JPS62105092A - Controller for nuclear reactor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a turbine control system for a boiling water nuclear reactor, and in particular, to an atomic control system that controls each state quantity of a nuclear reactor in parallel to improve responsiveness. Regarding a furnace control device.

[Background of the invention]

In conventional control systems for boiling water reactors (hereinafter referred to as BWRs), so-called governor-free operation in which turbine speed is given top priority results in large reactor pressure fluctuations, resulting in large neutron fluctuations and high neutron flux. There were concerns that it would lead to a scrum, and it was considered difficult. As a similar method, a control method was adopted in which the reactor pressure set point was changed in response to fluctuations in turbine speed, and the steam flow rate was temporarily increased or decreased, which was equivalent to governor-free operation. According to this method, it is possible to directly control the steam flow rate in response to turbine speed fluctuations to some extent, but compared to the method of directly controlling the regulator valve from the amount of turbine speed fluctuations, it has the following limitations in terms of quick response. Ta.

(a) Various compensation circuits are installed between the pressure setting device and the regulating valve in order to achieve stable pressure control, and a considerable time delay occurs in this section.

(b) Even if the pressure set point is changed according to the turbine speed deviation KE, the pressure will immediately follow, so the time for contributing to improving responsiveness is limited.

Incidentally, as an example of related technology, Japanese Patent Application Laid-Open No. 54-1
There is No. 44587.

[Purpose of the invention]

An object of the present invention is to provide a reactor control device in BνVR that corresponds to the amount of turbine speed fluctuation and directly coordinately controls the turbine steam flow rate 2w, child reactor pressure, and core flow i to realize governor-free operation. It is to be.

[Summary of the invention]

In a BWR, even if the pressure is varied within a predetermined range and at a rate below a predetermined rate of change, significant neutron flux fluctuations will not occur. The present invention attempts to realize governor-free operation by causing pressure fluctuations within these ranges.

In order to achieve the above object, the present invention first uses a regulator valve opening request signal bias setting device to switch from reactor pressure control to turbine speed control, and to add a bias to the output signal from the pressure controller. is provided to allow the low-value pass gate to select a signal for preferentially controlling the turbine speed.

Next, in order to perform governor-free operation within an allowable range of neutron flux fluctuations, a nonlinear speed regulation rate setting device is provided between the output of the turbine speed controller and the steam control valve and bypass valve of the turbine.

Further, regarding the signal from the turbine speed detector, after passing through a deviation limiter that limits the speed to a constant speed range, pressure fluctuations are integrated and used as the basis for determining whether or not one condition needs to be changed.

The pressure is changed according to the output to obtain the desired operating characteristics, but a circuit is provided to limit pressure fluctuations from the viewpoint of the allowable range of neutron flux fluctuations, and a signal is sent to the pressure controller marked #.

On the other hand, when the recirculation flow rate is busy, the output of the fjI divider is input to the nonlinear flow rate controller to make it insensitive to short-term minute fluctuations and to significantly extend the duration of governor-free operation.

[Embodiments of the invention]

Hereinafter, the present invention will be explained in detail using the embodiment shown in FIG. 1 and FIGS. 2 and 3.

FIG. 1 is a schematic configuration diagram showing an embodiment of a turbine control system equipped with a nuclear reactor control device according to the present invention. In the figure, the steam generated in reactor 1 is.

The main steam pipe 2 is led to a turbine 5 or a condenser 6 via a turbine steam control valve 3 or a turbine bypass valve 4.

The reactor pressure is controlled using the signal Cp from the pressure controller 8, so that the signal from the reactor pressure detector 7 has an offset corresponding to the output with respect to the pressure setting value Po. This is done by controlling the opening degree of the bypass valve 4. On the other hand, the turbine speed division is performed by controlling the opening degree of the turbine steam control valve 3 so that the signal from the turbine speed detector 11 matches the turbine speed setting value So.

A low value pass gate 9 is provided to determine the priority of reactor pressure control and turbine speed control.

When giving priority to normal reactor pressure control, either the output signal Cp of the pressure controller 8 or the sum C of the turbine speed deviation signal multiplied by the speed adjustment factor by the speed controller 12 and the load setting signal Lo
8, and the output signal Cp of the pressure controller 8 preferentially controls the opening degree of the turbine steam control valve 30. When the turbine speed increases significantly and CIl becomes smaller than C1, this priority relationship is reversed, and CB controls the opening degree of the turbine control valve 3 to control the reactor pressure and Cp.
Opening side nK of the turbine bypass valve 4 corresponding to Cs
It will be done more.

