JP2019120139A - Control device, gas turbine, combined cycle power generation plant, control method and program - Google Patents

Abstract

To provide a control device capable of setting a gas turbine output to a prescribed target value upon load reduction.SOLUTION: The control device calculates a target output of a gas turbine in load reduction of a combined cycle power generation plant generating power using the gas turbine and a steam turbine, calculates exhaust gas energy of the gas turbine on the basis of the calculated target output of the gas turbine, estimates an output of the steam turbine in load reduction on the basis of the calculated exhaust gas energy, and calculates a target output of the combined cycle power generation plant in the load reduction by adding the estimated output value of the steam turbine to the target output of the gas turbine.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a control device, a gas turbine, a combined cycle power plant, a control method and a program.

  Various control methods for combined cycle power plants using a gas turbine and a steam turbine have been proposed. For example, Patent Document 1 describes a method of controlling a gas turbine in a combined cycle power plant, a signal representing the contribution to the total output by the gas turbine output calculated based on the difference between the total output of the generator and the steam turbine output. A control method is disclosed for determining the fuel flow to the gas turbine to be proportionally responsive to the signal based on the error of the actual rotational speed of the gas turbine and its reference speed.

  In a combined cycle power plant, control may be performed to sharply reduce the load. An example of such load drop control is shown in FIG. First, the control device of the power generation plant calculates a target GT output, which is a target value of gas turbine output, based on a target T1T, which is a target value of turbine inlet temperature. On the other hand, regarding the output of the steam turbine, the control device calculates ST output which is the steam turbine output at the start of the load drop control. Then, the control device sets the sum of the target GT output and the ST output as a target CC output which is a target output of the combined cycle power plant. The control device controls the actual output of the power generation plant to be this target CC output. In FIG. 15, CC indicates a combined cycle power plant, GT indicates a gas turbine, and ST indicates a steam turbine. The same applies to the other drawings referred to below.

JP-H08-509048 gazette

  By the way, the heat capacity of the exhaust heat recovery boiler of the steam turbine is large, and when the load is dropped sharply, the output response of the steam turbine tends to be delayed. Then, even after the output of the power plant reaches the target CC output, the output of the steam turbine continues to decrease as the exhaust gas energy from the gas turbine decreases. This situation is shown in FIG. In FIG. 16, graph L1 is CC output, graph L2 is target CC output, graph L3 is GT output, and graphs CU and CL are upper and lower limit values set for GT output during load drop control, and graph L4. Indicates ST output. As shown, the CC output reaches the target CC output at time t1. The output of the gas turbine reaches an allowable range defined by the graphs CU and CL at time t0. If the output of the steam turbine does not change, while the target CC output can be maintained, the output of the gas turbine can also be controlled within the allowable range, but as described above, the output response of the steam turbine is delayed, so graph L4 shows As the steam turbine's output gradually decreases. Then, the controller raises the gas turbine output to maintain the target CC output in order to compensate for the reduction in the steam turbine output. Then, after time t2, the GT output indicated by the graph L3 exceeds the upper limit value of the allowable range indicated by the graph CU.

  For such deviation from the allowable range, the operator may make adjustments so that the output of the gas turbine is within the allowable range. However, if the adjustment is not good, equipment may be damaged and the power plant may be shut down. As described above, in the conventional load drop control, the gas turbine output may not be controlled within a predetermined allowable range due to the response delay of the steam turbine output.

  Then, this invention aims at providing the control apparatus which can solve the above-mentioned subject, a gas turbine, a combined cycle power plant, a control method, and a program.

  According to a first aspect of the present invention, a control device calculates a target output of the gas turbine at the time of load drop of a combined cycle power plant that generates power using a gas turbine and a steam turbine. And an exhaust gas energy calculating unit that calculates exhaust gas energy of the gas turbine based on the target output calculated by the gas turbine target output calculating unit; and the exhaust gas energy calculated by the exhaust gas energy calculating unit; A steam turbine output estimating unit for estimating the output of the steam turbine at the time of load drop, a target output of the gas turbine and an estimated value of the steam turbine, and the target output of the combined cycle power plant at the load drop Power plant target output calculation unit for calculating

  Further, according to a second aspect of the present invention, the control device controls the output of the gas turbine by feedback control based on the deviation between the target output and the actual output of the combined cycle power plant at the time of the load drop. And a gas turbine output lower limit setting unit configured to set a lower limit value of an output of the gas turbine at the time of the load decrease based on a target output of the gas turbine.

  Further, according to the third aspect of the present invention, the gas turbine output control unit performs output control of the gas turbine based on the output control command value calculated by the feedback control, and the gas turbine output lower limit value is set. The unit calculates the lower limit value of the output control command value corresponding to the lower limit value of the output of the gas turbine.

  Further, according to the fourth aspect of the present invention, the gas turbine output lower limit setting unit corrects the output control command value according to at least one of the atmospheric temperature, the atmospheric humidity, and the atmospheric pressure.

  Further, according to the fifth aspect of the present invention, the exhaust gas energy calculating unit is configured to calculate the exhaust gas flow rate based on the target output of the gas turbine, an atmospheric flow rate drawn by a compressor of the gas turbine, and an atmospheric temperature. The exhaust gas enthalpy is calculated based on the target output of the gas turbine, the atmospheric flow rate, and the atmospheric temperature, and the exhaust gas energy is calculated based on the exhaust gas flow rate and the exhaust gas enthalpy.

  Further, according to the sixth aspect of the present invention, the exhaust gas energy calculating unit corrects the exhaust gas flow rate in accordance with at least one of the atmospheric temperature, the atmospheric humidity, and the atmospheric pressure.

  Further, according to the seventh aspect of the present invention, the exhaust gas energy calculating unit corrects the exhaust gas enthalpy in accordance with at least one of the atmospheric temperature, the atmospheric humidity, and the atmospheric pressure.

  Further, according to the eighth aspect of the present invention, the decrease rate of the output of the combined cycle power plant at the time of the load drop is 5% per minute or more.

  Moreover, according to the 9th aspect of this invention, a gas turbine is provided with a compressor, a combustor, a turbine, and the control apparatus in any one of the above-mentioned.

  Further, according to a tenth aspect of the present invention, a combined cycle power plant includes the gas turbine described above, a steam turbine, and a generator.

