JPS6329081B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the control of nuclear power plants, and particularly to a turbine control device for a nuclear power plant equipped with a boiling water light water reactor (BWR).

[Conventional technology]

Conventionally, nuclear power plants have been operated under base load operation in which the output of the turbine generator is kept constant, and since the output is constant, there is no need to vary it. However, in recent years, as the ratio of nuclear power generation to the total amount of power generation has increased, nuclear power plants are also required to play an intermediate load role, and there is a desire for automation of operation suited to this requirement.

Figure 2 shows the system of the BWR power plant. reactor 1
The steam generated flows into the high-pressure turbine 4 through the main steam stop valve 2 and control valve 3, rotating the turbine, and then flows through the intermediate steam stop valve 5 and intercept valve 6 into the low-pressure turbine 7, which rotates the turbine. Rotate. The steam that has done the work is then returned to water in the condenser 8. During normal operation, the steam generated in the reactor reaches the condenser 8 through the above-mentioned system, but in case steam cannot flow into the turbine due to a turbine trip, etc. It has a bypass system that connects to the condenser 8 via the bypass valve 9. The turbine control device 11 detects the pressure from the plant with a main steam pressure detector 12 and an intermediate steam pressure detector 14, a turbine speed signal with a speed detector 13, and a generator output current with a current detector 15. It controls the control valve 3, intercept valve 6, bypass valve 9, etc.

Figure 3 shows the control system of the control device. The signal set by the speed setter 21 is compared with the signal from the speed detector 13 at an addition point 22, and the deviation signal after the comparison is multiplied by a gain according to the adjustment rate at a speed adjustment rate circuit 23. It is sent to addition point 25. At the addition point 25, the load signal set by the load setting device 24 is further added. On the other hand, the signal set by the pressure setting device 30 is compared with the feedback signal from the pressure detector 12 at an addition point 31, and the deviation signal after the comparison is multiplied by a gain according to the adjustment rate in a pressure adjustment rate circuit 32. , is sent to the low value selection circuit 27 as a signal representing the total flow rate of main steam flowing into the turbine based on the pressure deviation (hereinafter referred to as the total flow rate signal). The low value selection circuit 27 adjusts or subtracts the minimum signal among the three signals, which are the signal from the addition point 25, the total flow signal from the pressure adjustment rate circuit 32, and the limit signal from the load limiter 26, as a load signal. Valve control circuit 2
8 and opens and closes the control valve 3 shown in FIG. 2 to control the flow rate of main steam flowing into the turbine.

Note that 34 is a bypass valve control circuit. This circuit has a function of controlling the opening and closing of the bypass valve 9, and is operated by the output of the subtracter 33. The output of the pressure adjustment rate circuit 32 and the output of the low value selection circuit 27 are input to the subtracter 33, and the deviation between them is calculated. When this deviation is zero, that is, when the output of the pressure regulation rate circuit 32 is selected by the low value selection circuit 27, the regulator valve 3 is in normal operation controlled by the full flow signal, and the bypass valve 9 is in normal operation. is considered to be fully closed.

Here, the relationship between the load setter 24 and the speed adjustment rate will be explained. Here, the description will be made using percentages relative to the rated value.

Now, assuming that the speed adjustment rate is 5%, the gain K of the speed adjustment rate circuit 23 is K=1/0.05=20. Also, set the speed regulator 21 to 100%,
Assuming that the load setter 24 is 100% and the power system frequency has increased by 1%, the input from the summing point 25 to the low value selection circuit 27 is (100-101) x 20 + 100 = 80 (%). Become.

Furthermore, assuming that the frequency of the power system increases by 5%, the input from the summing point 25 to the low value selection circuit 27 is (100-105) x 20 + 100 = 0 (%), and as a result, the load becomes 0. .

Also, assuming that the frequency of the grid is 100% without fluctuation, the low value selection circuit 27
The input to is (100-100) x 20 + 100 = 100 (%).

As a result of the above, the setting value of the load setting device 24 is
100% means that up to 100% of the load on the turbine can be tolerated.

Next, the pressure control device 56 will be explained. The pressure control device 56 includes a pressure setting device 30 that sets the main steam pressure, a pressure detector 12 that detects the actual main steam pressure, an adder 31, and a pressure adjustment rate circuit 32.

The pressure regulation rate of nuclear turbine control equipment is usually
It is ^about 2.1Kg/cm2. Here, the pressure setting device 30
Assuming that the set value of is 64.7 Kg/cm ² and the actual pressure of the main steam is 66.8 Kg/cm ² , which is 2.1 Kg/cm ² higher than the set value, the output of the pressure control device, that is, the pressure regulation rate circuit. The output of No. 32 is (66.8-64.7)/2.1 x 100 = 100 (%), and under these main steam pressure conditions, the turbine can be operated until the load on the turbine reaches 100% of its rating.

Also, if the actual pressure is, for example, 66.8Kg/cm ² to 1.05
Assuming that it has decreased by Kg/cm ² , the output will be 1.05/2.1×100=50(%), and the allowable load on the turbine will decrease. In this way, the output of the pressure regulation rate circuit 32 is
On the one hand, it represents the permissible value of the actual load of the turbine.

