JPS6039845B2 - Nuclear turbine pressure control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a nuclear power turbine using a boiling water reactor as a steam generation source, and particularly relates to a pressure control device mainly including a steam control valve and a turbine bypass valve (hereinafter referred to as a bypass valve). .

In a nuclear power plant using a boiling water reactor as a steam generation source, the pressure of the reactor is controlled by controlling the steam pressure at the turbine inlet using a steam control valve and a bypass valve.

The flow of steam in this type of control system is as shown in FIG. 1, and the steam generated in the nuclear reactor 100 is transferred to the main steam stop valve 101, which is a turbine safety device, and the steam control valve 102, which controls the turbine inlet steam pressure. through the high pressure turbine 10
3.

The steam that has done work in the high pressure turbine 103 is transferred to the moisture separator 10
4, where moisture is removed, and then passes through a combination intermediate valve 105 to work in a low pressure turbine 106 and then to a condenser 10.
Condensation occurs at 7. The turbine bypass valve 108 serves to directly return excess steam generated from the reactor that is not needed by the turbine to the condenser 107 . In such a control system, the subordinate pressure history 109 is as shown in FIG.

The steam pressure at the turbine inlet is determined by the main steam stop valve 1 of the steam pipe (or header) that sends the steam generated from the reactor to the turbine side.
01, it is detected from the main steam pressure detection device 11 and converted into an electrical signal S. This turbine inlet steam pressure signal S. is compared with a predetermined pressure setting value V, in a pressure control circuit 211 adjusted to a lead/lag time constant unique to the plant, and a deviation signal S2 thereof is outputted from the pressure control circuit 211. This deviation signal S2 is converted into a steam flow rate signal S3, that is, a valve opening command signal, by a predetermined pressure adjustment rate control device 212. The signal S3 is sent to the low value control circuit 214 together with the steam control valve function command signal S5 (steam flow rate signal required on the turbine side) from the speed load control circuit 213 which receives the turbine speed signal S4 as input. . Low value priority circuit 21
The output signal S6 of No. 4 gives priority to the smaller one of the steam regulating valve opening command signal S3 of the pressure control circuit 211 and the steam regulating valve opening command signal S5 of the speed load control circuit 213. Send to. In this steam regulating valve control circuit 215, the steam regulating valve degree command signal S6 outputted from the low value priority circuit 214 is used as a nonlinear circuit 2 for correcting the nonlinearity of the steam flow rate with respect to the valve opening of the steam regulating valve.
18, and a signal S7 corresponding to the actual steam control valve opening degree.
The comparator 219 performs subtraction between
The deviation output signal is sent to the steam control valve servo amplifier 220.

The valve is opened until the deviation signal of the servo amplifier 22 disappears, that is, until the desired steam control valve function is reached. Usually, a plurality of such steam control valves are installed, and since nuclear turbines are operated at base load, the steam control valve control circuit is configured so that all the steam control valves have the same opening degree.

That is, in FIG. 2, steam regulating valve control circuits 215 are connected in parallel for the number of steam regulating valves, and all of them receive input from the low value priority circuit 214. In addition, the outputs of the pressure stabilization rate control device 212 and the low value priority circuit 214 are given to a bypass valve control circuit 217 for keeping the reactor pressure constant via a computing unit 216, and this circuit 217 is connected to the bypass valve control circuit 217. A request signal S8 is sent out. This will be explained in detail below. That is, in order to control the pressure on the nuclear reactor side, in principle, in a nuclear power turbine, steam generated on the nuclear reactor side passes through the steam control valve 102 and is all consumed by the turbines 103 and 106. Further, in order to give priority to the pressure control signal S3 under normal conditions, the signal S5 of the speed load control circuit 213 is biased with respect to the signal S2 from the pressure control circuit 211 by about 10% of the rated output in terms of turbine output. but,
When the speed load control must be used as the opening command signal for the steam regulating valve at the time of turbine startup, or when other signals such as a load limit signal are given priority as the steam regulating valve relation command signal, the pressure control circuit 211 A deviation occurs between the steam control valve opening command signal S3 and other signals. That is, if the opening command signal of the steam regulating valve is smaller than the steam regulating valve opening command signal S3 from the pressure control circuit 211, all the steam generated in the reactor cannot flow out to the turbine side by the steam regulating valve. A pressure increase in the reactor occurs. Therefore, the deviation is calculated by the calculation unit 216.
is subtracted by , and sent to the bypass valve control circuit 217 to send out the opening command signal S8 of the bypass valve 108.
Here, the amount of steam flowed by the bypass valve 108 by this signal S8 is determined from the amount of steam that must be consumed on the turbine side requested by the pressure control circuit 211.
The pressure in the reactor remains constant. That is, in this case, the main steam pressure will be controlled by the bypass valve 108. In the control device as described above, the steam regulating valve control circuit 215 includes a valve test circuit 221 for each steam regulating valve to check the operation of the steam regulating valve 102 or the sudden opening operation in an emergency.

