JP5745640B2 - Control device for gas turbine power plant - Google Patents

Description

  The present invention relates to a control device for a gas turbine power plant including a compressor, a combustor, a turbine, and a generator.

  A gas turbine power plant includes a compressor that pressurizes combustion air, a combustor that mixes and burns the pressurized combustion air and gas turbine fuel (hereinafter referred to as fuel) to generate high-temperature combustion gas, and combustion. And a turbine that drives a compressor and a generator using gas.

  As a fuel control system in such a gas turbine power plant, a premixed combustion system in which air and fuel are mixed and burned in advance is employed in order to reduce the amount of nitrogen oxide emissions generated in the combustor. In the premixed combustion method, the combustor is composed of a plurality of burners and a fuel system, and the premixed combustion part of the combustor is divided into a plurality of parts by these burners and the fuel system, and the combustion part is increased or decreased according to the operation load. Is. There has been proposed a method (combustion switching) of reducing the used fuel system and the combustion portion in accordance with an increase in the fuel flow rate when the load increases (see, for example, Patent Document 1).

  On the other hand, in order to improve the output / efficiency of a gas turbine power plant, there is an intake spray device that sprays droplets on combustion air at the compressor inlet (see, for example, Patent Document 2). As a control method of the intake spray device, there is disclosed a method of starting the supply of water to the intake spray device after the rated operation of the gas turbine power plant and reducing the amount of water sprayed by the intake spray device when reducing the load. (For example, refer to Patent Document 3).

Japanese Patent Laid-Open No. 11-343869 Japanese Patent Laid-Open No. 9-236024 JP 2006-226293 A

  In combustion switching at the time of load drop, as the fuel flow rate decreases, the fuel system that distributes the fuel flow rate is reduced, so the fuel flow rate that is supplied per used fuel system increases. . For this reason, at the time of combustion switching, it is known that the ratio between the fuel flow rate and the air flow rate (fuel / air ratio) increases, the combustion state becomes unstable, and the NOx concentration increases.

  An increase in the fuel-air ratio accompanying combustion switching when the load is reduced will be described with reference to FIGS. FIG. 9 shows changes in the generator load (upper stage) and fuel flow rate (lower stage) of a conventional gas turbine power plant, FIG. 10 shows a cross section of the burner constituting the combustor of the conventional gas turbine power plant, and FIG. FIG. 12 shows changes in fuel flow rate (upper stage) and fuel-air ratio (lower stage) due to combustion switching at the time of load drop in a conventional gas turbine power plant, with respect to gas turbine load in a gas turbine power plant. FIG.

  As shown in FIG. 9, in the gas turbine power plant, the flow rate of fuel supplied to the combustor decreases between the load drop start time Tsl and the load drop end time Tfl with the load drop of the generator.

  As shown in FIG. 10, the combustor is composed of a plurality of burners (a, b1, b2, b3, b4 in the figure), and each burner is supplied with fuel from a respective fuel supply system. During rated operation of a gas turbine power plant, all fuel supply systems are used to ignite all burners and maintain combustion. When the load drops from the rated operation, the fuel supply system to be used is reduced as the fuel flow rate decreases, and the plurality of burners are extinguished sequentially. Such a series of operations is called combustion switching. Specifically, for example, as shown from the left side to the right side of FIG. 10, the burners are sequentially extinguished in the order of b4, b3, b2, b1, and a from the state where the burners a, b1, b2, b3, and b4 are ignited. And use fuel supply system.

  In such combustion switching at the time of load drop, as shown in FIG. 11, the fuel system (used fuel supply system) that distributes the fuel flow rate is reduced as the total fuel flow rate decreases. For this reason, the fuel flow rate supplied per one fuel system used increases. FIG. 12 shows changes in the fuel flow rate and the fuel-air ratio (ratio of fuel flow rate to air flow rate) at the time of this combustion switching. The behavior of the fuel flow rate is shown on the top and the behavior of the fuel-air ratio is shown on the bottom. As shown in FIG. 12, immediately after the combustion switching (time Tsw in the figure), the fuel flow rate and the fuel-air ratio increase stepwise. Such a phenomenon destabilizes combustion and increases NOx concentration.

  On the other hand, since the above-described intake spray device reduces the amount of water sprayed due to a load drop, the combustion water at the time of switching the combustion is already in a state where there is no sprayed water amount or a very small amount at the time of combustion switching. There was no control means to improve destabilization.

  The present invention has been made based on the above-mentioned matters, and its purpose is to stably maintain the fuel-air ratio at the time of switching the combustion when the load of the generator is reduced while the intake spray device is in operation. It achieves combustion stabilization and low NOx.

  In order to achieve the above object, a first aspect of the present invention is a compressor for pressurizing combustion air, and a spray water supplied to a flow of air sucked into the compressor via a spray flow rate control valve. An intake spray device for spraying droplets; a combustor that mixes and burns the combustion air with fuel to generate high-temperature combustion gas, and switches combustion during operation; and the compressor using the combustion gas and Control of a gas turbine power plant comprising a turbine for driving a generator, a spray flow rate adjusting valve for controlling the flow rate of the spray water, and a compressor inlet inner blade for controlling the flow rate of air sucked into the compressor A fuel flow rate control means for calculating a fuel flow rate command value to the combustor, and a fuel that compensates for an increase in fuel / air ratio in the combustor that occurs at the time of combustion switching when the load of the generator drops. Calculate the air ratio correction command signal and Based on the command signal, and that a control means for controlling an opening degree of the opening degree of the compressor inlet in the wing and / or the spray flow rate control valve.