In the operation of a BWR having the above-mentioned control device, control is usually given to give priority to main steam pressure control. As a method, the low value selection circuit 2
7, a method is adopted in which the value of the other signal (in this case, the load signal, which is the output signal of the load setting device) is increased so that only the total flow signal, which is the output signal of the pressure adjustment rate circuit 32, is selected. . In this method, the operator recognizes the total flow rate signal from the pressure regulation rate circuit 32, which is the actual load, and uses the total flow rate signal to
This was achieved by manually setting the set value of the load setting device 24 to a value approximately % higher.

[Problem that the invention seeks to solve]

When the nuclear power plant was in base load operation, it was sufficient to perform the above load setting operation once or twice a year. However, as has been the case in recent years, when operations are performed in which the turbine generator output is changed each time based on instructions from a power dispatch center, the load setter has to be operated more frequently, increasing the burden on the operator.

An object of the present invention is to provide a turbine control device that can automate the operation of a nuclear power plant, that is, automatically follow the load setting device by adding a simple circuit, and can reduce the burden on operators. There is a particular thing.

[Means for solving problems]

The above purpose is to provide a circuit for determining the deviation between the output signal of the load setting device 24 and the output signal of the pressure adjustment rate circuit 23, and to automatically set the load setting device using a signal obtained by adding a constant bias signal to the deviation signal. This is achieved by

[Effect]

Since a constant bias is added to the deviation signal, the output of the load setter 24 is output from the pressure regulation rate circuit 32.
Automatically follows the output with a value deviated by the bias amount.

〔Example〕

An embodiment of the present invention will be described below.

In FIG. 1, the portion surrounded by dotted lines is the load follower 55. Its configuration is as follows: load setting device following width setting bias device (bias signal output means) 5
3, an adder (calculating means) 54, a comparator 51, and a comparator 52.

Next, its operation will be explained. Load setting device 2
The output signal of 4, the output of the pressure adjustment rate circuit 32, and the output of the load setter follow-up width setting bias device 53 are inputted to the adder 54, and added and subtracted as shown by the signs (+, -) in FIG. Do the following. The comparator 51 and the comparator 52 detect the calculation result, and the comparator 51
By driving the load setter 24 with the output pulse signal of the comparator 52, the load setter output automatically follows the output of the pressure regulation rate circuit 32 by 10% (this value of 10% is based on the output of the nuclear power plant). (This is a value that has been used empirically in turbine control).

Automatic tracking will be explained using a specific example. It is assumed that the output of the load setting device 24 is 50% as a percentage of the rated value, and the output of the pressure adjustment rate circuit 32 is 40%. Further, the output of the load setter follow-up width setting bias device 53 is constantly set at 10%. At this time, the output of the adder 54 is 40+10-50=0, so the comparators 51 and 52 do not operate and the set value of the load setter 21 does not change. Next, when the reactor output is increased, the actual pressure detected by the pressure detector 12 increases, and the output of the pressure regulation rate circuit 32 also increases. For example, assume that the output of the pressure regulation rate circuit 32 increases from 40% to 45%. The output of the adder 54 is 45+10-50=5>0, and the comparator 51 operates to increase the set value of the load setter 24, driving the load setter 24 and increasing the set value.

Now, when the output of the adder 54 becomes 5,
The output of the load setter 24 immediately increases from 50% to 55% based on the operation of the comparator 51 described above, so at this point the output of the comparator 51 becomes 0, and the output of the load setter 24 becomes equal to the pressure. It follows the output of the adjustment rate circuit 32 by 10%.

The same applies when the output of the pressure regulation rate circuit 32 decreases. In this case, comparator 52 operates.

FIG. 4 shows an operation chart of the automatic load following device 55. As the reactor output increases from _t1 to _t2 , the generator output (solid line in the graph) increases accordingly.

At this time, the output of the adder 54 becomes positive, the comparator 51 that drives the load setter 24 in the positive direction operates, and the output of the load setter 24 increases (dashed line in the graph).

If the reactor output is constant from t ₂ to _{t 3} , the generator output is also constant, and the output of the load setting device 24 is also constant.

When the reactor power is decreased from t ₃ to _{t 4} , adder 5
4 becomes negative, the comparator 52 operates, and the output of the load setter 24 decreases.

〔Effect of the invention〕

As described above, according to the present invention, as the reactor output is changed and the turbine generator output is changed, the output of the load setting device 24 can automatically follow the turbine generator output, and the burden on the operator is significantly reduced. be done.

It goes without saying that the present invention can also be applied to digital control systems.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a control device, FIG. 2 is a diagram showing a nuclear power plant system, FIG. 3 is a conventional diagram showing a control device, and FIG. 4 is an operation chart of an automatic load following circuit. 51...Comparator, 52...Comparator, 53...Load setter tracking width setting bias device, 54...Adder, 55...
Load following device.

Claims (1)

[Claims] 1. A nuclear power plant having a load setting device that sets the load applied to the turbine, and a pressure control device that sets the total steam flow rate of main steam based on the deviation between the pressure setting value and the actual pressure. In the turbine control device, a bias signal output means outputs a predetermined bias signal value; an output signal value of the load setting device and an output signal value of the pressure control device are input, and a deviation between these signal values is calculated. calculation means for outputting a value that is deviated by the value of the output signal of the bias signal output means with respect to the value determined by the calculation means; A turbine control device for a nuclear power plant, comprising a load following device that changes the set value so that the set value is deviated by the bias signal value with respect to the output signal value of the pressure control device. .