In order to give priority to turbine speed control i1' and achieve governor free operation, it is necessary to lower the C8 signal than the +Cp signal and cause the low value passage gate 9 to select the Cg flaw signal. Therefore, in the present invention, the turbine regulating valve opening request signal bar f
An ass projector 10 is installed on the input side of the low value passing gate 9. During governor free operation, the sum of the output signals Bt and Cp of the turbine control valve opening request signal bias setter 10 is set to be greater than CB. C8 controls the opening degree of the turbine control valve 30. On the other hand, the opening degree control of the turbine bypass valve 4 is performed in accordance with Cp and CsK, similarly to the conventional control device. The output signal 81 of the turbine control valve opening request signal bias setter 10 is determined as a steam light amount deviation value corresponding to neutron fluctuations. In this way, for a small turbine speed drop.

The opening degree control of the turbine control valve 3 by the Crt signal, that is, the governor free operation is performed without Cs increasing beyond Cp+Bt. Protective action is performed dynamically as the turbine speed decreases. Figure 2 shows these relationships.

A nonlinear speed regulation rate setting device 13 is installed on the output side of the speed controller 12 in order to perform banner-free operation with a pressure increase rate that is acceptable from the viewpoint of neutron flux fluctuations. Figure 3 shows an example of nonlinear characteristics. The bias value B2 is determined as the main steam cone difference value corresponding to the pressure increase rate (-B) that is allowable from the viewpoint of neutron flux fluctuations, and for turbine speed fluctuations in this range, P C8 decreases rapidly. (-B), CB is insensitive to a turbine speed increase that results in a main steam flow rate deviation exceeding (-B) up to a certain value. Furthermore, when the increase in turbine speed becomes large, the opening degree of the turbine control valve 3 is reduced in order to suppress turbine overspeed. The bias value Ll is determined as an allowable value from the viewpoint of turbine overspeed. For increasing turbine speed, C
Il is always smaller than Cp+B, and the opening degree of the turbine control valve 3 is controlled according to the C8 signal. FIG. 4 shows an example of the response when a relatively large increase in turbine speed occurs, and FIG. 5 shows an example of the response during a transient period when a large increase in speed occurs.

When the turbine speed increases beyond the dead zone, the opening degree of the turbine control valve 3 can be quickly reduced to suppress the turbine overspeed.

The above describes the control device for the turbine control valve 3 that is intended to achieve governor-free operation, but in reality, the reactor pressure fluctuates due to the deviation between the main steam flow rate and the reactor output, and the
, Since the signal is changed, governor-free operation can only be achieved for a very short period of time. In order to improve this, it is necessary to respond to fluctuations in the main steam flow rate, to change the reactor pressure within an allowable range, and to quickly change the reactor output. The turbine speed deviation limiter 14 has a limit value of 8
1. It passes the turbine speed deviation in B2 and shows the deviation between the reactor power and steam flow rate that actually occurred.

The integrator 15 has a time constant determined by the volume of the steam phase of the reactor, calculates pressure fluctuations caused by the deviation between the reactor output and the steam flow rate, and calculates the pressure fluctuation outside the actual reactor pressure within a predetermined range. The reactor pressure setting value is changed in response to the movement.

The pressure set value change restriction circuit 16 is provided to suppress pressure fluctuations to an allowable range from the viewpoint of neutron flux fluctuations. If the deviation between reactor power and steam flow 1 continues for a long time and the pressure exceeds a predetermined range, the pressure set point change command signal will not change, and as a result, Cp will change to maintain the pressure tolerance limit value. . Figure 6 shows an example of the response when the turbine speed S continues to decrease. Turbine 1.1! Weird S
CB increases and turbine steam it increases as .

The reactor pressure also decreases in accordance with the integral amount of deviation between the reactor output and the turbine steam flow rate. Due to the signal from the integrator 15, the reactor pressure set value also drops in response to the reactor pressure drop, so no change is seen in CP+81 for a while. When the reactor pressure change exceeds a predetermined value, the pressure set value changing circuit 16 is activated, and the pressure set value is fixed at the limit value.
At the same time, the Cp multiplier signal starts to decrease to maintain the reactor pressure at the pressure limit value, Cp+B+ becomes smaller than Cs, and the opening degree of the turbine control valve 3 is controlled.

The turbine steam flow rate is reduced due to the reduction of Cp+Bl, and the reactor pressure is automatically maintained near the pressure limit value.