  The second invention is a compressor that pressurizes combustion air, and an intake spray device that sprays droplets of spray water supplied via a spray flow rate control valve to a flow of air sucked into the compressor. A combustor that mixes and burns the combustion air with fuel to generate a high-temperature combustion gas and switches combustion during operation; and a turbine that drives the compressor and generator using the combustion gas; A fuel flow meter for measuring the flow rate of fuel supplied to the combustor, an air flow meter for measuring the flow rate of air sucked into the compressor, and a flow rate of the spray water supplied to the spray device A control device for a gas turbine power plant, comprising: a spray flow meter; an atmospheric condition detector for measuring atmospheric temperature, humidity, and the like; and a spray flow rate control valve for controlling a flow rate of the spray water, wherein the combustor Fuel to calculate the fuel flow rate command value to Flow rate control means; air flow rate control means for calculating an air flow rate command value to the compressor; measured values of the air flow meter, the fuel flow meter, the spray flow meter, the atmospheric condition detector; and the fuel A spray flow rate correction command value that takes in a flow rate command value and the air flow rate command value and compensates for an increase in the fuel-air ratio in the combustor that occurs at the time of combustion switching when the load of the generator drops. A spray flow rate control means for calculating a control start time based on a value and controlling the opening of the spray flow rate control valve based on a spray flow rate command value obtained by adding the spray flow rate correction command value from the control start time. And

  Furthermore, the third invention is a compressor that pressurizes combustion air, an intake spray device that sprays droplets of spray water on the flow of air sucked into the compressor, and the combustion air mixed with fuel A combustor that generates high-temperature combustion gas by combustion and switches combustion during operation, a turbine that drives the compressor and generator using the combustion gas, and a fuel flow rate that is supplied to the combustor A fuel flow meter for measuring the flow rate, an air flow meter for measuring the flow rate of air sucked into the compressor, a spray flow meter for measuring the flow rate of the spray water supplied to the spray device, and the temperature and humidity of the atmosphere A control device for a gas turbine power plant comprising an atmospheric condition detector for measuring the air flow and a compressor inlet inner blade for controlling the flow rate of air sucked into the compressor, wherein the fuel flow rate to the combustor Fuel flow rate control means for calculating a command value; Spray flow rate control means for calculating a spray flow rate command value to the spray device, each measured value of the air flow meter, the fuel flow meter, the spray flow meter, the atmospheric condition detector, the fuel flow rate command value, and the An air flow rate correction command value that takes in the spray flow rate command value and compensates for an increase in the fuel / air ratio in the combustor that occurs at the time of combustion switching when the load of the generator drops, and a control start time based on the air flow rate correction command value And an air flow rate control means for controlling the opening degree of the compressor inlet inner blade based on the air flow rate command value to which the air flow rate correction command value is added from the control start time.

  A fourth aspect of the invention is a compressor for pressurizing combustion air, and an intake spray device for spraying droplets of spray water supplied via a spray flow rate control valve to a flow of air sucked into the compressor. A combustor that mixes and burns the combustion air with fuel to generate a high-temperature combustion gas and switches combustion during operation; and a turbine that drives the compressor and generator using the combustion gas; A fuel flow meter for measuring the flow rate of fuel supplied to the combustor, an air flow meter for measuring the flow rate of air sucked into the compressor, and a flow rate of the spray water supplied to the spray device A spray flow meter, an atmospheric condition detector for measuring atmospheric temperature and humidity, a spray flow rate control valve for controlling the flow rate of the spray water, and a compressor inlet for controlling the flow rate of air sucked into the compressor Gas turbine power plant with inner wing A control device, a fuel flow rate control means for calculating a fuel flow rate command value to the combustor, an air flow rate control means for calculating an air flow rate command value to the compressor, the air flow meter, and the fuel flow rate In the combustor that takes in each measured value of the meter, the spray flow meter, the atmospheric condition detector, the fuel flow rate command value, and the air flow rate command value, and is generated at the time of combustion switching at the time of load drop of the generator The spray flow rate correction command value that compensates for the increase in the fuel / air ratio of the engine and the control start time based on the spray flow rate correction command value are calculated, and the spray flow rate command value to which the spray flow rate correction command value is added from the control start time is Spray flow rate control means for controlling the opening of the spray flow rate control valve, and the air flow rate control means includes the measured values of the air flow meter, the fuel flow meter, the spray flow meter, and the atmospheric condition detector. The fuel flow rate An air flow rate correction command value and an air flow rate correction command value for taking in the command value and the spray flow rate command value and compensating for an increase in the fuel-air ratio in the combustor that occurs at the time of combustion switching at the time of load drop of the generator Is calculated, and the opening degree of the compressor inlet inner blade is controlled based on the air flow rate command value to which the air flow rate correction command value is added from the control start time.

  According to the present invention, since the intake spray amount and / or the air flow rate are controlled so as to compensate in advance for fluctuations in the fuel-air ratio due to combustion switching, unstable combustion during combustion switching can be suppressed. As a result, combustion stabilization and NOx reduction at the time of load drop of the gas turbine power plant can be achieved.

1 is a system configuration diagram showing a gas turbine power plant provided with a first embodiment of a control device for a gas turbine power plant of the present invention. FIG. It is a flowchart figure which shows the processing flow of 1st Embodiment of the control apparatus of the gas turbine power plant of this invention. It is a characteristic view which shows the characteristic of the fuel flow rate command signal in 1st Embodiment of the control apparatus of the gas turbine power plant of this invention. It is a characteristic figure showing change of spray flow rate command signal (upper stage), spray flow rate (middle stage), and fuel-air ratio (lower stage) in a 1st embodiment of a control device of a gas turbine power plant of the present invention. It is a system block diagram which shows the gas turbine power plant provided with 2nd Embodiment of the control apparatus of the gas turbine power plant of this invention. It is a flowchart figure which shows the processing flow of 2nd Embodiment of the control apparatus of the gas turbine power plant of this invention. It is a characteristic view which shows the change of the air flow rate command signal (upper stage), the air flow rate (middle stage), and the fuel-air ratio (lower stage) in 2nd Embodiment of the control apparatus of the gas turbine power plant of this invention. It is a characteristic view which shows the change of the spray flow volume (upper stage) and the fuel-air ratio (lower stage) in 3rd Embodiment of the control apparatus of the gas turbine power plant of this invention. It is a characteristic view which shows the change of the generator load (upper stage) and the fuel flow rate (lower stage) at the time of load drop of the conventional gas turbine power plant. It is arrangement | positioning sectional drawing of the burner which comprises the combustor of the conventional gas turbine power plant. It is a characteristic view which shows the fuel flow rate for every burner with respect to the gas turbine load in the conventional gas turbine power plant. It is a characteristic view which shows the change of the fuel flow rate (upper stage) and the fuel-air ratio (lower stage) in the combustion switching at the time of load fall of the conventional gas turbine power plant.