  Further, according to an eleventh aspect of the present invention, the control method comprises the steps of: calculating a target output of the gas turbine at the time of load drop of a combined cycle power plant performing power generation using a gas turbine and a steam turbine; Calculating exhaust gas energy of the gas turbine based on the target output of the gas turbine; estimating the output of the steam turbine at the time of load drop based on the calculated exhaust gas energy; And calculating the target output of the combined cycle power plant at the time of the load drop by adding the estimated output of the steam turbine to the target output of the gas turbine.

  Further, according to a twelfth aspect of the present invention, a program includes a computer for controlling a combined cycle power plant that generates power using a gas turbine and a steam turbine, the gas turbine at the time of load drop of the combined cycle power plant. A means for calculating a target output of the gas turbine, a means for calculating exhaust gas energy of the gas turbine based on the calculated target output of the gas turbine, the steam at the time of load drop based on the calculated exhaust gas energy It functions as means for estimating the output of a turbine, and means for calculating the target output of the combined cycle power plant at the time of load drop by adding the estimated output of the steam turbine to the target output of the gas turbine.

  According to the present invention, it is possible to settle the output of the gas turbine within a predetermined allowable range while lowering the output of the combined power plant at a desired speed to the target value at the time of load drop control of the combined power plant.

It is a systematic diagram of the combined cycle power plant in a first embodiment concerning the present invention. It is a block diagram of a control device in a first embodiment concerning the present invention. It is a figure explaining the control method of the combined cycle power plant in a first embodiment concerning the present invention. It is a figure showing an example of a result of control in a first embodiment concerning the present invention. It is a figure which shows an example of the calculation method of the output control command value of a gas turbine. It is a figure explaining the calculation method of the control command value about the load of a gas turbine. It is a figure which shows an example of the result of having calculated control command value by load drop control in 1st embodiment which concerns on this invention. It is a figure explaining the calculation method of the control command value about the load of the gas turbine in a first embodiment concerning the present invention. It is a 1st figure which shows an example of the result of having calculated output control command value based on the calculation method of a first embodiment concerning the present invention. It is a 2nd figure which shows an example of the result of having calculated output control command value based on the calculation method of a first embodiment concerning the present invention. It is a flow chart which shows an example of load fall control in a first embodiment concerning the present invention. It is a block diagram of a control device in a second embodiment concerning the present invention. It is a figure explaining the control method of the combined cycle power plant in a second embodiment concerning the present invention. It is a figure which shows an example of the calculation method of the output control command value of the gas turbine in 2nd embodiment which concerns on this invention. It is a figure explaining the conventional load drop control. It is a figure which shows an example of the result of the conventional load drop control. It is a figure which shows an example of the hardware constitutions of the control apparatus in 1st embodiment-2nd embodiment of this invention.

First Embodiment
Hereinafter, a control method at the time of load drop of the combined cycle power plant according to the first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a system diagram of a combined cycle power plant according to a first embodiment of the present invention.
As shown in FIG. 1, the gas turbine combined cycle power plant 1 of the present embodiment (hereinafter referred to as the power plant 1) generates steam by the heat of the gas turbine 10 and the exhaust gas exhausted from the gas turbine 10. An exhaust heat recovery boiler 20, a steam turbine 30 (a high pressure steam turbine 31, an intermediate pressure steam turbine 32, and a low pressure steam turbine 33) driven by steam from the exhaust heat recovery boiler 20, and each of the turbines 10, 31, 32, 33 And a condenser 35 for returning the steam exhausted from the low pressure steam turbine 33 to water, and a control device 100 for controlling each of these devices.

  The gas turbine 10 includes a compressor 11 that compresses external air to generate compressed air, a combustor 12 that mixes compressed air with fuel gas and burns it to generate high-temperature combustion gas, and a turbine driven by the combustion gas 13 and a fuel flow control valve 14 for adjusting the flow rate of fuel supplied to the combustor 12. The combustor 12 is connected to a plurality of fuel lines for supplying fuel from the fuel supply source to the combustor 12. A fuel flow control valve 14 is provided in each fuel line. An exhaust port of the turbine 13 is connected to an exhaust heat recovery boiler 20.

  The exhaust heat recovery boiler 20 includes a high pressure steam generation unit 21 that generates high pressure steam to be supplied to the high pressure steam turbine 31, a medium pressure steam generation unit 22 that generates medium pressure steam to be supplied to the medium pressure steam turbine 32, and low pressure steam The low pressure steam generation unit 24 generates low pressure steam to be supplied to the turbine 33, and the reheating unit 23 heats the steam exhausted from the high pressure steam turbine 31.

  The high pressure steam generating unit 21 of the exhaust heat recovery boiler 20 and the steam inlet of the high pressure steam turbine 31 are connected by a high pressure main steam line 41 for leading high pressure steam to the high pressure steam turbine 31. The steam outlet of the high pressure steam turbine 31 and medium pressure The steam inlet of the steam turbine 32 is connected by an intermediate pressure steam line 44 leading the steam exhausted from the high pressure steam turbine 31 to the steam inlet of the intermediate pressure steam turbine 32 through the reheating part 23 of the exhaust heat recovery boiler 20, The low pressure steam generation unit 24 of the exhaust heat recovery boiler 20 and the steam inlet of the low pressure steam turbine 33 are connected by a low pressure main steam line 51 which leads low pressure steam to the low pressure steam turbine 33.

The steam outlet of the medium pressure steam turbine 32 and the steam inlet of the low pressure steam turbine 33 are connected by a medium pressure turbine exhaust line 54. A condenser 35 is connected to a steam outlet of the low pressure steam turbine 33. A water supply line 55 for leading the condensed water to the exhaust heat recovery boiler 20 is connected to the condenser 35.
The medium pressure steam generation unit 22 of the exhaust heat recovery boiler 20 and the portion of the medium pressure steam line 44 upstream of the reheating unit 23 are connected by a medium pressure main steam line 61.

  The high pressure main steam line 41 is provided with a high pressure steam stop valve 42 and a high pressure main steam control valve 43 for adjusting the amount of steam flowing into the high pressure steam turbine 31. The medium pressure steam line 44 is provided with a medium pressure steam stop valve 45 and a medium pressure steam control valve 46 for adjusting the amount of steam flowing into the medium pressure steam turbine 32. The low pressure main steam line 51 is provided with a low pressure steam stop valve 52 and a low pressure main steam control valve 53 for adjusting the amount of steam flowing into the low pressure steam turbine 33.

