JP2009300038A - Boiler controller and boiler control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a boiler controller concurrently improving control followability of power generation output, a main steam pressure, and enthalpy of steam. <P>SOLUTION: The boiler controller includes a first control loop adjusting an opening of a governor by a power generation output deviation calculated by a load demand signal and a power generation output value, a second control loop controlling a fuel flow rate by a main steam pressure deviation calculated by a main steam pressure set value and a main steam pressure value, a third control loop controlling a supply water flow rate by an enthalpy deviation of steam calculated by an enthalpy set value of steam and an enthalpy value of steam, an integral parameter calculating means for calculating an integral parameter from a load change rate of a boiler and an input value of control specifications, and a wasted time compensating means for inputting the integral parameter and at least to deviations of the power generation output deviation, the main steam pressure deviation, and the enthalpy deviation of steam to output at least two boiler manipulated variables based on the input deviations. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a boiler control device and a boiler control method, and in particular, a boiler control device and a boiler control capable of simultaneously improving control followability such as power generation output, main steam pressure, and steam enthalpy at a high load change rate. Regarding the method.

  Conventionally, there is a proposal described in Patent Document 1 regarding control over steam pressure and steam temperature in a steam generator. According to this proposal, two delay elements are provided in the control apparatus for both the delay of fuel combustion with respect to the output target value and the time delay when the feed water flow rate passes through the evaporator heat transfer surface. Techniques to be corrected by this are disclosed.

  FIGS. 8 and 9 are diagrams for explaining the boiler control device previously examined by the present inventors. FIG. 8 is a general control device for power generation output, main steam pressure, and steam enthalpy in the boiler / turbine system. FIG. 9 is a diagram showing a signal system of the control device.

  As shown in FIG. 8, the feed water is introduced into the boiler device by the pump 11, most of the feed water is led to the water wall 14 through the economizer 12, and a part of the feed water is supplied from the branch point 22 to the primary spray water 23 and Used as secondary spray water 24. The water wall 14 constitutes the outer peripheral wall of the furnace 13, and the water passing through the water wall 14 is heated by the combustion gas generated by the combustion of the fuel. This is converted into steam through the cage 15 and the brackish water separator 16, and in this example, is sequentially heated by the primary superheater 17, the secondary superheater 18 and the tertiary superheater 19 to become superheated steam.

  The superheated steam is supplied to a steam turbine 21 (only a high-pressure turbine is shown in the figure) via a governor (gas pressure adjusting valve) 20 to contribute to power generation, and further sent to a reheat loop (not shown).

  In the control of the boiler / turbine system, a main steam pressure set value 60 and a steam enthalpy set value 70 are generated by function generators (Fx) 30 and 31 based on a load request signal (MWD) 50. The amounts to follow the load request signal (MWD) 50, the main steam pressure set value 60, and the steam enthalpy set value 70 are the power generation output value 51, the main steam pressure value 61, and the steam enthalpy value 71.

  An output deviation value 52 between the load request signal (MWD) 50 and the power generation output value 51 is obtained by a subtractor 32. A main steam pressure deviation value 62 between the main steam pressure set value 60 and the main steam pressure value 61 is obtained by the subtractor 33. The enthalpy deviation value 72 of steam between the enthalpy set value 70 of steam and the enthalpy value 71 of steam is obtained by the subtractor 34. These deviation values 52, 62, 72 are input to PI (differentiation / integration) controllers 53, 63, 73 after appropriate non-dimensionalization, and feedback adjustment amounts 111, 112, 113 are calculated.

  Among these, the feedback adjustment amount 111 of the power generation output deviation value 52 becomes a command signal to the governor 20 and adjusts the opening degree of the governor 20.

  The feedback adjustment amount 112 of the main steam pressure deviation value 62 is added to the load request signal (MWD) 50 by the adder 35 to become a boiler input command signal (BID) 200. On the one hand, this boiler input command signal (BID) 200 generates a feed water flow rate preceding signal 201 by a function generator (Fx) 36, and on the other hand a fuel flow rate command signal 202 by a function generator (Fx) 37. The feed water flow preceding signal 201 is added to the feedback adjustment amount 113 of the steam enthalpy deviation value 72 in the addition block 38 and becomes the feed water flow command signal 301 to instruct the drive operation of the feed water pump 11. The fuel flow rate command signal 202 instructs the fuel flow rate input operation to the furnace 13 (burner).

  FIG. 9 is a diagram for explaining how the feedback adjustment amount acts on the boiler / turbine system and what results are output in the control system.

  The process for calculating the feedback adjustment amounts 111, 112, and 113 is as described with reference to FIG. As shown in FIG. 9, the boiler / turbine system 20000 is represented by three types of processes in which the input to the boiler / turbine system is converted into output, and is generally expressed by the ratio of the Laplace conversion between the output of the system system and the input. A block including a G12, G22, G32 block expressed by a transfer function and an addition block 40 expressing that the three types of transfer functions are affected is described in a block format. Feedback adjustment amounts 111, 112, and 113 are input to the boiler / turbine system as control values, and based on them, the input and output expressed by the transfer functions G12, G22, and G32 and the addition block 40 are performed in the boiler / turbine system. The power generation output value 51, the main steam pressure value 61, and the steam enthalpy value 71 appear as the output of the boiler / turbine system (in order to simplify the drawing, the main steam pressure value 61 is output as a representative example in FIG. 9). Is shown).