<First Embodiment>
Hereinafter, a first embodiment of a control device for a gas turbine power plant according to the present invention will be described with reference to the drawings. FIG. 1 is a system configuration diagram showing a gas turbine power plant equipped with a first embodiment of a control device for a gas turbine power plant of the present invention, and FIG. 2 is a first diagram of a control device for a gas turbine power plant of the present invention. FIG. 3 is a flow chart showing the processing flow of the embodiment, FIG. 3 is a characteristic diagram showing the characteristics of the fuel flow rate command signal in the first embodiment of the control device for the gas turbine power plant of the present invention, and FIG. 4 is the gas of the present invention. It is a characteristic view which shows the change of the fuel flow rate command signal (upper stage), spray flow rate (middle stage), and fuel-air ratio (lower stage) in 1st Embodiment of the control apparatus of a turbine power plant.
In FIG. 1, a gas turbine power plant includes a compressor 1 that pressurizes combustion air, a combustor 2 that mixes and burns combustion air and fuel to generate high-temperature combustion gas, and compresses the combustion gas. The turbine 4 that drives the machine 1 and the generator 70 and the intake spray device 3 that sprays droplets on the flow of air sucked into the compressor 1 are roughly configured.

  The air flow rate sucked into the compressor 1 is adjusted by the compressor inlet inner blade 11, and the fuel flow rate supplied to the combustor 2 is adjusted by the fuel flow rate control valve 12, and sprayed from the intake spray device 3 to the air flow. The spray flow rate is adjusted by the spray flow rate control valve 13. These adjusting devices 11, 12 and 13 are respectively controlled by command signals from the control device 24.

  In the present embodiment, when the load of the gas turbine power plant is lowered, the output of the generator 70 is lowered (referred to as a load drop of the generator 70), and the combustion switching occurs when the flow rate of fuel supplied to the combustor 2 is reduced. In order to stably maintain the fuel-air ratio in the combustor 2, a control device 24 is provided for controlling the spray flow rate adjusting valve 13 so as to increase the spray flow rate before switching to combustion.

  The control device 24 calculates the intake air flow rate and outputs it as air flow rate command signals Uigv 31 and 41, and the fuel flow rate control circuit 22 calculates the fuel flow rate and outputs it as fuel flow rate command signals Ucmb 32 and 42. And a spray flow rate control circuit 23 that calculates the spray flow rate and outputs it as a spray flow rate command signal Uwac 33.

  As shown in FIG. 1, the spray flow rate control circuit 23 measures, as inputs, a detection signal of an air flow meter 51 that measures an air flow rate sucked into the compressor 1 and a fuel flow rate supplied to the combustor 2. Detection signal of the fuel flow meter 52, detection signal of the spray flow meter 53 that measures the spray flow rate sprayed from the intake spray device 3, and detection signal of the atmospheric condition detector 54 that measures the temperature, humidity, pressure, etc. of the atmosphere And at least one of an air flow rate command signal Uigv 41 output from the air flow rate control circuit 21 and a fuel flow rate command signal Ucmb 42 output from the fuel flow rate control circuit 22. However, the signal may be used as long as it can be used for calculation of the spray flow rate. Further, the spray flow rate control circuit 23 generates a spray flow rate command signal Uwac 33 that is input to the spray flow rate adjustment valve 13 as an output. The air flow meter 51 is not limited to the one that directly measures the air flow rate, and may be any device that can identify the air flow rate, such as a device that calculates the air flow rate based on pressure.

  The air flow control circuit 21 and the fuel flow control circuit 22 have, as inputs, a detection signal from the air flow meter 51, a detection signal from the fuel flow meter 52, a detection signal from the spray flow meter 53, and a detection from the atmospheric condition detector 54. The gas turbine power generation receives at least one of the signal, the air flow rate command signal Uigv31, the fuel flow rate command signal Ucmb32, the spray flow rate command signal Uwac33, the rotation speed of the compressor 1, and the load of the gas turbine 4. Based on the change in state quantity at the time of plant load drop, the air flow rate control circuit 21 calculates the air flow rate, the fuel flow rate control circuit 22 calculates the fuel flow rate, and as an output, the air flow rate control circuit 21 outputs air. The flow rate command signals Uigv 31 and 41 and the fuel flow rate control circuit 22 generate fuel flow rate command signals Ucmb 32 and 42.

  The air flow rate command signal Uigv 31 is output from the air flow rate control circuit 21 to the operation end of the compressor inlet inner blade 11, and the air flow rate is controlled by changing the opening degree of the compressor inlet inner blade 11. The fuel flow rate command signal Ucmb 32 is output from the fuel flow rate control circuit 22 to the fuel flow rate adjustment valve 12, and the fuel flow rate is controlled by changing the opening of the fuel flow rate adjustment valve 12. The spray flow rate command signal Uwac 33 is output from the spray flow rate control circuit 23 to the spray flow rate control valve 13, and the spray flow rate is controlled by changing the opening of the spray flow rate control valve 13.

  At the time of load drop of the gas turbine power plant, the spray flow rate control circuit 23 determines the spray flow rate according to the atmospheric state and the state quantity of the gas turbine plant, and outputs the spray flow rate command signal Uwac 33 to the spray flow rate control valve 13. To do. At this time, a spray flow rate (hereinafter referred to as a compensated spray flow rate) that compensates for an increase in the fuel-air ratio accompanying the combustion switching is determined from a certain time before the combustion switching time until the combustion switching is completed. The output of the flow rate command signal Uwac 33 is a feature of the first embodiment of the present invention. Here, the predetermined time is a time until the change in the spray flow rate affects the fuel-air ratio.

