.
  • Such prior art systems place limits on the turbine operation without commanding that the desired changes be accomplished by the shortest possible sequence within such limits. For example, when turbine speed or acceleration is varied due to a control signal derived from a present calculation of rotor stress, the change in rotor stress due to the operating change is necessarily delayed due to thermal energy storage in the rotor metal.
  • means for determining the temperature of turbine steam in at least one predetermined steam flow region associated in direct heat transfer relation with a predetermined turbine rotor portion Improved control of the turbine is provided by combining the steam temperature determining means with means for determining a real time representation of heat flow to the rotor portion.
  • the calculated heat flow representation is compared with a reference heat flow representation, which reference is selected as corresponding to maximum allowable rotor strain, and a comparison signal thus derived is processed by control signal means to provide a control signal for maintaining the turbine speed or load in such a way as to optimize the heat flow to the rotor at the value which maintains rotor strain substantially at the maximum allowable limit.
  • the system of this invention provides an advantage over previously used systems by immediately modifying the turbine operation to maintain rotor strain substantially equal to the maximum allowable value, as contrasted to present stress control wherein a differential between present rotor strain and the maximum allowable value of rotor strain is the basis for 3 limiting turbine operation.
  • the steam temperature is determined in one or more predetermined re gions, the heat flow to the rotor surface and present rotor surface strain are determined, and a limit is placed on the rate at which the turbine operating level is changed in order to limit the extent of the rotor strain while meeting end controlled variable demand.
  • rapid starting of the turbine is accomplished by directing operation toward steady maximum allowable rotor surface strain during startup while limiting rotor strain below a maximum limit. Operation during load transients is also controlled to achieve rapid load change under conditions of maximum allowable rotor strain.
  • the system of this invention utilizes a general purpose programmed digital computer for determining end variable control actions during transient and steady state operation with dynamic constraints computed as a function of heat flow in one or more predetermined steam flow regions.
  • the method of this invention may be used in conjunction with the method of operation disclosed in the Berry patent for providing control limits based upon rotor strain, bore loading and easing strain whereby, when any of such limits is exceeded, operation of the heat flow control provided by the invention can be over-ridden.
  • FIG. 1 shows a schematic diagram of a large electric power plant steam turbine supplied with steam by a steam generating system and operated in association with certain sensor and control devices in accordance with the principles of the'invention.
  • FIG. 2 shows a schematic diagram of a programmed digital computer control system operable with the steam turbine and its associated devices shown in FIG. 1 in accordance with the principles of the invention.
  • FIG. 3 shows an enlarged portion of a longitudinal section through a high pressure section of the steam turbine of FIG. 1 and certain sensor devices placed therein.
  • FIG. 4 shows a control logic flow diagram employed in part of an overall programming system which operates the computer of FIG. 2 to control turbine operation in accordance with the principles of the invention.
  • FIG. 5 shows a more detailed flow diagram of a portion of the diagram of FIG. 4.
  • FIG. 6 shows a simplified block diagram illustrating the alternate procedure of calculating a plurality of differential heat flow representations corresponding to different turbine regions, and determining the lowest of same, which low representation is used to develop the system control signal.
  • FIG. 1 a large single reheat steam turbine 10 constructed in a wellknown manner and operated and controlled in accordance with the principles of the invention as part of a fossil fuel fired electric power plant 12.
  • Other types of steam turbines such as extraction turbines, reactor turbines, back pressure turbines, etc. can also be controlled in accordance with the principles of the invention.
  • the turbine 10 is provided with a single output shaft 14 which drives a conventional large alternating current generator 16 to produce three phase (or other phase) electric power as measured by a conventional power detector 18.
  • the generator 16 is connected (not shown) through one or more breakers (not shown) per phase to a large electric power network and when so connected causes the turbogenerator arrangement to operate at synchronous speed under steady state conditions. Under transient electric load change conditions, system frequency may be affected and conforming turbogenerator speed changes would result.
  • power contribution of the generator 16 to the network is normally determined by the turbine steam flow which in this instance is supplied to the turbine 10 at substantially constant throttle pressure.
  • the turbine 10 is of the multistage axial flow type and includes a high pressure section 20, an intermediate pressure section 22 and a low pressure section 24.
  • Each of these turbine sections may include a plurality of expansion stages provided by stationary vanes and an interacting bladed rotor connected to the shaft 14.
  • turbines operated in accordance with the present invention can have other forms with more or fewer sections tandemly connected to one shaft or compoundly coupled to more than one shaft.
  • the constant throttle pressure steam for driving the turbine 10 is developed by a steam generating system 26 which is provided in the form of a conventional drum type boiler operated by fossil fuel such as pulverized coal or natural gas. From a generalized standpoint, the present invention can also be applied to steam turbines associated with other types of steam generating systems such as nuclear reactor and once through boiler systems.
  • the turbine 10 in this instance is further of the double ended steam chest type, and turbine inlet steam flow is directed through a plurality of throttle valves and a plurality of governor valves designated as inlet valves 25.
  • the double ended steam chest type and other steam chest types such as the single ended steam chest type or the end bar lift type may involve varying numbers and/or arrangements of throttle valves. More detailed description on a particular throttle and governor valve arrangement is presented in the aforementioned Birnbaum and Giras copending application.
  • the preferred turbine startup method is to (I) raise the turbine speed from the turning gear speed of about 2 rpm. to about 80 percent of the synchronous speed under throttle valve control and then (2) transfer to governor valve control and raise the turbine speed to the synchronous value, close the power system breaker(s) and meet the load demand.
