JP2597014B2 - Advance control signal correction device for boiler control - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an advance control signal correction device for boiler control in a control signal of a thermal power generation boiler.

[Conventional technology]

FIG. 3 shows a preceding control signal circuit in a conventional thermal power boiler. In the figure, reference numeral 1 denotes a differentiator, and 2 denotes a proportional calculator.

Conventionally, in order to improve controllability at the time of load change, the leading control signal 1 is proportional to the speed of the load change (load command signal 10S).
1S to 13S are added to water supply, fuel and air, which are the main control variables of the thermal power boiler.

For example, if the proportional calculator P is set so that the preceding control signal amount becomes 1 when the load change speed is 1% / min, 3% /
In the case of minutes, the preceding control signal amount is three.

[Problems to be solved by the invention]

In the control of the thermal power generation boiler using the conventional prior control signal circuit described above, the amount of the preceding control signal is determined only by the speed of the load change, the load change width is large, and the proportional arithmetic unit is used in accordance with the case where a large amount of the preceding control signal is required. When the speed of the load change is the same even when the load change width is small, the preceding control signal has the same amount and the optimum control result is not always obtained.

[Means for solving the problem]

The present invention takes the following means for solving the above-mentioned problems.

That is, as a preceding control signal correction device for boiler control, in a preceding control signal circuit for improving controllability when a load fluctuates in a thermal power generation boiler, a change rate limiter that inputs a load target value, And a function of inputting the load target value and outputting the change width of the difference, and a function of inputting the output of the subtractor and outputting a predetermined function that outputs a low value when the input is small. A generator,
Means for correcting the output signal of the preceding control signal circuit with the output of the function generator, wherein the change rate limiter outputs the load command signal when the load target value does not change,
The output is held for a predetermined time at the same time as the load target value changes.

[Action]

By the above means, the change rate limiter normally outputs the input load command signal as it is, but when the load target value changes, the output is simultaneously held for a predetermined time and input to the subtractor. The subtractor sends the range of change in the difference between the held load command signal and the load target value to the function generator. When the input is small, the function generator sends a predetermined function output, which is a low value output, to the output signal correcting means to correct the preceding control signal.

In this way, the preceding control signal is corrected according to the fluctuation range of the load.

〔Example〕

 One embodiment of the present invention will be described with reference to FIGS.

The description of the portions described in the conventional example will be omitted to avoid redundancy, and portions related to the present invention will be mainly described.

The output of the differentiator 1 is input to the proportional calculator 2 via the multiplier 3. The change rate limiter 5 receives the load command signal 10S and the load target value 15S, and sends the load command signal 10S to the subtractor 6. Further, the subtractor 6 inputs the load target value 15S and sends the output to the multiplier 3 via the function generator 4. Function generator 4
Outputs the function shown in FIG. 2, that is, the correction value 17S.

In the above configuration, the rate-of-change limiter 5 sets the load target value 15
Holds the output for a predetermined time at the same time as S changes. Further, the subtractor 6 inputs the held load command signal 10S and the load target value 15S, and inputs a change width 16S of the difference to the function generator 4. As shown in FIG. 2, the function generator 4 inputs a correction value 17S of 0.2 to 1.2 to the multiplier 3 according to the input, multiplies the output signal of the differentiator 1 and inputs it to each proportional calculator 2. .

In this way, when the load change width 16S is small, the preceding control signals 11S to 13S are reduced by multiplying 0.2 as the correction value 17S, and when the change width 16S is large, the preceding control signals 11S to 13S are multiplied by a correspondingly large value. By increasing the signals 11S to 13S, the optimum preceding control signal output for all load change patterns was realized.

〔The invention's effect〕

 As described above, the present invention has the following effects.

(1) Optimum control can be performed for all load change patterns, and unnecessary movements of, for example, water supply, fuel, and air have been eliminated.

(2) As a result, the steam temperature controllability at the time of load change and the time required for stabilization of the boiler are greatly reduced, and as a result, the operation of the thermal power generation boiler can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention, FIG. 2 is an input / output diagram of the function generator of FIG. 1 of the embodiment, and FIG. 3 is a block diagram of a conventional device. 1 ... differentiator, 2 ... proportional operator, 3 ... multiplier, 4 ...
... Function generator, 5 ... Change rate limiter, 6 ... Subtractor

Claims (1)

(57) [Claims] A change rate limiter for inputting a load command signal and a load target value, an output of the change rate limiter, and a control signal circuit for improving controllability of the thermal power generation boiler when a load fluctuates. A subtractor that inputs the load target value and outputs a change width of the difference, and a function generator that outputs a predetermined function that outputs a low value when the output of the subtractor is input and the input is small. Means for correcting the output signal of the preceding control signal circuit with the output of the function generator, wherein the rate-of-change limiter outputs the load command signal when the load target value does not change. A preceding control signal correction device for boiler control, wherein the output is held for a predetermined time at the same time as the value changes.