JP2868932B2 - Load distribution control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load distribution control device for a multi-can boiler installed in parallel for the purpose of obtaining steam or electric power.

[0002]

2. Description of the Related Art Conventionally, a configuration shown in FIG. 2 is known as a load distribution control device for a multi-can boiler installed in parallel for the purpose of obtaining steam or electric power.

The conventional load distribution control device shown in FIG. 2 shows a configuration of a load distribution control device of a multi-can boiler in which three boilers are installed in parallel, and the main steam pressure controller 1 is used as a master. As the combustion control devices 2a, 2b,
In order to implement the load distribution of the boiler connected to 2c, the set value from each of the load distribution ratio setting devices 3a, 3b, 3c is multiplied by the set value A from the main steam pressure controller 1 in the multipliers 4a, 4b, 4c. Of each combustion control device 2a, 2b, 2
The combustion control of c is performed.

In this conventional load distribution control device, when the combustion control devices 2a, 2b, 2c enter the cascade mode, they are controlled by the multiplied values.

[0005]

However, in such a conventional load distribution control device, the main steam pressure controller 1 as a boiler master transmits the combustion control devices 2a, 2b, 2 to each other.
c It is very difficult to make a bumpless press when connecting to each of them, and when determining the gain of the main steam pressure controller 1, it is necessary to use a control gain for controlling boilers having different process gains. It is difficult to decide,
There was a problem that response was slow or hunting occurred. For example, when the combustion control device 2a is in the cascade mode, control is performed by multiplying the signal A from the main steam pressure controller 1 by the load distribution ratio.
Alternatively, when the combustion control device 2c is put into the cascade mode, there is a problem that bumps are generated and affect the plant connected to the boiler.

The gain of the main steam pressure controller 1 is always constant regardless of the value of the load distribution ratio set by the load distribution ratio setting devices 3a, 3b, 3c. When the process gains of the boilers connected to 2b and 2c are different from each other, there is a problem in controllability, and there is a problem that a response is slow or a hunting phenomenon occurs.

The present invention has been made in view of such a conventional problem. In load distribution control of a multi-can boiler, a smooth control system without hunting when performing load distribution can be introduced. It is an object of the present invention to provide a load distribution control device that can set the gain of a steam pressure controller to an appropriate value and can enhance the controllability of the entire control system.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a load distribution control device for a boiler, wherein a load distribution ratio setting device, a single gain setting device for each boiler, and a load control device for each of these boilers are provided for the output of a main steam pressure controller. A first multiplier for multiplying the outputs of the distribution ratio setter and the independent gain setter, a adder for summing the outputs of the first multiplier, and an adder for the output of the main steam pressure controller. A second multiplier for outputting a correction gain by multiplying the outputs, a divider for performing a division using an output of the second multiplier as a denominator and a final control amount for each boiler as a numerator, a cascade mode A switching unit that switches from the output of the load distribution ratio setting unit to the output of the divider and outputs the result when the control mode shifts from the control mode other than the above to the cascade mode. The output of the multiplying an output of said second multiplier, is provided with a third multiplier for outputting as a load distribution ratio to each boiler.

[0009]

According to the load distribution control device of the present invention, the output of the main steam pressure controller is automatically changed even if the load distribution ratio is changed by the load distribution ratio setting device, the independent gain setting device, the multiplier and the adder. Set an appropriate gain.

[0010] When the mode is switched to the cascade mode, the load distribution to each boiler is not performed by the load distribution ratio setting device, and the final control amount immediately before the mode switching to each boiler is determined by the output of the main steam pressure controller. By dividing the value and multiplying the divided value by the output of the main steam pressure controller, the control amount immediately before and after the cascade mode is maintained, and the bumpless control is performed.

In this way, the gain of the main steam pressure controller is always kept properly, and the bumpless control can be performed when the cascade mode is switched.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention, showing a load distribution control device for a three-can boiler.

The output ΔMV (current output−previous output) of the main steam pressure controller 1 is output after being subjected to gain correction by the multiplier 5, and the previous output and ΔMV are added by the adder 6. And the output m is given to multipliers 7a, 7b, 7c connected to the combustion controllers 2a, 2b, 2c of each boiler.

The gain correctors 8a, 8b, 8 of each boiler
c is obtained by multiplying the set values of the load distribution ratio setting devices 3a, 3b, 3c and the individual gain setting devices 9a, 9b, 9c for each boiler in the multipliers 10a, 10b, 10c, and calculating all of these values. Are added by the adder 11 and output to the multiplier 5.

Further, the bumpless switch 12 of each boiler
a, 12b, and 12c are respectively the gain corrector 8 described above.
a, 8b, 8c load distribution ratio setting devices 2a, 2b, 2c
, And the dividers 13a, 13b, and 13c are multiplied by the switches 14a, 14b, and 14c.
b, 7c.

Between the multipliers 7a, 7b, 7c and the combustion controllers 2a, 2b, 2c, cascade / automatic switches 15a, 15b, 15c are provided, respectively.

