WO2003060304A1 - Gas turbine apparatus - Google Patents

Gas turbine apparatus Download PDF

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Publication number
WO2003060304A1
WO2003060304A1 PCT/JP2003/000156 JP0300156W WO03060304A1 WO 2003060304 A1 WO2003060304 A1 WO 2003060304A1 JP 0300156 W JP0300156 W JP 0300156W WO 03060304 A1 WO03060304 A1 WO 03060304A1
Authority
WO
WIPO (PCT)
Prior art keywords
value
sensor
gas turbine
measured
error
Prior art date
Application number
PCT/JP2003/000156
Other languages
French (fr)
Inventor
Terence Mckelvey
Eishi Marui
Masahiro Miyamoto
Tadashi Kataoka
Tai Furuya
Original Assignee
Ebara Corporation
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
Priority claimed from JP2002003314A external-priority patent/JP2003206755A/en
Priority claimed from JP2002012124A external-priority patent/JP2003214179A/en
Application filed by Ebara Corporation filed Critical Ebara Corporation
Priority to AU2003201761A priority Critical patent/AU2003201761A1/en
Publication of WO2003060304A1 publication Critical patent/WO2003060304A1/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02C—GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS
    • F02C9/00—Controlling gas-turbine plants; Controlling fuel supply in air- breathing jet-propulsion plants
    • F02C9/26—Control of fuel supply
    • F02C9/28—Regulating systems responsive to plant or ambient parameters, e.g. temperature, pressure, rotor speed
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02C—GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS
    • F02C9/00—Controlling gas-turbine plants; Controlling fuel supply in air- breathing jet-propulsion plants
    • F02C9/26—Control of fuel supply
    • F02C9/263—Control of fuel supply by means of fuel metering valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
    • F05D2270/00—Control
    • F05D2270/30—Control parameters, e.g. input parameters
    • F05D2270/303—Temperature
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
    • F05D2270/00—Control
    • F05D2270/30—Control parameters, e.g. input parameters
    • F05D2270/304—Spool rotational speed