This is the contact point 2 regardless of the steam control valve function command signal S6.
21a to the servo amplifier 2201 valve test signal S9
Enter. However, in this type of circuit, when a steam control valve opening/closing test is performed, the steam flowing into the turbine side changes, which is accompanied by a change in the pressure of the reactor, which is not preferable. Further, this pressure change is detected by the pressure control circuit 211, and a steam control valve opening command signal is issued to the steam control valves in other pressure control states to correct the pressure change, thereby attempting to keep the pressure constant. However, bringing about a pressure change is itself undesirable for a nuclear reactor, and this occurs primarily because the valve that is in the controlled state is separated from the control when testing the opening and closing of the steam control valve. This type of pressure change also occurs when the steam control valve enters an uncontrolled state due to failure of a servo amplifier or the like and is undesirable. This invention has been made in view of the above circumstances, and aims to provide a pressure control device for a nuclear turbine that can suppress pressure changes to the reactor side even when the steam control valve is placed in an uncontrolled state. purpose.
To achieve this object, according to the present invention, a plurality of steam control valves and a turbine bypass valve are opened based on the output of a pressure control circuit that inputs a turbine inlet steam pressure signal and outputs a valve function command signal. In a pressure control device for a nuclear power turbine that performs pressure control by controlling a pressure of a plurality of steam control valves, the pressure control device includes a calculation means for calculating an average value from signal values corresponding to actual relations of the plurality of steam control valves, and the valve relation command. Comparing means for comparing the signal and the output signal of the calculation means and outputting a comparison deviation signal thereof, and bypass valve control means for controlling the turbine bypass valve based on the comparison deviation signal output from the comparison means, Even if any of the steam regulating valves among the plurality of steam regulating valves becomes uncontrolled,
The turbine bypass valve is controlled in advance of the actual pressure change in the nuclear turbine to suppress the pressure change in the reactor. Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 3 shows an embodiment of the present invention, and the same reference numerals as in FIG. 2 indicate similar objects. In the figure, the servo amplifier 22 of the steam control valve control circuit 215 is driven by the output of the comparator 219, and the comparator 21
9 is a nonlinear circuit 218' that corrects the valve opening command signal S6 of the low value priority circuit 216 and the nonlinear characteristics of the actual control valve.
The signal S7 corresponding to the actual opening degree of the adjusting valve is compared with the signal S7. Further, the outputs of the non-linear circuits 218' of the control valve control circuits 215 and 215' are input to an adder 30 and added. The output of this adder 300 is converted to a value (n is the number of control valve control circuits) via a constant circuit 301. The output of this constant circuit 301 is used as one of the inputs of the arithmetic unit 302. Further, the other input of this calculator 302 is the output S3 of the pressure control circuit 212 via the pressure adjustment rate control device 212.
The computing unit 302 outputs the deviation of these inputs to drive the bypass valve control circuit 217. In addition, the computing unit 302
The alarm calendar 303 may be driven by the output. According to the above configuration, one of the input signals in the arithmetic unit 302 that drives the bypass valve control circuit 17 is a signal passed through the nonlinear circuit 218' that compensates the nonlinear characteristics of the valve for the actual steam control valve function. Since all the steam regulating valves are controlled to the same opening degree, a constant circuit is used in which the opening degrees of the steam regulating valves that have passed through all the nonlinear circuits are summed up by the calculator 300 and divided by the number n of steam regulating valves. 301, it is possible to form a steam flow rate signal that is actually flowing through the steam control valve.

Therefore, when the steam control valve is controlling the pressure, the signal S3 from the pressure control system and the signal from the constant circuit 301 are equal, so the output signal to the bypass valve control circuit 217 is zero. That is, the bypass valve is not controlled. Furthermore, when any steam regulating valve is in an uncontrolled state and the valve is closed, the signal of the constant circuit 301 indicates an output signal corresponding to the change in the opening degree of the steam regulating valve. The output signal of the constant circuit 301 decreases by the amount that the constant circuit 301 is closed, causing a deviation from the signal A (S3) from the pressure control circuit 211, and the output signal S5 of the bypass control circuit 217 causes the bypass valve to increase Only open. Therefore, even if the steam control valve leaves the controlled state and performs a valve closing operation, pressure control is achieved without increasing the reactor pressure. FIG. 4 shows another embodiment, in which, in addition to the configuration shown in FIG. 3,
Comparator 400, constant circuit 401, and contact 221a',
221b.