Next, the operation of the load distribution control device having the above configuration will be described.

In order to apply gain correction to the main steam pressure controller 1, a load distribution ratio setting device 3 for setting the combustion ratio of each of the combustion control devices 2a, 2b, 2c.
Manually operated by a, 3b, 3c, for example, a
A load distribution ratio of 1, a2, a3 (a1 + a2 + a3 = 1.0) is set.

The individual gain setting units 9a, 9b, 9
The gain of each of the combustion control devices 2a, 2b, 2c is set to, for example, b1, b2, b3 by c.

Then, these set values are multiplied by multipliers 10, 10b and 10c, and gains c1, c2 and c3 for each boiler are set as follows: c1 = a1 * b1; c2 = A2 * b2; c3 = a3 * b3 These are added together by the adder 11, and as a final gain correction value d, d = c1 + c2 + c3 = a1 * b1 + a2 * b2 + a3 * b3 is obtained and given to the multiplier 5. Thus, gain correction is performed on the current operation amount ΔMV. In this way, a gain is applied to the set values of the individual gain setting devices 9a, 9b, 9c determined when each boiler is operated independently according to the load distribution ratio. And the appropriate gain can be applied.

With respect to the manipulated variable ΔMV thus obtained,
Next, the addition with the previous operation amount is performed in the adder 6, and the output is used as the combustion control device 2a, 2b,
2c.

The cascade / automatic switch 15a,
When the mode is switched to the cascade mode by 15b, 15c, the switch 14 of the bumpless switch 12a, 12b, 12c is provided to each of the combustion control devices 2a, 2b, 2c.
a, 14b, 14c are load distribution ratio setting devices 3
a, 3b, and 3c, the operation amounts m output from the main steam pressure controller 1 via the adder 6 are multiplied by load distribution ratios a1, a2, and a3, respectively. Each combustion control device 2a, 2
The load is distributed to b and 2c, and combustion control is performed.

However, if it is necessary to perform bumpless control when switching to the cascade mode, the bumpless switches 12a, 12b and 12c use the switch 1
4a, 14b and 14c are divided by dividers 13a, 13b and 13c
Side, and the final manipulated variable of each of the combustion control devices 2a, 2b, and 2c other than in the cascade mode is n1,
For n2 and n3, n1 / m, n2 / m, n
3 / m, this is given to multipliers 7a, 7b, 7c, and at the beginning of cascade mode switching, the manipulated variable n
The bumpless control is performed by continuously outputting 1, n2, and n3 to prevent the influence of a sudden change in the operation amount.

Then, as the system settles down, the switch 1
4a, 14b and 14c are used as load distribution ratio setting devices 3a and 3
Switch to b, 3c side to control combustion.

In this way, the gain correction is automatically set to an appropriate value for the main steam pressure controller 1 even if the load distribution ratio of each boiler is changed, and the combustion control devices 2a, 2b, 2c are set. When it is desired to switch to the cascade mode, bumpless control can be performed so that no bump is generated even when the mode is freely switched to the cascade mode, and thereafter the operation can be performed so as to slowly change the load distribution ratio to a predetermined one.

[0027]

As described above, according to the present invention, the gain of the output of the main steam pressure controller is corrected by the load distribution ratio setting device, the independent gain setting device, the multiplier and the adder. Therefore, even if the load distribution ratio is changed, an appropriate gain can be automatically set, and a load distribution ratio setting device,
Since the bumper is connected to the combustion control device using a divider and a multiplier, no bump is generated even when switching to the cascade mode. The labor burden for control can be reduced, and the driving operation can be facilitated.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention.

FIG. 2 is a block diagram of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main steam pressure controller 2a, 2b, 2c Combustion control device 3a, 3b, 3c Load distribution ratio setting device 5 Multiplier 6 Adder 7a, 7b, 7c Multiplier 8a, 8b, 8c Gain corrector 9a, 9b, 9c Single gain setting device 10a, 10b, 10c Multiplication device 11 Addition device 12a, 12b, 12c Bumpless switching device 13a, 13b, 13c Divider 14a, 14b, 14c Switching device 15a, 15b, 15c Cascade / automatic switching device

Claims (1)

(57) [Claims] 1. A load distribution control device for a multi-can boiler, comprising: a load distribution ratio setting device for each boiler, a single gain setting device, and a load distribution ratio setting device for each of these boilers. A first multiplier for multiplying the output of the gain setter, a adder for summing the outputs of the first multiplier, and multiplying the output of the main steam pressure controller by the output of the adder. A second multiplier that outputs a correction gain; a divider that performs division using an output of the second multiplier as a denominator and a final control amount for each boiler as a numerator; and a cascade from a control mode other than the cascade mode. A switching device that switches from the output of the load distribution ratio setting device to the output of the divider when the mode is shifted to the mode, and outputs the output of the switching device to the second switch. Multiplying the output of the adder, the load distribution control apparatus characterized by comprising providing a third multiplier output as a load distribution ratio to each boiler.