Next, the operation mechanism of the spray flow rate control circuit 23 will be described with reference to FIGS.
In FIG. 2, first, in step S101, it is determined whether or not the gas turbine power plant is in a load drop state. As a determination method, for example, the detection signal of the air flow meter 51 or the air flow rate command signal Uigv31 or the detection signal of the fuel flow meter 52 or the fuel flow rate command signal Ucmb32 is monitored, and these signals are monitored as time passes. There is a method for judging that the gas turbine power plant is at the time of load drop if it is lowered. In addition to this determination method, a known method for determining a load drop in a gas turbine power plant may be used. If it is determined that the gas turbine power plant is at a load drop, the determination is YES and the process proceeds to step S102. If it is determined that the load is not at a load drop, the determination is NO and the process proceeds to step S105.

  In step S102, the time difference between the current time and the time Tsw at which the combustion switching is predicted to be performed is calculated, and whether or not this time difference is longer than the time ΔTwac until the fuel / air ratio is affected by the change in the spray flow rate. To be judged. That is, it is determined whether or not the current time is earlier than the preferred time (fuel / air ratio compensation control start time) Tsw−ΔTwac for starting the fuel / air ratio compensation control.

  The time ΔTwac until the fuel / air ratio is affected by the change in the spray flow rate is a value determined in advance based on experiments and calculations. For example, when time ΔTwac is the time from when the droplets are sprayed from the intake spray device 3 to the time when the droplet reaches the inlet of the combustor 2, the amount of droplets sprayed from the intake spray device 3 and the combustor 2 The amount of droplets reaching the inlet can be measured or calculated and determined from the delay in change. The amount of droplets sprayed from the intake spray device 3 is a spray flow rate measured by the spray flow meter 53, and the amount of droplets reaching the inlet of the combustor 2 is determined from the supply air flow rate to the combustor 2. The flow rate is obtained by subtracting the intake air flow rate of the compressor 1. The supply air flow rate to the combustor 2 is a value measured by a flow meter (not shown) provided at the air inlet of the combustor 2, and the intake air flow rate of the compressor 1 is measured by the air flow meter 51. Is the value to be

  The fuel-air ratio compensation control start time Tsw-ΔTwac is determined based on the fuel flow command signal Ucmb32, the detection signal from the fuel flow meter 52, the air flow command signal Uigv31, the detection signal from the air flow meter 51, or the load on the generator. It is the time specified based on

A method for calculating the fuel-air ratio compensation control start time Tsw-ΔTwac will be described with reference to FIG. FIG. 3 shows a time-series change of the fuel flow rate command signal Ucmb32. The fuel flow rate command signal Ucmb decreases with time as the load drops, reaches Ccmb at time Tsw, and combustion switching is started.
(1) The fuel flow rate command signal Ucmb at time Tsw-ΔTwac can be approximated as Ccmb + ΔTwac × dUcmb / dT, where dUcmb / dT is the amount of change per unit time of the fuel flow rate command signal Ucmb32. Here, Ccmb is a value determined according to a predetermined sequence or rule.
(2) Therefore, when the condition Ucmb = Ccmb + ΔTwac × dUcmb / dT is satisfied, it is determined that the current time is time Tsw−ΔTwac.

  Returning to FIG. 2, if it is determined in step S102 that the current time is ΔTwac or more before the predicted combustion switching time Tsw, YES is determined and the process proceeds to step S103, where the current time is ΔTwac relative to the predicted combustion switching time Tsw. If it is determined that it is not before, NO is determined and the process proceeds to step S105.

  In step S103, a spray flow rate that compensates for an increase in the fuel-air ratio that is expected to occur at the combustion switching predicted time Tsw is calculated and output as a spray flow rate command signal Uwac33. As a method for determining the spray flow rate to compensate for the increase in the fuel-air ratio, as shown in the change in the spray flow rate in the middle of FIG. 4, the spray flow rate obtained by increasing the additional amount ΔQwac with respect to the spray flow rate Qwac0 at time Tsw-ΔTwac. The compensation spray flow rate is good.

  The additional amount ΔQwac is predetermined based on experiments and calculations. Specifically, for example, as shown in FIG. 12, at the combustion switching time Tsw, the fuel flow rate per fuel flow supply system used is increased from Qf1 to Qf2, and the fuel-air ratio is increased from N1 to N2. In this case, the additional amount ΔQwac can be calculated as ΔQwac = (Qf2−Qf1) / Qf1 × Qa using the fuel flow rate, or ΔQwac = (N2−N1) / N1 × Qa using the fuel-air ratio. Here, Qa is the supply air flow rate to the combustor 2 at the combustion switching time Tsw or the time Tsw−ΔTwac.

  The basis for this equation is described below. The fuel-air ratio immediately before combustion switching is N1 = Qf1 / Qa, and the fuel-air ratio immediately after conventional combustion switching is N2 = Qf2 / Qa. Here, it is necessary to satisfy Qf1 / Qa = Qf2 / (Qa + ΔQwac) in order to compensate the air flow rate as Qa + ΔQwac and keep the fuel-air ratio immediately after combustion switching at the same value N1 as immediately before combustion switching. . By transforming this equation, ΔQwac = (Qf2-Qf1) / Qf1 × Qa is derived, and when N2 = Qf2 / Qa and N1 = Qf1 / Qa are substituted and expressed in fuel-air ratio, ΔQwac = (N2-N1) / N1 × Qa is derived.

  As a method for determining the compensated spray flow rate, there is also a method in which the spray flow rate obtained by increasing the spray flow rate Qwac0 at a predetermined rate is used as the compensated spray flow rate, and is a value determined according to a predetermined procedure as described above. However, it may be an amount that compensates for an increase in the fuel-air ratio at the time of switching combustion.