  The control device 100 performs power control of the gas turbine 10 and power control of the steam turbine 30 to generate power by the generator 34. Further, for example, when the output of the generator 34 is to be sharply dropped due to an abnormality or the like, the control device 100 performs load drop control. When the output of the generator 34 is to be rapidly dropped, for example, it is a situation where the output of the generator 34 is to be dropped at a rate of 100% per minute. The load drop control in the present embodiment is not limited to the case of dropping at a rate of 100% / min, and is suitable for control when the output of the generator 34 is dropped at a rate of drop faster than 5% / min. As an example of applying the load drop control of the present embodiment, so-called runback operation can be mentioned.

FIG. 2 is a block diagram of a control device in the first embodiment according to the present invention.
As illustrated, the control device 100 includes an input reception unit 101, a sensor information acquisition unit 102, a gas turbine target output calculation unit 103, an exhaust gas energy calculation unit 104, a steam turbine output estimation unit 105, a power plant target output calculation unit 106, and a gas. A turbine output control unit 107, a gas turbine output lower limit command value calculation unit 108, a steam turbine output control unit 109, and a storage unit 110 are provided. The control device 100 is configured by a computer.

The input receiving unit 101 receives an input of an instruction operation from a user or an input of various signals from another device. The input receiving unit 101 receives, for example, an input of a signal (load drop instruction signal) instructing execution of load drop control.
The sensor information acquisition unit 102 acquires measurement values of sensors from an output meter, a temperature sensor, and the like included in the combined cycle power plant. For example, the sensor information acquisition unit 102 acquires an output measured by the output meter 16 of the generator 34 or an atmospheric temperature measured by the temperature sensor 15 provided on the inlet side of the compressor 11. Similarly, the sensor information acquisition unit 102 may acquire measured values of atmospheric pressure and atmospheric humidity from a pressure sensor or a humidity sensor (not shown) provided on the inlet side of the compressor 11.

The gas turbine target output calculation unit 103 calculates a target output of the gas turbine 10 during load drop control.
The exhaust gas energy calculation unit 104 calculates exhaust gas energy of the gas turbine 10 based on the target output of the gas turbine 10. Specifically, the exhaust gas energy calculation unit 104 calculates the flow rate and enthalpy of the exhaust gas discharged by the gas turbine 10 based on the target output of the gas turbine 10, multiplies the exhaust gas flow rate by the exhaust gas enthalpy, and calculates the exhaust gas energy. calculate.
The steam turbine output estimation unit 105 estimates the output of the steam turbine at the time of load drop control, based on the exhaust gas energy calculated by the exhaust gas energy calculation unit 104.

The power generation plant target output calculation unit 106 adds the target output of the gas turbine 10 calculated by the gas turbine target output calculation unit 103 and the estimated value of the steam turbine output estimated by the steam turbine output estimation unit 105 to generate the power plant 1 Calculate the target output of
The gas turbine output control unit 107 controls the gas turbine output at the time of load drop control. For example, the gas turbine output control unit 107 performs feedback control based on the deviation between the target output of the power generation plant 1 calculated by the power generation plant target output calculation unit 106 and the actual output of the power generation plant 1 so that the deviation becomes zero. Output control command value is calculated. The gas turbine output control unit 107 controls the output of the power plant 1 to be a target value based on the calculated output control command value.

The gas turbine output lower limit command value calculation unit 108 calculates the lower limit value of the output control command value corresponding to the lower limit value of the output of the gas turbine 10 at the time of load drop control.
The steam turbine output control unit 109 controls the opening and closing of the high pressure steam stop valve 42, controls the opening degree of the high pressure main steam control valve 43, controls the opening and closing of the medium pressure steam stop valve 45, and controls the medium pressure steam control valve 46. The output of the steam turbine 30 is controlled by controlling the opening degree, controlling the opening and closing of the low pressure steam stop valve 52, controlling the opening degree of the low pressure main steam control valve 53, and the like.
The storage unit 110 stores various information.
In addition, although the control apparatus 100 is equipped with the other various functions regarding control of the power generation plant 1, description of the function which is not related to this embodiment is abbreviate | omitted.

Next, load drop control according to the present embodiment will be described with reference to FIG.
FIG. 3 is a view for explaining a control method of the combined cycle power plant in the first embodiment according to the present invention.
The load drop control is executed when the input reception unit 101 acquires a load drop instruction signal. First, the gas turbine target output calculation unit 103 calculates the target output of the gas turbine 10 based on the target T1T, which is a target value of a predetermined turbine inlet temperature. The predetermined target T1T is, for example, a value determined based on the upper limit (the graph CU of FIG. 16) and the lower limit (the graph CL of FIG. 16) of the gas turbine output at the time of load drop control. The target T1T may be input together with the load drop instruction signal from the input receiving unit 101, for example, or may be stored in advance by the storage unit 110.

  As illustrated, the gas turbine target output calculation unit 103 includes a function Fx1. The function Fx1 is a function or a table that defines the relationship between the target T1T and the target output of the gas turbine 10 at the time of load drop control. The gas turbine target output calculation unit 103 inputs the target T1T into the function Fx1, and calculates the target output of the gas turbine 10 according to the target T1T. The gas turbine target output calculation unit 103 outputs the target output of the gas turbine 10 to the exhaust gas energy calculation unit 104 and the power generation plant target output calculation unit 106.

  Next, the exhaust gas energy calculation unit 104 calculates the flow rate of the exhaust gas discharged from the gas turbine 10. The exhaust gas energy calculation unit 104 has a function Fx2 that defines the relationship between the output of the gas turbine 10 and the opening degree of an IGV (inlet guide vane) (not shown) provided on the inlet side of the compressor 11. The exhaust gas energy calculation unit 104 inputs the target output calculated by the gas turbine target output calculation unit 103 into Fx2, and calculates an IGV opening degree according to the target output of the gas turbine 10. The IGV opening is related to the air flow which the compressor 11 sucks, and the larger the IGV opening, the higher the air flow to be sucked. The exhaust gas energy calculation unit 104 includes a function Fx3 for calculating the exhaust gas flow rate from the ambient temperature, the output of the gas turbine 10, and the opening of the IGV. The exhaust gas energy calculation unit 104 inputs the measured value of the atmospheric temperature by the temperature sensor 15 acquired by the sensor information acquisition unit 102, the target output of the gas turbine 10, and the IGV opening calculated using the function Fx2 to the function Fx3. Then, the exhaust gas flow rate is calculated.