  In order to control the main steam pressure value (Ppv) 61 to follow the main steam pressure set value (Pset) 60, the main steam pressure deviation value 62 is obtained by the subtractor 33, and PI control is performed based on the deviation value 62. The feedback adjustment amount 112 is obtained by the device 63.

  When this feedback adjustment amount 112 is input to the boiler / turbine system 20000, a pressure change value 2522 is generated along the causal relationship defined by the physical law. That is, the boiler input command signal (BID) 200 is obtained from the feedback adjustment amount 112, and the boiler device is controlled by the feed water flow rate preceding signal 201 and the fuel flow rate command signal 202, so that the pressure change value 2522 is generated in the furnace 13. Then, when the pressure change value 2522 converges to zero, the main steam pressure set value (Pset) 60 is obtained.

  Here, the causal relationship is referred to as a transfer function in terms of system theory, and the feedback adjustment amount 112 is input to the transfer function (G22) 2022, and a pressure change value 2522 is obtained. The pressure change value 2522 is added by the addition block 40 with the feedback change amount 111 of the governor 20 via the other transfer function (G12) 2012 as a disturbance, and the feedback adjustment amount of the water supply operation amount is also added to the pressure change value 2522. 113 is also added by the addition block 40 by the pressure change value 2532 via another transfer function (G32) 2032.

  To show these intuitively, first, the addition of the pressure change value 2512 via the transfer function (G12) 2012 is as follows. If the opening of the governor 20 is reduced, the main steam pressure immediately rises. Is based on the causal relationship that descents immediately. The addition of the pressure change value 2532 via the transfer function (G32) 2032 is based on the causal relationship that the main steam pressure rises slowly if a large amount of feed water is flowed, and the main steam pressure falls slowly in the reverse operation. is there.

Here, the governor 20 is operated to follow the power generation output value (MW) 51 to the load request signal (MWD) 50, and the feed water pump 11 is operated to set the steam enthalpy value 71 to the steam enthalpy setting. This is to follow the value 70.
JP 7-502803 JP

  In the control device proposed in Patent Document 1, two disturbances to pressure control occur. One of them is that when the enthalpy of steam is controlled by the water supply operation, this water supply operation affects the main steam pressure. The governor opening is operated to bring the power generation output to the setting, but the effect of this governor operation on the main steam pressure is more than that due to the boiler input, which is the main operation amount of the main steam pressure. There is a temporal mismatch that is fast.

  In the boiler / turbine control system shown in FIG. 8, the main steam pressure response time by adjusting the opening of the governor 20 is several times faster than the main steam pressure response time by boiler input operation as described above. It is. Therefore, when the governor 20 is operated for power generation output (MW) control, the effect immediately acts as a disturbance on the main steam pressure, and in order to remove this, the movement is predicted in advance, and the reverse disturbance is reversed. A direction moving action must be applied from the boiler input to the main steam pressure. However, the use of such prior information in boiler input is not possible from a causal relationship.

  In the control system examined earlier, the above-described difference in response speed is not taken into consideration, and therefore it is difficult to suppress the pressure change value 2512 derived from the operation of the governor 20 among the disturbance terms of the main steam pressure value 61.

  Further, suppression of the pressure change value 2532 which is a disturbance term is not actively performed. For this reason, the operation for causing the power generation output value (MW) 51 or the steam enthalpy value 71 to follow the respective set values acts as a disturbance to the main steam pressure value 61, and in order to stably control the main steam pressure, PI Control must be performed with a low gain. Then, the followability of the main steam pressure is slow, and as a result, the followability of the power generation output value (MW) is also slowed, and there is a fear that the deviation value of the power generation output value (MW) cannot be kept within a specified range.

  An object of the present invention is to provide a boiler control device and a boiler control method capable of simultaneously improving the follow-up performance of control such as power generation output, main steam pressure, and steam enthalpy.

In order to achieve the above object, the first means of the present invention is to open the governor provided in the main steam path based on the power generation output deviation value calculated from the load request signal for the boiler and the power generation output value from the steam turbine. A first control loop that controls the flow rate of main steam supplied to the steam turbine by adjusting
A second control loop for controlling a fuel flow rate to be introduced into the burner based on a main steam pressure set value calculated based on the load request signal and a main steam pressure deviation value calculated based on the main steam pressure value;
A third control loop for controlling the feed water flow rate to be supplied to the water wall based on the steam enthalpy setting value calculated based on the load request signal and the steam enthalpy deviation value calculated based on the steam enthalpy value;
A positive parameter calculation means for calculating a positive parameter from the load change rate of the boiler and the input value of the control specification;
Input at least two deviation values of the power generation output deviation value, main steam pressure deviation value, steam enthalpy deviation value and the positive parameter, and output at least two boiler operation amounts based on the inputted deviation value And a waste time compensation means.

