JPS61233801A - Control object setting device - Google Patents

Abstract

PURPOSE:To decrease the start time of a power generating plant by adopting the constitution that a changing route in an object setting is made variable depending on the type of an external increase/decrease signal so as to speed up the control operation. CONSTITUTION:A manual setting circuit 6 outputs a manual setting output Y1 in response to a manual increase PB 8 and a manual decrease PB 9. In this case, the rate of change of the output Y1 when the ON time of the PB 8 or PB 9 is Ta (sampling period)X10msec or below is 1/10 of that when the ON time is more than TaX10msec. Further, a high speed setting circuit 5 for a computer outputs a computer setting output Y2 depending on the increase/ decrease command form the computer. The rate of change in the setting value Y2 in this case is constant regardless of the ON time of the increase/decrease command. Then a switch 7 discriminates either the manual setting output Y1 or the computer setting output Y2 is to be used as an actual setting value and outputs a setting value Y.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a control target setting device that receives a plurality of sets of external increase/decrease signals and converts the signals into target values for a control loop.

[Background of the invention]

In recent years, thermal power plants have taken on the role of load adjustment plants during peak power times.

For this reason, D S S (Daily 5tart 5t
(op) is required, and the challenge is how quickly to start up the plant and supply power.

Conventionally, as described in Japanese Unexamined Patent Publication No. 56-132603, in a DSS plant, a startup curve is incorporated into control information in advance for the purpose of rapid startup of the plant, and speed and load settings are performed in accordance with this startup curve. This reduces startup time.

There are also examples of rapid startup of plants by predicting and calculating the thermal stress that will occur in the turbine rotor and setting the maximum speed increase rate or load change rate that will not cause excessive thermal stress at plant startup. .

The purpose of the above is to achieve high-speed startup of the plant by increasing the speed increase rate or load change rate, and in fact, efforts have been made to significantly shorten the startup time, but the time caused by the setting device itself is In addition, losses are not taken into consideration, and the guaranteed plant start-up time is becoming increasingly strict, so there is a need to further shorten the start-up time. Currently, some plants have strict start-up time guarantees that require hot start-up (start-up 6 hours after plant shutdown) to complete startup from ignition to rated load within 70 minutes. I am under pressure to do so. When the turbine speeds up, the maximum rate is 375 (rpm/win) for the turbine speed up rate.
) to save time. Even when the load increases, the maximum load rate that is determined by the boiler's load followability is used, but it takes a considerable amount of time to set the target load rate and the target load setting operation (about 0 to 6100% or 0%).
It takes about 1 minute of travel time from /sin to the maximum load rate. ) is a considerable loss of one hour.

The setting device reduces the rate of change of the target value in response to external increase/decrease signals so that fine adjustments can be made manually. This rate of change is the same for other increase/decrease signals, so when setting a target using a computer, the target setting operation becomes very slow.As a known example, a manual setting device (M
ST) can be mentioned.

However, since a computer can set targets with higher precision than manual operation, even if the setting operation is performed at a faster setting rate than the manual setting rate, the error from the target value can be made very small.

From the above background, external (manual settings, computer settings)
It became necessary to develop a high-speed target setter that could vary the rate of change in target setting depending on the type of increase/decrease signal from tc).

[Purpose of the invention]

An object of the present invention is to provide a control target setting device that can speed up control operations and shorten the start-up time of a power plant.

[Summary of the invention]

Up until now, a single manual setting device has been used as a setting device when performing set value control using a computer. This manual setting device literally allows the operator to manually set the control target value. This configuration is as shown in FIG. The operator visually checks the current setting value and confirms the “increase” in Figure 1.
Or turn ON the "decrease" PB. When this PB is turned on, the PBON time is detected in the setting device, and the set value is increased or decreased according to this time. The operator operates the PB so that the target set value is achieved while confirming the change in the set value by reading the value on an indicator provided on the setting device. At this time, the rate of change of the set value with respect to the PBON time is
It is adjusted so that the operator can set it to any value while reading the setting value instructions, and normally it takes about 60 seconds to change from 0 to 100%. Also, if the PBON time is within a certain period of time, the rate of change during this period is further reduced by about 1/10 so that minute adjustments can be made.

When setting this control target value using a computer, an operation similar to the PBON operation by an operator is performed.

That is, the PBON time required to change the set value to the target set value is calculated, and a pulse width output corresponding to the calculated time is output to the manual setting device. At this time, since this is done via a manual setting device, the rate of change is controlled by the rate of change adjusted according to the manual operation, and the time required to complete the setting to the control target value is not much different from when using manual operation. When setting with a computer, unlike setting by an operator, the current value and target value can be detected as digital values, so the pulse width can be determined strictly by calculation, and the pulse width output is an integer multiple of 5m5ec. Since it can be controlled within the range of , there is no need for fine adjustment in principle.Therefore, there is no need to limit the rate of change as with manual operation, and the set value can be changed at the maximum rate of change within a range that does not cause disturbance to the control. things are possible. This operating state is shown in FIG. Reducing start-up time is an important issue for today's heat generating plants, and predictive control of thermal stress is being adopted to ensure that the turbine's speed increase rate, load change rate, etc. can be maintained at the maximum allowable rate for the turbine. It is becoming. However, on the control device side that provides this set value, 1
Since this is done via a manual setting device, it takes about 1 minute to change the setting from 0 to 100%, although in principle high-speed setting is possible.