Definitions

  • the present invention relates to a gas turbine apparatus, and more particularly, to a gas turbine apparatus which can accurately control a fuel control valve of a gas turbine engine.
  • a typical gas turbine apparatus comprises a turbine rotatably mounted through a rotating shaft; a combustor for generating a combustion gas; a fuel control valve for controlling an amount of fuel supplied to the combustor; and an air compressor for compressing air.
  • the fuel adjusted by the fuel control valve and the air compressed by the air compressor are supplied to the combustor, so that an air/fuel mixture consisting of the compressed air and the fuel is formed within the combustor.
  • the combustor burns the air/fuel mixture and, therefore generates a combustion gas. Then, the combustor supplies the combustion gas to the turbine, so that the turbine can consequently rotate at high speed.
  • a variety of operation controls such as a start-up control, a constant speed operation control, and the like are performed by controlling an opening degree of the fuel control valve.
  • a load suddenly decreases, the amount of supplied fuel must be suddenly reduced to maintain a constant speed operation of the gas turbine apparatus.
  • combustion within the engine stops if the amount of supplied fuel is reduced to a fixed amount or less, combustion within the engine stops . This problem is referred to as "flame out”.
  • the opening degree of the fuel control valve is controlled to ensure the fixed amount of supplied fuel even in such an event .
  • a difference (error) between an opening instruction value and an actual opening degree of the valve may gradually occur. Specifically, even if means for controlling the valve outputs a constant opening instruction value to the fuel control valve, the actual opening degree of the valve may not reach the opening instruction value, resulting in a value below the opening instruction value. As such, without recognizing the difference between the opening instruction value and the actual opening degree of the valve, if the means for controlling the valve outputs a certain opening instruction value to the fuel control valve, problems such as the above-mentioned "flame out" would occur in a worst case.
  • a typical gas turbine apparatus further comprises a variety of sensors, for example, a CIT sensor for measuring a Combustor Inlet air Temperature (CIT); an EGT sensor for measuring an Exhaust Gas Temperature (EGT); an OIL sensor for measuring the pressure of oil supplied for cooling and lubrication of bearings; and the like.
  • CIT Combustor Inlet air Temperature
  • EGT Exhaust Gas Temperature
  • OIL OIL sensor
  • deterioration in measurement precision of a sensor is found after the recognition of an unusual value, such as an extremely high or low value, measured by the sensor.
  • an unusual value such as an extremely high or low value
  • a measured value which may be neither extremely high nor extremely low, but which deviates from an actual/required value, would be used in deciding each factor, resulting in the problems mentioned above.
  • the following methods have been proposed. Specifically, three sensors are used for measuring a single object to be measured, and a measured value that differs the greatest from each of the other measurements is excluded from the three measurements, in order to improve measurement precision.
  • this method uses three sensors for every object to be measured, it results in a problem of increased costs. As a result, this method is actually employed only in particular apparatuses such as an atomic power generator.
  • a gas turbine apparatus comprises a turbine controller, wherein the turbine controller comprises : a device for calibrating an opening instruction value of a fuel control valve provided to control the amount of supplied fuel and, therefore, automatically calibrates the opening degree of the fuel control valve.
  • the device comprises: first means for determining a theoretical opening value of the valve from an air/fuel ratio at the time of ignition of the gas turbine, the air/fuel ratio is calculated based on a temperature of air to be mixed with the fuel; second means for detecting an opening difference between the theoretical opening value determined by the first means and the opening instruction value at the time of ignition of the gas turbine; and means for calibrating the opening instruction value of the fuel control valve after the ignition based on the opening difference detected by the second means .
  • a gas turbine apparatus comprises a sensor system, the sensor system comprises : at least one sensor for measuring a physical amount of at least one object to be measured; a storage unit for storing a log of data measured by the sensor; an error detector for detecting an error between a current measured value taken by the sensor and a predetermined reference value, the predetermined re erence value is a selected datum taken in an identical or similar operating environment to a current measured value, from among the data stored in the storage unit; means for modifying the current measured value based on the error detected by the error detector; and means for providing the modified current measured value to the turbine controller.
  • the system f rther comprises : a first warning unit for outputting a first signal for stopping operation of a target to be controlled, when the error detected by the error detector exceeds a tolerable range; and a second warning unit for generating a second signal for warning, when the error detected by the error detector holds within the tolerable range but exceeds a predetermined range.
  • Fig. 1 is a general block diagram illustrating a first embodiment of a gas turbine apparatus according to the present invention
  • Fig. 2 is a block diagram of a sensor system according to the present invention which is comprised in the gas turbine apparatus illustrated in Fig. 1;
  • Fig. 3 is a diagram for describing when a first signal for warning is transmitted from a first warning unit in a measurement processor comprised in the sensor system illustrated in Fig. 2;
  • Fig. 4 is a graph showing the relationship between a measured oil pressure and an actual oil pressure, as a function of elapsed time for describing operational effects of the sensor system according to the present invention
  • Fig. 5 is a graph showing the relationship between an opening instruction value and an actual opening value of a fuel control valve
  • Fig. 6 is a block diagram for describing a function of calibrating an opening instruction value of a fuel control valve by a turbine controller comprised in the gas turbine apparatus illustrated in Fig. 1;
  • Fig. 7 is a graph showing an exhaust gas temperature (EGT), an opening instruction value (FCV) of the fuel control valve, and a rotational speed (NR) upon starting of an engine;
  • EGT exhaust gas temperature
  • FCV opening instruction value
  • NR rotational speed
  • Fig. 8 is a graph showing the relationship between a combustor inlet air temperature (CIT) and a theoretical opening value of the valve based on a theoretical air/fuel ratio at the time of ignition; and Fig. 9 is a general block diagram illustrating a second embodiment of the gas turbine apparatus according to the present invention.
  • CIT combustor inlet air temperature
  • FIG. 1 is a general view of a gas turbine apparatus according to the present invention. As illustrated in Fig. 1, the gas turbine apparatus 100 according to the present invention comprises a turbine
  • a combustor 2 for burning an air/fuel mixture consisted of a fuel and air in order to generate a combustion gas; a fuel control valve
  • the gas turbine apparatus 100 also comprises a heat exchanger 4 for heating the air used for combustion, making use of the heat of the combustion gas; and a turbine controller 11 for controlling the turbine 1.
  • the turbine 1 has a plurality of rotor blades (not shown) which receive a fluid for rotation, and is rotatably supported within a casing (not shown) through a rotating shaft 6.
  • the air compressor 3 is configured to be driven by the turbine 1 through the rotating shaft 6 in order to compress air.
  • the air compressor 3 is connected to the combustor 2 through a pipe 7, such that air compressed by the air compressor 3 is supplied to the combustor 2 through the pipe 7.
  • the heat exchanger 3 is installed midway in the pipe 7 , so that the air compressed by the air compressor 3 is heated by the heat exchanger
  • the fuel control valve 19 is disposed at an upstream side of the combustor 2.
  • a fuel supplied from a fuel supply source, not shown, passes through the fuel control valve 19 before it is supplied to the combustor 2.
  • An opening degree of the fuel control valve 19 is variable, so that the amount of fuel supplied to the combustor 2 is adjusted by manipulating the opening degree.
  • the fuel and air (from the pipe 7) supplied to the combustor 2 form an air/fuel mixture within the combustor 2, and the air/fuel mixture is burnt within the combustor 2 to generate a high- temperature and high-pressure combustion gas. Then, this combustion gas is supplied to the turbine 1, causing the turbine l to rotate at a high speed.
  • a generator 5 is connected to the end of the rotating shaft 6 , such that the generator 5 is driven to rotate through the rotating shaft 6 for generating electric power.
  • the combustion gas supplied to the turbine 1 is exhausted after it is sent to the heat exchanger 4 through the pipe 8.
  • the gas turbine apparatus 100 also comprises a part which generates heat by itself, bearing as like, so that an oil pump 15 for circulating a cooling oil is provided for cooling down this part .
  • a portion of the cooling oil circulated by the oil pump 15 is also supplied to a bearing (not shown) for rotatably supporting the rotating shaft 6 , functioning as a lubricant oil for maintaining the lubricating performance of the bearing.
  • the gas turbine apparatus 100 comprises a sensor system which comprises a variety of sensors and a measurement processor 21.
  • the variety of sensors comprise a CIT sensor 17 for measuring the temperature of the compressed air sent to the combustor 2; an EGT sensor 18 for measuring the temperature of exhaust gases; and an OIL sensor 16 for measuring the pressure of oil supplied for cooling and lubrication (OIL) .
  • the measurement processor 21 performs processing such as modifications to respective values based on the values measured by the variety of sensors .
  • the CIT sensor 17 is attached to the pipe 7 in close proximity to the combustor 2.
  • the CIT sensor 17 measures the temperature (CIT) of air heated by the heat exchanger 4 immediately before it flows into the combustor 2.
