JPH0415439B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to an output control device for a nuclear power plant.

Technical background of the invention and its problems Conventionally, the reactor output and generator output of a boiling water nuclear power plant (BWR) have been controlled in such a way that the output of the reactor is controlled to obtain a commensurate generator output. I have to. There are two control methods for controlling the reactor output: output control using control rods and control of the coolant flow rate in the core using recirculation pumps. Normally, a certain amount of control rod withdrawal and insertion is performed.
The characteristic shape of the reactor power distribution is determined, and then the recirculation pump is controlled to change the coolant flow rate to raise or lower the power.

The recirculation pump was controlled by a pump speed setting device, which was manually operated by the operator. Therefore, when operating the recirculation pump speed to obtain a predetermined electrical output,
It is difficult to perform other monitoring or operations. By the way, when setting the speed of the recirculation pump, it is necessary to monitor the reactor output in parallel. This is because when attempting to obtain a predetermined electrical output, the reactor output may sometimes exceed the specified output. For example, this may occur when the vacuum level of the condenser decreases and the efficiency of the turbine decreases. In such a case, the electrical output should be set so that the reactor output is below the specified value. There must be.
Currently, the output of this reactor is monitored using a neutron instrumentation system.

Therefore, there is an idea to automate the control of electrical output, but due to the characteristics of the detector, there is no suitable process quantity as the main feedback for this output control.
It was difficult to automate.

Purpose of the Invention The first purpose of the invention is to reduce the burden on operators by detecting the main steam flow rate as the reactor output and automatically controlling the reactor output based on it. An object of the present invention is to obtain an output control device for a nuclear power plant that can prevent excessive thermal stress on fuel during ascending and descending.

In addition to the object of the first invention, a second object of the invention is to obtain an output control device for a nuclear power plant that can accurately match the electrical output ultimately required by the power system.

Summary of the Invention The first invention is characterized in that the first stage pressure signal of the turbine is used as the main steam flow rate signal when automatically controlling the output of the nuclear reactor.

A second invention is characterized in that, in addition to the features of the first invention, the final target value is adjusted to match the electrical output.

Embodiment of the Invention FIG. 1 shows a configuration diagram of an embodiment of the present invention. In a boiling type nuclear power plant, a nuclear reactor 1, a high pressure turbine 2, a low pressure turbine 3, and a generator 4 are the main equipment. Main steam from the reactor 1 is led to a high pressure turbine 2 through a main steam pipe 100, and outlet steam from the high pressure turbine 2 is led to a moisture separator 102 via a low pressure steam pipe 101.
and enters the low pressure turbine 3. The high pressure turbine 2 and the low pressure turbine 3 are directly connected to a generator 4 via a turbine shaft 103. The outlet steam of the low pressure turbine 3 is cooled in the condenser 5 and becomes condensate, which is then sent to the condensate pipe 104, the condensate pump 105, and the feed water heater 10.
6. React to the reactor 1 via the water supply pump 107, etc.
It has become a cycle of going back. Furthermore, reactor 1
A large number of core neutron flux detectors 10 are installed in the reactor core. A large number of position detectors 12 for control rods 11 that control the output of the reactor are also installed.

On the other hand, the reactor 1 has a recirculation loop 110A, 1
10B, and recirculation pumps 111A and 11, respectively.
1B to circulate coolant through the core. The recirculation pumps 111A and 111B are controlled by using a motor, a generator, and a fluid coupling, generally called an MG set, and the speed of the recirculation pump is controlled by controlling the transmission efficiency of the fluid coupling. Recirculation flow controller (PLR) for this speed control
200 is a speed controller 201 and a speed setter 20
2. Consists of a manual/automatic switch 203. Additionally, speed detectors 204A and 204B are installed to detect the speeds of the recirculation pumps 111A and 111B, and the output of each detector is transmitted to the speed controller 201.
connected to. In addition, a manual speed setting device 20
5 is also connected to the recirculation flow control device 200.

On the other hand, the steam control valve 120 attached to the main steam pipe 100 is controlled by a pressure control device 122 so that the pressure signal of the main steam pressure detector 121 is a constant value. Furthermore, the output of the pressure detector 130 that detects the pressure after the first stage of the high-pressure turbine 2 is
Process input device (PI) of control computer 300
301. The output of the power detector 140 of the generator 4 is also connected to the process input device 301 . The output of the speed setter 202 of the recirculation flow rate control device 200 is connected to the process input device 301, and the output of the process output device (Pφ) 302 of the control computer 300 is connected to the speed setter 202 and the manual/automatic switch 203. connected to. Then, the output of the process output device 302 is connected to the automation panel 310, and the operation signal output of the automation panel 310 is connected to the process input device 301. The control computer 300 also includes an arithmetic and control unit (CPU) 303, a storage device 304, and a peripheral device 30.
5 etc. are provided.

Generally, in a boiling water nuclear power plant, the turbines 2 and 3 and the generator 4 are operated following the reactor 1, which is a so-called turbine/generator follow operation, and the pressure control device 122 controls the main steam pressure The pressure in the furnace 1 is controlled to be constant. Therefore, in order to control the output of the reactor 1, the control rods 1
1 or the manual setting device 205 of the recirculation flow rate control device 200, the present invention attempts to automatically control the settings of the recirculation flow rate control device 200.

