JPH1069312A - Method for preparing assumed detection signal in plant controller of thermal power plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain the reliability of a plant controller without multiplexing a detector by calculating substitutive signals for substituting actual detection signals from the detection signals in a relating other equipment by using a function based on relation. SOLUTION: When a pressure gage 9 is normal, a switching device 11 outputs low pressure steam pressure detection signals (a) as a low pressure steam pressure. The pressure gage 7 is connected to a subtractor 13 and sends out low pressure drum pressure detection signals (b). Generator output is converted to pressure loss (c) through a function generator 15 and the pressure loss (c) is inputted to the subtractor 13. The characteristics of the function generator 15 are led out from setting data in respective load bands. The pressure loss (c) is subtracted from the low pressure drum pressure detection signals (b) in the subtractor 13 and low pressure steam pressure substitutive signals (d) are outputted. Then, when the abnormality of the pressure gage 9 for generating the low pressure steam pressure detection signals (a) is detected by a different device, abnormality detection signals are inputted to the switching device 11, connection is switched and the low pressure steam pressure substitutive signals (d) are outputted as the low pressure steam pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a plant control device, and more particularly to a plant control device for a thermal power plant having a boiler and a steam turbine.

[0002]

2. Description of the Related Art In a conventional thermal power plant, in order to improve control reliability, a plurality of, for example, two or three detectors for detecting the same process amount are provided, and control of the control due to abnormality of the detector itself is performed. This prevents problems. Alternatively, the detection signal used for the control operation and the signal used for the monitoring are separated, and the reliability is ensured by grasping the abnormality of the elements constituting the control system as soon as possible.

[0003]

However, if a plurality of identical detectors are provided and multiplexed, not only the cost of the detectors increases, but also the cost of equipment for selecting a normal detector and the cost of related wiring. In addition, the cost of mounting the plant has increased, and the manufacturing and installation costs of the plant have increased. On the other hand, if the detector is 1
If the detector fails, the control based on the detection signal is not normal if the detector fails, which may cause another serious problem, and therefore, the reliability is low. If the control detection signal and the monitoring signal are not separated, the actual situation of the plant cannot be grasped. I had to give up driving. Therefore, the present invention provides a method for generating an alternative detection signal or an assumed detection signal that can be used for control operation when a detector becomes abnormal without multiplexing the detector, and maintaining the reliability of the plant control device. The task is to provide

[0004]

SUMMARY OF THE INVENTION In order to solve the above problems, according to the present invention, a thermal power plant including a plurality of devices connected in a predetermined relationship so that water changes in a predetermined state is controlled. In the plant control apparatus, an alternative signal or an assumed detection signal instead of the actual detection signal is calculated from the detection signals of other related devices using a function based on the relationship. For example, since the generator output has a predetermined relationship with the pressure loss of the steam pipe, the low-pressure steam pressure is calculated from the generator output and the steam drum pressure. Further, a substitute detection signal of the steam drum temperature is calculated using a steam table including a saturation temperature function based on the steam drum pressure, that is, the steam pressure in the drum. Further, a spray flow rate signal is calculated as an assumed detection signal from a feed water pump outlet flow meter signal at the outlet of the feed water pump and a feed water flow rate signal from the feed water flow meter at the steam drum inlet side.

[0005]

Embodiments of the present invention will be described below with reference to the accompanying drawings. In a thermal power plant, a low-pressure (steam) drum 1 and a low-pressure turbine 3 are usually connected by a steam pipe 5 as shown in FIG. A generator (not shown) is driven to generate an electric output.
In the plant control, the pressure gauge 7 and the pressure gauge 9 detect and use the low-pressure drum pressure and the low-pressure steam pressure, respectively. Here, when an abnormality occurs in the pressure gauge 9, FIG.
The alternative detection signal of the low-pressure steam pressure is calculated in the manner shown in FIG. In FIG. 1, a low pressure steam pressure detection signal a from the pressure gauge 9 is shown.
Enters the switch 11 and when the pressure gauge 9 is normal, the switch 1
1 outputs the low-pressure steam pressure detection signal a as a low-pressure steam pressure and uses it for plant control. The pressure gauge 7 is connected to a subtractor 13 and sends out a low-pressure drum pressure detection signal b.
The generator output is converted into a pressure loss via a function generator 15, and the pressure loss c is input to a subtractor 13. The characteristic of the function generator 15 is derived from the settling data in each load band, and is conceptually shown in FIG. Then, in the subtractor 13, the low pressure drum pressure detection signal b
From the low pressure steam pressure substitute signal d.
Is output. When an abnormality of the pressure gauge 9 that generates the low-pressure steam pressure detection signal a is detected by another device, the abnormality detection signal enters the switch 11 and switches the connection to change the low-pressure steam pressure alternative signal d to the low-pressure steam pressure. Output as

