JPH04366798A - Turbine controller - Google Patents

Abstract

PURPOSE:To provide a turbine controller by which reactor pressure can be stably held constant without closing up a steam regulating valve even if in the tripled main steam pressure signal lines of the turbine controller either two lines of them fail in the direction in which pressure is lowered. CONSTITUTION:Tripled main steam pressure signals v12, v13, v14 are input respectively to input signal detectors 23a, 23b, 23c. Signals of this line are output to an intermediate value selector 25 via contacts 24a, 24b, 24c. Main steam pressure backup signals V16, V17, V18 each of which is higher than a set pressure signal v5 are generated by a backup signal generator 27 and signals of this line are given to the intermediate value selector 25 via contacts 28a, 28b, 28c. Signal switches 29a, 29b, 29c are connected to the contacts 24a, 24b, 24c of the main steam pressure signal line and to the contacts 28a, 28b, 28c of the main steam pressure backup signal line.

Description

[Detailed description of the invention]

[Purpose of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbine control system for a nuclear power plant.

0002

2. Description of the Related Art An example of a turbine main steam system in a nuclear power plant is shown in FIG.

In FIG. 2, steam generated in a nuclear reactor 1 flows into a turbine 4 through a main steam stop valve (hereinafter referred to as MSV) 2 and a steam control valve (hereinafter referred to as CV) 3 to drive the turbine. , and then condensed in the condenser 5. Also,
Some steam is transferred from the turbine bypass valve (
(hereinafter referred to as TBV) 6, bypasses the turbine 4, and flows into the condenser 5. Always keep MSV2 fully open and C
The turbine speed and turbine inlet steam pressure are controlled by adjusting the valve openings of V3 and TBV6.

In this case, the turbine inlet steam pressure and the turbine speed are detected by a pressure detector 7 provided before the main steam stop valve 2 and a speed detector 8 attached to the turbine shaft, respectively.

In the new type of reactor, the turbine speed and the reactor dome pressure are controlled by detecting the reactor dome pressure instead of the turbine inlet steam pressure and adjusting the valve openings of CV3 and TBV6. Figure 3 shows the circuit configuration of the turbine control device.

In FIG. 3, the deviation between the set speed signal v1 set by the speed setter 9 and the actual speed signal v2 detected by the speed detector 8 is calculated by the adder 10, and further calculated by the load setter 11. The given setting signal v3 is added to adder 1.
2 and input to the low value selector 13 as the speed load command signal v4. On the other hand, the deviation between the set pressure signal v5 set by the pressure setting device 14 and the actual pressure signal v6 detected by the pressure detector 7 is calculated by the adder 15, and a low value is selected as the pressure deviation signal v7 (=v6 - v5). The signal is input to the device 13.

The low value selector 13 selects the speed load command signal v4.
In addition to the pressure deviation signal v7, the load limit signal v8 from the load limiter 16 and the maximum flow rate limit signal v9 from the maximum flow rate limiter 17 that limits the reactor maximum steam flow rate are input, and the lowest value among these is input. is output to the steam regulating valve position control circuit 18 as the steam regulating valve flow rate command signal v10.

Further, the difference between the pressure deviation signal v7 and the steam control valve flow rate command signal v10 is calculated by an adder 19, and is inputted to a low value selector 20 as a pressure flow rate deviation signal. Further, the deviation between the maximum flow rate limit signal v9 and the steam control valve flow rate command signal v10 is calculated by an adder 21, and is inputted to the low value selector 20 as a flow rate deviation signal. The low value selector 20 selects the low value from among these inputs and outputs it to the turbine bypass valve position control circuit 22 as the turbine bypass valve flow rate command signal v11.

[0009] Using the above-mentioned turbine control device, the following pressure control operation is normally performed. In pressure control operation, the speed load command signal v4 is set by the load setting device 11.
is set to be slightly higher than the pressure deviation signal v7. Further, since the load limit signal v8 and the maximum flow rate limit signal v9 are also set higher than the pressure deviation signal v7, the low value selector 13 selects the pressure deviation signal v7 as the steam control valve flow rate command signal v10. Therefore, v
7 = V10, so the calculation result of the adder 19 is zero,
Since this signal is also selected by the low value selector 20, the turbine bypass valve flow rate command signal v11 becomes zero. In this way, the turbine inlet steam pressure is controlled by CV3 and T
BV6 is fully closed.

During pressure control operation, the actual speed signal v2 increases, the load setting signal v3 decreases, the pressure setting signal v5 increases, the load limit signal v8 decreases, and the maximum flow rate limit signal v9
When a decrease occurs and becomes smaller than the pressure deviation signal v7, that signal is selected by the low value selector 13 and becomes the steam control valve flow rate command signal v9, and the CV3 operates in the closing direction. For example, load limit signal v8 decreases and v9 =
When v8 < v7, the adder 19 calculates v7 - v
8 is outputted, and is outputted via the low value selector 20 as the turbine bypass valve flow rate command signal v11. As a result, excess steam flows through the TBV 6 to the condenser 5.