  • Similar but reverse practices are involved.
  • Other transfer practices can be employed, but it is unlikely that transfer would ever be made at a loading point about 40 percent rated loading because of throttling efficiency considerations.
  • the reheater system 28 After the steam has coursed past the first stage im- 'pulse blading to the last stage reaction blading of the high pressure section 20, it is directed to a reheater system 28 which is associated with the boiler 26.
  • the reheater system 28 might typically include a pair of parallel connected reheaters coupled to the boiler 26 in heat transfer relation as indicated by the reference character 29 and associated with opposite sides of the turbine casing.
  • reheat valves 33 are provided and these include one or more normally open check or stop valves and one or more intercept valves operable to provide reheat steam flow cutback modulation under turbine overspeed conditions.
  • the boiler control system controls boiler operations so that steam throttle pressure is held substantially constant.
  • a throttle pressure detector 38 of suitable conventional design measures the steam throt tle pressure to provide assurance of substantially constant throttle pressure supply, and, if desired as a programmed computer protective system override control function, turbine control action can be adapted to throttle pressure control as well as or in place of speed and/or load control if the throttle pressure falls outside predetermined constraining safety and turbine condensation protection limits.
  • An impulse chamber steam pressure detector 40 develops signals for use in programmed computer control of turbine load and ultimately power plant electrical load.
  • Respective hydraulically operated valve actuators indicated by the reference character 42 are provided for the throttle and governor inlet valves 25. Hydraulically operated actuators indicated by the reference characters 44 are also provided for the reheat stop and intercept valves 33 A computer sequenced and monitored high pressure fluid supply 46 provides the controlling fluid for actuator operation of the valves 25 and 33.
  • a computer supervised lubricating oil system (not shown) is separately provided for turbine plant lubricating requirements.
  • the respective actuators 42 and 44 are of conventional construction, and the actuators 42 and the actuators 44 associated with the intercept valves are operated by respective stabilizing position controls indicated by the reference characters 48 and 50. These controls each include a conventional position error feedback operated analog controller (not indicated) which drives a suitable known actuator servo valve (not indicated) in the well-known manner. Reheat intercept 6 valve position control is imposed typically only when reheat steam flow cutback modulation is required. Stop valve operation requires no feedback position control and instead is manually or computer directed with conventional trip or other suitable emergency operation.
  • position detectors are provided in suitable conventional form, for example they can make conventional use of linear variable differential transformer operation in generating negative position feedback signals for algebraic summing with respective position setpoint signals SP in developing the respective input position error signals.
  • the combined position control, hydraulic actuator, valve position detector element and other miscellaneous devices form a local hydraulic-electrical analog valve position control loop for each throttle and governor inlet steam valve.
  • the position setpoints SP are computer determined and supplied to the respective local loops and updated on a periodic basis. Setpoints SP are also determined for the intercept valve controls.
  • a speed detector 52 is provided to determine the turbine shaft speed for speed control, for centrifugal stress determination and turbine constraint operation, for frequency participation control purposes, and preferably also for rotor surface heat transfer conductance computation associated with rotor thermal strain control.
  • the speed detector 52 can for example be in the form of a reluctance pickup (not shown) magnetically coupled to a notched wheel (not shown) on the turbogenerator shaft 14.
  • the process sensor equipment further includes an impulse chamber steam temperature detector 54 and easing temperature detectors 56, all of which are employed in programmed computer loading andthermal strain determination as subsequently described more fully.
  • Analog and/or pulse signals produced by the speed detector 52, the power detector 18, the pressure detectors 38 and 40, the temperature detectors 54 and 56, the valve position detectors PDIV and PDRV and other sensors (not specifically shown) and status contacts (not specifically shown) are all applied to a digital computer control system 60 (FIG. 2) which provides turbine steady state and transient operation control on an on line real time basis and further provides system monitoring, sequencing, supervising, alarming, display and logging functions.-
  • the programmed digital computer control system 60 operates the turbine 10 with improved dynamic performance characteristics, and can include conventional hardware in the form of a central processor 62 and associated input/output interfacing equipment such as that sold by Westinghouse Electric Corporation and described in detail in Westinghouse Engineer," May, 1970, Volume 30, No. 3, pages 88 through 93.
  • the control system of this invention may utilize, for performing the indicated calculations, any general purpose programmable computer having real time capability, in combination with the control apparatus illustrated in FIG. 1 and the required interface equipment, or equivalents thereof, as illustrated in FIG. 2.
  • special purpose analog computer apparatus may be utilized for making the specific calculations required to practice this invention in controlling the operation of any particular turbine.
  • the interfacing equipment for the computer processor 62 includes a conventional contact closure input system 64 which scans contact or other similar signals representing the status of various plant and equipment conditions. Such contacts are generally indicated by the reference character 66 and might typically be contacts of mercury wetted relays (not shown) which are operated by energization circuits (not shown) capable of sensing the predetermined conditions associated with the various system devices. Status contact data is used in interlock logic functioning in control or other programs, protection and alarm system functioning, programmed monitoring and logging and demand logging, functioning of a computer executed manual supervisory control 68, etc.
  • the contact closure input system 64 also accepts digital load reference signals as indicated by the reference character 70.