According to a second means of the present invention, in the first means,
The input value of the control specification is a main steam allowable pressure deviation value.

According to a third means of the present invention, in the first means,
The waste time compensation means includes first compensation element calculation means, second compensation element calculation means, and addition means,
The power generation output deviation value and the positive parameter are input to the first compensation element calculation means to output a first output signal, and the enthalpy deviation value of the steam is input to the second compensation element calculation means. To output a second output signal,
The first output signal, the second output signal, and the main steam pressure deviation value are added by the adding means to output a third output signal.

According to a fourth means of the present invention, in the third means,
The first compensation element calculation means comprises incomplete differentiation calculation means, waste time difference setting means, multiplication means, and addition means,
The power generation output deviation value and a positive parameter are input to the incomplete differentiation calculation means, and the incomplete differentiation of the power generation output deviation value is calculated by a delay time,
The difference between the waste time of the main steam pressure response due to the operation of the governor set in the waste time difference setting means and the waste time of the main steam pressure response due to the operation of the boiler input is calculated by the incomplete differential calculation means. The incomplete differentiation of the generated power output deviation value is multiplied by the multiplication means,
The multiplied value and the power generation output deviation value are added by the adding means to output a differential result value.

The fifth means of the present invention is:
Based on the power generation output deviation value calculated from the load request signal for the boiler and the power generation output value from the steam turbine, the main steam flow rate supplied to the steam turbine is controlled by adjusting the opening of the governor provided in the main steam path And
Based on the main steam pressure set value calculated based on the load request signal and the main steam pressure deviation value calculated based on the main steam pressure value, the fuel flow rate to be introduced into the burner is controlled,
Based on the steam enthalpy setting value calculated based on the load request signal and the steam enthalpy deviation value calculated based on the steam enthalpy value, the feed water flow rate supplied to the water wall is controlled,
Calculate positive parameter from boiler load change rate and control specification input value,
Input at least two deviation values of the power generation output deviation value, main steam pressure deviation value, steam enthalpy deviation value and the positive parameter, and output at least two boiler operation amounts based on the inputted deviation value It is characterized by doing.

According to a sixth means of the present invention, in the fifth means,
The input value of the control specification is a main steam allowable pressure deviation value.

A seventh means of the present invention is the fifth means,
The power generation output deviation value and the positive parameter are input to a first compensation element calculation means to output a first output signal,
The steam enthalpy deviation value is input to the second compensation element calculation means to output a second output signal,
The first output signal, the second output signal, and the main steam pressure deviation value are added to output a third output signal.

The eighth means of the present invention is the seventh means,
The power generation output deviation value and a positive parameter are input to the incomplete differentiation calculation means to calculate the incomplete differentiation of the power generation output deviation value by the delay time,
The difference between the waste time of the main steam pressure response due to the governor operation and the waste time of the main steam pressure response due to the boiler input operation and the incomplete differentiation of the power generation output deviation value calculated by the incomplete differentiation calculation means Multiply
The multiplied value and the power generation output deviation value are added to output a differential result value.

  According to the configuration of the present invention, since the bias components from the governor and the feed water flow rate are added in the control loop for controlling the main steam pressure by the boiler input, the disturbance to the pressure due to the change of the governor and the feed water flow rate is added. Is removed. For this reason, the main steam pressure can be controlled by a boiler input using a sufficiently large PI gain. Therefore, the responsiveness and controllability of the main steam pressure are drastically improved, thereby simultaneously improving the power generation output and the followability of the steam enthalpy.

  In addition, the upper limit of the bias amount is suppressed except for when the load change rate is high for the preceding signal required so that the feedback due to power generation output deviation does not affect the main steam. Damage to hardware equipment such as is reduced.

  The core idea of the present invention is to adopt a control method in which the governor operation is an operation that causes a faster response than other operation amounts, so that the disturbance to the main steam pressure control is not caused. That is, the change in the governor operation amount is added to the boiler input as a bias to cancel the operation induced by the governor operation. This suppresses the governor operation for controlling the power generation output from acting as a disturbance on the pressure.

  At the same time, a positive parameter γ for controlling the maximum value of the initial manipulated variable of the bias amount is introduced so that it can be adjusted from time to time as a function of the load change rate and the control specification input value. In generating such a bias, it is necessary to accurately determine the time until the governor operation affects the main steam pressure and the time until the boiler input affects the main steam pressure, that is, the waste time of each control loop. This waste time is obtained from the actual machine response characteristics under the step input.

  The basis of the present invention is based on the fact that the disturbance of the pressure control loop may be removed. Thereby, the feedback adjustment amount of the main steam pressure deviation can be operated only by the main steam pressure via the boiler input. By adopting such a configuration, it becomes possible to sufficiently increase the PI control gain of the pressure control loop, and the followability to the main steam pressure set value is improved. As a result, the followability of the power generation output is also improved. .