Further, the exhaust gas energy calculating unit 104 has a function Fx4 for calculating the enthalpy of the exhaust gas from the atmospheric temperature, the output of the gas turbine 10, and the opening degree of the IGV. The exhaust gas energy calculation unit 104 inputs the measured value of the atmospheric temperature by the temperature sensor 15 acquired by the sensor information acquisition unit 102, the target output of the gas turbine 10, and the IGV opening calculated using the function Fx2 to the function Fx4. Then, the exhaust gas enthalpy is calculated.
The exhaust gas energy calculation unit 104 includes a multiplier P1. The exhaust gas energy calculation unit 104 calculates the exhaust gas energy by calculating the product of the exhaust gas flow rate and the exhaust gas enthalpy using the multiplier P1. The exhaust gas energy calculation unit 104 may estimate the exhaust gas energy by the following equation (1).
Exhaust gas energy = a × (exhaust gas flow × exhaust gas enthalpy) + b (1)
a and b are predetermined constants. The exhaust gas energy calculation unit 104 outputs the calculated value of the exhaust gas energy to the steam turbine output estimation unit 105.

The steam turbine output estimation unit 105 includes a function Fx5 that defines the relationship between exhaust gas energy and the output of the steam turbine. The steam turbine output estimating unit 105 inputs the value of the exhaust gas energy calculated by the exhaust gas energy calculating unit 104 into the function Fx 5 to estimate the output of the steam turbine 30. The steam turbine output estimation unit 105 outputs the estimated output value of the steam turbine 30 to the power generation plant target output calculation unit 106.
Next, the power generation plant target output calculation unit 106 calculates the target power of the power generation plant 1 by summing the target output of the gas turbine 10 and the estimated output value of the steam turbine 30.

  As described with reference to FIGS. 15 and 16, in the case of conventional load drop control, the target output of the power plant 1 is calculated by setting the output at the start of load control to the steam turbine output. In this control method, the delay in the output of the steam turbine 30 is compensated by increasing the output of the gas turbine 10. Therefore, in the time zone in which the output of the steam turbine 30 stops decreasing and the output is stabilized, the output of the gas turbine 10 may deviate from the target predetermined allowable range and exceed the upper limit value. On the other hand, according to the load drop control of the present embodiment described in FIG. 3, the output of the steam turbine is estimated according to the target output of the gas turbine 10. Thus, the target output of the power plant 1 can be calculated by summing the final estimated output of the steam turbine 30 and the target output of the gas turbine 10 in consideration of the response delay, so the output of the steam turbine 30 is stable. Even after that, the output of the gas turbine 10 can be settled within a predetermined tolerance.

Next, the effect of the load drop control according to the present embodiment will be described with reference to FIG.
FIG. 4 is a view showing an example of the result of control in the first embodiment according to the present invention.
As in FIG. 16, graph L1 is the output of power plant 1, graph L2 is the target output of power plant 1, graph L3 is the output of gas turbine 10, and graphs CU and CL are the outputs of gas turbine 10 during load drop control. The upper limit value and the lower limit value, and the graph L4 indicate the output of the steam turbine 30. As illustrated, the output of the power plant 1 reaches the target output of the power plant 1 at time t1 ′. The output of the gas turbine 10 settles within the allowable range indicated by the graphs CU and CL after time t2 '. This is an effect of adjusting the target output of the power generation plant 1 according to the output predicted value of the steam turbine 30 by the load drop control of the present embodiment.

  On the other hand, the output of the gas turbine 10 deviates from the allowable range until the time t2 'from the start of the load drop control. As described above, only by estimating the output of the above-described steam turbine 30 and controlling the output of the gas turbine 10, depending on the target output of the power plant 1, the load lowering speed, or other operating conditions, It may take some time for the output to settle within tolerances. On the other hand, control device 100 may further perform control to prevent the output of gas turbine 10 from falling below graph CL.

Here, the output control command value related to the output control of the gas turbine 10 will be described.
FIG. 5 is a diagram showing an example of a method of calculating the output control command value of the gas turbine. The gas turbine output control unit 107 performs each control shown in FIG. 5 to control the output of the gas turbine 10. For example, the gas turbine output control unit 107 executes load control to calculate a control command value LDCSO (load limit control signal output) that brings the actual load closer to the target load, and executes the rotational speed control to execute the actual rotational speed. Calculate a control command value GVCSO (govenor control signal output) that brings the engine speed close to the target rotational speed, execute exhaust gas temperature control, and calculate a control command value EXCSO (exhaust control signal output) such that the exhaust gas temperature falls within the allowable range. Blade path temperature control is executed to calculate a control command value BPCSO (blade pass control signal output) such that the blade path temperature (the temperature of the combustion gas) falls within the allowable range. The gas turbine output control unit 107 selects a minimum value from among these control command values (LDCSO, GVCSO, EXCSO, BPCSO), and sets the selected value as the total fuel flow command value CSO (control signal output). CSO is an output control command value.

  Further, the gas turbine output control unit 107 executes a combustion load calculation to calculate a control command value CLCSO (combustion load control signal output) based on T1T etc. Calculate the allocation command value. The gas turbine output control unit 107 multiplies the total fuel flow rate command value CSO by the fuel distribution command value to each fuel system, and calculates the fuel flow rate command value for each fuel system of the pilot system, main system, and top hat system. Do. Then, the gas turbine output control unit 107 controls the fuel flow control valve 14 provided in each fuel line based on the calculated fuel flow command value to adjust the fuel flow to each fuel system.

FIG. 6 is a diagram for explaining a method of calculating a control command value related to the load of the gas turbine.
The calculation method of LDCSO by load control is shown in FIG. The gas turbine output control unit 107 calculates, based on the deviation between the actual output of the power generation plant 1 and the target output, an LDCSO that cancels the deviation by PI control and approaches zero. For example, the gas turbine output control unit 107 includes a function that determines the relationship between the gas turbine output and the LDCSO, and calculates the LDCSO using this function. Also in the load drop control whose result is illustrated in FIG. 4, the gas turbine output control unit 107 calculates LDCSO by the method shown in FIG. 6.