  • the load reference 70 can be manually set or it can be automatically supplied as by an economic dispatch computer (not shown). In the load control mode of operation, the load reference 70 defines the desired megawatt generating level and the computer control system 60 operates the turbine 10 to supply the power generation demand.
  • Input interfacing is also provided by a conventional analog input system 72 which samples analog signals from the plant 12 at a predetermined rate such as 15 points per second for each analog channel input and converts the signal samples to digital values for computer entry.
  • the analog signals are generated by the power detector 18, the impulse pressure detector 40, the valve position detectors PDIV and PDRV, the temperature detectors 54 and 56, and miscellaneous analog sensors 74 such as the throttle pressure detector 38 (not specifically shown in FIG. 2), various steam flow detectors, other steam temperature detectors, miscellaneous equipment operating temperature detectors, generator hydrogen coolant pressure and temperature detectors, etc;
  • a conventional pulse input system 76 provides for computer entry of pulse type detector signals such as those generated by the speed detector 52.
  • the computer counterparts of the analog and pulse input signals are used in control program execution, protection and alarm system functioning, programmed and demand logging, etc.
  • Information input and output devices provide for computer entry and output of coded and noncoded information. These devices include a conventional tape reader and printer system 78 which is used for various purposes including for example program entry into the central processor core memory. A conventional teletypewriter system 80 is also provided and it is used for purposes including for example logging printouts as indicated by the reference character 82. Alphanumeric and/or other types of displays 81, 83 and 85 are used to 8 communicate current rotor strain, accumulated rotor strain fatigue, and other information.
  • a conventional interrupt system 84 is provided with suitable hardware and circuitry for controlling the input and output transfer of information between the computer processor 62 and the slower input/output equipment.
  • an interrupt signal is applied to the processor 62 when an input is ready for entry or when an output transfer has been completed.
  • the central processor 62 acts on interrupts in accordance with a conventional executive program. in some cases, particular interrupts are acknowledged and operated upon without executive priority limitations.
  • Output interfacing is provided for the computer by means of a conventional contact closure output system 86 which operates in conjunction with a conventional analog output system 88 and with a valve position control output system 90.
  • a manual control 92 is coupled to the valve position control output system and is operable therewith to provide manual turbine control during computer shutdown and other desired time periods.
  • Certain computer digital outputs are applied directly in effecting program determined and contact controlled control actions of equipment including the high pressure valve fluid and lubrication systems as indicated by the reference character 87, alarm devices 94 such as buzzers and displays, and predetermined plant auxiliary devices and systems 96 such as the generator hydrogen coolant system.
  • Computer digital information outputs are similarly applied directly to the tape printer and the teletypewriter system and the display devices 81, 83 and 85.
  • the turbine high pressure section 20 includes a casing or cylinder wall 100 within which a rotor 182 is supported for rotation.
  • Casing strain at predetermined casing locations is based on conventional outer and inner wall temperature thermocouple probes 104 and 106 which form a part of the casing temperature detectors 56.
  • a suitable steam temperature sensor (not specifically shown but included as a part of the analog sensors 78) can also be employed in the intermediate pressure section 22, such as in the inlet steam pipe but preferably in the IP inlet steam chamber (not shown). lP steam temperature data is used in the computation of rotor bore-thermal stress in the intermediate pressure section 22.
  • a conventional thermocouple probe 114 is appropriately supported by the casing 100 to measure'the impulse chamber steam temperature.
  • FIGS. 4 and 5 there are shown flow diagrams representing the manner of calculating the the more specific program steps charted in FIG. 5,-
  • the Westinghouse W-2500 has the requisite capacity and is suitable for use as the central processor 62.
  • the Westinghouse Digital Electro- Hydraulic (DEH) Control System for large steam turbine generators may be utilized in practicing this invention.
  • Table 1 set forth below gives definitions for the symbols used in the flow charts of FIGS. 4 and 5. It is to be noted that some of the arithmetic operations are repre- Q,, Rotor heat flow limit. i.e., heat flow for maximum allowable rotor strain.
  • H heat transfer coefficient f (W SF) A rotor surface area T, first stage temp. (measured) T rotor volume average temp. (defined in the Berry patent) SF Steam Flow Rate (measured) W,- shaft speed (measured) P, first stage pressure (measured) DTO T T. a measure of rotor surface strain D'l'P predicted DTO DTO DDTO, where DDTO d(DTO)/dt, extrapolated rate of change of DTO.
  • block 310 represents the collective steps of calculating representations of DTO, DTP, Q, T and T.
  • the input variables to block 310 are obtained as illustrated in FIGS.
  • the representation of Q is a representation of heat flow to the rotor surface.
  • Q may represent calculated heat flow to other regions of the turbine, such as the rotor bore, or casing walls.
  • the significance of the calculated heat flow term is that it represents not merely a present temperature condition at a given region, but represents the rate at which temperature and strain itself at such region is changing.
  • H represents the heat transfer coefficient at the rotor surface, and takes into account surface film and all other considerations affecting heat transfer'from the steam to the rotor surface.
  • Q is a direct function of H, which in turn is a function of W and SF, measured quantities.
  • H is primarily a function of W and under load control conditions, H is primarily a function of SF.
  • Q is modulated, and when the turbine is under load control, Q is modulated by controlling steam flow.
  • this system entails control of turbine operation so as to control heat flow, with heat flow being maintained at a level corresponding to optimum turbine performance.
  • the computer means carries out the function of calculating the difference between Q, and Q, representing the difference between the heat flow limit corresponding to maximum allowable rotor strain and the present heat flow.
  • Q is the permissible heat flow for maximum stress under normal transient conditions. While generally treated as a constant, it is to be noted that Q, may be periodically recalculated to take into account the mode of control, centrifugal force loadings, or other considerations as noted below.