  In order to remove such disturbance, an operation amount bias that cancels the disturbance may be added to the boiler input. In other words, the bias component caused by the governor and the bias component caused by the water supply may be added to the feedback amount of the boiler input. At this time, since the response of the main steam pressure accompanying the adjustment of the governor opening is several times faster than the response of the main steam pressure accompanying the boiler input, the bias is required to be compensated in advance as described above. It becomes a signal that rises greatly at the beginning of generation.

  Such a signal having a peak at an initial stage is called a differential type, but is suppressed by a certain positive parameter γ so that the differential type signal does not become sudden. The positive parameter γ is calculated from, for example, a look-up table from the load change rate of the boiler device and the corresponding control specification information.

  The “input value of the control specification” described in this specification refers to, for example, a steam enthalpy deviation of + A [° C.] to −B [° C.] and a main steam pressure deviation of + C [MPa] to −D [MPa]. The power generation output deviation is + E [%] to -F [%], and the control specified values predetermined for controlling the boiler / turbine system safely and efficiently, such as the main steam allowable pressure deviation value. Show.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an overall control device for power generation output, main steam pressure, and steam enthalpy in a boiler / turbine system according to an embodiment of the present invention.

  As shown in FIG. 1, feed water is introduced into a boiler device by a pump 11, most of which is led to a water wall 14 via a economizer 12, and part of the feed water is supplied from a branch point 22 to a primary spray water 23 and Used as secondary spray water 24. The water wall 14 constitutes the outer peripheral wall of the furnace 13, and the water passing through the water wall 14 is heated by the combustion gas generated by the combustion of fuel by the burner. This is converted into steam through the cage 15 and the brackish water separator 16, and in the present embodiment, is sequentially heated by the primary superheater 17, the secondary superheater 18, and the tertiary superheater 19 to become superheated steam.

  The superheated steam passes through a governor 20 provided in the main steam path, is supplied to a steam turbine 21 (only a high-pressure turbine is shown in the figure), contributes to power generation, and is further sent to a reheat loop (not shown).

  The boiler / turbine system is controlled by a function generator (Fx) 30, 31 based on a load request signal (MWD) 50 for the boiler device, and a main steam pressure set value 60 and a steam enthalpy set value (primary superheater inlet). Enthalpy setting value) 70 is generated. The amounts to follow the load request signal (MWD) 50, the main steam pressure set value 60, and the steam enthalpy set value 70 are the measured power generation output value 51, the main steam pressure value 61, and the steam enthalpy value 71. .

  An output deviation value 52 between the load request signal (MWD) 50 and the power generation output value 51 is obtained by a subtractor 32. A main steam pressure deviation value 62 between the main steam pressure set value 60 and the main steam pressure value 61 is obtained by the subtractor 33. The enthalpy deviation value 72 of steam between the enthalpy set value 70 of steam and the enthalpy value 71 of steam is obtained by the subtractor 34. These deviation values 52, 62, 72 are input to the PI controllers 53, 63, 73 after appropriate non-dimensionalization, and feedback adjustment amounts 111, 112, 113 are calculated.

  The power generation output feedback adjustment amount 111, the main steam pressure feedback adjustment amount 112, and the steam enthalpy feedback adjustment amount 113 are input to the boiler dynamic characteristic waste time compensation device 1000. For the feedback adjustment amount 112 of the main steam pressure, a third output signal 102 is newly obtained after the arithmetic processing. The feedback adjustment amounts 111 and 113 are used to generate the third output signal 102 in the boiler dynamic characteristic waste time compensation device 1000.

  Thereafter, the feedback adjustment amount 111 of the power generation output and the feedback adjustment amount 113 of the enthalpy of steam are output as they are from the boiler dynamic characteristic waste time compensation device 1000, and the feedback adjustment amount 111 of the power generation output becomes a command signal to the governor 20, 20 opening degree adjustment is performed.

  The third output signal 102 is added to the load request signal (MWD) 50 as a feedback component of the boiler input by the adder 35 to become a boiler input command signal (BID) 200. On the one hand, this boiler input command signal (BID) 200 generates a feed water flow rate preceding signal 201 by a function generator (Fx) 36, and on the other hand a fuel flow rate command signal 202 by a function generator (Fx) 37.

  The feed water flow leading signal 201 is added to the steam enthalpy feedback adjustment amount 113 by the addition block 38 and becomes a feed water flow command signal 301 to instruct a drive operation of the feed water pump 11. The fuel flow rate command signal 202 instructs the fuel flow rate input operation to the furnace 13 (burner).

  The load change rate 1110 calculated by the load change rate calculator (dL / dt) 1100 based on the load request signal (MWD) 50, and the control specification command signal given at that time stored in the control specification storage means 1300 1310 is input to the γ arithmetic circuit 1500, and a positive parameter γ1510 is calculated based on both pieces of input information. The positive parameter γ1510 is input to the boiler dynamic characteristic waste time compensation device 1000.