  In step S104, it is determined whether combustion switching has been completed. Combustion switching completion determination methods include a method of determining that combustion switching has been completed when a predetermined time has elapsed from the start of combustion switching, or that combustion switching has been completed when the exhaust gas temperature or exhaust flow rate has reached a predetermined value. There are methods to judge. Alternatively, any other method may be used as long as it is a known method for detecting completion of combustion switching. If it is determined that the combustion switching has been completed, it is determined YES and the process proceeds to step S105. If it is determined that the combustion switching has not been completed, NO is determined and the process returns to step S103.

  In step S105, follow-up control is performed so that the spray flow rate becomes the desired spray flow rate. The desired spray flow rate is, for example, the spray flow rate required for the combustion air to reach a predetermined humidity, or the spray flow rate required for the ratio of the predetermined spray flow rate to the air flow rate, for the operation purpose at that time. Necessary spray flow rate. Specifically, the spray flow rate required for the combustion air to reach a predetermined humidity is, for example, the difference between the amount of water vapor for achieving the predetermined humidity and the amount of water vapor in the atmosphere. These values are calculated based on the air flow rate and humidity. The air flow rate is calculated based on the detection signal of the air flow meter 51 or the air flow rate command signal Uigv31, and the humidity is calculated based on the detection signal of the atmospheric condition detector 54 that measures the atmospheric temperature, humidity, pressure, and the like. Is done.

  Specifically, the spray flow rate required to become a ratio between the predetermined spray flow rate and the air flow rate is, for example, a value obtained by multiplying the ratio between the predetermined spray flow rate and the air flow rate by the air flow rate. The air flow rate is calculated based on the detection signal of the air flow meter 51 or the air flow rate command signal Uigv31.

  Then, based on the spray flow rate measured by the spray flow meter 53, P control, PI control, or PID control is executed so that the spray flow rate follows the desired spray flow rate. In the follow-up control method, when the spray flow rate is higher than the desired spray flow rate, the spray flow rate command signal Uwac 33 that sprays a smaller amount is output, and vice versa, the spray flow rate command signal that sprays a larger amount. Any known method may be used as long as it outputs Uwac33.

  Changes in the spray flow rate command signal Uwac 33, the spray flow rate from the intake spray device 3, and the fuel-air ratio of the combustor 2 when the spray flow rate control circuit 23 is operated as shown in the flowchart of FIG. This will be described with reference to FIG.

  As shown in the upper part of FIG. 4, the spray flow rate adjusting valve 13 is controlled to follow the desired spray flow rate from the start of load lowering to the time Tsw−ΔTwac, and thereafter until the combustion switching completion time Tcom. The fuel-air ratio compensation control is performed so as to increase, and after the combustion switching completion time Tcom, the follow-up control is performed again to the desired spray flow rate.

  At this time, as shown in the middle part of FIG. 4, the spray flow rate is increased from Qwac0 to Qwac0 + ΔQwac after reaching time Tsw-ΔTwac, thereby increasing the combustion air flow rate and the fuel-air ratio in the lower part of FIG. It drops like a solid line. The reduction in the fuel-air ratio here is caused by an increase in the air flow rate compared to the conventional air flow rate. Thereafter, at the time Tsw, the fuel-air ratio increases due to combustion switching. At this time, by performing control to lower the fuel / air ratio in advance before the time of occurrence of combustion switching, the mode of increase in the fuel / air ratio that occurs at the time of conventional combustion switching (indicated by the broken line in the lower part of FIG. 4) is shown in FIG. It can change like the aspect displayed with the continuous line of 4 lower stage, and can suppress the raise amount of fuel-air ratio.

  According to the first embodiment of the control device for a gas turbine power plant of the present invention described above, the intake spray amount is controlled so as to compensate for the fluctuation of the fuel-air ratio in advance. Combustion can be suppressed. As a result, combustion stabilization and NOx reduction at the time of load drop of the gas turbine power plant can be achieved.

<Second Embodiment>
Hereinafter, a second embodiment of a control device for a gas turbine power plant according to the present invention will be described with reference to the drawings. FIG. 5 is a system configuration diagram showing a gas turbine power plant equipped with the second embodiment of the control device for the gas turbine power plant of the present invention, and FIG. 6 is a second diagram of the control device for the gas turbine power plant of the present invention. FIG. 7 is a flowchart showing a processing flow of the embodiment, and FIG. 7 is an air flow rate command signal (upper stage), an air flow rate (middle stage), and a fuel-air ratio in the second embodiment of the control device of the gas turbine power plant of the present invention. It is a characteristic view which shows the change of (lower stage). 5 to 7, the same reference numerals as those shown in FIGS. 1 to 4 are the same parts, and detailed description thereof is omitted.

  In the first embodiment of the gas turbine power plant according to the present invention, in order to stabilize combustion and reduce NOx when the load of the gas turbine power plant drops, the spray flow rate is increased before the combustion switching. A control device 24 for controlling the flow control valve 13 is provided. On the other hand, the second embodiment is different in that it includes a control device 24 that controls the opening of the compressor inlet inner blade 11 so as to increase the air flow rate before the combustion switching. Other facilities constituting the gas turbine power plant are the same as those in the first embodiment.

  More specifically, the operations of the spray flow rate control circuit 23 and the air flow rate control circuit 21 in the control device 24 are different from those of the first embodiment. In the first embodiment, the fuel / air ratio is compensated and controlled using the spray flow rate. In the second embodiment, the fuel / air ratio is compensated and controlled using the air flow rate. For this reason, various signals used for fuel-air ratio compensation are input to the spray flow rate control circuit 23 in FIG. 1, but are input to the air flow rate control circuit 21 in FIG.

  In the present embodiment, the spray flow rate control circuit 23 outputs a spray flow rate command signal Uwac 33 such that the spray flow rate follows the desired spray flow rate.

