JP3417658B2 - Pressure control device for nuclear power plant - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nuclear power plant, and more particularly to a pressure control device equipped with two types of pressure detectors having different characteristics and suitable for optimally controlling the reactor pressure.

[0002]

2. Description of the Related Art A main steam system and a turbine bypass system of a nuclear power plant will be described with reference to FIG. The flow rate of the steam generated in the nuclear reactor 1 is adjusted by the steam control valve 2 and guided to the steam turbine 3. This steam expands in the steam turbine 3, and the generator 4 directly connected by this work is driven to obtain an electric output. In addition to the main steam system , a turbine bypass system is provided which branches from the upstream side of the steam control valve 2 and reaches the condenser via the turbine bypass valve 5.

During normal operation, the pressure of the reactor 1 is adjusted by the steam control valve 2, and at this time, the turbine bypass valve 5
Is kept fully closed, but the opening of the steam control valve 2 is restricted when the plant is stopped or when an accident occurs in the transmission system. Adjusted by 5.

By the way, the opening degrees of the steam control valve 2 and the turbine bypass valve 5 are controlled by a pressure control device described below. In FIG. 7, the pressure signal output from the pressure detector 6 installed at the inlet of the steam turbine or at the reactor is input to the pressure controller 7, compared with the set pressure of the pressure setter 8, and the deviation calculator 9 calculates the deviation. Is calculated. The pressure deviation obtained here is input to the pressure regulation rate circuit 10,
The deviation signal multiplied by the pressure regulation rate is input to the low value selection circuit 11 as the total steam flow rate command signal. In the low value selection circuit 11, the low value signal is compared with the limit signal given from the load control device 12, and the low value signal is selected and output as the steam control valve opening signal. Further, the deviation calculator 13 calculates a deviation between the total steam flow rate command signal and the limit signal from the load determination device 12, and the deviation signal is output as a turbine bypass valve opening signal.

Normally, the pressure detector 6 is increased in number to improve reliability, but only one system is shown here for simplification. Further, the pressure detector 6 used here is capable of detecting a wide range of pressures, and further, particularly high accuracy is required in the pressure detection range as a measure for the load operation of the steam turbine.

[0006]

By the way, in recent years, in a nuclear power plant, there is a demand for automating the plant start / stop operation for the purpose of reducing the burden on the operator. In order to realize this, it is necessary to control the reactor pressure to a pressure lower than the conventional pressure, and the pressure detector 6 is required to have a wider detection capability.

However, when a pressure detector having a wide range of detection capability is applied, sufficient accuracy required in the load control range may not be obtained, and therefore, a narrow band having high accuracy at least in the load control range. A method is used in which a pressure detector and a broadband pressure detector capable of detecting a wide range are used together.

However, when two types of pressure detectors having different characteristics are used, switching of detection signals is indispensable. Therefore, when signals are switched, a disturbance due to a deviation occurs between the two signals and the pressure changes. There is a problem that the control falls into a disorder.

Therefore, an object of the present invention is to provide a nuclear power plant capable of maintaining stable pressure control when controlling the reactor pressure by using two types of pressure detectors having different characteristics. To provide a pressure control device.

[0010]

The present invention allows for a wide range of detection of steam pressure at the reactor or steam turbine inlet.
At least one broadband pressure sensor for broadband and
And at least the load control range from the pressure detector for the wide band
At least one for narrow band with high accuracy in
Narrow band pressure detector and within the detection range of the narrow band pressure detector
The pressure signal from the narrow band pressure detector and the wide band pressure detector
The first deviation output that outputs the deviation signal from the pressure signal from the output device
The calculator and the deviation signal are changed at a gentle and constant ratio.
The first change rate limiter and the output of the first change rate limiter are wideband.
A first adder for adding to the pressure signal of the pressure detector, and a narrow band
From a broadband pressure detector outside the detection range of the pressure detector
Between the pressure signal of the instrument and the pressure signal from the narrow band pressure detector
A second deviation calculator that outputs a signal and the deviation signal
The second rate-of-change limiter that changes at a constant ratio
Add output of rate limiter to pressure signal of narrow band pressure detector
Within the detection range of the second adder and the narrow band pressure detector
The second gate connecting the second deviation calculator and the second rate-of-change limiter
Open the circuit and connect the first deviation calculator and the first change rate limiter
While closing the first gate circuit, the pressure from the second adder
Select the force signal to the signal selector and detect the narrow band pressure detector.
Connect the first deviation calculator and the first rate-of-change limiter outside the output range.
Open the first gate circuit, and set the second deviation calculator and the second change rate.
While closing the second gate circuit connecting the limiter,
A judgment device that causes the signal selector to select the pressure signal from the calculator
And the pressure selected and output from the signal selector.
The reactor pressure is controlled by a signal.