  FIG. 2 is a diagram showing the configuration of the boiler dynamic characteristic waste time compensation device 1000 and the flow of input / output signals around it. The process for calculating the feedback adjustment amounts 111, 112, and 113 is as described with reference to FIG.

  In the present embodiment, the boiler dynamic characteristic waste time compensation device 1000 includes first compensation element calculation means (DBp) 1012, second compensation element calculation means (DBF) 1032, and an addition block 39. The first compensation element calculation means (DBp) 1012 receives the feedback adjustment amount 111 of the power generation output and the positive parameter γ1510 obtained by the γ calculation circuit 1500 to obtain the first output signal 1512.

  The second compensation element calculation means (DBF) 1032 receives the feedback adjustment amount 113 of the enthalpy of steam and obtains a second output signal 1532. The output signals 1512 and 1532 are added to the feedback adjustment amount 112 of the main steam pressure by the addition block 39 and input to the boiler / turbine system 20000 as the third output signal 102 from the boiler dynamic characteristic waste time compensator 1000. .

  The boiler turbine system 20000 is represented as a block diagram including a first transfer function (G12) 2012, a second transfer function (G22) 2022, a third transfer function (G32) 2032, and an addition block 40.

  The third output signal 102 is input to the boiler turbine system 20000, and the second transfer function (G22) 2022 in the boiler turbine system 20000 is used to change the pressure change value 2522 along the causal relationship defined by the physical law. Will occur. That is, as shown in FIG. 1, the boiler input command signal (BID) 200 is obtained from the feedback adjustment amount 112, and the boiler device is controlled by the feed water flow rate preceding signal 201 and the fuel flow rate command signal 202. The value 2522 is generated. Then, when the pressure change value 2522 converges to zero, the main steam pressure set value (Pset) 60 is obtained.

  Here, the causal relationship is referred to as a transfer function in terms of system theory. The third output signal 102 is input to the boiler / turbine system 20000, and the pressure is changed by the second transfer function (G22) 2022. The value 2522 is obtained. A pressure change value 2512 obtained by the first transfer function (G12) 2012 from the feedback adjustment amount 111 of the governor 20 as a disturbance is added to the pressure change value 2522 by the addition block 40, and feedback adjustment of the water supply operation amount is performed. The pressure change value 2532 obtained from the amount 113 by the third transfer function (G32) 2032 is also added.

  The addition of the pressure change value 2512 is based on a causal relationship in which the main steam pressure immediately increases when the opening of the governor 20 is reduced, and the main steam pressure immediately decreases when the governor 20 is opened. The addition of the pressure change value 2532 is based on a causal relationship in which the main steam pressure slowly rises when a large amount of water is supplied and the main steam pressure slowly falls in the reverse operation.

  The first compensation element calculation means (DBp) 1012 takes into account the fact that the response speed of the main steam pressure by the governor operation is several times faster than the response speed of the main steam pressure by the boiler input operation. The contents will be described with reference to FIG.

  As shown in FIG. 3, the first compensation element calculation means (DBp) 1012 includes a waste time compensation calculation device 1590 and an operation amount reversing device 1595. The first compensation element calculation means (DBp) 1012 receives the feedback adjustment amount 111 of the power generation output and the positive parameter γ1510 obtained by the γ calculation circuit 1500.

  Then, the feedback adjustment amount 111 is differentiated by the waste time compensation computing device 1590 in consideration of the value of the positive parameter γ1510, and the differentiation result value 1511 is inputted to the manipulated variable inverting device 1595, and finally to the boiler input. The first output signal 1512 is obtained as the amount of bias.

  Here, the meaning of “differentiation” will be described with reference to FIG. 4, which is a diagram showing details of the waste time compensation calculation device 1590. As shown in the figure, the waste time compensation calculation device 1590 includes an incomplete differentiation calculation circuit 1591, a waste time difference setting unit 1592, a multiplier 1593, and an addition block 1594.

  The incomplete differentiation operation circuit 1591 calculates the incomplete differentiation s / (1 + γs) of the feedback adjustment amount 111 of the power generation output based on the delay time, and the obtained value and the waste time difference Δτ preset in the waste time difference setting unit 1592. Is multiplied by the multiplier 1593, and the value and the feedback adjustment amount 111 are added by the addition block 1594 to obtain a differentiation result value 1511. This can be expressed by the following formula.

(Differential result value 1511) =
(Feedback adjustment amount 111) + Δτ × s / (1 + γs) × (Feedback adjustment amount 111)
The waste time difference Δτ is a value obtained by subtracting the waste time τ12 of the main steam pressure response due to the operation of the boiler input from the waste time τ22 of the main steam pressure response due to the operation of the governor, that is, Δτ = τ22−τ12. Normally, the waste time τ12 is about 1/2 to ３ of the waste time τ22 and is smaller than the waste time τ22. Therefore, the waste time difference Δτ> 0 is usually a positive value.