  • An example of a normal transient condition is the condition of startup, or acceleration, where the temperature gradient through the rotor is substantially a constant, and under which conditions the heat transfer coefficient changes with speed in a manner such thatchanging speed causes a corresponding change in heat flow.
  • a similar steady state transient condition exists where, at synchronous speed, the turbine is called upon to deliver an increasing load at a constant rate of increase, i.e., a ramp increase.
  • the difference representation 0,, Q, and referred to as DQ is operated upon as shown in parallel blocks 330 and 351, by multiplication and integration respectively, and summed at 332 to produce a signal which is representative ofthe first derivative, designated as DNR, of the speed signal NR.
  • the DNR signal is limited in step 350 by a high rate limit HRL and a low rate LRL, as discussed more fully hereinbelow in connection with FIG. 5.
  • the DNR signal is gated, as shown at block 360, and is either passed or not passed corresponding to 1 1 limit controls derived from the DTO and DTP values, to produce a gated DNR signal referred to as GDNR.
  • the DTO signal is operated upon in block '366 to determine the comparison of DTO and DTOLIM,a predetermined limit of DTO.
  • the DTOLIM' signal represents the maximum value of calculated DTO permissible to maintain operation without rotor strain, and corresponds to the maximum permissible present value of rotor strain.
  • the comparison in block 366 comprises a direct check upon present strain.
  • DTO is greater than DTOLIM
  • a signal is derived, as indicated in block 362, to cause the gating operation as illustrated in block 360 to cause the GDNR signal to be zero, i.e., the DNR signalis multiplied by zero.
  • DTO is found to be less than DTOLIM
  • DTPLIM represents a limiting value of DTP, or the maximum value of predicted rotor strain.
  • a signal is developed at blocks 360 and 362 to cause the DNR signal to be reduced to zero, i.e., make GDNR equal to zero.
  • the DNR signal is gated straight through, i.e., multiplied by one, such that DGNR equals DNR.
  • the GDNR signal being a gated representation of thefirst derivative of the speed control signal, is oper ated upon as shown in block 370.
  • this operation comprises the step of integrating the GDNR signal to obtain an NR signal representing the speed control signal.
  • the speed control signal represents the basic command for controlling the speed of the turbine, as during startup, in order to bring turbine operation to the desired (synchronous) speed in the quickest time'and substantially at but not exceeding rotor strain limits.
  • heat transfer from the impulse chamber steam to the rotor surface is assumed to be proportional to speed (since the heat transfer coefficient changes primarily as a function of speed), and thus in controlling speed the heat flow to the rotor is accordingly controlled.
  • the control signal NR may be further operatedupon at speed/load control block 382, 'in ordcr to develop a desired valve position signal.
  • the NR signal when in the speed control mode of operation, the NR signal may be processed as a function of W and/or W and when in the load control mode of operation, the load control signal LR may be further processed as a function of LS and/or LR.
  • the processed signal is then operated upon at block 386 to determine digital output valve position values which are transmitted to valve position control 90.
  • the digital output valve position values may be modified by calcu lated maximum value signals from block 388, which calculations are referred to further hereinbelow.
  • FIG. 5 there is shown a flow chart for a specific computer subroutine for calculating the speed reference signal NR as a function of heat flow.
  • the start of the subroutine is understood to be initiated periodically when the control calculations are carried out by digital computer, and at a rate sufficient to maintain real time control.
  • the computer means is comprised of analog circuitry, the calculations are performed continuously.
  • H calculated at 405
  • H is primarily a function of the rate at which the steam passes relative to the rotor.
  • speed is relatively low, and the change in speed comprises substantially all of the relative change, such thatsteam flow itself is not a significant factor.
  • W measured at 52
  • H is presumed to be primarily a function of W (measured at 52).
  • H k W 1000
  • k is a true constant
  • H is presumed to be primarily a function of SF (measured at 74).
  • the calculation Q (T, T,,) H A is performed at step 410.
  • the T, variable is measured at the impulse chamber (see FIG. 3) and the value thus monitored by detector S4 is introduced through the analog input system 72.
  • the analog signal is converted into digital form.
  • the value ofQ is next subtracted from O as shown at block 320, to obtain a reference signal DQ, representing the difference between the value of heat flow at which turbine operation is maintained at maximum heat stress, and the present calculated heat flow.
  • the DQ signal is next multiplied, as shown at block 330, by a gain function g,, to derive the signal designated as DNR(P), being the proportional component of DNR.
  • a parallel path for obtaining DNR(I), the integral component of DNR comprises determining, as shown at 421, whether the value of Q Q is greater than or equal to zero, or less than zero. If the former is the case, a positive incremental signal INC, having a constant value of is devel-- oped at 423. If Q -Q is less than zero, a negative incremental signal having a constant yalue of V is developed as shown at 425. The incremental signal,
  • TlE DNR signal is limited by the functions illustrated within block 350.
  • DNR is first compared with the high rate limit HRL, as shown at 431, representing a maximum allowable rate of increase of speed. If DNR is greater than or ,equal to HRL, a limited DNR signal designated as LDNR is derived which is equal to HRL, asshown at 434. If DNR is less than HRL, or within the high rate limit, the DNR signal is then compared with the low rate limit signal LRL, as shown at 433. If DRL is equal to or lower than LRL a minimum allowable rate of increase of speed, LDNR is set equal to LRL, as shown at 437. If DNR is greater than LRL (as well as being less than l-IRL), LDNR is set equal to DNR.
  • the subroutine next performs the constraint checks indicated at 364, 366 in-FIG. 4. As shown at 440 in FIG. 5, DTO is examined to see if it is less than DTO- LIM, and DTP is examined to see if it is less than DTPLIM. If these conditions are met, the LDNR signal is integrated, by the trapezoidal integration function indicated at 450, similarly to the step illustrated at 340, 2
  • the old value of NR i.e., NR (1. 1), is provided as the NR signal.