That's right . The present invention is directed to the output signal of the signal selector.
When switching, whether the decision circuit is connected to the first and second gate circuits
Each of the paths is provided with a time delay timer that retains the contact signal output from the determiner for a certain period of time.

Further, the present invention replaces the rate of change limiter with a bias.
A difference calculator and an integrator are provided .

[0013]

When the two types of pressure detectors having different characteristics are used, the pressure signal from the wide band pressure detector is changed to the output signal of the narrow band pressure detector capable of highly accurate detection in response to the load operation of the steam turbine. Will need to be switched. In this switching, if there is a deviation between the two signals, the pressure control will be temporarily broken.

In order to eliminate this deviation, in the present invention, a deviation signal between the pressure signal from the narrow band pressure detector and the pressure signal from the wide band pressure detector is obtained within the detection range of the narrow band pressure detector. This is added to the pressure signal of the broadband pressure detector and output. On the other hand, outside the detection range, a deviation signal between the pressure signal from the wide band pressure detector and the pressure signal from the narrow band pressure detector is obtained, and this deviation signal is added to the pressure signal of the narrow band pressure detector and output. By adding this deviation signal, the pressure signal from the wideband pressure detector and the pressure signal from the narrowband pressure detector are detected even if the narrowband pressure detector is switched to during the load operation of the steam turbine, for example. Becomes the same value, the signal is not disturbed, and stable pressure control can be continued.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, the input end of the pressure control device 14 is connected to a wide band pressure detector 15 and a narrow band pressure detector 16 that individually transmit signals, and a reactor pressure signal is input. The same circuit is provided in the pressure control device 14 along the signal path. That is, the broadband pressure detector 1
The fifth side is the first adder 17, and the branch path is the first deviation calculator 1
9, the first gate circuit 21 and the first rate-of-change limiter 23, while the narrow band pressure detector 16 side is provided with the second adder 1
8, the branch path is the second deviation calculator 20, the second gate circuit 2
2 and the second change rate limiter 24.

Further, a judging device 26 for inputting the pressure signal from the narrow band pressure detector 16 is provided, and the contact signal is compared with the predetermined set pressure to determine the contact signal as the first and second gate circuits 21 and 22 and the signal. It is adapted to be output to the selector 25.

In the first deviation calculator 19, there is a deviation between the pressure signal from the narrow band pressure detector 16 and the pressure signal from the wide band pressure detector 15, and in the second deviation calculator 20, the deviation signal is between the wide band pressure detector. A deviation is calculated between the pressure signal from 15 and the pressure signal from the narrow band pressure detector 16, and the obtained deviation signals are respectively the first and second gate circuits 21 and 21.
22, it is output to the first and second adders 17 and 18 through the first and second change rate limiter 23, 24.

When the first gate circuit 21 is judged to be within the detection range of the narrow band pressure detector 16 by comparison with the set pressure in the judging device 26, it is closed by the contact signal issued from the judging device 26, while The second gate circuit 22 is adapted to be closed at other times. The first and second rate-of-change limiters 23, 24 have the first and second change rates for the control operation.
The deviation signals to the adders 17 and 18 are changed to a gentle constant ratio.

Further, in the signal selector 25, the contacts open and close according to the contact signal from the judging device 26 . When it is determined by the determiner that it is within the detection range of the narrow band pressure detector 16, the signal of the narrow band pressure detector 16 is selected as the pressure signal, and in other cases, the pressure signal from the wide band pressure detector 15 is selected. Is selected.