  FIG. 5 is a diagram specifically showing details of the operation of the waste time compensation calculation device 1590 as a time trend (time characteristic).

  “A” in the figure is a time trend of the feedback adjustment amount 111 of the power generation output. When the opening degree of the governor 20 is adjusted based on this feedback adjustment amount 111, it is immediately transmitted via the transfer function (G 12) 2012. Appears as a pressure change value 2512. This is the time trend b shown in FIG.

  On the other hand, the feedback adjustment amount 111 is input to the first compensation element calculation means (DBp) 1012 to obtain a first output signal 1512 as a bias to the boiler input. This is the time trend c shown in FIG.

  The first output signal 1512 is converted as shown in the time trend c, but the amount added to the pressure fluctuation is a part of the pressure change value 2522 (see FIG. 2) shown in the time trend d. This is an amount obtained by converting the first output signal 1512, that is, the time trend c by the transfer function (G 22) 2522.

  However, in the time trend c, if a sufficient preceding value, that is, a differential amount is secured at the beginning of time, the sum of the time trend b (pressure change value 2512) and the time trend c (pressure change value 2522) is correspondingly the time trend e. Thus, the influence on the pressure from the feedback adjustment amount 111 is offset.

  Here, similar cancellation is shown for the second compensator (DBF) 1032, and then the first compensator (DBp) 1012 has a problem in contrast to the second compensator (DBF) 1032. The solution will be described next.

  First, the operation of the second compensator (DBF) 1032 will be described with reference to FIG. First, a change in the feedback adjustment amount 113 of the steam enthalpy deviation value 72 is considered as a trigger. The time trend f indicates a change in the feedback adjustment amount 113, and this feedback adjustment amount 113 is related to the feed water flow command signal 301 that instructs the drive operation of the feed water pump 11. The feedback adjustment amount 113 is input to the transfer function (G32) 2032 as shown in FIG. 2, and a pressure change value 2532 is output. The pressure change value 2532 slowly passes through the waste time τ32 as in the time trend g. And change.

  In order to cancel the pressure change value 2532, the feedback adjustment amount 113 is input to the second compensator (DBF) 1032 to obtain a second output signal 1532 that is a bias amount (see time trend h). ). It should be noted that this bias amount (second output signal 1532) is generated with a delay of τ32−τ22 = τD32. The waste time τ 32 is the time until the pressure change occurs, the waste time τ 22 is the time until the bias affects the main steam pressure, and the delay time τ D 32 is the delay time of the second output signal 1532.

  The bias amount (second output signal 1532) starts to affect the main steam pressure after time τ22 from the occurrence of the bias. However, since the bias amount (second output signal 1532) is delayed by time τD32 from the feedback adjustment amount 113 as a trigger, the bias amount (second output signal 1532) eventually affects the main steam pressure. Is after τD32 + τ22 from the input of the feedback adjustment amount 113 (see time trend i). This amount is τD32 + τ22 = (τ32−τ22) + τ22 = τ32.

  Therefore, after all, the influence on the main steam pressure by the bias amount (second output signal 1532) from the feed water to the boiler input is after the time τ22 from the trigger of the feedback adjustment amount 113, and the bias amount (second If the magnitude of the output signal 1532) is appropriately set, the pressure change (time trend i) due to the bias amount (second output signal 1532) becomes the pressure change (time trend g) due to the water supply trigger (feedback adjustment amount 113). Can be offset. The offset result is shown as a time trend j.

  It should be noted in the operation of this compensation element calculation means (DBF) 1032 that the influence of the main steam pressure by the feed water is later than the influence of the main steam pressure by the boiler input, and τ32> τ22. Therefore, τD32 = τ32−τ22> 0. Thus, the bias for canceling the trigger can be generated after the trigger in terms of time.

  However, in the compensation element calculation means (DBp) 1012 having the trend shown in FIG. 5, when the corresponding delay time τD12 is calculated, it can be seen that τD12 = τ12−τ22 <0 and a negative value is obtained. That is, in FIG. 5, the bias signal (time trend c) for canceling the pressure change (time trend b) due to the feedback adjustment amount 111 (time trend a) that triggers the governor 20 is greater than the trigger (time trend a). Must occur first.

  However, since the information of the trigger (time trend a) is obtained and the bias signal (time trend c) is generated, it is impossible to generate a scheduled harmonic bias signal as described above.

  Therefore, a very large bias signal is generated immediately when the trigger is generated, and works to cancel the pressure change (time trend d) where the scheduled harmonic bias signal would cancel. This is the meaning of the differentiation, that is, the preceding signal in the compensation element calculation means (DBp) 1012. As seen in the bias signal (time trend c) in FIG. 5, a very large bias signal (initial peak) is generated when the trigger occurs. Must.

  However, the fact that such a very large signal is temporarily added to the boiler input means that the operation value of the water supply or fuel is very fast considering that the preceding value of the water supply or fuel is determined by the boiler input. This means that it must be operated largely, and is a situation that should be avoided from the viewpoint of damage to the operating end of a hardware device such as a pump or a valve.