  • a measurement taken by the CIT sensor 17 is sent to the turbine controller 11 through the measurement processor 21.
  • the turbine controller 11 relies on this measured value to determine the amount of supplied fuel optimal for the ignition and combustion of the air/fuel mixture, and to determine an opening instruction value of the fuel control valve 19 to provide that amount of supplied fuel.
  • the EGT sensor 18 is attached to the pipe 8 which connects the turbine 1 to the heat exchanger 4 as mentioned above. A measurement taken by the EGT sensor 18 is also sent to the turbine controller 11 through the measurement processor 21, such that the turbine controller 11 utilizes this measured value for applications such as control for the rotational speed of the turbine 1 , and the like .
  • the OIL sensor 16 is disposed near the oil pump 15 as mentioned above.
  • the turbine controller 11 determines based on a value measured by the OIL sensor 16 whether a cooling action and lubrication for the bearing are performing properly or not . Since the general control in the turbine controller 11 based on the measured values of the CIT sensor 17, EGT sensor 18 and OIL sensor 16 is known, detailed description thereon is omitted.
  • the measurement processor 21 when an error is found in any value measured by a particular sensor, the measurement processor 21 automatically modifies the measured value to cancel out the error. Then, the modified value is sent to the turbine controller 11 for use in safely operating the gas turbine apparatus 100.
  • Fig. 2 is a block diagram describing the configuration of the measurement processor 21 in the sensor system according to the present invention.
  • the measurement processor 21 comprises a measurement recorder 22 for recording data measured by the respective sensors; an error detector 23 for detecting an error between a value measured by each sensor and a predetermined reference value; a measurement modifying unit 26 for modifying the measured value of each sensor based on the error detected by the error detector 23; and a first and second error occurrence warning unit 24 and 25 for transmitting an operation stop signal and an error occurrence warning signal when the error detected by the error detector 23 exceeds a first and a second predetermined reference range, respectively.
  • data measured by the respective sensors are first sent to the measurement recorder 22, respectively. Only data measured under predetermined conditions , out of the sent data, are recorded in the measurement recorder 22 on a sensor- by-sensor basis.
  • the data measured under the predetermined conditions refer to those measured data from the CIT sensor 17 and EGT sensor 18 which have been taken immediately before the start of the gas turbine apparatus 100.
  • the CIT sensor 17 and EGT sensor 18 measure the temperatures (CIT and EGT) which are recorded in the measurement recorder 22.
  • the CIT and EGT values measured immediately before the start are recorded as substantially constant values each time the gas turbine apparatus 100 is started.
  • the measured value of the OIL sensor 16 under the predetermined condition refers to an oil pressure measured by this sensor when the gas turbine apparatus 100 is operating in a non-load condition. This measured data is also recorded in the measurement recorder 22. Since the oil pressure during the non-load condition continues at a certain constant value. the data measured during this condition is recorded as a substantially constant value.
  • measurements recorded in the measurement recorder 22 are utilized in the error detector 23, next described, as reference values for detecting errors .
  • the error detector 23 selects a predetermined value from the data recorded in the measurement recorder 22 on a sensor-by-sensor basis , and uses the selected data as a reference value for detecting an error in a datum of each sensor.
  • the selected predetermined value refers to the CIT or EGT value taken by a new CIT or EGT sensor immediately before the start of the gas turbine apparatus 100, or the oil pressure measured by new OIL sensor when the gas turbine apparatus 100 is operating in a non-load condition. Then, by comparing the reference value with a value measured at the same timing or in the same operating situation as the data of the reference value, an error between the measured and the referenced values is detected.
  • An error detected by the error detector 23 is sent to the first error occurrence warning unit 24 as an error signal, together with a measured value of an associated sensor.
  • a first reference range which defines tolerable errors, has been previously set in the first error occurrence warning unit 24 for each sensor. The first reference range is set to be centered at the reference value selected in the error detector 23. Then if an error exceeds the first reference range (tolerable range) , as determined based on the error signal sent from the error detector 23, the first error occurrence warning unit 24 transmits a first error occurrence warning signal (operation stop signal). Further, as illustrated in Fig. 2, an operation stopping unit 31 is connected to the first error occurrence warning unit 24.
  • the operation stopping unit 31 Upon transmission of the first error occurrence warning signal, the operation stopping unit 31 stops a starting operation for the gas turbine apparatus 100 or the operation of the gas turbine apparatus 100 in response to this signal.
  • Fig. 3 is a diagram for describing when the first error occurrence warning unit transmits the first error occurrence warning signal.
  • the first reference range is set within a span of ⁇ centered at a reference value P. Since a high measurement precision is provided while a sensor is functioning normally, an error between a measured value and the reference value is substantially zero. Therefore, the error detected by the error detector 23 holds within the first reference range, as represented by a letter "A" in Fig. 3. In this case, the first error occurrence warning signal is not transmitted.
  • the operation stopping unit 31 stops the starting operation for the gas turbine apparatus 100 or the operation of the gas turbine apparatus 100 in response to this signal.
  • the error signal and measurement output from the first error occurrence warning unit 24 are next sent to the second error occurrence warning unit 25.
  • the second error occurrence warning unit 25 is basically similar in configuration to the first error occurrence warning unit 24 described above, the second error occurrence warning unit 25 sets a second reference range (a span over ⁇ ⁇ ' centered at the reference value P, where ⁇ ' ⁇ ) narrower than the above-mentioned first reference range. Then, if the error signal sent to the second error warning unit 25 exceeds the second reference range, the second error occurrence warning unit 25 transmits a second error occurrence warning signal (a signal corresponding to a deterioration in measurement precision) .
  • an alarm 32 is connected to the second error occurrence warning unit 25.
  • an alarm is generated, for example, from the alarm 32 to the operator of the gas turbine apparatus 100 in response to this signal.
  • the alarm 32 can generate an alarm of a different sound (frequency) for each sensor.
  • the alarm 32 may be an alarm indicator (for example, a rotating lamp, LED, or the like) for visually displaying that a value measured by a sensor exceeds the second reference range.
  • the second error occurrence warning unit 25 With the employment of the second error occurrence warning unit 25 as described above, an operator can recognize that a deterioration in a sensor s measurement precision has occurred when a value measured by the sensor exceeds the second reference range, so that the deterioration in measurement precision can be found before the sensor completely fails .
  • the error signal and measured value output from the second error occurrence warning unit 25 is sent to the measurement modifying unit 26.
  • the measurement modifying unit 26 adds or subtracts a modification value to or from the measured value in order to cancel out the error, thereby modifying the measured value. For example, when an error ⁇ [Pa] is found between a measured value taken by the OIL sensor 16 and the reference value, the measurement modifying unit 26 may add a modification value - ⁇ [Pa] to the value measured by the OIL sensor 16, thereby canceling out the error.
  • Each value thus modified is sent to the turbine controller 11, as illustrated in Fig. 2, for use in a variety of controls for the gas turbine apparatus 100, as described above.
  • Fig. 4 is a diagram showing an oil pressure measured by the sensor 16 and an actual oil pressure, as a function of an elapsed time. While Fig. 4 is described using the OIL sensor 16, similar operations are performed as well when another sensor is used.
  • a solid line indicates the value measured by the OIL sensor 16, while a dotted line indicates the actual oil pressure equal to the reference value.
  • a minimum oil pressure is generally set for purposes of protecting the gas turbine engine 100, such that the operation of the gas turbine apparatus 100 is stopped when the oil pressure is detected to be lower than this minimum oil pressure.
  • the OIL sensor 16 is measuring a value higher than the reference value by ⁇ [Pa] .
  • an error detected by the error detector 23 is ⁇ [Pa] . Therefore, the measurement modifying unit 26 adds a value for canceling out the error, i.e., - ⁇ [Pa] to the measured value.
  • the modified value which is eventually derived, is equal to the reference value, causing the measured value to decrease to the value indicated by the dotted line in Fig. 4.
  • a measured value is detected at time "t2" as falling across the minimum oil pressure unless any modification is added to the measured value.
  • the measured value (dotted line) modified by the measurement modifying unit 26 the measured value is detected at time “tl” as falling across the minimum oil pressure.
  • the modified measured value decreases to the minimum oil pressure earlier by the time "t2-tl" than the measured value before the modification, so that the measured value falling across the minimum oil pressure is determined at an earlier stage.
  • the sensor system according to the present invention is not limited to the foregoing embodiment, but can be modified in various manners without departing from the spirit of the present invention.
  • the present invention can of course extend the object measured by the sensor to other than CIT, EGT and oil pressure, as well as can be applied to any other apparatus than the gas turbine apparatus 100.
