JPH03156602A - Method and device for control of plant - Google Patents

Abstract

PURPOSE:To improve the reliability of a plant protecting function by providing a means which inputs plural process value signals to one of two types of controllers, e.g. a master controller and sends the relative process value to the other type of controllers, e.g. the sub-loop controllers respectively. CONSTITUTION:Plural process value signals like a water supply flow rate signal 42 used to a cross limit circuit 601 as the boiler input value, a fuel flow rate signal 16, an air flow rate signal 53, etc., are inputted to a master controller 600 independent of the sub-loop controllers 700, 800 and 900. A means is provided to send the process value signals related to the controllers 700 - 900 respectively forming the cross limit circuit 601 via the controller 600. Therefore the circuit 601 which outputs a fuel command based on the water supply flow rate can work even though the water supply sub-loop controller 700 is cut off. As a result, the reliability is improved for a boiler protection control function.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to plant control, and particularly to a plant control device and control method suitable for boiler protection control.

[Conventional technology]

Conventional plant control equipment consists of a microcontroller, a mask controller,
This is often performed by a control system composed of a plurality of subloop controllers positioned below it. This is called a hierarchical function distribution system, and it is based on the idea that a failure in one subloop will not affect other subloop systems.It is a system configuration with extremely high autonomy, and is related to this type of equipment. For example, Japanese Patent Application Laid-Open No. 61-29901 can be mentioned.

On the other hand, regarding cross limit circuits in thermal power plant control systems, please refer to the magazine Thermal Power and Nuclear Power Generation VOL.
, 29, Nu 12, "Improvement of controllability of subcritical pressure once-through boiler", p88. The basic concept is described on p. 89. 6 Cross limit circuits are designed to maintain the flow rate of feed water, fuel, and air, which are the boiler input amounts, to maintain the power generation amount at that time and to ensure optimal combustion. If there is a deviation from the process amount, other input amounts are raised or lowered to appropriate amounts commensurate with the deviated process amount in order to continue stable combustion.

For example, if the air flow rate signal drops below the allowable range for some reason, the fuel flow rate is also lowered to an amount commensurate with the air flow rate drop, controlling the boiler to prevent incomplete combustion. Therefore, cross limit control can be said to be one type of boiler protection control.

The prior art will be described below with reference to FIGS. 6 to 11.

FIG. 6 shows an overview of the thermal power plant control system.

First, in response to the load request signal 7 from the central power supply station, the plant automatic control device 6 uses the load command calculation block 610 to generate a load command signal 602 corresponding to the output capacity of the power plant.
Create.

This load command signal 602 is transmitted to the generator output control block 6
90, it is compared with the current output signal 31 of the generator 3, and if there is an excess or deficiency, the control signal 691 is used to open or close the steam control valve installed at the inlet of the turbine 2, and set the generator output to the required value. maintain it.

On the other hand, the load command signal 602 takes into account the correction amount 604 of the main steam pressure correction calculation block 603 for maintaining the steam pressure signal 22 of the turbine 2 population at a specified value, which changes due to the opening and closing of the steam control valve, and the boiler input amount A command signal 605 is created.

This boiler input amount command signal is the boiler input amount. Basic demand signals for water, fuel, and air.

In response to the boiler input amount command signal 605, the function generator 710
Now, a feed water flow rate commensurate with the boiler input amount command signal 605 is programmed, and a basic feed water flow rate command signal 702 is output.

The cross limit circuit 701 compares this basic water supply flow rate command signal 702 with the fuel flow rate signal 16 and outputs a water supply command signal 711.

Here, details of the cross limit circuit will be described later using FIGS. 7 and 8.

The water supply command signal 711 is compared with the water supply flow rate signal 42 in a calculation block 790, and the water supply flow rate adjustment opening/closing command signal 7 is generated.
14 to open and close the water supply flow rate control valve 41.

At the same time, the boiler input amount command 605 is sent to the function generator 606
A combustion amount program command signal 607 is created.

In the steam temperature correction block 608, a combustion correction signal 609 is calculated to maintain the turbine inlet main steam temperature 23, which changes due to water supply control, at a specified value, and is added to the combustion amount program command signal 607, and the combustion amount basic command is calculated. signal 611
Create.