Therefore, in order to shorten the start-up time, the present invention provides a high-speed setting circuit dedicated to the computer without using a manual setting device when setting by a computer, and uses this high-speed setting circuit to set the control target value. This is a multi-set increase/decrease signal input type target setting device.

Therefore, if one device is used, there is no restriction on the rate of change in the case of setting by a computer, so the set value can be changed at high speed, and the start-up time of the plant can be significantly shortened.

[Embodiments of the invention]

Examples of the present invention will be described below.

FIG. 4 shows an embodiment of the invention.

FIG. 4 is a functional block diagram of a "multiple set increase/decrease signal input type target setting device" having a high-speed setting circuit 5 using a computer.
FIG. 6 is a functional block diagram when the embodiment shown in FIG. 4 is applied to a power generation plant.

First, the functions of the ``multiple set increase/decrease signal input type target setter'' will be explained.

In the figure, the "multi-set increase/decrease signal input type target setter" which has a high-speed setting function using a computer has a manual setting circuit 6 by an operator, a high-speed setting circuit 5 using a computer, and which one of these two setting outputs is output. It is constituted by a switch 7 that outputs a set value after determining whether to use it as an actual set value.

The functions of the manual setting circuit 6 are as follows. That is, when the 1 manual increase PB8 is turned on, 141 #j is output as the output of the AND circuit 1, and □ in FIG.
When B9 is turned on, x2 becomes “1” as the output of AND circuit 2.
" is output. When PB8 is OFF, X1 = O, P
When B9 is 0FF (7), the 1 manual setting circuit 6 which becomes X, =O is these xl.

Perform the following calculation using x2 as input and manually set output Y□
Output.

WK when a Xl = 1 p Xs = O,
Add +1 to

(WX　1≦10) When bx□=O,X,=1, WK is -1.

(WK1≧-10) Q　IWK, +<10 mule.

d If IWK□1=10.

e Set the division exception to WK.

f X, =X, =O,X□ =X, =
1. X, = 1 or X, = 117) when WKi = O, W
K, = 0 where WK, -WK is an internal variable for calculation of the manual setting circuit 6.
) T: sampling period (msee).

FIG. 3 shows the operation of this setting circuit. The horizontal axis represents time, and the vertical axis represents the setting value Y1. The set value Y is integrated using the output Y of the switch 7 as the initial value only when PB8 or PB9 is ONL, but the rate of change of the set value Y1 at this time is 10XTSmsoc or more unless PB is ONL. If the FB is turned on for more than 10XTS msec, then the following will occur.

Therefore, Rate 1=Rate2X1/10.

ON time of PB8 or PB9 is T, X 10 m5e
The rate of change of Yl in time less than c is T, x 10 mse
It becomes 1710 when it is equal to or more than e. This is done to facilitate manual fine-tuning.
m-Ca are the upper and lower limits of the manual setting output method Y, and the value of Yl is limited so that c2≧Yl≧C1.6 Next, the high-speed setting circuit 5 using a computer will be explained. The inputs Xa and X4 of the high-speed setting circuit 5, like the inputs X□ and X2 of the number of moves setting circuit 6, become king only when the increase or decrease command from the computer to the logical product 3 or 4 is ON. The high-speed setting circuit 5 performs the following calculation using these inputs Xa = X4, and outputs a computer setting output Y2.

aX, =1. When X, = O(7), WK, +
Do 1.

When b X, = O, X, = 1 (7), wKa is -1.

d Set the division exception to WK4.

When eX, =X, =O or X, =X4=1, WK, =WK
,=0 Here, WK, , WK are internal variables for calculation of the high-speed setting circuit 5, and C4 is a setting value change rate coefficient for computer setting. FIG. 5 shows the operation of this setting circuit. Y2 is integrated using the output Y of the switch 7 as the initial value only when the increase or decrease command from the computer is ON, but the set value Y at this time
The rate of change Rate 3 of 1 is regardless of the ONL and time of the increase/decrease commands.In the case of a computer, this is done by accurately calculating the time of the increase/decrease command ON and outputting it as the output during the pulse, so fine adjustment is required. It is not necessary, therefore, immediately after the input x1 or X changes from O to 1, as in the case of manual setting.

This is because there is no need to slow down the rate of change. C4 also sets the maximum allowable rate on the plant side. The switch 7 sets the manual setting value Y1. Using computer setting output Y2 as input, the following calculation is performed and setting output Y is output.

a　X, or when X=1, Y=Y.

b x, =X, =O (71 o'clock Y=Y1 The operation of this switch 7 is as follows.

■ When manual increase PB8 or manual area PB9 is OFF and the computer tank and decrease output are OFF, the value of Y is Y=Y. At this time, since the value of Y□ does not change, the value of Y is also held.