  • valve position control 90 controls the throttle valve (on-off), or valves, during the startup phase until the turbine speed reaches a predetermined speed short of full speed, e.g., about 3,000 r.p.m. for a synchronous speed of 3,600 r.p.m. At this point, control is transferred to the control or governor valve, or valves, which modulate steam input to any value between full' off and full on, for bringing speed up to the full synchronous value.
  • the Q reference signal which is inputted at step 320 may be the same'value, or may be another value chosen for load mode operation.
  • the difference signal, DQ represents the difference between calculated (present) heat flow and the reference heat flow under load conditions, which DQ signal is operated upon in the same manner as when in the startup mode.
  • the limits HRL and LRL, stored in memory represent maximum rates of increase of load.
  • DLR the value of DO after having been multiplied by the gain function at block 330
  • LDLR the limited value of DLR
  • GDLR the gated value of LDLR
  • LR the final signal generated after the integrate step at 370
  • LR the load '14 control reference signal.
  • the basic technique of this invention may also be applied to casing strain and/or bore strain, by calculating (at block 310-A) heat flow to the casing (Q and heat flow to the rotor bore (designated Q As shown in FIG. 6, each of these values may be compared (at 320-A) with a corresponding reference (Q Q etc.) and respective values of DO (normalized) may be obtained which are compared at 465 to determine the low limit DQ representation.
  • the lowest value representation of DO is chosen as controlling, and is thereafter processed to obtain the desired control signal.
  • system operation may be controlled on the basis of heat flow to that turbine region wherein heat flow is closest to the limit for maintaining maximum strain.
  • the fatigue damage per cycle may be calculated, and a tally maintained of accumulated fatigue damage, permitting more accurate rotor plastic 0 strain fatigue supervision and/or control.
  • the signals produced by such subroutine may be used to modify the Q signal, or may be processed at block 388 to determine maximum values of steam valve positions. In this manner, while the system is under the heat flow 5 control of this invention, it may also be subjected to limit control on the basis of calculated present loadings and strain at various regions of the turbine.
  • the inputs to difference box 320-A may include Q signals from any or all of the turbine sections, such that low limit select 465 provides that system operation be controlled by the heat flow representation of that turbine section having the most limiting thermal condition.
  • An improved steam turbine system comprising:
  • a steam turbine having a portion subject to thermal stress when said turbine is in operation
  • the improved steam turbine system as described in claim 2 comprising means for generating a difference representation representing the difference between a reference heat flow and said rotor heat flow, and means for generating a control signal as a function of said difference representation, and wherein said controlling means controls operation of said steam turbine as a function of said control signal.
  • the improved steam turbine system as described in claim 3 comprising means for detecting steam temperature and steam pressure in a predetermined turbine region in heat transfer relation with said rotor and for generating therefrom a steam temperature signal and a steam pressure signal, and wherein said means for generating a representation of heat flow to said rotor performs the function of calculating heat flow to the rotor on the basis of said steam temperature and steam pressure signals.
  • the improved steam turbine system as described in claim 4 comprising means for determining rotor speed and generating a rotor speed signal, and wherein said means for generating said heat flow representation makes said heat flow calculation as a function of rotor speed when said system is controlling the speed of said turbine.
  • the improved steam turbine system as described in claim 5, comprising means for determining steam flow in said region and generating a steam flow signal, and wherein said means for generating a heat flow representation makes said heat flow calculation as a function of said steam flow signal when said system is controlling turbine load.
  • a control system for a steam turbine comprising:
  • control system for a steam turbine as described in claim 14, wherein said means for controlling steam flow includes steam valve means positioned to determine steam flow through said turbine so as to control turbine speed.
  • control system for a steam turbine as described in claim 15, wherein said means for controlling steam flow includes steam valve means positioned to determine steam flow so as to control load delivered by the turbine.
  • a control system for controlling the operation of a steam turbine comprising:
  • control system as described in claim 18, comprising a general purpose programmed digital com- 17 puter which performs the following functions:
  • said operating representation is a speed representation
  • An improved method for operating a steam turbine, which turbine when operating has one or more portions thereof subject to thermal stress, comprising:
  • step of generating said heat flow signal comprises determining steam temperature and pressure in a predetermined turbine region in heat transfer relation with the surface of said rotor; calculating heat flow to the rotor as a function of said determined steam temperature and pressure; and controlling turbine operation as a function of said calculated rotor heat flow.
  • the improved method for operating a steam turbine as described in claim 25, comprising determining rotor speed and calculating heat flow to the rotor as a function also of rotor speed, and controlling turbine speed as a function of the calculated rotor heat flow.
  • the improved method for operating a steam turbine as described in claim 23, comprising generating a plurality of heat flow signals representing heat flow to a plurality of respective turbine portions subject to heat stress; selecting a limiting one of said heat flow signals; and generating said control signal as a function of said selected heat flow signal.
  • a method for operating a steam turbine comprisin i. determining steam temperature in a predetermined turbine region separate from and in heat transfer relation with a preselected turbine rotor portion;
  • step of controlling the steam turbine speed comprises:
  • a method for controlling a steam turbine comprising:
  • a method for controlling steam turbine operation using a digital computer comprising:
  • An improved steam turbine system comprising:
  • c. means for generating a second representation of a second predetermined temperature condition at a predetermined temperature region in heat transfer relation with said portion;
  • An improved steam turbine system comprising:
  • c. means for generating a second representation of a second predetermined temperature condition at a predetermined temperature region in heat transfer relation with said portion;