If the absolute value of the output signal of the integrator 15 exceeds a predetermined value, the nonlinear flow controller 17 adds a limited old correction signal to the flow request signal of the direct recirculation flow side. By installing the nonlinear flow controller 17, it is possible to avoid unnecessary responses of the reactor output to minute and short-term fluctuations that account for most of the load fluctuations during governor-free operation, and the reactor It is possible to eliminate the reverse response phenomenon caused by the delay in answering. In addition, for small but relatively long-lasting load fluctuations, if a correction signal of a limited value is added to the direct recirculation flow rate request signal when the limit value is exceeded, it is possible to quickly change the output. It becomes possible to significantly extend the duration of governor-free operation. The limit value of the correction signal is based on the main steam flow rate tolerance B1. Since it is a minute amount determined as a change in core flow rate that provides a change in output corresponding to B2, even if the recirculation flow is input directly to the request signal, it will not have an adverse effect on operability or the like. The output of the nonlinear flow controller 17 is input to a recirculation flow controller 18 that controls the flow rate of the jet pump in the reactor 1 .

- Fig. 7 shows an example of governor free operation according to the present invention. When a slight increase in turbine speed S occurs, Cg decreases,
The opening degree of the turbine control valve 3 is throttled to reduce the turbine steam flow rate so as to suppress an increase in turbine speed. Along with this, the pressure setting value increases in a manner that follows the rise in reactor pressure, so that no significant change occurs in Cp+81. The turbine speed S eventually returns to a steady value due to a decrease in the turbine steam flow rate. Accordingly, the turbine steam flow rate also returns to its steady value. On the other hand, the neutron flux increases as the reactor pressure increases, but when the integral value of the deviation between the reactor power and the turbine steam flow rate exceeds a predetermined value, the core flow sharply decreases, albeit slightly. Subsequent increases will be suppressed. If a subsequent drop in turbine speed S occurs, the response described above will be the opposite, effectively controlling turbine speed S. Subsequent small speed fluctuations can be dealt with only by controlling the opening of the turbine control valve 3, and therefore the core flow rate is not changed. control amount as the main control variable, and simultaneously control the turbine adjustment valve opening, reactor pressure, and recirculated gJ light amount, and change them within a predetermined range and within a predetermined pressure change rate. It has become possible to achieve reactor pressure control that prioritizes turbine speed, which was thought to be difficult, and allows smooth governor-free operation without effectively suppressing neutron flux fluctuations.

By realizing governor-free operation, the load following ability of boiling water nuclear power plants can be significantly improved.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of a turbine side-turning system to which the reactor control system according to the present invention is applied, Fig. 2 is a functional explanatory diagram of the turbine control valve opening request signal bias setting device according to the present invention, and Fig. 3 is a nonlinear speed Figure 4 is an explanatory diagram of the function of the regulation rate setter. Figure 4 is a diagram explaining the function of the nonlinear speed regulation rate setter when a slight increase occurs in the turbine speed. Figure 5 is a diagram explaining the function of the nonlinear speed regulation rate setter when a large increase occurs in the turbine speed. Function explanatory diagram of nonlinear speed regulation rate setter,
FIG. 6 is an explanatory diagram of the response when the turbine speed continues to decrease, and FIG. 7 is a diagram illustrating the plant c5 response in the BWR employing the antibacterial device according to the present invention. l... Nuclear reactor, 2... Main steam pipe, 3... Turbine control valve. 4.-turbine bypass valve, 5...turbine, 6...
・Condenser, 7... Pressure detector, 8... Pressure controller,
9...Low value passage gate, 10...Adjustment valve opening request signal bias setter, 11...Turbine speed detector, 1
2... Turbine speed controller, 13... Nonlinear speed regulation rate setter, 14... Turbine speed deviation limiter, 15
...Integrator, 16...Pressure set value change restriction circuit, 1
7... Nonlinear flow controller, 18... Recirculation flow controller.

Claims (1)

[Claims] 1. The output of the reactor pressure controller and the output of the turbine speed controller are supplied to the turbine steam control valve via a low value selection means to drive the turbine, and the reactor output is controlled by the recirculation flow rate controller. In nuclear reactor control equipment, there is a bias setting device that adds a constant bias value to the output of the pressure controller and forcibly selects the output of the speed controller, and an integral that integrates the deviation between the set value and detected value of the turbine speed. The vessel and
a pressure set value change restriction circuit that outputs a signal to the pressure controller to change the reactor pressure according to the integral value; and a signal that causes the recirculation flow rate controller to change the core flow rate when the integral result exceeds a tolerance value. A nuclear reactor control device characterized by comprising: a nonlinear flow rate controller that outputs .