Each circuit provided after the pressure signal selector 25 is the same as that shown in FIG. 7, and the description thereof will be omitted.

The operation of the embodiment configured as described above will be described. The reactor pressure is detected by the narrow band pressure detector 16,
It is input to the determiner 26 as a pressure signal. When the pressure signal is equal to or lower than the lower limit of the detection range, the pressure signal from the broadband pressure detector 15 is input to the deviation calculator 9 through the signal selector 25, and the steam control valve opening signal according to the calculation result is generated. That is, this time, the first gate circuits 21 is cut, the pressure signal of the wideband pressure detector 15 is output as it is. On the other hand, the contacts of the second gate circuit 22 are closed, and a deviation is obtained between the pressure signal of the wide band pressure detector 15 and the pressure signal of the narrow band pressure detector 16 in the second deviation calculator 20. It is input to the second adder 18 through the 2 change rate limiter 24, where the narrow band pressure detector 16
Is added to the pressure signal from. The signal obtained at this time is equal to the pressure signal of the broadband pressure detector 15.

When the pressure fluctuates and rises from this state and exceeds the lower limit of the detection range of the narrow band pressure detector 16, a contact signal is output from the judging device 26 to the signal selector 25 to switch the contact, The pressure signal from band pressure detector 16 is conducted. In this switching, the deviation signal obtained by the second deviation calculator 20 as described above is added to the pressure signal from the narrow band pressure detector 16, and the wide band pressure detector 1
Since it has the same value as the pressure signal of 5, it is possible to switch smoothly without any disturbance.

At the same time, the second gate circuit 22 is cut off by the contact signal from the judging device 26 and the deviation signal is changed to zero.
The output signal of the adder 18 is the broadband pressure detector 1 so far.
The pressure signal from 5 changes to the pressure signal from the narrow band pressure detector 16.

As described above, the pressure of the reactor can be controlled according to the pressure signal from the wide band pressure detector 15 having a low detection range, and the pressure signal from the narrow band pressure detector 16 can be used as a measure for the load operation of the steam turbine. High-precision pressure control according to the above is also possible.

Regarding switching from the narrow band pressure detector 16 to the wide band pressure detector 15, when the contact signal becomes below the lower limit of the detection range of the narrow band pressure detector 16, the contact signal is the signal selector 25.
Is output to the broadband pressure detector 15. At this time, since the deviation signal obtained by the first deviation calculator 19 is added to the pressure signal from the wide band pressure detector 15,
The pressure signal has the same value and can be switched smoothly.

Another embodiment of the present invention will be described.

The present embodiment is suitable for avoiding a situation in which a disturbance is generated at the time of switching the pressure signal and the pressure control is squeezed. In FIG. 2, the first and second gate circuits 2
First and second time delay timers 27 and 28 are provided on the route from 1 and 22. The contact signal output from the determiner 26 is the first and second time delay timers 27, 2
It is retained for a certain period of time at 8, and then output to the first and second gate circuits 21 and 22.

In the embodiment shown in FIG. 1, the first and second rate-of-change limiters 2 for changing the deviation signals from the first and second deviation calculators 19 and 20 into a gentle and constant ratio.
Instead of 3, 24, as shown in FIG.
It may be configured by 0 and integrators 31 and 32. Needless to say, the embodiment of FIG. 2 can also be constructed in the same manner.

Further, with respect to the pressure control device of the nuclear power plant, it is general to increase the reliability by multiplexing, which is constructed as shown in FIG. Although the pressure control devices 14a and 14b of this embodiment are of two series, more pressure control devices can be used. The pressure control devices 14a and 14b are provided with signal selectors 33a and 33b, respectively, and can be used by switching between the series.

An embodiment in which a wide band pressure detector and a narrow band pressure detector are multiplexed is shown in FIG. This is because, for example, the wide-band pressure detectors 15a and 15b and the narrow-band pressure detectors 16a and 16b have a plurality of detection means, each of which is provided with a signal selector 34a or 34b. A pressure signal selected from the wide band pressure detectors 15a and 15b and the narrow band pressure detectors 16a and 16b is input to the pressure control device 14 and used for control.
The detection means may be three or more series.