[0006] In the low-pressure drum 1, the temperature is also detected by the thermometer 17 in addition to the pressure. As shown in FIG. 4, the drum temperature detection signal f output from the thermometer 17 is
When the thermometer 17 is normal, the drum temperature detection signal f is output as it is from the switch 19 as the drum temperature, and is used for plant control. The pressure gauge 7
The low pressure drum pressure detection signal b is output to the function generator 21 and is converted into a drum temperature substitution signal g by a function of the saturation temperature obtained from the steam table (see FIG. 5). When an abnormality occurs in the thermometer 17, an abnormality detection signal enters the switch 19, switches the connection, outputs a drum temperature alternative signal g as a drum temperature signal, and uses it for plant control.

In a thermal power plant, as shown in FIG. 6, a water supply pump 23, a economizer 25 and a drum 27 are provided.
Are connected to the pipes, and flow meters 29 and 31 are provided in the pipe, and output a feedwater pump outlet flow rate detection signal and a feedwater flow rate detection signal, respectively. Although the spray flow rate of the spray flow 32 separated on the upstream side of the economizer 25 is not detected by an actual flow meter, an assumed spray flow rate is calculated as shown in FIG. In FIG. 7, a feedwater pump outlet flow detection signal m output from the flowmeter 29 enters the subtractor 33 as a positive input, while a feedwater flow detection signal n output from the flowmeter 31 is
It enters the subtractor 33 as a negative input. In this way, the assumed spray flow rate is calculated by the subtracter 33 and output.
When the above-described method of creating the substitute signal and the assumed signal is incorporated in a plant control device of an actual thermal power plant, a digital system as shown in FIG. 8 is used. That is, the above-described function generator and subtractor are integrated in the central processing unit 35, and data such as pressure loss of the pipe and a steam table are stored in the memory 37, and are appropriately called up by the central processing unit 35 and used for calculation. . And pressure gauge 7, thermometer 1
7. The flow meters 29 and 31 are connected to the central processing unit 35, and the low pressure drum pressure detection signal b, the drum temperature detection signal f,
Feedwater pump outlet flow rate detection signal m and feedwater flow rate detection signal n
To the central processing unit 35. Then, the substitute signals and the assumed detection signals calculated by the calculation are displayed on the CRT 39 and output by the printer 41 as necessary. Of course, it is used by incorporating it into plant control.

[0008]

As described above, according to the present invention,
Each parameter of the thermal power plant is obtained by a detector installed in advance, but its alternative detection signal or assumed detection signal is calculated and created from other parameters having a predetermined relationship. When it becomes
An alternative signal is selected and used so that plant control can proceed reliably without multiplexing detectors.

[Brief description of the drawings]

FIG. 1 is a partial system diagram showing a part of a thermal power plant according to an embodiment of the present invention.

FIG. 2 is a conceptual system diagram for implementing the method of the embodiment.

FIG. 3 is a characteristic diagram showing characteristics of one component member in FIG. 2;

FIG. 4 is a system diagram for performing a method according to another embodiment of the present invention.

FIG. 5 is a characteristic diagram showing characteristics of one component member in FIG. 2;

FIG. 6 is a partial system diagram showing another portion of the thermal power plant.

FIG. 7 is a system diagram showing another embodiment related to the partial system diagram of FIG. 6;

FIG. 8 is a conceptual diagram when each of the embodiments is incorporated into a control device of an actual plant.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 low-pressure drum 3 low-pressure turbine 7, 9 pressure gauge 11 switch 13 subtracter 15 function generator 17 thermometer 19 switch 21 function generator 23 feedwater pump 25 economizer 27 drum 29, 31 flow meter 32 spray flow 33 subtraction Container 35 Central processing unit 37 Memory

Claims (4)

[Claims] 1. A plant control apparatus for controlling a thermal power plant comprising a plurality of devices connected in a predetermined relationship, wherein the device control unit uses a function based on the relationship from detection signals from other related devices using a function based on the relationship. A method for generating an assumed detection signal in a plant control device of a thermal power plant, wherein the detection signal is calculated. 2. The assumption detection in the plant control device for a thermal power plant according to claim 1, wherein the plant control device for the thermal power plant calculates a low-pressure steam pressure from a generator output and a steam drum pressure. How to create a signal. 3. The plant control device for a thermal power plant, wherein a steam drum temperature is calculated from a steam drum pressure using a saturation temperature function.
A method for creating an assumed detection signal in a plant control device for a thermal power plant according to the above. 4. The assumption in the plant control apparatus for a thermal power plant according to claim 1, wherein the plant control apparatus for the thermal power plant calculates a spray flow rate signal from a feed water pump outlet flow rate signal and a feed water flow rate signal. How to create a detection signal.