  • the turbine controller 11 performs a PID feedback control for the turbine 1. Specifically, the turbine controller 11 employs, as feedback values, a current rotational speed (rotational speed) of the turbine 1 detected by the rotational speed detector 12 disposed near the end of the rotating shaft 6 , a current acceleration
  • the turbine controller 11 manipulates the opening degree (opening instruction value) of the fuel control valve 19 in order to adjust the flow of the fuel supplied to the combustor 2.
  • the opening degree opening instruction value
  • the turbine controller 11 manipulates the opening degree (opening instruction value) of the fuel control valve 19 in order to adjust the flow of the fuel supplied to the combustor 2.
  • the turbine controller 11 controls the opening degree of the fuel control valve 19 in a feedback manner such that the rotational speed of the turbine 1 remains constant, as detected by the rotational speed detector 12.
  • the turbine controller 11 controls the opening degree of the fuel control valve 19 in a feedback manner such that the rotational speed of the turbine 1 remains constant, as detected by the rotational speed detector 12.
  • the measurement processor 21 of the sensor system is connected to the turbine controller 11, so that measured values modified by the measurement modifying unit 26 are sent to the turbine controller 11.
  • the turbine controller 11 monitors, for example, modified EGT (temperature of exhausted gases after combustion) to control the fuel control valve 19 such that this temperature does not excessively rise.
  • the turbine controller 11 decides whether the engine is in the cold state or hot state based on CIT (temperature of compressed air sent to the combustor) modified by the measurement modifying unit 26 and controls, for example, the air/fuel ratio at the ignition upon starting.
  • FIG. 5 shows the relationship between the opening instruction value and actual opening value of the fuel control valve.
  • a solid line “A” in Fig. 5 indicates, for example, the normal (new) fuel control valve, where the opening instruction value matches the actual opening value.
  • the fuel control valve 19 operates such that the actual opening reaches 40 %.
  • a difference between the opening instruction value and actual opening value of the fuel control valve may gradually occur.
  • a dotted line “B” in Fig. 5 indicates an example where such a difference (error) "C” occurs, showing that the actual opening value reaches merely 35 % whereas the opening instruction value indicates 40 %.
  • Fig. 6 is a block diagram for describing a function of calibrating the opening instruction value of the fuel control valve in the turbine controller 11 according to the present invention.
  • the turbine controller 11 comprises means for automatically detecting the difference "C" (see Fig. 5) between an opening instruction value and the actual opening value in order to automatically calibrate the opening instruction value such that the error is canceled out .
  • the turbine controller 11 adds or subtracts a calibration value for canceling out the difference "C" to or from the opening instruction value in order to calculate a calibrated opening instruction value.
  • the actual opening value before a calibration is 40 %
  • the actual opening value is 35 % and a difference between these values is -5 %
  • a calibration value +5 % is added to the original opening instruction value to derive a calibrated opening instruction value 45 % which is applied to the fuel control valve.
  • the actual opening value of the fuel control valve is brought to 40 % exactly as instructed by the original instruction value.
  • Fig.7 is a graph showing the exhaust gas temperature EGT, the opening FCV of the fuel control valve 19, and the rotational speed NR upon starting the engine.
  • the turbine controller 11 Upon starting the engine, the turbine controller 11 first uses a motor to increase the rotational speed NR to a constant speed. Then, after increasing the rotational speed to the constant speed, the turbine controller 11 opens the fuel control valve 19, and gradually increases the valve opening while operating an ignition plug. As a constant air/fuel ratio is reached by gradually increasing the valve opening, the engine ignites. This starts the combustion of fuel gas, and a combustion gas is supplied to the turbine, causing an increase in the rotational speed of the rotating shaft .
  • the turbine controller 11 detects an ignition timing " ⁇ i" of the engine by sensing a sudden increase in the combustion exhaust gas temperature EGT.
  • the turbine controller 11 detects the ignition timing "Tl” of the engine, maintains constant the opening instruction value of the fuel control valve 19 at the ignition timing "Tl”, and stores the opening instruction value FCV at the ignition timing "Tl” .
  • the turbine controller 11 further detects the ignition timing "Tl” of the engine, detects the rotational speed of the engine at the ignition timing "Tl”, calculates the air/fuel ratio at the ignition timing "Tl” from the opening instruction value FCV and rotational speed NR at the ignition timing "Tl”, and stores the air/fuel ratio.
  • FIG. 8 is a graph showing the relationship between the combustor inlet air temperature CIT and theoretical opening value at the theoretical air/fuel ratio at the ignition timing "Tl" .
  • the turbine controller 11 previously stores a relational equation which represents the graph of Fig. 8. It can be seen with reference to Fig. 8 that the theoretical air/fuel ratio at the ignition timing is a function of the combustor inlet air temperature CIT, and that the inlet air temperature is low and the theoretical opening value is large when the engine is cold (upon cold starting) . Conversely, when the engine is re-started while it is hot (upon hot starting), the combustor inlet air temperature tends to be higher, and the theoretical opening value tends to be lower.
  • the air/fuel ratio refers to the ratio of the amount of air to the amount of fuel.
  • the amount of air is proportional to the rotational speed
  • the amount of fuel is proportional to the opening value.
  • the air/fuel ratio at which the ignition is possible depends on the combustor inlet air temperature.
  • a theoretical opening value exists corresponding to the combustor inlet air temperature CIT.
  • the inlet air temperature CIT at the rotational speed (NR) upon ignition and the theoretical valve opening based on the stoichiometric air/fuel ratio upon ignition, as shown in Fig. 8.
  • a corresponding theoretical opening value is found given the inlet air temperature CIT at the time of ignition.
  • the aforementioned difference "C” is comparable to a difference between the opening instruction value FCV at the ignition timing tl, derived from a sudden increase detected in the exhaust gas temperature EGT, and the theoretical opening value corresponding to the inlet air temperature to the combustor 2 at that time.
  • the turbine controller 11 monitors the exhaust gas temperature EGT upon ignition to detect the ignition timing "Tl”, derives the air/fuel ratio upon ignition based on the inlet air temperature CIT at the timing "Tl”, determines the theoretical opening value based on the derived air/fuel ratio, calculates the difference "C” between the theoretical opening value and the opening instruction value found at the timing tl, and stores difference "C” as a calibration value.
  • the turbine controller 11 can calculate a correct theoretical opening value at the ignition timing "Tl” using the correct inlet air temperature CIT upon ignition. As a result, the turbine controller 11 can calculate the difference "C" (calibration value) between the opening instruction value and the theoretical opening value at the ignition timing "Tl". As described with reference to Fig. 6, the opening instruction value is calibrated by the calibration value. Therefore, even if there is a difference between an instruction value and the actual value of the fuel control valve 19, the turbine controller 11 can calibrate the instruction value to conduct a correct control. Such a calibration value is particularly effective in setting the opening instruction value for preventing an igniting engine from "flame out" .
  • the valve opening degree for determining the minimum fuel amount cannot be correctly held for maintaining the ignited state. Even if there is a difference between the instruction value and actual value of the valve, this instruction value can be calibrated to determine a correct actual opening degree.
  • the present invention can accordingly avoid the problems caused by an error such as "flame out" to improve the reliability of the gas turbine apparatus 100.
  • the fuel control valve 19 when a difference occurs between an opening instruction value and an actual opening value of a fuel control valve, the fuel control valve 19 must be replaced or repaired. However, according to the present invention, since the calibration value is detected, the difference between the opening instruction value and actual opening value of the fuel control valve 19 can be canceled out. Consequently, even if the difference exists, the fuel control valve 19 need not be repaired or replaced. In other words , the present invention advantageously eliminates the need for an effort of maintenance for the fuel control valve 19.
  • an alarm is generated for a operator to replace or repair the fuel control valve 19. In this event, the extremely large error may be visually displayed.
  • Fig. 9 is a general block diagram illustrating a second embodiment of the gas turbine apparatus according to the present invention.
  • the gas turbine apparatus 100" illustrated in Fig. 9 does not comprise the means for modifying measured data of sensors.
  • the present invention it is not always necessary for the present invention to comprise the measurement recorder 22 for the purpose of calibration for only an error of the opening instruction value.
  • the turbine controller 11 accurately can control the fuel control valve 19 in consideration of the difference "C" between an opening instruction value and a theoretical opening value upon ignition, in a manner similar to the first embodiment, so that the reliability of the gas turbine apparatus can be improved as compared with the conventional gas turbine.
  • gas turbine apparatus 100 is not limited to the plurality of illustrated examples described above, but may be modified in various manners without departing from the spirit of the invention.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Control Of Turbines (AREA)