FIG. 7 shows an example of transition of control command values LDCSO, GVCSO, EXCSO, BPCSO at the time of load drop control.
FIG. 7 is a view showing an example of the result of calculating the control command value at the time of load drop control in the first embodiment according to the present invention.
As shown, BPCSO and EXCSO show close behavior, and the behavior of LDCSO and CSO match. That is, at the time of load drop control, LDCSO becomes the minimum value among the control command values, and the value of LDCSO is selected as CSO. Here, referring to FIG. 4, the actual output of the power plant 1 exceeds the target output for a while after the start of the load drop control. According to the control method shown in FIG. 6, the value of LDCSO continues to decrease during this time. Then, the value of the total fuel flow rate command value CSO (CSO is the same as LDCSO from FIG. 7) also decreases, and as a result, the output of the gas turbine 10 falls below the lower limit indicated by the graph CL, as pointed out in FIG. The case arises.

If the actual output of the power plant 1 exceeds the target output, the LDCSO continues to decrease as shown in FIG. At this time, as pointed out in FIG. 4, the output of the gas turbine 10 sometimes falls below the lower limit value indicated by the graph CL. Therefore, in the present embodiment, the gas turbine output lower limit command value calculation unit 108 sets a value greater than or equal to the value indicated by the graph CL as the output lower limit value of the gas turbine 10 at the time of load drop control. Is controlled so that the output of the gas turbine 10 does not fall below this output lower limit.
FIG. 8 is a view for explaining a method of calculating a control command value related to the load of the gas turbine in the first embodiment according to the present invention.
The calculation method of LDCSO by load drop control of this embodiment is shown in FIG. The gas turbine output control unit 107 calculates the deviation between the actual output of the power plant 1 and the target output. The gas turbine output control unit 107 calculates an LDCSO that sets this deviation to zero.
Further, the gas turbine output lower limit command value calculation unit 108 calculates a gas turbine target output from the target T1T. For example, the gas turbine output lower limit command value calculation unit 108 includes Fx1 of FIG. 3, and calculates a gas turbine target output by Fx1. Next, the gas turbine output lower limit command value calculation unit 108 calculates CSO matching the gas turbine target output. For example, the gas turbine output lower limit command value calculation unit 108 includes a function that determines the relationship between the gas turbine output and CSO, and calculates the total fuel flow rate command value CSO using this function. This CSO is the lower limit value of the output control command value corresponding to the output lower limit value of the gas turbine 10 at the time of load drop control.

The gas turbine output control unit 107 acquires CSO and sets it as the LDCSO lower limit value. The gas turbine output control unit 107 compares the LDCSO calculated by the PI control with the LDCSO lower limit, and outputs the LDCSO calculated by the PI control if the LDCSO calculated by the PI control is equal to or more than the LDCSO lower limit. The gas turbine output control unit 107 outputs the LDCSO lower limit value if the LDCSO calculated by the PI control is less than the LDCSO lower limit value. Then, as described with reference to FIG. 5, the gas turbine output control unit 107 selects a minimum value from among LDCSO control command values and sets it as CSO (According to the control exemplified in this embodiment, LDCSO is minimum. Value), determine the amount of fuel supplied to each fuel system.
In the control exemplified in the present embodiment as described with reference to FIG. 5, the LDCSO lower limit value is selected as the lower limit value of the total fuel flow rate command value CSO at the time of load drop control. It is not limited to the configuration. For example, the gas turbine output lower limit command value calculation unit 108 may be configured to set a lower limit value for CSO calculated by the gas turbine output control unit 107.

Next, results of load drop control when the process of setting the lower limit value of LDCSO described in FIG. 8 is added are shown in FIGS. 9 and 10.
FIG. 9 is a first diagram showing an example of the result of calculating the output control command value based on the calculation method of the first embodiment according to the present invention.
As illustrated, when the lower limit value of LDCSO is set by the method shown in FIG. 8, LDCSO is different from the case illustrated in FIG. 7 even if the actual output of the power plant 1 exceeds the target output. It never falls below the value. Therefore, the value of CSO also does not fall below the LDCSO lower limit value.

FIG. 10 is a second diagram showing an example of the result of calculating the output control command value based on the calculation method of the first embodiment according to the present invention.
As in FIG. 4, graph L1 is the output of power plant 1, graph L2 is the target output of power plant 1, graph L3 is the output of gas turbine 10, and graphs CU and CL are the outputs of gas turbine 10 during load drop control. The upper limit value and the lower limit value, and the graph L4 indicate the output of the steam turbine 30. As illustrated, the output of the gas turbine 10 becomes a value within the allowable range indicated by the graphs CU and CL at time t1 ′ ′ and is thereafter controlled to the allowable range. This is an effect of setting the lower limit value to CSO which determines the output of the gas turbine 10 by the gas turbine output lower limit command value calculation unit 108.
As shown in FIG. 10, according to the present embodiment, the target output value of the power plant 1 based on the estimated output value of the steam turbine 30 and the output lower limit value of the gas turbine 10 are set to execute load drop control. Thereby, the output of the power plant 1 can be reduced to the target output at a desired speed while controlling the output of the gas turbine 10 within an allowable range.

Next, the flow of load drop control according to the present embodiment will be described.
FIG. 11 is a flowchart showing an example of load drop control according to the first embodiment of the present invention.
First, the input receiving unit 101 acquires a load drop instruction signal (step S11). Then, the gas turbine target output calculation unit 103 calculates the target output of the gas turbine 10 based on the predetermined target T1T and the function Fx1 (step S12). Next, the sensor information acquisition unit 102 acquires the measured value of the atmospheric temperature from the temperature sensor 15 (step S13). Next, the exhaust gas energy calculation unit 104 calculates the IGV opening based on the target output of the gas turbine 10 calculated in step S102 and the function Fx2 (step S14). Next, based on the target output of the gas turbine 10 calculated in step S12, the measured value of the atmospheric temperature acquired in step S13, the IGV opening calculated in step S14, and the function Fx3. The exhaust gas flow rate is calculated (step S15). In addition, the exhaust gas energy calculation unit 104 is based on the target output of the gas turbine 10 calculated in step S12, the measured value of the atmospheric temperature acquired in step S13, the IGV opening calculated in step S14, and the function Fx4. The exhaust gas enthalpy is calculated (step S16). Next, the exhaust gas energy calculation unit 104 calculates exhaust gas energy by multiplying the exhaust gas flow rate by the exhaust gas enthalpy. Next, the steam turbine output estimation unit 105 estimates the output of the steam turbine 30 based on the exhaust gas energy and the function Fx5 (step S17). Next, the power generation plant target output calculation unit 106 adds up the target output of the gas turbine 10 calculated in step S12 and the estimated output value of the steam turbine 30 calculated in step S17 to obtain the target output of the power generation plant 1 Is calculated (step S18). The power generation plant target output calculation unit 106 outputs the target output of the power generation plant 1 to the gas turbine output control unit 107.