This combustion amount basic command signal 611 is compared with the water supply flow rate 42 in a cross limit circuit 601, and a combustion amount request signal 615 is output. This combustion amount request signal 615 is further compared with the air flow rate 53 in a cross limit circuit 801 to generate a fuel flow rate command signal 803.

This fuel command signal 803 is compared with fuel flow +116 in a fuel flow control calculation block 890, and the fuel flow adjustment command 803 is compared with fuel flow +116.
8 opens and closes the fuel flow control valve 15.

Further, a function generator 902 generates an air flow rate basic command signal 903 based on the combustion amount request signal 614.

The cross limit circuit 901 compares and verifies the basic air flow rate command signal and the fuel flow rate signal 16 to create an air flow rate command signal 907.

The air flow rate control calculation block 990 compares the air flow rate command signal 907 and the air flow rate signal 53, and opens and closes the forced draft fan inlet vane control 1-live 51 to control the boiler input air flow rate.

The above is an overview of the control device for a thermal power plant.

FIG. 7 shows a cross limit circuit of a conventional distributed control control device.

The control device includes a mask controller 600, a water supply subloop controller 700, a fuel subloop controller 800, and an air subloop controller 900.

The outline of the control device is as described above, and here we will explain the concept of distributed control and the cross limit circuit.

The master controller creates a boiler input amount command signal 605 and a combustion amount request signal 615, the boiler input amount command signal 605 is sent to the water supply subloop controller 700, and the combustion amount request signal 615 is sent to the fuel subloop controller 800.
and air subloop controller 900.

The function of the cross limit circuit 701 in the water supply subloop controller 700 is as follows.

That is, the function generator 7 uses the boiler input command signal 605 as an index.
At step 10, a water supply flow rate basic command signal 702 is created. On the other hand, the fuel flow rate signal 16 from the fuel subloop controller 800 is received, and using this as an index, the function generator 705 outputs the lower limit limit program signal 7 for the water supply flow rate basic command signal.
Outputs 06. This program is based on the 01 curve shown in FIG.

That is, the normal water supply flow rate value for the fuel flow rate signal is Qi
If it is expressed as , the normal value minus the allowable value is set as the lower limit value of the water supply flow rate command, and if the water supply flow rate basic command signal is lower than this, the high value selector 703 is set. Fuel-based program value 7
．． An operation to return to 06 is performed.

Furthermore, in the function generator 707, an upper limit value for the water supply flow rate basic command signal is set by programming Q2 in FIG. 8, and when the water supply command signal exceeds this output signal 708, Low value selector 709 operates to lower the value of fuel-based program high limit signal 708 .

Next, the cross limit circuit 601 for the basic combustion amount command signal 611 will be explained.

This cross limit circuit 601 applies a limit to the combustion amount command signal for the fuel flow rate and air flow rate from the water supply flow rate, and when the combustion amount command signal deviates from the normal balance value and increases with respect to the water supply flow rate. The function is to return the water to a position commensurate with the water supply flow rate.

That is, the function generator 612 programs the Q5 curve of FIG. 9 using the water supply flow rate signal 42 from the water supply subloop controller 700 as an index.

This is set by giving an allowable upper limit width to the normal balance curve Q4 for the water supply flow rate.

Here, in the case where the combustion amount basic command signal 611 is output above the upper limit signal 613 based on the water supply flow rate signal, the signal 613 is selected via the low value selector 614 to prevent the combustion amount command from increasing. It is something to do.

The cross limit circuit 801 of the fuel subloop controller 800 limits the fuel flow rate command signal 615 from the mask controller 600 using a fuel flow rate upper limit program signal 805 based on the air flow rate signal 53 created by the function generator 804. receive. This signal 805 is the first
The ρ3 curve shown in Fig. 1 is programmed, and the fuel flow rate command normal balance curve Q for the air flow rate signal. This is to prevent the fuel flow rate from becoming excessive relative to the air flow rate.

That is, the combustion amount basic command signal 615 is compared with the fuel command upper limit signal 805 based on the air flow rate, and if the combustion amount basic command signal exceeds this, the low value selector 802
The upper limit signal 805 is selected to prevent unstable combustion due to an imbalance in the air-fuel ratio.