Comparator 400', low value priority circuit 214 and constant circuit 30
It uses the output of 1 as input and sends out the deviation output,
This output is sent to constant circuit 401 via contact 221a'. The fixed quantity circuit 401 is for inputting the number of inputs (M steam blades, the number of Metsuna control circuits), and the output of this circuit 401 is the one before the servo amplifier 220 of each steam control valve control circuit 215, 215'. It is input to comparator 219.

Each contact 221a', 221b is connected to the valve test circuit 2.
This is a contact that closes or opens when the contact 221a of No. 21 is closed for testing, and a contact similar to the contact 221b is provided in each steam control valve control circuit. This embodiment has the purpose of eliminating pressure changes when the steam control valve enters an uncontrolled state, as well as eliminating load fluctuations during valve stall.
A mechanism is added that distributes the flow rate signal of a closed valve to the valve open signal of the remaining valves. That is, the flow rate signal B obtained by summing the function signal S7 of each control valve through the nonlinear circuit 218' and the arithmetic unit 300 and dividing by the number of valves n and the low value priority circuit 2
A comparator 400 compares the signal C (S6) from 14 with the signal C (S6). At the time of the first valve test, if the comparator 400 is to perform the first valve test, the contact 221a is activated by a command from the valve test circuit 221 of the first steam control valve control circuit 215 prior to the valve test. ' is closed, contact 22
1b opens (Fig. 5 A, mouth). Here, valve test circuit 2
When the contact 221a of the test button 21 closes (FIG. 5C), an output deviation signal is generated from the comparator 40, and since the contact 221a', which is closed during the valve test, is closed, the constant circuit 4
The deviation signal is evenly distributed to the valves other than the valves being tested via 01. That is, the first valve is fully closed (FIG. 5, 2), and the remaining valves are opened accordingly (FIG. 5, tree).
As a result, during a valve test, the remaining valves can compensate for the load reduction caused by closing the first valve and keep the load constant. When the bypass valve is opened due to such reasons, it is possible to eliminate pressure changes and load fluctuations. According to this invention, as described above, the steam flow rate signal from the pressure control circuit is compared with the signal corresponding to the actual opening degree of the steam control valve, and the bypass valve is controlled based on the deviation signal. It is possible to provide a highly safe pressure control device for a nuclear power turbine that can achieve its purpose without causing a pressure change when a steam control valve is in an uncontrolled state such as during a valve test.

[Brief explanation of drawings]

Fig. 1 is a pressure control system diagram of a nuclear turbine, Fig. 2 is a system diagram of a conventional pressure control device, Figs. 3 and 4 are system diagrams of an embodiment of the present invention, and Fig. 5 is a system diagram of a pressure control device of a conventional pressure control device. FIG. 5 is an explanatory diagram of the operation of the embodiment of FIG. 4; 100...Nuclear reactor, 102...Steam control valve, 103,1
06...Turbine, 108...Turbine bypass valve, 109
... Pressure control device, 211 ... Pressure control circuit, 21
2... Pressure regulation rate control device, 213... Speed load control circuit, 214... Low value priority circuit, 215, 215'
...Steam control valve control circuit, 217...Bypass valve control circuit, 218, 218'...Nonlinear circuit, 219, 30
0,302,400...Comparator, -220...Servo amplifier, 221...Valve test circuit, 301,401...Constant circuit, 303...Alarm circuit, S. ...Turbine inlet steam pressure signal, S7...Steam control valve opening signal, S5...
・Bypass valve opening command signal. Multi-J scheme 3 figures Younger brother figure 2 Younger brother figure 4

Claims (1)

[Claims] 1 A nuclear power plant that performs pressure control by controlling the opening degrees of multiple steam control valves and turbine bypass valves based on the output of a pressure control circuit that inputs a turbine inlet steam pressure signal and outputs a valve opening command signal. In the turbine pressure control device, a calculation means for calculating an average value from signal values corresponding to the actual opening degrees of the plurality of steam control valves, and a comparison between the valve opening command signal and an output signal of the calculation means. and a comparison means for outputting the comparison deviation signal, and a bypass valve control means for controlling the turbine bypass valve by the comparison deviation signal output from the comparison means, A nuclear power turbine characterized in that even if a steam control valve goes into an uncontrolled state, a turbine bypass valve is controlled in advance of an actual pressure change in the nuclear turbine to suppress pressure changes in the nuclear reactor. pressure control device.