  On the other hand, when the target output of the gas turbine 10 is calculated in step S12, the gas turbine output lower limit command value calculation unit 108 calculates the lower limit value of the output control command value (step S19). The gas turbine output lower limit command value calculation unit 108 outputs the LDCSO lower limit value to the gas turbine output control unit 107.

  The gas turbine output control unit 107 controls the output of the gas turbine 10 by PI control so that the output of the power generation plant 1 becomes a target output determined in consideration of the estimated value of the final output of the steam turbine. (Step S20). Thereby, the output of the gas turbine 10 can be stabilized within the allowable range even in a situation where the output response of the steam turbine 30 is delayed with respect to the rapid load drop of the power plant 1. Further, the gas turbine output control unit 107 controls the output of the gas turbine 10 such that the output of the gas turbine 10 does not decrease below the output corresponding to the LDCSO lower limit value. As a result, the output of the gas turbine 10 can be controlled within a predetermined allowable range through load drop control.

  Further, by estimating the steam turbine output at the time of settling during load drop control and setting the target output of the power plant 1, adjustment by the operator for controlling the output of the gas turbine 10 within the allowable range is not necessary. . Therefore, it is possible to save trouble of adjustment and to prevent trouble caused by adjustment error.

  The control device 100 illustrated in FIG. 2 may not include the gas turbine output lower limit command value calculation unit 108. In that case, the control device 100 executes the load drop control by the processing excluding step S19 in the flowchart of FIG.

Second Embodiment
Hereinafter, load drop control according to a second embodiment of the present invention will be described with reference to FIGS. 12 to 14.
FIG. 12 is a block diagram of a control device in a second embodiment according to the present invention.
The same code | symbol is attached | subjected to the same thing as the function part which comprises the control apparatus 100 which concerns on 1st embodiment among the structures which concern on 2nd embodiment of this invention, and each description is abbreviate | omitted.
As illustrated, the control device 100A includes an input reception unit 101, a sensor information acquisition unit 102, a gas turbine target output calculation unit 103A, an exhaust gas energy calculation unit 104A, a steam turbine output estimation unit 105, a power plant target output calculation unit 106, and a gas A turbine output control unit 107, a gas turbine output lower limit command value calculation unit 108A, a steam turbine output control unit 109, and a storage unit 110 are provided.

The gas turbine target output calculation unit 103A calculates the target output of the gas turbine 10 that has been corrected according to the values of various parameters that affect the output of the gas turbine. The various parameters that affect the output of the gas turbine are, for example, parameters related to air that the gas turbine 10 sucks, such as ambient temperature, ambient humidity, and ambient pressure.
The exhaust gas energy calculation unit 104A calculates exhaust gas energy that has been corrected according to the values of various parameters that affect exhaust gas energy. Various parameters affecting exhaust gas energy are similar to various parameters affecting gas turbine output.

The gas turbine output lower limit command value calculation unit 108A calculates the LDCSO lower limit value corrected according to the values of various parameters that affect the output of the gas turbine.
The parameters that affect the output of the gas turbine and the exhaust gas energy may be fuel gas calories, fuel type and composition, fuel temperature, fuel density, methane concentration, Wobbe index, etc., in addition to the above examples.

FIG. 13 is a diagram for explaining a control method of the combined cycle power plant in the second embodiment according to the present invention.
The load drop control of this embodiment will be described using FIG. Descriptions of processes similar to those in FIG. 3 will be omitted. In addition, an atmospheric temperature will be described as an example of a parameter that affects the output of the gas turbine and the exhaust gas energy.
First, the gas turbine target output calculation unit 103A calculates the target output of the gas turbine 10. Next, the gas turbine target output calculation unit 103A calculates a gain according to the atmospheric temperature by a predetermined function or the like, and multiplies the target output of the gas turbine 10 by the gain (S101). Similarly, the gas turbine target output calculation unit 103A may calculate the gain according to the atmospheric humidity by a predetermined function or the like, and may multiply the target output by the gain according to the atmospheric humidity. Similarly, the gas turbine target output calculation unit 103A may calculate the gain according to the atmospheric pressure by a predetermined function or the like, and may multiply the target output by the gain according to the atmospheric humidity. A function for calculating the gain according to the atmospheric temperature and the like is stored in the storage unit 110.

  Next, the exhaust gas energy calculation unit 104A performs the same process as in FIG. 3 to calculate the exhaust gas flow rate. The exhaust gas energy calculating unit 104A further calculates a gain according to the atmospheric temperature by a predetermined function or the like, and multiplies the gain by the exhaust gas flow rate (S102). The exhaust gas energy calculation unit 104A may calculate a gain corresponding to the atmospheric pressure and a gain corresponding to the atmospheric humidity, and may multiply each gain by the exhaust gas flow rate.

  Further, the exhaust gas energy calculation unit 104A performs the same process as that shown in FIG. 3 to calculate the exhaust gas enthalpy. The exhaust gas energy calculating unit 104A further calculates a gain according to the atmospheric temperature by a predetermined function or the like, and multiplies the gain by the exhaust gas enthalpy (S103). The exhaust gas energy calculation unit 104A may calculate a gain corresponding to the atmospheric pressure and a gain corresponding to the atmospheric humidity, and may multiply each gain by the exhaust gas enthalpy.