  In other words, the problem of the compensation element calculation means (DBp) 1012 is that the bias signal must be raised very quickly at the time when the trigger is raised, and that the disturbance to the main steam pressure can be sufficiently removed. There is a demand for coexistence of contradictory elements.

  In order to solve this problem, a method for setting the parameter γ for incomplete differentiation in a timely manner based on the load change rate and the control specification input value will be described with reference to FIG. The upper part of the figure shows the relationship between the positive parameter γ (horizontal axis) and the main steam pressure deviation ΔP (vertical axis), and the lower part of the figure shows the positive parameter γ (horizontal axis) and the boiler input command signal (BID). ) With the amplitude ΔBID (vertical axis).

  Each is plotted against three levels of load change rates dL / dt1, dL / dt2, and dL / dt3, where dL / dt1 is, for example, a load change rate of 5% / min, and dL / dt1> dL The order is / dt2> dLdt3. Moreover, although the main steam allowable pressure deviation ΔPspec is shown in the upper diagram, the control specification requires that the main steam pressure deviation ΔP is equal to or less than the main steam allowable pressure deviation ΔPspec. In the control specification storage means 1300 shown in FIG. 1, the relationship among the main steam pressure deviation ΔP, the main steam allowable pressure deviation ΔPspec and the positive parameter γ is stored in advance.

  As is apparent from the upper diagram, for example, if the positive parameter γ is not set to be larger as the load change rate dL / dt is higher, such as the load change rate dL / dt1, the pressure deviation ΔP becomes the main steam allowable pressure deviation ΔPspec. There is a risk of exceeding.

  Therefore, in the present embodiment, the positive parameter γ for the load change rate dL / dt1 is set to a point γ1 where the main steam allowable pressure deviation ΔPspec and the line of the load change rate dL / dt1 intersect. Similarly, the point γ2 or the point γ3 is taken for other load change rates dL / dt2 and dL / dt3.

  In this way, by setting γ as a point where the main steam allowable pressure deviation ΔPspec also intersects with respect to a specific load change rate dL / dt, the pressure deviation ΔP can always exceed the main steam allowable pressure deviation ΔPspec. In addition, preset control specifications can be satisfied.

On the other hand, for example, in the positive parameter γ1, the amplitude ΔBID of the boiler input is larger than that in the positive parameter γ2 or the positive parameter γ3. In this embodiment of the present invention, the boiler input command signal ( (BID) is considered to suppress the amplitude ΔBID at the same time.
According to the present invention, in a boiler control device that controls steam enthalpy with feed water to improve temperature response and simultaneously achieves power generation output control by controlling main steam pressure with fuel, power generation output control or steam temperature The feedback adjustment for control suppresses the disturbance that will be applied to the pressure control as much as possible, and at the same time, the initial change of the adjustment amount can be suppressed to reduce the damage to the equipment at the operation end as much as possible. There is an effect.

1 is a block diagram showing an overall control device for power generation output, main steam pressure, and steam enthalpy in a boiler / turbine system according to an embodiment of the present invention. It is a figure which shows the structure of the boiler dynamic characteristic waste time compensation apparatus which concerns on embodiment of this invention, the flow of the input / output signal of the periphery, and the transfer function in a boiler turbine system. It is a block diagram of the 1st compensation element calculating means (DBp) which concerns on embodiment of this invention. It is a block diagram of the waste time compensation calculating apparatus which concerns on embodiment of this invention. It is a figure which shows the detail of an effect | action of the waste time compensation calculating apparatus as a time trend. It is a figure which shows the effect | action of the 2nd compensation apparatus (DBF) which concerns on embodiment of this invention as a time trend. It is a figure for demonstrating the method to set the parameter (gamma) of incomplete differentiation timely with load change rate and control specification in embodiment of this invention. It is a block diagram which shows the whole control apparatus of the electric power generation output in the boiler turbine system examined previously, the main steam pressure, and the enthalpy of steam. It is a figure which shows the signal system of the control apparatus in the boiler turbine system, and the transfer function in a boiler turbine system.