■ When manual increase PB8 or manual area PB9 is ON and computer increase/decrease output is OFF, Y = Y□ ■ When manual increase PB8 and manual area PB9 are OFF and computer increase/decrease output X or X4 is 1, Y = Y2 ■ Calculator When the increase/decrease output X or x4 is 1, even if 1 manual increase PB8 or manual range PB9 is ONL, Y=Y8 and manual operation is invalid.

■ If the computer tank and the reduced output X, , X, are ONL while manual increase PB8 or manual area PB9 is ON, Y=Y8, manual operation is invalidated, and computer operation takes priority. Also, at this time, WK of manual setting circuit 5.

WK is reset to "0".

Note that the function of this switch is originally one operating end.

This should be determined based on the concept of priority between computer and manual operations when operating the setting device, in this example.

The case of "computer priority" was described. In addition, there are cases where a ``manual priority'' or ``computer/manual selection switch'' is provided.In these cases, the processing of the switch 7 is as follows.

■ In case of manual priority a X, or when X2=1 Y=Y2bx□=X,
When =O Y=Y1 ■ In the case of calculator and manual selection switcha Calculator selection Y=Y2b Manual selection
Y=Y□ Next, an example in which the present invention is applied to a power generation plant will be explained using FIG.

When operating manually, the operator 1 inputs the plant information 27
A control target value is determined, and the set value is set in a plurality of sets of increase/decrease signal input type target value setting device 17 via the manual operation device 16. The manual operation device 16 is equipped with P'B for increasing direction and PB for decreasing direction, and the target is set by checking the deviation between the target value and the indicated value and pressing the corresponding PB. This manual setting command 24 is selected by the plurality of sets of increase/decrease signal input type target value setter 17 when the computer output signal 22 is not output, and is outputted as the control set value 25 to the controller 18. The controller 18 outputs the controller output 2 which was at the control setting value 25.
Roll a 6 to operate the control equipment and control the plant.

When operating automatically, the computer 12 determines the timing from the plant information 27 using the setting timing determining unit 13, and at the setting timing, calculates the deviation 21 between the target value and the current value in order to match the control target value corresponding to that timing. The subtracter 14 performs the calculation and outputs the result to the pulse width calculation section 15. The pulse width calculation section 15 calculates a pulse width corresponding to the setting deviation 21 using the pulse rate stored in advance, and outputs the pulse width 22 to the target value setter 17 of multiple set increase/decrease signal input type. Based on this output, a plurality of sets of increase/decrease signal input type target value setter 17 is automatically operated.

The computer side output 22 is selected to output the control setting value 25 to the controller 18. The subsequent equipment linkages operate the plant 19 in the same manner as during manual operation.

FIG. 7 shows a case where the plant is started (load increase) without using a multi-set increase/decrease signal input type target value setter.

From this figure, the load rise curves for the case where the plant is started using the solid line and the dashed line, respectively, are shown.

A total of 157 seconds of time was lost due to the time delay required for setting the target load rate and target load setting device.

This occurs when the setting operation is performed without using a multi-set increase/decrease signal input type target value setter. It is clear that by using the device of the present invention, the startup time can be shortened by about 2 minutes, and it is possible to eliminate fuel loss due to load increase congestion.

〔Effect of the invention〕

In the past, with the aim of rapid plant startup, startup time was shortened by changing the startup east line, but there is a limit to how much time can be shortened due to the inherent characteristics of the plant; There was a limit and no further reduction in time could be expected. In contrast, the present invention aims to improve the characteristics of the setting device itself that influences plant startup, and to shorten the plant startup time. This is a very effective countermeasure.

The manual setting device can be set to enable minute settings.
e is variable depending on how long the push button is pressed, and when using this setting device in a computer setting, it is possible to set the target value with higher accuracy, but it involves unnecessary operations, resulting in considerable time loss. Conventionally, there is no device that can bypass this setting rate selection and set the target value at high speed.

Figure 7 shows the actual start-up results (solid line) in an actual plant, and the dead time required for setting the load nat a and target load is 157 seconds, which is equivalent to a little less than 4% of the time in a plant that requires a 70-minute start-up. . This time can be saved sufficiently by using wood, and it can be said that it is sufficiently effective in starting up in one minute. This dead time is caused by the setting device, so during this dead time, even though the boiler is storing fuel that can increase the load, it is not used effectively. This can greatly contribute to fuel savings.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the setting device, FIG. 2 is a functional block diagram of the manual setting device, and FIG. 3 is an explanatory diagram of the operation of the manual setting device. FIG. 4 is a functional block diagram of the multi-manual setting device, FIG. 5 is an explanatory diagram of the multi-manual setting device operation, FIG. 6 is a setting operation block diagram, and FIG. 7 is a plant startup curve diagram. 1.2, 3.4...Logic product circuit, high...speed setting circuit, 6...manual setting circuit, 7...switcher, 8,9...
...Manual PB.

Claims (1)

[Claims] 1. In a control target setter that accepts multiple sets of external increase/decrease signals and converts the signals into target values for the control loop, set the speed at which the target value of the setter is moved for each set of increase/decrease signals. A control target setting device characterized by having a circuit that changes each time.