The air subloop controller 900 includes a cross limit circuit 901 that inputs a signal from the fuel flow rate 16.

Basic combustion amount command signal 6 from mask controller 600
15 is received, and a function generator 902 generates an air flow rate basic command signal 903 that matches this.

On the other hand, the function generator 904 programs the Q7 curve in FIG. 10 using the fuel flow rate signal 16 as an index and sets a lower limit value for the air flow rate basic command signal 903.

That is, if the air flow rate basic command signal becomes a signal below the lower limit value based on the fuel flow rate, the high value selector 90
By selecting the lower limit signal 905 in step 6, this circuit prevents the air flow rate from falling excessively below the fuel flow rate, resulting in unstable combustion.

[Problem to be solved by the invention]

In a conventional plant control device, for example, when the water supply sub-loop controller is turned off, the water supply flow rate signal is no longer sent to the controller forming the cross limit circuit, so the cross limit control is excluded.

As described above, the conventional technology does not take into account the boiler protection control function when the subloop controller is disconnected, and has the drawback that the function is partially degraded when the subloop controller is disconnected.

An object of the present invention is to provide a plant control device and a control method that have a distribution mechanism that can protect a boiler even when a subcontroller is disconnected.

[Means to solve the problem]

In order to achieve the above object, a plant control device according to the present invention includes a plurality of controllers.

In a plant control device, one controller inputs a process quantity signal to be controlled via the other controller, and transmits it to the other controller to control the mutually related process quantities among multiple controllers in a distributed manner. The controllers are configured to include means for inputting a plurality of process quantity signals and transmitting process quantity signals associated with each of the other controllers via one controller.

One controller may be configured to include a plurality of controllers having the same mechanism.

Further, each of the other controllers may be configured to include a plurality of pairs of controllers having the same mechanism.

Furthermore, it is equipped with multiple controllers, and one controller inputs the process quantity signal to be controlled via the other controller, and transmits it to the other controller to control the mutually related process quantities among the multiple controllers in a distributed manner. In this plant control method, a plurality of process quantities are input to one controller, and process quantity signals related to each of the other controllers are transmitted via the one controller to control the plant.

One controller may be composed of a plurality of controllers having the same mechanism, and may have a multiplexed configuration.

Further, each of the other controllers may be configured to be composed of a plurality of pairs of controllers having the same mechanism and to be multiplexed.

Furthermore, the plant is equipped with multiple controllers that input flow rate signals for boiler feed water, fuel, and air to control the respective flow rates, and when one of the flow rates deviates from the specified flow rate, the deviated flow rate In a control device for a thermal power plant equipped with a cross limit circuit that limits the flow rate of the other according to the The controller includes means for transmitting a flow rate signal to the cross limit circuit of each controller.

A plurality of pairs of each controller may be provided.

Also, a plurality of cross limit circuit signal detectors that detect each flow rate signal and send it to each cross limit circuit, and a plurality of process control detectors that directly send the signal to at least one process control cross limit circuit. It is also possible to have a configuration in which

[Effect]

According to the present invention, since the process amount is input to each of the other controllers (subloop controllers) via one controller (mask controller) of the plant control device, the cross limit can be maintained even if the other controller is disconnected. Signals to the circuit are unaffected.

Furthermore, by multiplexing one controller or the other controller, even if one series fails, operation can be performed using a standby controller.

By transmitting the process amount to the other controller via an independently provided controller, the signal to the cross limit circuit is not affected even if one of the other controllers is disconnected.

Furthermore, by providing a signal detector for the cross limit circuit and a detector for process control, the cross limit control signal is not affected even if one of the detectors fails.

〔,Example〕

An embodiment of the present invention will be described with reference to FIG.

The present invention includes a plurality of controllers, one controller inputs a process quantity signal to be controlled via the other controller, and transmits the process quantity signal to the other controller so that the process quantity signals are related to each other between the plurality of controllers. In a plant control device that performs distributed control of the water supply flow rate signal 42, fuel flow rate signal 16. A plurality of process quantity signals such as the air flow rate signal 53, which in conventional technology were input to each subloop controller (the other controller), are now input to a mask controller (one controller) 600 independent of these subloop controllers. This configuration is provided with means for inputting a plurality of process amount signals and transmitting process amount signals related to each of the subloop controllers 700, 800, and 900 in which a cross limit circuit is formed via the mask controller 600.