[0031]

As described above, according to the present invention, the pressure detector for a wide band and the pressure detector for a narrow band for detecting the steam pressure at the inlet of the reactor or the turbine are provided so as to be within the detection range of the narrow band pressure detector. The pressure signal obtained by adding the deviation signal between the pressure signal of the narrow band pressure detector and the pressure signal of the wide band pressure detector to the pressure signal from the wide band pressure detector when The pressure signal from the band pressure detector is added with the deviation signal between the pressure signal from the wide band pressure detector and the pressure signal from the narrow band pressure detector to obtain the pressure signal. There is no gap between them, and it is possible to suppress the occurrence of disturbance due to the gap.

Therefore, according to the present invention, the pressure control of the nuclear reactor does not become out of order, the stable nuclear reactor pressure control can be maintained at all times, and the reliability in plant operation can be improved.

[Brief description of drawings]

FIG. 1 is a functional block diagram showing an embodiment of a pressure control device according to the present invention.

FIG. 2 is a functional block diagram showing another embodiment of the present invention.

FIG. 3 is a functional block diagram showing another embodiment of the present invention.

FIG. 4 is a functional block diagram showing another embodiment of the present invention.

FIG. 5 is a functional block diagram showing another embodiment of the present invention.

FIG. 6 is a system diagram showing a main steam turbine bypass system of a general nuclear power plant.

FIG. 7 is a functional block diagram showing a conventional pressure control device.

[Explanation of symbols]

14, 14a, 14b ... Pressure control device 15, 15a, 15b ... Broadband pressure detector 16, 16a, 16b ... Narrow band pressure detector 17 ... 1st adder 18 ... Second adder 19 ... 1st deviation calculator 20 ... 2nd deviation calculator 21 ......... First gate circuit 22 ......... Second gate circuit 25, 33a, 33b, 34a, 34b ... Signal selector 26 ......... Judger 27 ... 1st time delay timer 28 ………… Second time delay timer

Claims (3)

(57) [Claims] 1. At least one wideband pressure detector for a wide band capable of detecting a wide range of steam pressure at the inlet of a reactor or a steam turbine, and a precision higher than that of the pressure detector for the wide band at least in a load control range. At least one narrow band pressure detector for narrow band, and a deviation signal between the pressure signal from the narrow band pressure detector and the pressure signal from the wide band pressure detector within a detection range of the narrow band pressure detector A first deviation calculator for outputting
First change that changes the deviation signal at a gentle and constant rate
A rate limiter, a first adder for adding the output of the first rate-of-change limiter to the pressure signal of the wideband pressure detector, and a first adder from the wideband pressure detector outside the detection range of the narrowband pressure detector. A second deviation calculator for outputting a deviation signal between the pressure signal and the pressure signal from the narrow band pressure detector;
Second rate-of-change system that changes the signal at a gentle and constant rate
Limiter, a second adder for adding the output of the second rate-of-change limiter to the pressure signal of the narrow band pressure detector, and the second deviation calculator within the detection range of the narrow band pressure detector.
A second gate circuit connecting the second change rate limiter opening-out, wherein
A first game connecting the first deviation calculator and the first rate-of-change limiter
Circuit is closed and the pressure signal from the second adder is selected by the signal selector, and the first deviation calculator and the first change rate control are performed outside the detection range of the narrow band pressure detector.
-Out a first gate circuit for connecting the limiter unit opens, the second deviation calculation unit
And a second gate circuit that connects the second rate-of-change limiter and a determiner that causes the signal selector to select the pressure signal from the first adder. A pressure control device for a nuclear power plant, wherein the reactor pressure is controlled by a selected and output pressure signal. 2. A time delay timer for holding a contact signal output from the judging device for a certain time in a path from the judging device to the first and second gate circuits in response to switching of the output signal by the signal selector. the pressure control device of a nuclear power plant of claim 1 Symbol mounting, characterized in that provided respectively. 3. A pressure control system for a nuclear power plant according to claim 1, characterized in that a deviation calculator and the integrator in place of the change rate limiter.