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Control Of Turbines (AREA)
US331738A 1973-02-13 1973-02-13 System and method for improved steam turbine operation Expired - Lifetime US3928972A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US331738A US3928972A (en) 1973-02-13 1973-02-13 System and method for improved steam turbine operation
CA191,029A CA1029456A (en) 1973-02-13 1974-01-28 System and method for improved steam turbine control responsive to heat flow
JP1688174A JPS5543084B2 (enExample) 1973-02-13 1974-02-13
IT20718/74A IT1007719B (it) 1973-02-13 1974-04-08 Impianto e metodo perfezionati per la regolazione di una turbina a vapore

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US331738A US3928972A (en) 1973-02-13 1973-02-13 System and method for improved steam turbine operation

Publications (1)

Publication Number Publication Date
US3928972A true US3928972A (en) 1975-12-30

Family

ID=23295173

Family Applications (1)

Application Number Title Priority Date Filing Date
US331738A Expired - Lifetime US3928972A (en) 1973-02-13 1973-02-13 System and method for improved steam turbine operation

Country Status (4)

Country Link
US (1) US3928972A (enExample)
JP (1) JPS5543084B2 (enExample)
CA (1) CA1029456A (enExample)
IT (1) IT1007719B (enExample)

Cited By (28)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4091450A (en) * 1976-01-28 1978-05-23 Bbc Brown Boveri & Company Limited Method and apparatus for set point control for steam temperatures for start-up of the turbine and steam generator in unit power plants
FR2370856A1 (fr) * 1976-11-12 1978-06-09 Westinghouse Electric Corp Systeme de commande des temperatures des turbines a basse pression de centrales electriques
US4121424A (en) * 1976-02-16 1978-10-24 Hitachi, Ltd. Method of starting up turbines
US4181840A (en) * 1975-02-13 1980-01-01 Westinghouse Electric Corp. Anticipative turbine control
US4228359A (en) * 1977-07-29 1980-10-14 Hitachi, Ltd. Rotor-stress preestimating turbine control system
US4253308A (en) * 1979-06-08 1981-03-03 General Electric Company Turbine control system for sliding or constant pressure boilers
FR2481741A1 (fr) * 1980-04-30 1981-11-06 Gen Electric Procede et appareil pour assurer la mise en charge commandee d'une turbine a vapeur en fonction des contraintes thermiques
US4303369A (en) * 1978-05-10 1981-12-01 Hitachi, Ltd. Method of and system for controlling stress produced in steam turbine rotor
US4355514A (en) * 1979-09-28 1982-10-26 Kraftwerk Union Aktiengesellschaft Control device for steam turbines with reheater
US4357803A (en) * 1980-09-05 1982-11-09 General Electric Company Control system for bypass steam turbines
US4482814A (en) * 1983-10-20 1984-11-13 General Signal Corporation Load-frequency control system
EP0128593A3 (en) * 1983-06-14 1985-10-23 Hitachi, Ltd. Method of controlling operation of thermoelectric power station
US4827429A (en) * 1987-06-16 1989-05-02 Westinghouse Electric Corp. Turbine impulse chamber temperature determination method and apparatus
US5621654A (en) * 1994-04-15 1997-04-15 Long Island Lighting Company System and method for economic dispatching of electrical power
US5900555A (en) * 1997-06-12 1999-05-04 General Electric Co. Method and apparatus for determining turbine stress
WO2002050618A3 (en) * 2000-12-19 2002-08-08 Capstone Turbine Corp Microturbine/capacitor power distribution system
US20020163819A1 (en) * 2000-11-07 2002-11-07 Treece William A. Hybrid microturbine/fuel cell system providing air contamination control
US20030230088A1 (en) * 2002-05-22 2003-12-18 Siemens Aktiengesellschaft Method and device for operating a steam power plant, in particular in the part-load range
US6870279B2 (en) * 1998-01-05 2005-03-22 Capstone Turbine Corporation Method and system for control of turbogenerator power and temperature
US20050285574A1 (en) * 2004-06-25 2005-12-29 Huff Frederick C Method and apparatus for providing economic analysis of power generation and distribution
CN100416047C (zh) * 2005-03-16 2008-09-03 株式会社东芝 涡轮机起动控制器及涡轮机起动控制方法
US20140373540A1 (en) * 2013-06-25 2014-12-25 Mitsubishi Hitachi Power Systems, Ltd. Start Control Unit for Steam Turbine Plant
US20150019104A1 (en) * 2013-07-10 2015-01-15 General Electric Company Gas turbine engine controller with event trigger
US20150135721A1 (en) * 2012-07-12 2015-05-21 Siemens Aktiengesellschaft Method for supporting a mains frequency
DE102013226551A1 (de) * 2013-12-19 2015-06-25 Siemens Aktiengesellschaft Regeleinrichtung und Verfahren umfassend eine Dampfturbine
US9328633B2 (en) 2012-06-04 2016-05-03 General Electric Company Control of steam temperature in combined cycle power plant
US20180156073A1 (en) * 2016-12-05 2018-06-07 Doosan Heavy Industries Construction Co., Ltd. System and method for fast startup of a combined cycle power plant
EP3460202A1 (de) * 2017-09-22 2019-03-27 Siemens Aktiengesellschaft Dampfturbinenregelung