That is, the fuel flow rate signal 16 used in the cross limit circuit 701 for the fuel water supply command formed by the water supply subloop controller 700 is
0 and is sent to the water supply sub-loop controller 700 for use.

Further, the water supply flow rate signal 42 used in the cross limit circuit 601 that outputs the combustion amount command from the water supply flow rate is input to the mask controller 600 and then used.

Similarly, the air flow rate signal 53. which is provided in the fuel subloop controller 800 and used in the cross limit circuit 801 which outputs the fuel command from the air flow rate. The fuel flow rate signal 16 provided in the air subloop controller 900 and used in the cross limit circuit 901 that outputs an air command from the fuel flow rate is also connected to the mask controller 600.
This is then used in each cross limit circuit.

According to this embodiment, even in a case where the water supply subloop controller 700 is disconnected, for example, the cross limit circuit 601 that outputs the fuel command from the water supply flow rate can operate, and its function can be continued.

Furthermore, in the case where the fuel subloop controller 800 is disconnected, the cross limit circuit 701 that outputs the water supply command from the fuel flow rate and the cross limit circuit 901 that outputs the air command from the fuel flow rate are operable and their functions continue. It has the effect of

Similarly, even in the case where the air sub-loop controller 900 is disconnected, the cross limit circuit that outputs the fuel command from the air flow rate is operable.

Its function has the effect of being continued.

Therefore, in the past, when the subloop controller was disconnected, the function of the cross limit circuit of the master control configured using the boiler input signal was lost, but this embodiment eliminates these drawbacks. This makes it possible to improve the boiler protection control function.

In addition, by inputting the water, fuel, and air flow rate signals used for cross limit control to a mask controller independent of the subloop controller, the system enables each subloop controller to switch from automatic operation to manual operation when the mask controller is disconnected. Since the logic is conventionally configured, even if it is controlled manually, for example, the water supply flow rate signal is input to the mask controller, and no functional degradation occurs.

Another embodiment that further improves the invention of FIG. 1 is shown in FIG.

This embodiment is based on the configuration shown in FIG. 1 and has a completely duplexed or multiplexed configuration by providing a plurality of mask controllers 600.

This embodiment has one main system as shown in Fig. 12, that is, the microcontroller has a power supply, CPU, and PIlo each configured in a single layer, whereas as shown in Fig. 13, the microcontroller has completely independent and identical mechanisms. When the main mask controller is disconnected, the reliability of the control by the cross limit circuit can be improved by switching to the standby master controller even when the main mask controller is disconnected.

Further, FIG. 3 shows another embodiment in which the subloop controller has a completely duplex configuration.

In this embodiment, each of the other controllers (sub-controllers 700, 800, 900) of the main system is connected to a plurality of pairs of controllers 700B, 800B having the same mechanism,
It is configured by duplicating 900B, and the second
It is possible to ensure functionality and reliability equivalent to those explained in the figure.

That is, even when the main system of the water supply subloop controller is cut off, for example, it is possible to switch to the standby system and continue operation, making it possible to improve the reliability of cross limit control.

FIG. 4 shows an embodiment of a configuration in which, among the water supply, fuel, and air signals, the signals used in the cross limit circuit are directly input to the respective controllers.

According to this embodiment, for example, even when the water supply subloop controller 700 is cut off, the mask controller inputs the water supply signal without going through the water supply subloop controller.
without causing the cross limit circuit 601 to stop functioning.
It becomes possible to satisfy the restriction function.

Further, as another embodiment of the present invention, the plant is provided with a plurality of controllers that input flow rate signals of boiler water supply, fuel, and air and control the respective flow rates, and the flow rate of one of them deviates from the specified flow rate. In a control device for a thermal power plant equipped with a cross limit circuit that limits the flow rate of one side according to the flow rate of one side that deviates from the flow rate of the other side, it is necessary to at least input each flow rate signal independently from each controller. One controller is provided, and each controller is provided with means for transmitting a flow rate signal to the cross limit circuit of each controller.