  As shown in FIG. 5, the air flow rate control circuit 21 measures the detection signal of the air flow meter 51 that measures the air flow rate sucked into the compressor 1 and the fuel flow rate supplied to the combustor 2 as inputs. Detection signal of the fuel flow meter 52, detection signal of the spray flow meter 53 that measures the spray flow rate sprayed from the intake spray device 3, and detection signal of the atmospheric condition detector 54 that measures the temperature, humidity, pressure, etc. of the atmosphere And at least one of a fuel flow rate command signal Ucmb 62 output from the fuel flow rate control circuit 22 and a spray flow rate command signal Uwac 63 output from the spray flow rate control circuit 23. However, other signals may be used as long as they can be used for the calculation of the air flow rate. Further, the air flow rate control circuit 21 generates an air flow rate command signal Uigv31 that is input to the compressor inlet inner blade 11 as an output.

  In the load drop of the gas turbine power plant, the air flow rate control circuit 21 determines the opening of the compressor inlet inner blade 11 so that the air flow rate satisfying a predetermined condition is sucked into the compressor 1, and the air flow rate command Output as signal Uigv31. At this time, the air flow rate that compensates for the increase in the fuel-air ratio accompanying the combustion switching is determined and output as the air flow rate command signal Uigv31 until the combustion switching is completed from a certain time before the combustion switching time. These are the features of the second embodiment of the present invention. Here, the predetermined time is a time until the change in the air flow rate affects the fuel-air ratio.

Next, the operation mechanism of the air flow rate control circuit 21 will be described with reference to FIGS.
The flow of the air flow rate control circuit 21 is different from the flow of the spray flow rate control circuit 23 in the first embodiment in that the operation target is not the spray flow rate but the suction air flow rate. It is the same.
In FIG. 6, first, in step S201, it is determined whether or not the gas turbine power plant is in a load drop state. The determination is performed by the same determination method as in the first embodiment. If it is determined that the gas turbine power plant is at a load drop, the determination is YES and the process proceeds to step S202. If it is determined that the load is not at a load drop, the determination is NO and the process proceeds to step S205.

  In step S202, the time difference between the current time and the time Tsw at which the combustion switching is predicted to be performed is calculated, and the time difference until the change in the opening of the compressor inlet inner blade 11 affects the fuel-air ratio. It is determined whether or not the time is greater than ΔTigv. In other words, it is determined whether or not the current time is earlier than the preferred time (fuel / air ratio compensation control start time) Tsw−ΔTigv for starting the fuel / air ratio compensation control. If it is determined that the current time is ΔTigv or more before the predicted combustion switching time Tsw, the determination is YES and the process proceeds to step S203. If it is determined that the current time is not before ΔTigv before the predicted combustion switching time Tsw. , NO is determined, the process proceeds to step S205.

  In step S203, an air flow rate that compensates for an increase in the fuel / air ratio that is expected to occur at the combustion switching prediction time Tsw is calculated and output as an air flow rate command signal Uigv31. As a method for determining the air flow rate that compensates for the increase in the fuel-air ratio, as shown in the air flow characteristic diagram in the middle of FIG. 7, the air flow rate Qigv0 at time Tsw-ΔTigv is determined in advance by experiments and calculations. The air flow rate obtained by increasing the compensation air flow rate ΔQigv may be calculated, or the air flow rate obtained by increasing the air flow rate Qigv0 at a predetermined rate may be calculated.

  In step S204, it is determined whether combustion switching has been completed. The determination is performed by the same determination method as in the first embodiment. If it is determined that the combustion switching has been completed, it is determined YES and the process proceeds to step S205. If it is determined that the combustion switching has not been completed, NO is determined and the process returns to step S203.

  In step S205, the air flow rate is controlled to follow the desired air flow rate. The desired air flow rate is, for example, an air flow rate required to achieve a predetermined fuel-air ratio, or an air flow rate required to satisfy a relationship with a predetermined gas turbine load. Any known method for determining the hourly air flow rate may be used.

  When the air flow rate control circuit 21 is operated as shown in the flowchart of FIG. 6 described above, the air flow rate command signal Uigv 31, the air flow rate sucked into the compressor 1, and the fuel-air ratio of the combustor 2 The transition will be described with reference to FIG.

  As shown in the upper part of FIG. 7, the compressor inlet inner blade 11 is controlled to follow the desired air flow rate until the time Tsw−ΔTigv after the gas turbine power plant starts load drop, and then the combustion switching completion time is reached. The fuel-air ratio compensation control is performed until Tcom, and after the combustion switching completion time Tcom, the desired air flow rate is again controlled in step S205.

  At that time, as shown in the middle part of FIG. 7, the air flow rate is increased from Qigv0 to Qigv0 + ΔQigv after reaching time Tsw-ΔTigv, thereby increasing the combustion air flow rate and the fuel-air ratio in the lower part of FIG. It drops like a solid line. The reduction in the fuel-air ratio here is due to an increase in the air flow rate compared to the conventional air flow rate. Thereafter, at the time Tsw, the fuel-air ratio increases due to combustion switching. At this time, by performing control to lower the fuel / air ratio in advance before the time of occurrence of combustion switching, the mode of increase in the fuel / air ratio that occurs at the time of conventional combustion switching (indicated by the broken line in the lower part of FIG. 7) is shown in FIG. 7 can be changed as shown in the lower solid line, and the fuel / air ratio increase can be suppressed.

  Thus, when the air flow rate control circuit 21 is operated as shown in the flowchart of FIG. 6 described above, the spray flow rate control circuit 23 is operated as shown in the flowchart of FIG. 2 according to the first embodiment. The same effect as the case can be obtained. This embodiment is particularly effective when the spray flow rate cannot be used beyond a certain operating range.

  According to the second embodiment of the control device for a gas turbine power plant of the present invention described above, the air flow rate is controlled so as to compensate for the fluctuation of the fuel-air ratio in advance, so that unstable combustion at the time of combustion switching is prevented. Can be suppressed. As a result, combustion stabilization and NOx reduction at the time of gas turbine power plant load drop can be achieved.

  Further, in the applied gas turbine power plant, the control range of the spray flow rate is limited, and it is possible to cope with the case where the spray flow rate cannot be used beyond a certain operation range, and the above-described effects can be achieved.