[0011]

[Problem to be Solved by the Invention] When an increase in the pressure setting signal v5, a decrease in the load setting signal v3, and a decrease in the load control signal v8 occur during normal pressure control operation, this signal becomes the steam regulator flow rate command signal v10. selected as, CV
As mentioned above, CV3 operates in the closing direction, but even if CV3 closes a little, TBV6 opens and the reactor pressure is controlled to be constant. However, the TBV6 of a nuclear power plant is generally designed to flow a part of the turbine rated steam flow rate, so in the triple pressure detection system, any two of the systems are activated at the same time. If a failure occurs in the "low" direction, the CV3 valve will close rapidly and the reactor 1 will fall into a severe condition, which in the worst case may lead to a reactor scram.

The object of the present invention is to provide a triple main steam pressure signal system in which any two of the systems are at low pressure.
It is an object of the present invention to provide a turbine control device that can maintain a constant and stable reactor pressure without completely closing a CV even when a failure occurs in one direction. [Structure of the invention]

[0013]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a steam control valve that regulates the amount of steam introduced into the turbine, and a steam control valve that controls the amount of steam that bypasses the turbine and is discharged to the condenser. and a turbine bypass valve, and controls the turbine speed and turbine inlet steam pressure or reactor dome pressure by adjusting the opening degree of the steam control valve and the turbine bypass valve based on both the actual pressure signal and the actual speed signal. In the equipment, there is an input signal detector that outputs a signal when an abnormal value occurs in the detected main steam pressure signal, and when a signal is received from this input signal detector, the main steam pressure signal is cut off and a backup This device is characterized by being provided with a signal switcher that switches contacts to guide a signal, and a backup signal transmitter that outputs a backup signal with a higher value than the set pressure signal.

[0014]

[Operation] As a result, even if any two of the three pressure detection circuits fail in the "low" direction, stable pressure control is performed without the CV being fully closed.

[0015]

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

Triple main steam pressure signal v12,v
13 and v14 are input signal detectors 23a and 23b, respectively.
, 23c. Each signal v12, v13 of this system
, v14 are output to the intermediate value selector 25 via contacts 24a, 24b, and 24c. The intermediate value selector 25 selects the intermediate value among these, and outputs it to the adder 26 as the actual pressure signal v15.

On the other hand, main steam pressure backup signals v16, v17, and v18, which are higher in value than the set pressure signal v5, are generated by the backup signal generator 27 and applied to the intermediate value selector 25 via contacts 28a, 28b, and 28c, respectively. It will be done. In addition, signal switchers 29a, 29b, 29c
are contacts 24a, 24b, 24c of the main steam pressure signal system and contacts 28a, 28b, 2 of the main steam pressure backup signal system.
8c, respectively. Trigger signals for switching both signal systems are applied from input signal detectors 23a, 23b, 23c to signal switchers 29a, 26b, 26c. Next, the effect will be explained.

One system of triplexing will be explained. The main steam pressure signal v12 is compared with a set signal by an input signal detector 23a equipped with a comparator, and when it is out of a permissible value, a trigger signal is output to the signal switch 28a. As a result, the contact 24a switches to the contact 28a, and the main steam pressure backup signal v16, which is slightly higher than the determined pressure, is input from the backup transmitter 27 to the intermediate value selector 25. The same goes for the remaining Z lines that are triplexed.

In this way, any two of the triplexed signals, ie, v12-v13, v12-v14,
Even when a failure occurs in the direction of the signal "low" in the combination of v13-v14, a backup signal is input to the intermediate value selector 25 from the failed system.

Therefore, even if a failure occurs in the direction of "low" main steam pressure, the output of the intermediate value selector 25 does not decrease and is output as a main steam pressure signal, so that the CV
3 never fully closes. Thus, the reactor pressure can take over and remain stable, and a reactor scram cannot occur.

[0021]

As explained above, according to the present invention, even if any two of the three main steam pressure signal systems in the Durbin control device fail at the same time in the direction of "low" pressure, This has an excellent effect in that the complete closure of the CV does not occur and an unclosed reactor scram can be avoided.

[Brief explanation of drawings]

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

FIG. 2 is a system diagram showing a turbine main steam system of a conventional nuclear power plant.

FIG. 3 is a block diagram showing an example of a conventional turbine control device.

[Explanation of symbols]

3...Steam control valve 4...Turbine 23a, 23b, 23c...Input signal detector 25...Intermediate value selector 27...Backup signal transmitter 29a, 29b, 29c...Signal switch

Claims (1)

[Claims] 1. A steam control valve that adjusts the amount of steam introduced to the turbine, and a turbine bypass valve that adjusts the amount of steam that bypasses the turbine and is discharged to the condenser, and includes an actual pressure signal and an actual speed signal. In a turbine control device that controls the turbine speed and turbine inlet steam pressure or reactor dome pressure by adjusting the opening degrees of the steam control valve and the turbine bypass valve based on both of the following, an abnormal value is detected in the detected main steam pressure signal. an input signal detector that outputs a signal when a signal occurs, and a signal switch that switches a contact so as to cut off the main steam pressure signal while guiding a backup signal when receiving a signal from the input signal detector; A turbine control device comprising: a backup signal transmitter that outputs a backup signal having a higher value than a set pressure signal.