  The exhaust gas energy calculation unit 104A calculates exhaust gas energy by integrating the exhaust gas flow rate and the exhaust gas enthalpy corrected by multiplying the atmospheric temperature by a gain. The subsequent processing is the same as that of the first embodiment. That is, the steam turbine output estimation unit 105 estimates the output of the steam turbine 30 from the value of exhaust gas energy and the function Fx5, and the power generation plant target output calculation unit 106 estimates the target output of the gas turbine 10 and the output of the steam turbine 30 The target output of the power plant 1 is calculated by summing up the values.

It is known that the atmospheric conditions greatly affect the output of the gas turbine 10. According to the present embodiment, the gas turbine target output and the exhaust gas energy are corrected based on the ambient temperature and the like. By taking into consideration the influence of the atmospheric temperature or the like, the estimation accuracy of the output of the steam turbine can be improved, and the possibility of the output of the gas turbine 10 deviating from the allowable range can be further reduced.
Further, the correction may be performed with gains according to fuel gas calories, fuel type / composition, fuel temperature, fuel density, etc. as well as atmospheric conditions.

Next, a method of calculating the LDCSO lower limit value according to the present embodiment will be described with reference to FIG.
FIG. 14 is a diagram showing an example of a method of calculating an output control command value of a gas turbine according to a second embodiment of the present invention.
Descriptions of processes similar to those in FIG. 8 will be omitted. In addition, an atmospheric temperature will be described as an example of a parameter that affects the output of the gas turbine and the exhaust gas energy.
The gas turbine output control unit 107 calculates LDCSO such that the deviation between the output of the power generation plant 1 and the target output is zero.
The gas turbine output lower limit command value calculation unit 108A calculates a gas turbine target output from the target T1T. The gas turbine output lower limit command value calculation unit 108A inputs the gas turbine target output and the atmospheric temperature to a function that defines the relationship between the gas turbine output and the CSO for each atmospheric temperature, and corresponds to the gas turbine target output and the atmospheric temperature CSO is calculated (S104). As the atmospheric temperature is lower, CSO is larger (a1), and as the atmospheric temperature is higher, CSO is smaller (a2). A function that defines the relationship between the gas turbine output and CSO for each atmospheric temperature illustrated in FIG. 14 indicates this relationship. The CSO calculated in the correction process S104 is the LDCSO lower limit value. The gas turbine output lower limit command value calculation unit 108A further calculates the gain by a function that calculates the gain according to the atmospheric pressure, the atmospheric humidity, the fuel gas calorie, etc., and multiplies the CSO obtained as a result of S104 by the gain. A correction may be made.
The gas turbine output control unit 107 performs output control based on LDCSO calculated by PI control, but if LDCSO by PI control is less than the LDCSO lower limit value, it is based on the LDCSO lower limit value corrected according to the atmospheric temperature. Control of the gas turbine 10 is performed.

It is known that the atmospheric conditions greatly affect the output of the gas turbine 10. For example, a predetermined reference temperature is set as the atmospheric temperature by calculating CSO according to the atmospheric temperature etc. and setting the output corresponding to the CSO (LDCSO lower limit) to the lower limit of the gas turbine 10 at the time of normal load drop. Compared to the case where the lower limit value of the gas turbine 10 is set on an assumption, the possibility that the output of the gas turbine 10 deviates from the allowable range can be further reduced.
In addition, although it is desirable to perform all the correction processing S101 to S104 demonstrated in FIG. 13, FIG. 14, you may be comprised so that only any one or two correction processing may be performed.

Next, the flow of processing according to the present embodiment will be described with reference to FIG.
First, the input receiving unit 101 acquires a load drop instruction signal (step S11). Next, the gas turbine target output calculation unit 103A calculates the target output of the gas turbine 10 that has been corrected based on the value of the parameter that affects the gas turbine output such as the ambient temperature (step S12). Next, the sensor information acquisition unit 102 acquires the measured value of the atmospheric temperature (step S13). Next, the exhaust gas energy calculation unit 104A calculates the IGV opening (step S14). Next, the exhaust gas energy calculation unit 104A calculates the exhaust gas flow rate corrected with the value of the parameter that affects the exhaust gas energy such as the ambient temperature (step S15). Further, the exhaust gas energy calculation unit 104A calculates the exhaust gas enthalpy corrected by the value of the parameter that affects the exhaust gas energy such as the ambient temperature (step S16). Next, the exhaust gas energy calculation unit 104A calculates the exhaust gas energy based on the exhaust gas flow rate and the exhaust gas enthalpy. Next, the steam turbine output estimation unit 105 estimates the output of the steam turbine 30 (step S17). Next, the power generation plant target output calculation unit 106 calculates the target power of the power generation plant 1 (step S18).
On the other hand, the gas turbine output lower limit command value calculation unit 108A calculates the LDCSO lower limit value corrected by the value of the parameter that affects the gas turbine output such as the atmospheric temperature (step S19).
The gas turbine output control unit 107 controls the output of the gas turbine 10 by PI control (step S20).

FIG. 17 is a diagram showing an example of a hardware configuration of a control device in the first and second embodiments of the present invention.
The computer 900 is, for example, a PC (Personal Computer) or a server terminal device including a CPU 901, a main storage device 902, an auxiliary storage device 903, an input / output interface 904, and a communication interface 905. The above-described control devices 100 and 100A are implemented in the computer 900. The operation of each processing unit described above is stored in the auxiliary storage device 903 in the form of a program. The CPU 901 reads a program from the auxiliary storage device 903 and develops the program in the main storage device 902, and executes the above processing according to the program. Further, the CPU 901 secures a storage area corresponding to the storage unit 110 in the main storage unit 902 according to the program. Further, the CPU 901 secures, in the auxiliary storage device 903, a storage area for storing data being processed, in accordance with a program.

  In at least one embodiment, the auxiliary storage device 903 is an example of a non-temporary tangible medium. Other examples of non-transitory tangible media include magnetic disks connected via an input / output interface 904, magneto-optical disks, CD-ROMs, DVD-ROMs, semiconductor memories, and the like. Further, when this program is distributed to the computer 900 through a communication line, the computer 900 that has received the distribution may deploy the program in the main storage unit 902 and execute the above processing. Further, the program may be for realizing a part of the functions described above. Furthermore, the program may be a so-called difference file (difference program) that realizes the above-described function in combination with other programs already stored in the auxiliary storage device 903.