Abstract

A gas turbine apparatus has a turbine controller. The turbine controller determines a theoretical opening value of the valve from an air/fuel ratio upon ignition of the gas turbine, and calibrates the opening instruction value after the ignition based on an opening difference between the theoretical opening value and the opening instruction value. The air/fuel ratio is calculated based on the temperature of air to be mixed with the fuel upon ignition of the gas turbine. The apparatus further comprises at least one sensor for measuring a physical amount of at least one object to be measured; an error detector for detecting an error between a current value measured by the sensor and a predetermined reference value; means for modifying the current value based on the error detected by the error detector; and means for providing the modified current measured value to the turbine controller.

Description

DESCRIPTION GAS TURBINE APPARATUS
TECHNICAL FIELD The present invention relates to a gas turbine apparatus, and more particularly, to a gas turbine apparatus which can accurately control a fuel control valve of a gas turbine engine.
BACKGROUND ART A typical gas turbine apparatus comprises a turbine rotatably mounted through a rotating shaft; a combustor for generating a combustion gas; a fuel control valve for controlling an amount of fuel supplied to the combustor; and an air compressor for compressing air. In these components, the fuel adjusted by the fuel control valve and the air compressed by the air compressor are supplied to the combustor, so that an air/fuel mixture consisting of the compressed air and the fuel is formed within the combustor. The combustor burns the air/fuel mixture and, therefore generates a combustion gas. Then, the combustor supplies the combustion gas to the turbine, so that the turbine can consequently rotate at high speed.
In such a gas turbine apparatus, a variety of operation controls such as a start-up control, a constant speed operation control, and the like are performed by controlling an opening degree of the fuel control valve. For example, when a load suddenly decreases, the amount of supplied fuel must be suddenly reduced to maintain a constant speed operation of the gas turbine apparatus. However, if the amount of supplied fuel is reduced to a fixed amount or less, combustion within the engine stops . This problem is referred to as "flame out". To avoid this problem, the opening degree of the fuel control valve is controlled to ensure the fixed amount of supplied fuel even in such an event .
Unfortunately, during use of the fuel control valve, a difference (error) between an opening instruction value and an actual opening degree of the valve may gradually occur. Specifically, even if means for controlling the valve outputs a constant opening instruction value to the fuel control valve, the actual opening degree of the valve may not reach the opening instruction value, resulting in a value below the opening instruction value. As such, without recognizing the difference between the opening instruction value and the actual opening degree of the valve, if the means for controlling the valve outputs a certain opening instruction value to the fuel control valve, problems such as the above-mentioned "flame out" would occur in a worst case.
A typical gas turbine apparatus further comprises a variety of sensors, for example, a CIT sensor for measuring a Combustor Inlet air Temperature (CIT); an EGT sensor for measuring an Exhaust Gas Temperature (EGT); an OIL sensor for measuring the pressure of oil supplied for cooling and lubrication of bearings; and the like.
Data measured by these sensors are utilized as determination factors or safely and reliably staring up the gas turbine apparatus or for safely continuing operation of the gas turbine apparatus . Likewise, in this case, an error between a measured value of each sensor and an actual value may occur due to a deterioration in the measurement precision of each sensor. As mentioned above. values including such an error are utilized in decision of a variety of factors. Therefore, such an error affects a variety of controls for the gas turbine engine. Possible problems are, for example, a failure in starting up the gas turbine apparatus , and a delay in stopping its operation, although it is necessary to immediately stop the gas turbine apparatus when a fault is found. In other words, deterioration in measurement precision of a sensor is found after the recognition of an unusual value, such as an extremely high or low value, measured by the sensor. Thus, until it has been found that a deterioration in the measurement precision of the sensor has become critical, a measured value, which may be neither extremely high nor extremely low, but which deviates from an actual/required value, would be used in deciding each factor, resulting in the problems mentioned above. To solve these problems , the following methods have been proposed. Specifically, three sensors are used for measuring a single object to be measured, and a measured value that differs the greatest from each of the other measurements is excluded from the three measurements, in order to improve measurement precision. However, since this method uses three sensors for every object to be measured, it results in a problem of increased costs. As a result, this method is actually employed only in particular apparatuses such as an atomic power generator.
DISCLOSURE OF THE INVENTION
It is therefore an object of the present invention to accurately control the opening degree of a f el control valve in order to improve the reliability of a gas turbine apparatus and reduce the maintenance work thereof.
It is another object of the present invention to obtain an accurate physical amount of an object to be measured in order to improve reliability of the gas turbine apparatus and reduce maintenance work and costs .
It is a further object of the present invention to predict failures of sensors provided in a gas turbine apparatus .
To achieve the above objects, a gas turbine apparatus according to the present invention comprises a turbine controller, wherein the turbine controller comprises : a device for calibrating an opening instruction value of a fuel control valve provided to control the amount of supplied fuel and, therefore, automatically calibrates the opening degree of the fuel control valve.
Specially, the device comprises: first means for determining a theoretical opening value of the valve from an air/fuel ratio at the time of ignition of the gas turbine, the air/fuel ratio is calculated based on a temperature of air to be mixed with the fuel; second means for detecting an opening difference between the theoretical opening value determined by the first means and the opening instruction value at the time of ignition of the gas turbine; and means for calibrating the opening instruction value of the fuel control valve after the ignition based on the opening difference detected by the second means .
To achieve the above objects, a gas turbine apparatus according to the present invention comprises a sensor system, the sensor system comprises : at least one sensor for measuring a physical amount of at least one object to be measured; a storage unit for storing a log of data measured by the sensor; an error detector for detecting an error between a current measured value taken by the sensor and a predetermined reference value, the predetermined re erence value is a selected datum taken in an identical or similar operating environment to a current measured value, from among the data stored in the storage unit; means for modifying the current measured value based on the error detected by the error detector; and means for providing the modified current measured value to the turbine controller.
The system f rther comprises : a first warning unit for outputting a first signal for stopping operation of a target to be controlled, when the error detected by the error detector exceeds a tolerable range; and a second warning unit for generating a second signal for warning, when the error detected by the error detector holds within the tolerable range but exceeds a predetermined range.
BRIEF DESCRIPTION OF THE DRAWINGS The advantage and principles of the present invention will be obvious to those skilled in the art of gas turbine apparatuses from the following description of the best mode for carrying out the invention with reference to the accompanying drawings. In the drawings ,
Fig. 1 is a general block diagram illustrating a first embodiment of a gas turbine apparatus according to the present invention; Fig. 2 is a block diagram of a sensor system according to the present invention which is comprised in the gas turbine apparatus illustrated in Fig. 1;
Fig. 3 is a diagram for describing when a first signal for warning is transmitted from a first warning unit in a measurement processor comprised in the sensor system illustrated in Fig. 2;
Fig. 4 is a graph showing the relationship between a measured oil pressure and an actual oil pressure, as a function of elapsed time for describing operational effects of the sensor system according to the present invention;
Fig. 5 is a graph showing the relationship between an opening instruction value and an actual opening value of a fuel control valve;
Fig. 6 is a block diagram for describing a function of calibrating an opening instruction value of a fuel control valve by a turbine controller comprised in the gas turbine apparatus illustrated in Fig. 1;
Fig. 7 is a graph showing an exhaust gas temperature (EGT), an opening instruction value (FCV) of the fuel control valve, and a rotational speed (NR) upon starting of an engine;
Fig. 8 is a graph showing the relationship between a combustor inlet air temperature (CIT) and a theoretical opening value of the valve based on a theoretical air/fuel ratio at the time of ignition; and Fig. 9 is a general block diagram illustrating a second embodiment of the gas turbine apparatus according to the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION Fig. 1 is a general view of a gas turbine apparatus according to the present invention. As illustrated in Fig. 1, the gas turbine apparatus 100 according to the present invention comprises a turbine
1; a combustor 2 for burning an air/fuel mixture consisted of a fuel and air in order to generate a combustion gas; a fuel control valve
19 for controlling the amount of fuel supplied to the combustor 2; and an air compressor 3 for supplying compressed air to the combustor
2. The gas turbine apparatus 100 also comprises a heat exchanger 4 for heating the air used for combustion, making use of the heat of the combustion gas; and a turbine controller 11 for controlling the turbine 1.
The turbine 1 has a plurality of rotor blades (not shown) which receive a fluid for rotation, and is rotatably supported within a casing (not shown) through a rotating shaft 6. The air compressor
3 is configured to be driven by the turbine 1 through the rotating shaft 6 in order to compress air. The air compressor 3 is connected to the combustor 2 through a pipe 7, such that air compressed by the air compressor 3 is supplied to the combustor 2 through the pipe 7. The heat exchanger 3 is installed midway in the pipe 7 , so that the air compressed by the air compressor 3 is heated by the heat exchanger
4 before it is supplied to the combustor 2.
The fuel control valve 19 is disposed at an upstream side of the combustor 2. A fuel supplied from a fuel supply source, not shown, passes through the fuel control valve 19 before it is supplied to the combustor 2. An opening degree of the fuel control valve 19 is variable, so that the amount of fuel supplied to the combustor 2 is adjusted by manipulating the opening degree.
The fuel and air (from the pipe 7) supplied to the combustor 2 form an air/fuel mixture within the combustor 2, and the air/fuel mixture is burnt within the combustor 2 to generate a high- temperature and high-pressure combustion gas. Then, this combustion gas is supplied to the turbine 1, causing the turbine l to rotate at a high speed. A generator 5 is connected to the end of the rotating shaft 6 , such that the generator 5 is driven to rotate through the rotating shaft 6 for generating electric power. The combustion gas supplied to the turbine 1 is exhausted after it is sent to the heat exchanger 4 through the pipe 8.
The gas turbine apparatus 100 also comprises a part which generates heat by itself, bearing as like, so that an oil pump 15 for circulating a cooling oil is provided for cooling down this part .
A portion of the cooling oil circulated by the oil pump 15 is also supplied to a bearing (not shown) for rotatably supporting the rotating shaft 6 , functioning as a lubricant oil for maintaining the lubricating performance of the bearing.