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3338053A (en) * 1963-05-20 1967-08-29 Foster Wheeler Corp Once-through vapor generator start-up system
US3358450A (en) * 1965-12-21 1967-12-19 Combustion Eng Method and apparatus for steam turbine startup
US3359732A (en) * 1966-07-21 1967-12-26 Combustion Eng Method and apparatus for starting a steam generating power plant
US3561216A (en) * 1969-03-19 1971-02-09 Gen Electric Thermal stress controlled loading of steam turbine-generators
US3577733A (en) * 1968-07-16 1971-05-04 Gen Electric Rapid loading of steam turbines

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3338053A (en) * 1963-05-20 1967-08-29 Foster Wheeler Corp Once-through vapor generator start-up system
US3358450A (en) * 1965-12-21 1967-12-19 Combustion Eng Method and apparatus for steam turbine startup
US3359732A (en) * 1966-07-21 1967-12-26 Combustion Eng Method and apparatus for starting a steam generating power plant
US3577733A (en) * 1968-07-16 1971-05-04 Gen Electric Rapid loading of steam turbines
US3561216A (en) * 1969-03-19 1971-02-09 Gen Electric Thermal stress controlled loading of steam turbine-generators

Cited By (41)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4181840A (en) * 1975-02-13 1980-01-01 Westinghouse Electric Corp. Anticipative turbine control
US4091450A (en) * 1976-01-28 1978-05-23 Bbc Brown Boveri & Company Limited Method and apparatus for set point control for steam temperatures for start-up of the turbine and steam generator in unit power plants
US4121424A (en) * 1976-02-16 1978-10-24 Hitachi, Ltd. Method of starting up turbines
FR2370856A1 (fr) * 1976-11-12 1978-06-09 Westinghouse Electric Corp Systeme de commande des temperatures des turbines a basse pression de centrales electriques
US4228359A (en) * 1977-07-29 1980-10-14 Hitachi, Ltd. Rotor-stress preestimating turbine control system
US4303369A (en) * 1978-05-10 1981-12-01 Hitachi, Ltd. Method of and system for controlling stress produced in steam turbine rotor
US4253308A (en) * 1979-06-08 1981-03-03 General Electric Company Turbine control system for sliding or constant pressure boilers
US4355514A (en) * 1979-09-28 1982-10-26 Kraftwerk Union Aktiengesellschaft Control device for steam turbines with reheater
FR2481741A1 (fr) * 1980-04-30 1981-11-06 Gen Electric Procede et appareil pour assurer la mise en charge commandee d'une turbine a vapeur en fonction des contraintes thermiques
US4320625A (en) * 1980-04-30 1982-03-23 General Electric Company Method and apparatus for thermal stress controlled loading of steam turbines
US4357803A (en) * 1980-09-05 1982-11-09 General Electric Company Control system for bypass steam turbines
EP0128593A3 (en) * 1983-06-14 1985-10-23 Hitachi, Ltd. Method of controlling operation of thermoelectric power station
US4482814A (en) * 1983-10-20 1984-11-13 General Signal Corporation Load-frequency control system
US4827429A (en) * 1987-06-16 1989-05-02 Westinghouse Electric Corp. Turbine impulse chamber temperature determination method and apparatus
US5621654A (en) * 1994-04-15 1997-04-15 Long Island Lighting Company System and method for economic dispatching of electrical power
US5900555A (en) * 1997-06-12 1999-05-04 General Electric Co. Method and apparatus for determining turbine stress
US6070471A (en) * 1997-06-12 2000-06-06 General Electric Co. Method and apparatus determining turbine stress
US6870279B2 (en) * 1998-01-05 2005-03-22 Capstone Turbine Corporation Method and system for control of turbogenerator power and temperature
US20020163819A1 (en) * 2000-11-07 2002-11-07 Treece William A. Hybrid microturbine/fuel cell system providing air contamination control
WO2002050618A3 (en) * 2000-12-19 2002-08-08 Capstone Turbine Corp Microturbine/capacitor power distribution system
US6639328B2 (en) 2000-12-19 2003-10-28 Capstone Turbine Corporation Microturbine/capacitor power distribution system
US20030230088A1 (en) * 2002-05-22 2003-12-18 Siemens Aktiengesellschaft Method and device for operating a steam power plant, in particular in the part-load range
US6915635B2 (en) * 2002-05-22 2005-07-12 Siemens Aktiengesellschaft Method and device for operating a steam power plant, in particular in the part-load range
US20050285574A1 (en) * 2004-06-25 2005-12-29 Huff Frederick C Method and apparatus for providing economic analysis of power generation and distribution
US7288921B2 (en) * 2004-06-25 2007-10-30 Emerson Process Management Power & Water Solutions, Inc. Method and apparatus for providing economic analysis of power generation and distribution
US20080004721A1 (en) * 2004-06-25 2008-01-03 Emerson Process Management Power & Water Solutions, Inc. Method and Apparatus for Providing Economic Analysis of Power Generation and Distribution
US7385300B2 (en) 2004-06-25 2008-06-10 Emerson Process Management Power & Water Solutions, Inc. Method and apparatus for determining actual reactive capability curves
US7474080B2 (en) 2004-06-25 2009-01-06 Emerson Process Management Power & Water Solutions, Inc. Method and apparatus for providing economic analysis of power generation and distribution
CN100416047C (zh) * 2005-03-16 2008-09-03 株式会社东芝 涡轮机起动控制器及涡轮机起动控制方法
US9328633B2 (en) 2012-06-04 2016-05-03 General Electric Company Control of steam temperature in combined cycle power plant
US20150135721A1 (en) * 2012-07-12 2015-05-21 Siemens Aktiengesellschaft Method for supporting a mains frequency
US20140373540A1 (en) * 2013-06-25 2014-12-25 Mitsubishi Hitachi Power Systems, Ltd. Start Control Unit for Steam Turbine Plant
US9422826B2 (en) * 2013-06-25 2016-08-23 Mitsubishi Hitachi Power Systems, Ltd. Start control unit for steam turbine plant
US20150019104A1 (en) * 2013-07-10 2015-01-15 General Electric Company Gas turbine engine controller with event trigger
US9002617B2 (en) * 2013-07-10 2015-04-07 General Electric Company Gas turbine engine controller with event trigger
DE102013226551A1 (de) * 2013-12-19 2015-06-25 Siemens Aktiengesellschaft Regeleinrichtung und Verfahren umfassend eine Dampfturbine
US20180156073A1 (en) * 2016-12-05 2018-06-07 Doosan Heavy Industries Construction Co., Ltd. System and method for fast startup of a combined cycle power plant
EP3460202A1 (de) * 2017-09-22 2019-03-27 Siemens Aktiengesellschaft Dampfturbinenregelung
WO2019057425A1 (de) * 2017-09-22 2019-03-28 Siemens Aktiengesellschaft Dampfturbinenregelung
CN111148887A (zh) * 2017-09-22 2020-05-12 西门子股份公司 蒸汽涡轮机控制
US11047263B2 (en) 2017-09-22 2021-06-29 Siemens Energy Global GmbH & Co. KG Steam turbine control