<Third Embodiment>
Hereinafter, a third embodiment of a control device for a gas turbine power plant according to the present invention will be described with reference to the drawings. FIG. 8 is a characteristic diagram showing changes in the air flow rate command signal (upper stage) and the fuel-air ratio (lower stage) in the third embodiment of the control device for the gas turbine power plant of the present invention. In FIG. 8, since the same reference numerals as those shown in FIGS. 1 to 7 are the same parts, detailed description thereof will be omitted.
The third embodiment of the gas turbine power plant according to the present invention is a combination of the first embodiment and the second embodiment, and includes stabilization of combustion during load drop of the gas turbine power plant. In order to reduce NOx, the spray flow rate control valve 13 is controlled so as to increase the spray flow rate before switching the combustion, and the opening of the compressor inlet inner blade 11 is increased so as to increase the air flow rate before switching the combustion. A control device 24 for controlling is provided. Other facilities constituting the gas turbine power plant are the same as those in the first embodiment.

  The transition of the flow rate of combustion air supplied to the combustor 2 and the fuel-air ratio of the combustor 2 in the present embodiment will be described with reference to FIG.

  From the load drop start to time Tsw-ΔTwac, the spray flow rate control valve 13 is controlled to follow the desired spray flow rate, and the compressor inlet inner blade 11 is controlled to follow the desired spray flow rate. Thereafter, until the time Tsw-ΔTigv, the spray flow rate adjustment valve 13 is subjected to fuel-air ratio compensation control, while the compressor inlet inner blade 11 continues to follow the desired spray flow rate. After that, until the time Tcom, the spray flow rate adjustment valve 13 and the compressor inlet inner blade 11 are respectively subjected to fuel-air ratio compensation control. After time Tcom, the spray flow rate adjusting valve 13 is again subjected to desired spray flow rate tracking control, and the compressor inlet inner blade 11 is subjected to desired spray flow rate tracking control.

  At this time, the combustion air flow rate is the sum of the desired spray flow rate and the desired air flow rate from the load drop start to time Tsw-ΔTwac as indicated by the solid line in the upper part of FIG. Then, it increases from time Tsw-ΔTwac to time Tsw-ΔTigv, and further increases immediately after time Tsw-ΔTigv. This increases the combustion air flow rate only by the spray flow rate control valve 13 from time Tsw-ΔTwac to time Tsw-ΔTigv, but from time Tsw-ΔTigv to time Tcom, This is because the combustion air flow rate is increased by both the valve 13 and the compressor inlet inner blade 11. After the time Tcom, the combustion air flow rate follows the sum of the desired spray flow rate and the desired air flow rate.

  The change in the fuel-air ratio is equivalent to the conventional case (indicated by a dotted line) from the load drop start to time Tsw-ΔTwac, as indicated by the solid line in the lower part of FIG. Then, it decreases from time Tsw-ΔTwac to time Tsw-ΔTigv, and further decreases immediately after time Tsw-ΔTigv. This is due to the change in the combustion air flow rate described above. Thereafter, the fuel-air ratio rises due to combustion switching at time Tsw.

  As described above, the gas turbine system including the control device 24 having the spray flow rate adjustment function and the air flow rate adjustment function at the same time is the gas turbine system including the control device 24 having only the spray flow rate adjustment function (the lower broken line in FIG. 8). Compared with a gas turbine system equipped with a control device 24 having only an air flow rate adjustment function, the amount of increase in the combustion air flow rate can be significantly changed to ΔQigv + ΔQwac. The range of becomes wide. In addition, the responsiveness of changes in the combustion air flow rate can be improved, the fuel-air ratio can be reduced in a short time during the fuel-air ratio compensation control, and the time during which the fuel-air ratio is low can be shortened.

  FIG. 8 shows an example in which ΔTwac is longer than ΔTigv. Even when the magnitude relationship between the two is reversed, the gas turbine system including the control device 24 having both the spray flow rate adjustment function and the air flow rate adjustment function is Compared to a gas turbine system having a control device 24 having only a spray flow rate adjustment function and a gas turbine system having a control device 24 having only an air flow rate adjustment function, the range of the fuel-air ratio that can be compensated is widened. It is possible to improve the responsiveness of changes in the combustion air flow rate, to reduce the fuel / air ratio in a short time during fuel / air ratio compensation control, and to shorten the time when the fuel / air ratio is low There is no change.

  According to the third embodiment of the control device for a gas turbine power plant of the present invention described above, it is possible to obtain the same effects as those of the first and second embodiments described above, and to compensate the fuel air. The range of the ratio can be widened.

DESCRIPTION OF SYMBOLS 1 Compressor 2 Combustor 3 Intake spray device 4 Turbine 11 Compressor inlet inner blade 12 Fuel flow rate control valve 13 Spray flow rate control valve 21 Air flow rate control circuit 22 Fuel flow rate control circuit 23 Spray flow rate control circuit 24 Control device 31 Air flow rate command Signal 32 Fuel flow command signal 33 Spray flow command signal 41 Air flow command signal 42 Fuel flow command signal 51 Air flow meter 52 Fuel flow meter 53 Spray flow meter 54 Atmospheric condition detector 62 Fuel flow command signal 63 Spray flow command signal 70 Power generation Machine

Claims (4)