The gas turbine apparatus 100 comprises a sensor system which comprises a variety of sensors and a measurement processor 21. The variety of sensors comprise a CIT sensor 17 for measuring the temperature of the compressed air sent to the combustor 2; an EGT sensor 18 for measuring the temperature of exhaust gases; and an OIL sensor 16 for measuring the pressure of oil supplied for cooling and lubrication (OIL) . The measurement processor 21 performs processing such as modifications to respective values based on the values measured by the variety of sensors .
The CIT sensor 17 is attached to the pipe 7 in close proximity to the combustor 2. The CIT sensor 17 measures the temperature (CIT) of air heated by the heat exchanger 4 immediately before it flows into the combustor 2. A measurement taken by the CIT sensor 17 is sent to the turbine controller 11 through the measurement processor 21. As described later in detail, the turbine controller 11 relies on this measured value to determine the amount of supplied fuel optimal for the ignition and combustion of the air/fuel mixture, and to determine an opening instruction value of the fuel control valve 19 to provide that amount of supplied fuel.
The EGT sensor 18 is attached to the pipe 8 which connects the turbine 1 to the heat exchanger 4 as mentioned above. A measurement taken by the EGT sensor 18 is also sent to the turbine controller 11 through the measurement processor 21, such that the turbine controller 11 utilizes this measured value for applications such as control for the rotational speed of the turbine 1 , and the like .
The OIL sensor 16 is disposed near the oil pump 15 as mentioned above. The turbine controller 11 determines based on a value measured by the OIL sensor 16 whether a cooling action and lubrication for the bearing are performing properly or not . Since the general control in the turbine controller 11 based on the measured values of the CIT sensor 17, EGT sensor 18 and OIL sensor 16 is known, detailed description thereon is omitted.
In the sensor system according to the present invention, when an error is found in any value measured by a particular sensor, the measurement processor 21 automatically modifies the measured value to cancel out the error. Then, the modified value is sent to the turbine controller 11 for use in safely operating the gas turbine apparatus 100.
Fig. 2 is a block diagram describing the configuration of the measurement processor 21 in the sensor system according to the present invention. As illustrated in Fig. 2, the measurement processor 21 comprises a measurement recorder 22 for recording data measured by the respective sensors; an error detector 23 for detecting an error between a value measured by each sensor and a predetermined reference value; a measurement modifying unit 26 for modifying the measured value of each sensor based on the error detected by the error detector 23; and a first and second error occurrence warning unit 24 and 25 for transmitting an operation stop signal and an error occurrence warning signal when the error detected by the error detector 23 exceeds a first and a second predetermined reference range, respectively.
As illustrated in Fig. 2, data measured by the respective sensors are first sent to the measurement recorder 22, respectively. Only data measured under predetermined conditions , out of the sent data, are recorded in the measurement recorder 22 on a sensor- by-sensor basis. The data measured under the predetermined conditions refer to those measured data from the CIT sensor 17 and EGT sensor 18 which have been taken immediately before the start of the gas turbine apparatus 100. Specifically, each time the gas turbine apparatus 100 is started, the CIT sensor 17 and EGT sensor 18 measure the temperatures (CIT and EGT) which are recorded in the measurement recorder 22. Generally, since the gas turbine apparatus 100 before the start has been sufficiently cooled down and remains at room temperature, the CIT and EGT values measured immediately before the start are recorded as substantially constant values each time the gas turbine apparatus 100 is started. The measured value of the OIL sensor 16 under the predetermined condition refers to an oil pressure measured by this sensor when the gas turbine apparatus 100 is operating in a non-load condition. This measured data is also recorded in the measurement recorder 22. Since the oil pressure during the non-load condition continues at a certain constant value. the data measured during this condition is recorded as a substantially constant value.
Then, measurements recorded in the measurement recorder 22 are utilized in the error detector 23, next described, as reference values for detecting errors .
The error detector 23 selects a predetermined value from the data recorded in the measurement recorder 22 on a sensor-by-sensor basis , and uses the selected data as a reference value for detecting an error in a datum of each sensor. At that time, the selected predetermined value refers to the CIT or EGT value taken by a new CIT or EGT sensor immediately before the start of the gas turbine apparatus 100, or the oil pressure measured by new OIL sensor when the gas turbine apparatus 100 is operating in a non-load condition. Then, by comparing the reference value with a value measured at the same timing or in the same operating situation as the data of the reference value, an error between the measured and the referenced values is detected.
An error detected by the error detector 23 is sent to the first error occurrence warning unit 24 as an error signal, together with a measured value of an associated sensor. A first reference range, which defines tolerable errors, has been previously set in the first error occurrence warning unit 24 for each sensor. The first reference range is set to be centered at the reference value selected in the error detector 23. Then if an error exceeds the first reference range (tolerable range) , as determined based on the error signal sent from the error detector 23, the first error occurrence warning unit 24 transmits a first error occurrence warning signal (operation stop signal). Further, as illustrated in Fig. 2, an operation stopping unit 31 is connected to the first error occurrence warning unit 24.
Upon transmission of the first error occurrence warning signal, the operation stopping unit 31 stops a starting operation for the gas turbine apparatus 100 or the operation of the gas turbine apparatus 100 in response to this signal.
The operation of the first error occurrence warning unit 24 will be described with reference to Fig. 3. Fig. 3 is a diagram for describing when the first error occurrence warning unit transmits the first error occurrence warning signal. As indicated by a dotted line in Fig. 3, the first reference range is set within a span of ± centered at a reference value P. Since a high measurement precision is provided while a sensor is functioning normally, an error between a measured value and the reference value is substantially zero. Therefore, the error detected by the error detector 23 holds within the first reference range, as represented by a letter "A" in Fig. 3. In this case, the first error occurrence warning signal is not transmitted.
On the other hand, as a deterioration in measurement precision of a sensor results in a change in its measured value, an error detected by the error detector 23 eventually exceeds the first reference range, as represented by a letter "B" in Fig. 3. In this case, the first error occurrence warning signal is transmitted. Then, as the first error occurrence warning signal is transmitted, the operation stopping unit 31 stops the starting operation for the gas turbine apparatus 100 or the operation of the gas turbine apparatus 100 in response to this signal.
The error signal and measurement output from the first error occurrence warning unit 24 are next sent to the second error occurrence warning unit 25. While the second error occurrence warning unit 25 is basically similar in configuration to the first error occurrence warning unit 24 described above, the second error occurrence warning unit 25 sets a second reference range (a span over ± α' centered at the reference value P, where α'<α) narrower than the above-mentioned first reference range. Then, if the error signal sent to the second error warning unit 25 exceeds the second reference range, the second error occurrence warning unit 25 transmits a second error occurrence warning signal (a signal corresponding to a deterioration in measurement precision) .
As illustrated in Fig. 2, an alarm 32 is connected to the second error occurrence warning unit 25. When the second error occurrence warning signal is transmitted from the second error occurrence warning unit 24, an alarm is generated, for example, from the alarm 32 to the operator of the gas turbine apparatus 100 in response to this signal. In this event, the alarm 32 can generate an alarm of a different sound (frequency) for each sensor. The alarm 32 may be an alarm indicator (for example, a rotating lamp, LED, or the like) for visually displaying that a value measured by a sensor exceeds the second reference range.
With the employment of the second error occurrence warning unit 25 as described above, an operator can recognize that a deterioration in a sensor s measurement precision has occurred when a value measured by the sensor exceeds the second reference range, so that the deterioration in measurement precision can be found before the sensor completely fails .
The error signal and measured value output from the second error occurrence warning unit 25 is sent to the measurement modifying unit 26. The measurement modifying unit 26 adds or subtracts a modification value to or from the measured value in order to cancel out the error, thereby modifying the measured value. For example, when an error β [Pa] is found between a measured value taken by the OIL sensor 16 and the reference value, the measurement modifying unit 26 may add a modification value -β [Pa] to the value measured by the OIL sensor 16, thereby canceling out the error. Each value thus modified is sent to the turbine controller 11, as illustrated in Fig. 2, for use in a variety of controls for the gas turbine apparatus 100, as described above.
Next, an exemplary operational effect of the sensor system according to the present invention will be described in a specific manner with reference to Fig. 4. Fig. 4 is a diagram showing an oil pressure measured by the sensor 16 and an actual oil pressure, as a function of an elapsed time. While Fig. 4 is described using the OIL sensor 16, similar operations are performed as well when another sensor is used.
In Fig. 4, a solid line indicates the value measured by the OIL sensor 16, while a dotted line indicates the actual oil pressure equal to the reference value. Also, as shown in Fig. 4, a minimum oil pressure is generally set for purposes of protecting the gas turbine engine 100, such that the operation of the gas turbine apparatus 100 is stopped when the oil pressure is detected to be lower than this minimum oil pressure. As shown in Fig. 4, it is assumed that the OIL sensor 16 is measuring a value higher than the reference value by β [Pa] . In this case, an error detected by the error detector 23 is β [Pa] . Therefore, the measurement modifying unit 26 adds a value for canceling out the error, i.e., -β [Pa] to the measured value. As a result, the modified value, which is eventually derived, is equal to the reference value, causing the measured value to decrease to the value indicated by the dotted line in Fig. 4. As shown in Fig. 4, if some failure occurs in the oil pump
15, for example, to reduce the oil pressure, a measured value is detected at time "t2" as falling across the minimum oil pressure unless any modification is added to the measured value. On the other hand, according to the measured value (dotted line) modified by the measurement modifying unit 26, the measured value is detected at time "tl" as falling across the minimum oil pressure.
In other words , the modified measured value decreases to the minimum oil pressure earlier by the time "t2-tl" than the measured value before the modification, so that the measured value falling across the minimum oil pressure is determined at an earlier stage. As a result , it is possible to more rapidly stop the gas turbine apparatus 100, thereby obviating the gas turbine apparatus 100 from being damaged due to a deteriorated cooling action and an insufficiently lubricated bearing caused by a lower oil pressure. It should be understood that the sensor system according to the present invention is not limited to the foregoing embodiment, but can be modified in various manners without departing from the spirit of the present invention. For example, the present invention can of course extend the object measured by the sensor to other than CIT, EGT and oil pressure, as well as can be applied to any other apparatus than the gas turbine apparatus 100.