Also Published As

Publication number Publication date
JPS5543084B2 (enExample) 1980-11-04
IT1007719B (it) 1976-10-30
CA1029456A (en) 1978-04-11
JPS49113004A (enExample) 1974-10-28

Similar Documents

Publication Publication Date Title
US3928972A (en) System and method for improved steam turbine operation
US3588265A (en) System and method for providing steam turbine operation with improved dynamics
US4005581A (en) Method and apparatus for controlling a steam turbine
US4258424A (en) System and method for operating a steam turbine and an electric power generating plant
US3552872A (en) Computer positioning control system with manual backup control especially adapted for operating steam turbine valves
CA1098963A (en) Turbine power plant automatic control system
US3939328A (en) Control system with adaptive process controllers especially adapted for electric power plant operation
US3778347A (en) Method and system for operating a boiling water reactor-steam turbine plant preferably under digital computer control
KR100220307B1 (ko) 결합 사이클 터어빈의 과속 예상 및 제어 시스템
US4029952A (en) Electric power plant having a multiple computer system for redundant control of turbine and steam generator operation
US4031372A (en) System for manually or automatically transferring control between computers without power generation disturbance in an electric power plant or steam turbine operated by a multiple computer control system
US4029255A (en) System for operating a steam turbine with bumpless digital megawatt and impulse pressure control loop switching
US4283634A (en) System and method for monitoring and controlling operation of industrial gas turbine apparatus and gas turbine electric power plants preferably with a digital computer control system
US4071897A (en) Power plant speed channel selection system
US3630839A (en) System and method for operating a boiling water reactor-steam turbine plant
US4039804A (en) System and method for monitoring industrial gas turbine operating parameters and for providing gas turbine power plant control system inputs representative thereof
US3959635A (en) System and method for operating a steam turbine with digital computer control having improved automatic startup control features
US4259835A (en) System and method for monitoring industrial gas turbine operating parameters and for providing gas turbine power plant control system inputs representative thereof
US5433079A (en) Automated steam turbine startup method and apparatus therefor
US6198786B1 (en) Methods of reactor system pressure control by reactor core power modulation
US4246491A (en) System and method for operating a steam turbine with digital computer control having setpoint and valve position limiting
US4053746A (en) System and method for operating a steam turbine with digital computer control having integrator limit
US4090065A (en) System and method for operating a steam turbine with protection provisions for a valve positioning contingency
US4205380A (en) System and method for operating a steam turbine with digital computer control with accelerating setpoint change
US4427896A (en) System and method for operating a steam turbine with capability for bumplessly changing the system configuration on-line by means of system parameter changes