A compressor (1) for pressurizing combustion air, and an intake spray for spraying droplets of spray water supplied via a spray flow rate control valve (13) to the flow of air sucked into the compressor (1) An apparatus (3), a combustor (2) that mixes and burns the combustion air with fuel to generate a high-temperature combustion gas and switches combustion during operation, and the compressor ( 1) A turbine (4) for driving the generator (70), a spray flow rate adjusting valve (13) for controlling the flow rate of the spray water, and a flow rate of air sucked into the compressor (1). A control device for a gas turbine power plant comprising a compressor inlet inner blade (11),
Fuel flow rate control means (22) for calculating a fuel flow rate command value (32) to the combustor (2);
A fuel / air ratio correction command signal that compensates for an increase in the fuel / air ratio in the combustor (2) that is generated at the time of combustion switching at the time of load drop of the generator (70) is calculated, and the fuel / air ratio correction command signal is calculated. And a control means (24) for controlling the opening degree of the compressor inlet inner blade (11) and / or the opening degree of the spray flow rate adjusting valve (13). Control device. A compressor (1) for pressurizing combustion air, and an intake spray for spraying droplets of spray water supplied via a spray flow rate control valve (13) to the flow of air sucked into the compressor (1) An apparatus (3), a combustor (2) that mixes and burns the combustion air with fuel to generate a high-temperature combustion gas and switches combustion during operation, and the compressor ( 1) and a turbine (4) for driving a generator (70), a fuel flow meter (52) for measuring the flow rate of fuel supplied to the combustor (2), and the compressor (1). An air flow meter (51) for measuring the air flow rate, a spray flow meter (53) for measuring the flow rate of the spray water supplied to the spray device (3), and atmospheric conditions for measuring the temperature and humidity of the atmosphere A detector (54) and a spray flow rate control valve (13) for controlling the flow rate of the spray water; A control device for a gas turbine power plant was e,
Fuel flow rate control means (22) for calculating a fuel flow rate command value (32) to the combustor (2);
An air flow rate control means (21) for calculating an air flow rate command value (31) to the compressor (1);
The measured values of the air flow meter (51), the fuel flow meter (52), the spray flow meter (53), and the atmospheric condition detector (54), the fuel flow command value (32), and the air flow command Value (31), and a spray flow rate correction command value for compensating for an increase in the fuel-air ratio in the combustor (2) generated at the time of combustion switching at the time of load drop of the generator (70) and the spray flow rate correction A spray flow rate for calculating the control start time based on the command value and controlling the opening of the spray flow rate control valve (13) based on the spray flow rate command value (33) to which the spray flow rate correction command value is added from the control start time. A control device for a gas turbine power plant, comprising a control means (23). A compressor (1) for pressurizing combustion air; an intake spray device (3) for spraying droplets of spray water on a flow of air sucked into the compressor (1); and the combustion air as fuel A combustor (2) that generates a high-temperature combustion gas by mixing and burning and switches combustion during operation, and a turbine that drives the compressor (1) and the generator (70) using the combustion gas ( 4), a fuel flow meter (52) for measuring the flow rate of fuel supplied to the combustor (2), an air flow meter (51) for measuring the flow rate of air sucked into the compressor (1), A spray flow meter (53) for measuring the flow rate of the spray water supplied to the spray device (3), an atmospheric condition detector (54) for measuring atmospheric temperature, humidity and the like, and the compressor (1) Including a compressor inlet inner blade (11) for controlling a flow rate of air sucked into the compressor A control apparatus for an electric plant,
Fuel flow rate control means (22) for calculating a fuel flow rate command value (32) to the combustor (2);
Spray flow rate control means (23) for calculating a spray flow rate command value (33) to the spray device (3);
The measured values of the air flow meter (51), the fuel flow meter (52), the spray flow meter (53), and the atmospheric condition detector (54), the fuel flow command value (32), and the spray flow command. Value (33), and an air flow rate correction command value for compensating for an increase in the fuel / air ratio in the combustor (2) generated at the time of combustion switching at the time of load drop of the generator (70) and the air flow rate correction Air for controlling the opening of the compressor inlet inner blade (11) based on an air flow rate command value (31) obtained by calculating a control start time based on the command value and adding the air flow rate correction command value from the control start time. A control device for a gas turbine power plant, comprising: a flow rate control means (21). A compressor (1) for pressurizing combustion air, and an intake spray for spraying droplets of spray water supplied via a spray flow rate control valve (13) to the flow of air sucked into the compressor (1) An apparatus (3), a combustor (2) that mixes and burns the combustion air with fuel to generate a high-temperature combustion gas and switches combustion during operation, and the compressor ( 1) and a turbine (4) for driving a generator (70), a fuel flow meter (52) for measuring the flow rate of fuel supplied to the combustor (2), and the compressor (1). An air flow meter (51) for measuring the air flow rate, a spray flow meter (53) for measuring the flow rate of the spray water supplied to the spray device (3), and atmospheric conditions for measuring the temperature and humidity of the atmosphere A detector (54), a spray flow rate control valve (13) for controlling the flow rate of the spray water, A control device for a gas turbine power plant including a compressor inlet in the wing for controlling the flow rate of the air sucked into the serial compressor (1) (11),
Fuel flow rate control means (22) for calculating a fuel flow rate command value (32) to the combustor (2);
An air flow rate control means (21) for calculating an air flow rate command value (31) to the compressor (1);
The measured values of the air flow meter (51), the fuel flow meter (52), the spray flow meter (53), and the atmospheric condition detector (54), the fuel flow command value (32), and the air flow command Value (31), and a spray flow rate correction command value for compensating for an increase in the fuel-air ratio in the combustor (2) generated at the time of combustion switching at the time of load drop of the generator (70) and the spray flow rate correction A spray flow rate for calculating the control start time based on the command value and controlling the opening of the spray flow rate control valve (13) based on the spray flow rate command value (33) to which the spray flow rate correction command value is added from the control start time. Control means (23),
The air flow rate control means (21) includes the measured values of the air flow meter (51), the fuel flow meter (52), the spray flow meter (53), and the atmospheric condition detector (54), and the fuel flow rate. The command value (32) and the spray flow rate command value (33) are taken in to compensate for the increase in the fuel / air ratio in the combustor (2) that occurs at the time of combustion switching when the load of the generator (70) drops. An air flow correction command value and a control start time based on the air flow rate correction command value are calculated, and the compressor inlet inner blade is based on an air flow rate command value (31) to which the air flow rate correction command value is added from the control start time. The opening degree of (11) is controlled. The control apparatus of the gas turbine power plant characterized by the above-mentioned.

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