  Input acceptance unit 101, sensor information acquisition unit 102, gas turbine target output calculation units 103 and 103A, exhaust gas energy calculation units 104 and 104A, steam turbine output estimation unit 105, power generation plant target output calculation unit 106, gas turbine output control unit 107 All or part of the gas turbine output lower limit command value calculation units 108 and 108A and the steam turbine output control unit 109 are microcomputers, LSIs (Large Scale Integration), ASICs (Application Specific Integrated Circuits), PLDs (Programmable Logic Devices), It may be realized using hardware such as FPGA (Field-Programmable Gate Array).

In addition, without departing from the spirit of the present invention, it is possible to replace components in the above-described embodiment with known components as appropriate. Further, the technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the scope of the present invention. The single axis GTCC (Gas Turbine Combined Cycle) is illustrated in FIG. 1, but the control device 100, 100A can be applied to multi-axis GTCC.
The IGV opening is an example of the air flow that the compressor sucks. The gas turbine output lower limit command value calculation units 108 and 108A are an example of a gas turbine output lower limit value setting unit.

DESCRIPTION OF SYMBOLS 10 ... Gas turbine 11 ... Compressor 12 ... Combustor 13 ... Turbine 14 ... Fuel flow control valve 15 ... Temperature sensor 16 ... Power meter 20 ... Exhaust heat recovery Boiler 21 ... high pressure steam generation unit 22 ... medium pressure steam generation unit 23 ... reheating unit 24 ... low pressure steam generation unit 30 ... steam turbine 31 ... high pressure steam turbine 32 ... Medium pressure steam turbine 33 ... low pressure steam turbine 34 ... generator 35 ... condenser 41 ... high pressure main steam line 42 ... high pressure steam stop valve 43 ... high pressure main steam control valve 44 ... Medium pressure steam line 45 ... Medium pressure steam stop valve 46 ... Medium pressure steam control valve 51 ... Low pressure main steam line 52 ... Low pressure steam stop valve 53 ... Low pressure main steam control valve 54 ··· Medium pressure turbine exhaust line 55 ··· Water supply line 61 · · · Pressure main steam line 100, 100A ... Control device 101 ... Input reception unit 102 ... Sensor information acquisition unit 103, 103A ... Gas turbine target output calculation unit 104, 104A ... Exhaust gas energy calculation unit 105 ... Steam turbine output estimation unit 106 ... Power generation plant target output calculation unit 107 ... Gas turbine output control unit 108, 108A ... Gas turbine output lower limit command value calculation unit 109 ... Steam turbine output control unit 110: storage unit 900: computer 901: CPU
902: main storage unit 903: auxiliary storage unit 904: input / output interface 905: communication interface

Claims (12)

A gas turbine target output calculation unit that calculates a target output of the gas turbine at the time of load drop of a combined cycle power generation plant that generates power using a gas turbine and a steam turbine;
An exhaust gas energy calculating unit that calculates exhaust gas energy of the gas turbine based on the target output calculated by the gas turbine target output calculating unit;
A steam turbine output estimating unit configured to estimate an output of the steam turbine at the time of the load decrease based on the exhaust gas energy calculated by the exhaust gas energy calculating unit;
A power plant target output calculation unit that calculates the target output of the combined cycle power plant at the time of the load decrease by adding the target output of the gas turbine and the output estimated value of the steam turbine;
Control device comprising: A gas turbine output control unit configured to control an output of the gas turbine by feedback control based on a deviation between a target output and an actual output of the combined cycle power plant at the time of the load drop;
A gas turbine output lower limit value setting unit configured to set a lower limit value of an output of the gas turbine at the time of load decrease based on a target output of the gas turbine;
The control device according to claim 1, further comprising: The gas turbine output control unit performs output control of the gas turbine based on the output control command value calculated by the feedback control,
The gas turbine output lower limit setting unit calculates the lower limit of the output control command value corresponding to the lower limit of the output of the gas turbine.
The control device according to claim 2. The gas turbine output lower limit setting unit corrects the output control command value according to at least one of an atmospheric temperature, an atmospheric humidity, and an atmospheric pressure.
The control device according to claim 3. The exhaust gas energy calculation unit
An exhaust gas flow rate is calculated based on the target output of the gas turbine, an atmospheric flow rate drawn by the compressor of the gas turbine, and an atmospheric temperature;
Exhaust gas enthalpy is calculated based on the target output of the gas turbine, the atmospheric flow rate, and the atmospheric temperature,
The exhaust gas energy is calculated based on the exhaust gas flow rate and the exhaust gas enthalpy,
The control device according to any one of claims 1 to 4.   The control device according to claim 5, wherein the exhaust gas energy calculating unit corrects the exhaust gas flow rate according to at least one of an atmospheric temperature, an atmospheric humidity, and an atmospheric pressure.   The control device according to claim 5 or 6, wherein the exhaust gas energy calculating unit corrects the exhaust gas enthalpy in accordance with at least one of an atmospheric temperature, an atmospheric humidity, and an atmospheric pressure. The decrease rate of the output of the combined cycle power plant at the time of the load drop is 5% per minute or more.
The control device according to any one of claims 1 to 7. A compressor,
A combustor,
With the turbine,
The control device according to any one of claims 1 to 8.
Gas turbine with. A gas turbine according to claim 9;
With a steam turbine,
A generator,
Combined cycle power plant. Calculating a target output of the gas turbine at the time of load drop of a combined cycle power plant that generates power using a gas turbine and a steam turbine;
Calculating exhaust gas energy of the gas turbine based on the calculated target output of the gas turbine;
Estimating an output of the steam turbine at the time of the load drop based on the calculated exhaust gas energy;
Calculating the target output of the combined cycle power plant at the time of the load drop by adding the estimated output value of the steam turbine to the target output of the gas turbine;
Controlling method. A computer that controls a combined cycle power plant that generates electricity using a gas turbine and a steam turbine,
A means for calculating a target output of the gas turbine during load drop of the combined cycle power plant;
A means for calculating exhaust gas energy of the gas turbine based on the calculated target output of the gas turbine;
A means for estimating an output of the steam turbine at the time of the load drop based on the calculated exhaust gas energy;
A means for calculating a target output of the combined cycle power plant at the time of the load drop by adding the estimated output of the steam turbine to the target output of the gas turbine;
Program to function as.

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