Next, the turbine controller 11 will be described. The turbine controller 11 performs a PID feedback control for the turbine 1. Specifically, the turbine controller 11 employs, as feedback values, a current rotational speed (rotational speed) of the turbine 1 detected by the rotational speed detector 12 disposed near the end of the rotating shaft 6 , a current acceleration
(calculated as a changing rate of the rotational speed) of the turbine
I detected by an acceleration calculating unit, not shown, and the like, and generates a control signal in accordance with a PID operation for minimizing a deviation of each of these feedback values from a previously set target value. In accordance with the value operated by control signal, the turbine controller 11 manipulates the opening degree (opening instruction value) of the fuel control valve 19 in order to adjust the flow of the fuel supplied to the combustor 2. By thus controlling the amount of fuel supplied to the combustor 2 , the temperature of the combustion gas supplied to the turbine 1 is increased or decreased in order to control the rotational speed and acceleration of the turbine 1.
For example, during a constant speed operation of the gas turbine apparatus 100, the turbine controller 11 controls the opening degree of the fuel control valve 19 in a feedback manner such that the rotational speed of the turbine 1 remains constant, as detected by the rotational speed detector 12. During a starting operation for the gas turbine apparatus 100, in turn, the turbine controller
II controls the opening degree of the fuel control valve in a feedback manner such that the acceleration, calculated by differentiating the detected rotational speed, remains at a predetermined value.
As described above, the measurement processor 21 of the sensor system is connected to the turbine controller 11, so that measured values modified by the measurement modifying unit 26 are sent to the turbine controller 11. The turbine controller 11 monitors, for example, modified EGT (temperature of exhausted gases after combustion) to control the fuel control valve 19 such that this temperature does not excessively rise.
The CIT sensor 17, which measures the temperature of inlet air introduced into the combustor, plays an important role in detecting whether the engine is cold (in a cold state) or hot (in a hot state) upon starting. Thus, the turbine controller 11 decides whether the engine is in the cold state or hot state based on CIT (temperature of compressed air sent to the combustor) modified by the measurement modifying unit 26 and controls, for example, the air/fuel ratio at the ignition upon starting.
Fig. 5 shows the relationship between the opening instruction value and actual opening value of the fuel control valve. A solid line "A" in Fig. 5 indicates, for example, the normal (new) fuel control valve, where the opening instruction value matches the actual opening value. Specifically, as an opening instruction value 40 %, for example, is given from the turbine controller 11 to the fuel control valve 19, the fuel control valve 19 operates such that the actual opening reaches 40 %. However, during use of the fuel control valve 19, a difference between the opening instruction value and actual opening value of the fuel control valve may gradually occur. A dotted line "B" in Fig. 5 indicates an example where such a difference (error) "C" occurs, showing that the actual opening value reaches merely 35 % whereas the opening instruction value indicates 40 %. When such a fuel control valve is used, the instructed (controlled) operation is inaccurately performed, resulting in instable operations in controlling the gas turbine, as described above.
Fig. 6 is a block diagram for describing a function of calibrating the opening instruction value of the fuel control valve in the turbine controller 11 according to the present invention. The turbine controller 11 comprises means for automatically detecting the difference "C" (see Fig. 5) between an opening instruction value and the actual opening value in order to automatically calibrate the opening instruction value such that the error is canceled out . Specifically, the turbine controller 11 adds or subtracts a calibration value for canceling out the difference "C" to or from the opening instruction value in order to calculate a calibrated opening instruction value. For example, when the opening instruction value before a calibration is 40 %, the actual opening value is 35 % and a difference between these values is -5 %, a calibration value +5 % is added to the original opening instruction value to derive a calibrated opening instruction value 45 % which is applied to the fuel control valve. As a result, the actual opening value of the fuel control valve is brought to 40 % exactly as instructed by the original instruction value.
With the employment of the turbine controller 11 as described above, even if the difference "C" occurs between the opening instruction value and actual opening values of the fuel control valve 19, this error is automatically detected, with the result that a correct actual opening degree can be derived.
Next, the detection of the difference "C" between the opening instruction value (before calibration) and actual opening value will be described with reference to Figs .7 and 8. Fig.7 is a graph showing the exhaust gas temperature EGT, the opening FCV of the fuel control valve 19, and the rotational speed NR upon starting the engine. Upon starting the engine, the turbine controller 11 first uses a motor to increase the rotational speed NR to a constant speed. Then, after increasing the rotational speed to the constant speed, the turbine controller 11 opens the fuel control valve 19, and gradually increases the valve opening while operating an ignition plug. As a constant air/fuel ratio is reached by gradually increasing the valve opening, the engine ignites. This starts the combustion of fuel gas, and a combustion gas is supplied to the turbine, causing an increase in the rotational speed of the rotating shaft .
The turbine controller 11 detects an ignition timing "τi" of the engine by sensing a sudden increase in the combustion exhaust gas temperature EGT. The turbine controller 11 detects the ignition timing "Tl" of the engine, maintains constant the opening instruction value of the fuel control valve 19 at the ignition timing "Tl", and stores the opening instruction value FCV at the ignition timing "Tl" . The turbine controller 11 further detects the ignition timing "Tl" of the engine, detects the rotational speed of the engine at the ignition timing "Tl", calculates the air/fuel ratio at the ignition timing "Tl" from the opening instruction value FCV and rotational speed NR at the ignition timing "Tl", and stores the air/fuel ratio. Fig. 8 is a graph showing the relationship between the combustor inlet air temperature CIT and theoretical opening value at the theoretical air/fuel ratio at the ignition timing "Tl" . The turbine controller 11 previously stores a relational equation which represents the graph of Fig. 8. It can be seen with reference to Fig. 8 that the theoretical air/fuel ratio at the ignition timing is a function of the combustor inlet air temperature CIT, and that the inlet air temperature is low and the theoretical opening value is large when the engine is cold (upon cold starting) . Conversely, when the engine is re-started while it is hot (upon hot starting), the combustor inlet air temperature tends to be higher, and the theoretical opening value tends to be lower.
By the way, the air/fuel ratio refers to the ratio of the amount of air to the amount of fuel. The amount of air is proportional to the rotational speed, and the amount of fuel is proportional to the opening value. The air/fuel ratio at which the ignition is possible depends on the combustor inlet air temperature. When the rotational speed is fixed, a theoretical opening value exists corresponding to the combustor inlet air temperature CIT. Then, since the relationship has been established between the inlet air temperature CIT at the rotational speed (NR) upon ignition and the theoretical valve opening based on the stoichiometric air/fuel ratio upon ignition, as shown in Fig. 8. As such, a corresponding theoretical opening value is found given the inlet air temperature CIT at the time of ignition. Therefore, the aforementioned difference "C" is comparable to a difference between the opening instruction value FCV at the ignition timing tl, derived from a sudden increase detected in the exhaust gas temperature EGT, and the theoretical opening value corresponding to the inlet air temperature to the combustor 2 at that time.
As described above, the turbine controller 11 monitors the exhaust gas temperature EGT upon ignition to detect the ignition timing "Tl", derives the air/fuel ratio upon ignition based on the inlet air temperature CIT at the timing "Tl", determines the theoretical opening value based on the derived air/fuel ratio, calculates the difference "C" between the theoretical opening value and the opening instruction value found at the timing tl, and stores difference "C" as a calibration value.
It should be noted that the inlet air temperature CIT upon ignition is modified by the aforementioned sensor system. Therefore, the turbine controller 11 can calculate a correct theoretical opening value at the ignition timing "Tl" using the correct inlet air temperature CIT upon ignition. As a result, the turbine controller 11 can calculate the difference "C" (calibration value) between the opening instruction value and the theoretical opening value at the ignition timing "Tl". As described with reference to Fig. 6, the opening instruction value is calibrated by the calibration value. Therefore, even if there is a difference between an instruction value and the actual value of the fuel control valve 19, the turbine controller 11 can calibrate the instruction value to conduct a correct control. Such a calibration value is particularly effective in setting the opening instruction value for preventing an igniting engine from "flame out" . Stated another way, supposing that there is a difference between the opening instruction value and actual opening value of the fuel control valve 19, the valve opening degree for determining the minimum fuel amount cannot be correctly held for maintaining the ignited state. Even if there is a difference between the instruction value and actual value of the valve, this instruction value can be calibrated to determine a correct actual opening degree. Thus, the present invention can accordingly avoid the problems caused by an error such as "flame out" to improve the reliability of the gas turbine apparatus 100.
In the past, when a difference occurs between an opening instruction value and an actual opening value of a fuel control valve, the fuel control valve 19 must be replaced or repaired. However, according to the present invention, since the calibration value is detected, the difference between the opening instruction value and actual opening value of the fuel control valve 19 can be canceled out. Consequently, even if the difference exists, the fuel control valve 19 need not be repaired or replaced. In other words , the present invention advantageously eliminates the need for an effort of maintenance for the fuel control valve 19.
Preferably, if an extremely large difference is found through management of the difference (calibration value), an alarm is generated for a operator to replace or repair the fuel control valve 19. In this event, the extremely large error may be visually displayed.
Fig. 9 is a general block diagram illustrating a second embodiment of the gas turbine apparatus according to the present invention. As compared with the gas turbine apparatus 100 illustrated in Fig. 1, the gas turbine apparatus 100" illustrated in Fig. 9 does not comprise the means for modifying measured data of sensors. Thus, it is not always necessary for the present invention to comprise the measurement recorder 22 for the purpose of calibration for only an error of the opening instruction value. The turbine controller 11 accurately can control the fuel control valve 19 in consideration of the difference "C" between an opening instruction value and a theoretical opening value upon ignition, in a manner similar to the first embodiment, so that the reliability of the gas turbine apparatus can be improved as compared with the conventional gas turbine.
It should be understood that the gas turbine apparatus 100 according to the present invention is not limited to the plurality of illustrated examples described above, but may be modified in various manners without departing from the spirit of the invention.