Explanation of symbols

  11: feed pump, 12: economizer, 13: furnace, 14: water wall, 15: cage, 16: brackish water separator, 17: 1 primary superheater, 18: secondary superheater, 19: tertiary superheater , 20: governor, 21: steam turbine, 22: branch point, 23: primary spray, 24: secondary spray, 30: function generator, 31: function generator, 32: subtractor, 33: subtractor, 34 : Subtractor, 35: adder, 36: function generator, 37: function generator, 38: addition block, 39: addition block, 40: addition block, 50: load request signal, 51: power generation output value, 52: Output deviation value, 53: PI controller, 60: Main steam pressure set value, 61: Main steam pressure value, 62: Main steam pressure deviation value, 63: PI controller, 70: Steam enthalpy set value, 71: Steam Enthalpy value, 72: steam enthalpy deviation value, 73: I controller, 102: third output signal, 111: feedback adjustment amount of power generation output, 112: feedback adjustment amount of main steam pressure, 113: feedback adjustment amount of enthalpy of steam, 200: boiler input command signal, 201: Feed water flow preceding signal, 203: Fuel flow command signal, 1000: Boiler dynamic characteristic waste time compensation device, 1012: First compensation element calculation means, 1032: Second compensation element calculation means, 1100: Load change rate calculator, 1300: Control specification storage means, 1310: Control specification command signal, 1500: γ arithmetic circuit, 1510: Positive number parameter, 1511: Differential result value, 1512: First output signal, 1532: Second output signal, 1590: Waste time compensation calculation device, 1591: Incomplete differentiation operation circuit, 1592: Waste time difference setting unit, 1594: Addition block , 2000: boiler / turbine control system, 2012, 2022, 2032: transfer function, 2512, 2522, 2532: pressure change value.

Claims (8)

Based on the power generation output deviation value calculated from the load request signal for the boiler and the power generation output value from the steam turbine, the main steam flow rate supplied to the steam turbine is controlled by adjusting the opening of the governor provided in the main steam path A first control loop to
A second control loop for controlling a fuel flow rate to be introduced into the burner based on a main steam pressure set value calculated based on the load request signal and a main steam pressure deviation value calculated based on the main steam pressure value;
A third control loop for controlling the feed water flow rate to be supplied to the water wall based on the steam enthalpy setting value calculated based on the load request signal and the steam enthalpy deviation value calculated based on the steam enthalpy value;
A positive parameter calculation means for calculating a positive parameter from the load change rate of the boiler and the input value of the control specification;
Input at least two deviation values of the power generation output deviation value, main steam pressure deviation value, steam enthalpy deviation value and the positive parameter, and output at least two boiler operation amounts based on the inputted deviation value A boiler control device comprising waste time compensation means. In the boiler control device according to claim 1,
The boiler control device characterized in that an input value of the control specification is a main steam allowable pressure deviation value. In the boiler control device according to claim 1,
The waste time compensation means includes first compensation element calculation means, second compensation element calculation means, and addition means,
The power generation output deviation value and the positive parameter are input to the first compensation element calculation means to output a first output signal, and the enthalpy deviation value of the steam is input to the second compensation element calculation means. To output a second output signal,
The boiler control device, wherein the first output signal, the second output signal, and the main steam pressure deviation value are added by the adding means to output a third output signal. In the boiler control device according to claim 3,
The first compensation element calculation means comprises an incomplete differentiation calculation means, a waste time difference setting means, a multiplication means, and an addition means,
The power generation output deviation value and a positive parameter are input to the incomplete differentiation calculation means, and the incomplete differentiation of the power generation output deviation value is calculated by a delay time,
The difference between the waste time of the main steam pressure response due to the operation of the governor set in the waste time difference setting means and the waste time of the response of the main steam pressure due to the operation of the boiler input is calculated by the incomplete differential calculation means. The incomplete differentiation of the generated power output deviation value is multiplied by the multiplication means,
The boiler control device, wherein the multiplied value and the power generation output deviation value are added by the adding means to output a differential result value. Based on the power generation output deviation value calculated from the load request signal for the boiler and the power generation output value from the steam turbine, the main steam flow rate supplied to the steam turbine is controlled by adjusting the opening of the governor provided in the main steam path And
Based on the main steam pressure set value calculated based on the load request signal and the main steam pressure deviation value calculated based on the main steam pressure value, the fuel flow rate to be introduced into the burner is controlled,
Based on the steam enthalpy setting value calculated based on the load request signal and the steam enthalpy deviation value calculated based on the steam enthalpy value, the feed water flow rate supplied to the water wall is controlled,
Calculate positive parameter from boiler load change rate and control specification input value,
Input at least two deviation values of the power generation output deviation value, main steam pressure deviation value, steam enthalpy deviation value and the positive parameter, and output at least two boiler operation amounts based on the inputted deviation value A boiler control method characterized by: In the boiler control method according to claim 5,
The boiler control method, wherein an input value of the control specification is a main steam allowable pressure deviation value. In the boiler control method according to claim 5,
The power generation output deviation value and the positive parameter are input to a first compensation element calculation means to output a first output signal,
The steam enthalpy deviation value is input to the second compensation element calculation means to output a second output signal,
A boiler control method comprising: adding the first output signal, the second output signal, and the main steam pressure deviation value to output a third output signal. In the boiler control method according to claim 7,
The power generation output deviation value and a positive parameter are input to the incomplete differentiation calculation means to calculate the incomplete differentiation of the power generation output deviation value by the delay time,
The difference between the waste time of the main steam pressure response due to the governor operation and the waste time of the main steam pressure response due to the boiler input operation and the incomplete differentiation of the power generation output deviation value calculated by the incomplete differentiation calculation means Multiply
A boiler control method comprising: adding the multiplied value and the power generation output deviation value to output a differential result value.

Images