A plurality of pairs of respective controllers are provided, and the reliability of the thermal power plant control device is improved.

Furthermore, Figure 5 shows the water supply used for the cross limit circuit,
This is an example of a configuration in which the fuel and air flow rate detectors are installed independently of those for control, and are input directly to a controller forming a cross limit circuit.

In this embodiment, the power-off function of the sub-loop controller can be maintained at the same level as the invention shown in FIG. 4, and even if the detector fails, the control function can be satisfied.

〔Effect of the invention〕

According to the present invention, a means is provided for inputting a plurality of process quantity signals to one controller (mask controller) of a plant control device, and transmitting process quantities related to each of the other controllers (subloop controller). Because of this, even if the other controller is disconnected, the function of the cross limit circuit that continues to operate will not be lost.

The reliability of plant protection functions can be improved and unnecessary plant shutdowns can be avoided.

Furthermore, by multiplexing one controller or the other controllers 1 to 1, the reliability is further improved.

By providing a controller, it is possible to improve the reliability of the plant protection function in the same manner as described above.

Furthermore, since a cross limit circuit signal detector and a process control detector are provided, even if one of the detectors fails, a plant protection function is provided, further improving reliability.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram showing one embodiment of the present invention, Figures 2 to 5
The figure is a block diagram showing another embodiment of the present invention, Fig. 6 is a diagram of a thermal power plant control system, Fig. 7 is a diagram showing a cross limit circuit of the conventional technology, and Figs. Graphs showing limit restriction programs, 12th and 1st
Figure 3 is a configuration diagram of the microcontroller. 16... Fuel flow rate (process amount signal), 42... Water supply flow rate (process amount signal), 53... Air flow rate (process amount signal), 600... Master controller (one controller), 700...・・Water supply subloop controller (other controller), 800 ・・Fuel subloop controller (other controller), 900・
...Air subloop controller (the other controller). -1'l Fig. 8 Temperature machining quantity → Fig. Smoke゛Snoring quantity→ Fig. 6 昶'1f-j→ 1st drawing 'gLesu→ Fig. 2

Claims (1)

[Claims] 1. A plurality of controllers are provided, and one controller inputs a process quantity signal to be controlled via the other controller, and transmits the signal to the other controller so that the plurality of controllers can communicate with each other. In a plant control device that performs distributed control of process quantities related to the one controller, a plurality of the process quantity signals are inputted to the one controller, and the process quantities related to each of the other controllers are transmitted via the one controller. A plant control device comprising means for transmitting a signal. 2. The plant control device according to claim 1, wherein one controller is composed of a plurality of controllers having the same mechanism. 3. The plant control device according to claim 1, wherein each of the other controllers comprises a plurality of pairs of controllers having the same mechanism. 4. Equipped with a plurality of controllers, one controller inputs process quantity signals to be controlled via the other controller, and transmits them to the other controller to transmit process quantities related to each other between the plurality of controllers. In a plant control method that performs distributed control, the plant is controlled by inputting a plurality of the process quantities to the one controller, and transmitting the process quantity signals related to each of the other controllers via the one controller. A plant control method characterized by: 5. The plant control method according to claim 4, wherein one controller is composed of a plurality of controllers having the same mechanism and is multiplexed. 6. The plant control method according to claim 4, wherein each of the other controllers is composed of a plurality of pairs of controllers having the same mechanism and is multiplexed. 7. The plant is equipped with a plurality of controllers that input flow rate signals for boiler water, fuel, and air to control the respective flow rates, and when the flow rate of one of them deviates from the specified flow rate, the deviated one In a control device for a thermal power plant equipped with a cross limit circuit that limits the flow rate of one according to the flow rate of the other, at least one controller is provided that inputs each flow rate signal independently from each controller, A thermal power plant control device, characterized in that each controller is provided with means for transmitting a flow rate signal to the cross limit circuit of each controller. 8. The thermal power plant control device according to claim 7, wherein a plurality of pairs of respective controllers are provided. 9. A plurality of cross limit circuit signal detectors that detect respective flow signals and transmit them to respective cross limit circuits, and a plurality of process control detections that transmit directly to at least one process control cross limit circuit. 8. The thermal power plant control device according to claim 7, further comprising: a device for controlling a thermal power plant;