Claims

1. A gas turbine apparatus in which a mixture of air and fuel is burned to drive a gas turbine to rotate under the control of a turbine controller, wherein said turbine controller comprises: a device for calibrating an opening instruction value of a fuel control valve provided to control the amount of supplied fuel, to automatically calibrate the opening degree of said fuel control valve.
2. A gas turbine apparatus according to Claim 1, wherein said device for calibrating the opening instruction value comprises : first means for determining a theoretical opening value of the valve from an air/fuel ratio at the time of ignition of said gas turbine; second means for detecting an opening difference between said theoretical opening value determined by said first means and said opening instruction value at the time of ignition of said gas turbine; and means for calibrating the opening instruction value of said fuel control valve after the ignition based on the opening difference detected by said second means .
3. A gas turbine apparatus according to Claim 2 , wherein said first means comprises : means for calculating said air/fuel ratio at time of ignition of said gas turbine, based on the temperature of air to be mixed with the fuel, from a CIT sensor, at the time of ignition of said gas turbine; and means for determining said theoretical opening value based on said calculated air/fuel ratio.
4. A gas turbine apparatus according to any one of Claims 1 to 3, further comprising a sensor system, said sensor system comprises: at least one sensor for measuring a physical amount of at least one object to be measured; an error detector for detecting an error between a current value measured by said sensor and a predetermined reference value; means for modifying said current measured value based on the error detected by said error detector; and means for providing said modified current measured value to said turbine controller.
5. A gas turbine apparatus according to Claim 4, wherein said sensor system further comprises : a first warning unit for outputting a first signal for stopping the operation of said gas turbine apparatus when the error detected by said error detector exceeds a tolerable range; and a second warning unit for generating a second signal for warning when the error detected by said error detector holds within said tolerable range but exceeds a predetermined range.
6. A gas turbine apparatus according to Claim 4 or 5 , wherein said sensor system further comprises: a storage unit for storing a log of data measured by said sensor; and means for selecting a datum measured in an identical or similar operating environment to a current measured value, from among the data stored in said storage unit to set said selected datum as said predetermined reference value for use in said error detector.
7. A gas turbine apparatus according to Claim 6 , wherein said means for selecting is adapted to select a value measured by said sensor immediately before a start of said gas turbine and set as said predetermined reference value for use in said error detector.
8. A gas turbine apparatus according to any one of Claims 4 to 7, wherein said at least one sensor is any one of a CIT sensor, an
EGT sensor and an OIL sensor, or an arbitrary combination thereof.
9. A sensor system for measuring a physical amount, comprising: at least one sensor for measuring a physical amount of at least one object to be measured; an error detector for detecting an error between a current value measured by said sensor and a predetermined reference value; means for modifying said current measured value based on the error detected by said error detector; and means for providing said modified current measured value to said turbine controller.
10. A sensor system according to Claim 9, further comprising: a first warning unit for outputting a first signal for stopping the operation of a target to be controlled when the error detected by said error detector exceeds a tolerable range; and a second warning unit for generating a second signal for warning when the error detected by said error detector holds within said tolerable range but exceeds a predetermined range.
11. A sensor system according to Claim 9 or 10, further comprising: a storage unit for storing a log of data measured by said sensor; and means for selecting a datum measured in an identical or similar operating environment to a current measured value, from among the data stored in said storage unit to set said selected value as said predetermined reference value for use in said error detector.
12. A sensor system according to Claim 11, wherein said means for selecting is adapted to select a value measured by said sensor immediately before a start of said gas turbine and set as said predetermined reference value for use in said error detector.
13. A sensor system according to any one of Claims 9 to 12, wherein: said at least one sensor is any one of a CIT sensor, an EGT sensor and an OIL sensor, or an arbitrary combination thereof; and said target to be controlled is a gas turbine apparatus .
PCT/JP2003/000156 2002-01-10 2003-01-10 Gas turbine apparatus WO2003060304A1 (en)

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JP2002012124A JP2003214179A (en) 2002-01-21 2002-01-21 Sensor system and gas turbine device with the same

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US6847129B2 (en) * 2001-12-07 2005-01-25 Ebara Corporation Turbine generator starting method and turbine generation system
US9157376B2 (en) 2012-10-02 2015-10-13 General Electric Company Methods and systems for detecting an oscillation error
US9176002B2 (en) 2012-10-02 2015-11-03 General Electric Company Methods and systems for detecting an oscillatory event

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US4866940A (en) * 1988-07-25 1989-09-19 Westinghouse Electric Corp. Computer aided tuning of turbine controls
JPH07269373A (en) * 1994-03-29 1995-10-17 Hitachi Ltd Gas turbine system, its control method and controller
GB2351777A (en) * 1999-07-08 2001-01-10 Moog Inc Use of a calibration orifice in a gas turbine engine fuel system before starting
WO2001025738A1 (en) * 1999-10-05 2001-04-12 Cilliers Bartolomomeus Johanne Measuring twist due to torque in a rotating shaft
JP2003056366A (en) * 2001-08-16 2003-02-26 Toshiba Corp Turbine controller

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Publication number Priority date Publication date Assignee Title
US4866940A (en) * 1988-07-25 1989-09-19 Westinghouse Electric Corp. Computer aided tuning of turbine controls
JPH07269373A (en) * 1994-03-29 1995-10-17 Hitachi Ltd Gas turbine system, its control method and controller
GB2351777A (en) * 1999-07-08 2001-01-10 Moog Inc Use of a calibration orifice in a gas turbine engine fuel system before starting
WO2001025738A1 (en) * 1999-10-05 2001-04-12 Cilliers Bartolomomeus Johanne Measuring twist due to torque in a rotating shaft
JP2003056366A (en) * 2001-08-16 2003-02-26 Toshiba Corp Turbine controller

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6847129B2 (en) * 2001-12-07 2005-01-25 Ebara Corporation Turbine generator starting method and turbine generation system
US9157376B2 (en) 2012-10-02 2015-10-13 General Electric Company Methods and systems for detecting an oscillation error
US9176002B2 (en) 2012-10-02 2015-11-03 General Electric Company Methods and systems for detecting an oscillatory event

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