When increasing or decreasing the output of the nuclear reactor 1 of a boiling water nuclear power plant, it is necessary to keep the output increase rate constant and within a certain range in order to minimize the thermal stress on the fuel. In order to keep the rate of increase in output constant, conventional manual operations were performed by checking either the rate of increase in the output of the generator 4 or the rate of increase in the average value of the neutron flux detector 10. It was. However, even if the output of the reactor 1 is constant, the output of the generator 4 is subject to disturbance when the degree of vacuum in the condenser 5 decreases, and the sensitivity of the neutron flux detector 10 decreases with operation.

Therefore, in the present invention, we focus on the fact that the steam pressure after the first stage of the high-pressure turbine 2 and the main steam flow rate can be defined as a fixed relationship, and use the value obtained from the first stage pressure as the main steam flow rate signal to control the main steam flow rate. It is used for. That is, Q is the main steam flow rate, P
When P is the first stage pressure, the first stage pressure P is detected by the detector 130 and the main steam flow rate Q is determined from the relationship Q=f(P). The relationship between the main steam flow rate Q and the first stage pressure P is as shown in FIG.

Next, FIG. 2 shows a control block diagram of the present invention. The command value generator 500 generates a control command value _Rq from the control target value, that is, the output target value, and the output change rate set by the operator on the automation panel 310. This command value Rq is the reactor power that changes at the power change rate toward the power target value. The output R _q of the command value generator 500 is input to an adder 520 . Meanwhile, the recirculation flow controller 200 and the process are controlled by the speed setter 202.
The output of the recirculation pumps 111A and 111B is fed back to the speed controller 201 through the control element 540, and the speeds are controlled in accordance with the deviation. Speed controller 2
recirculation pump 111A controlled by the output of 01;
By increasing or decreasing the core coolant flow rate driven by 111B, the main steam flow rate Q is obtained through the process characteristic 550 (pump speed - neutron flux), and the process characteristic 560 (main steam flow rate - first stage pressure) is obtained. The first stage pressure P is obtained through Further, the electric output W is obtained through the process characteristics 570 of the turbine and generator driven by the main steam flow rate Q.

The first stage pressure P is controlled by a control element 52 that also serves as a converter.
4, it is converted into a feedback signal Fq, which is a main steam flow rate signal as the reactor output, and is input to an adder. In this way, the first stage pressure P of the turbine is used as the main feedback signal.

The adder 520 calculates the deviation signal Δ _q by Δ _q = R _q −F _q , and uses it as the element signal d of the speed setter 202 via the control element 521 . Furthermore, the request signal d and the output of the speed setter 202 are inputted as feedback via the control element 523 and matched, and the deviation signal is sent to the speed setter 202 via the control element 502.
It converts into an output signal to 2 and outputs it. On the other hand, the electrical output W is input as feedback via the control element 525, and the output MW of the final target value generator 510 is
Output △W which is the deviation signal of the electrical output
is input to the limiter 526. The limiter 526 outputs the electric output deviation signal ΔW to the gate 527, and the gate 527 controls the gate depending on the magnitude of the deviation. The output of gate 527 is input to adder 520.

In the embodiment described above, an example was described in which a control computer was used as an output control device, but the gist of the first and second inventions is that the main steam flow rate Q is a converted value from the first stage pressure of the turbine. The second invention is to control the rise and fall of the output by controlling the furnace output and when it approaches the target value, the final value is controlled by electrical output, and the output control device uses a microprocessor. Needless to say, it can be realized even with an analog control device.

Effects of the Invention If the electrical output of the generator is used to automatically control the rise and fall of the output, there is a risk that the reactor output will be controlled beyond the specified level, such as when the turbine efficiency decreases. For example, by using the converted value from the turbine's first stage pressure signal as the main steam flow rate signal, it is possible to automatically control the reactor output with high precision, and when the output rises or falls, thermal stress can damage the integrity of the fuel. This has the effect of reducing fear.

According to the second invention, in addition to the effects of the first invention, since the final target value is matched by the electrical output,
This eliminates the need for small auxiliary operations by operators, resulting in the safe and efficient operation of nuclear power plants.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram when the output control device of the present invention is applied to a nuclear power plant, Fig. 2 is a control block diagram showing an embodiment of the present invention, and Fig. 3 is a main steam flow rate and first stage pressure. FIG. 1... Nuclear reactor, 2... High pressure turbine, 3... Low pressure turbine, 4... Generator, 5... Condenser, 20
0... Recirculation flow rate control device, 130... First stage pressure detector, 300... Control computer.

Claims (1)

[Claims] 1. A detector for detecting the first stage pressure of a high-pressure turbine of a nuclear power plant, and a target output value and output change rate of a reactor of the nuclear power plant are input, and the output target value is adjusted to the target output value. a command value generator that outputs the reactor power that changes at the output change rate as a command value; a converter that converts the first stage pressure signal detected by the detector into a main steam flow rate signal; for automatically controlling the output of the nuclear reactor, comprising: an adder that calculates a deviation from the main steam flow rate signal; and a converter that converts the output of the adder into a speed setting value request signal for a recirculation pump; An output control device for a nuclear power plant, characterized in that the main steam flow rate signal obtained by converting the first stage pressure signal is used as the main steam flow rate signal as the main feedback. 2. Input the output target value and output change rate of the reactor of the nuclear power plant and the detector that detects the first stage pressure of the high-pressure turbine of the nuclear power plant, and use the output change rate to move toward this output target value. a command value generator that outputs changing reactor power as a command value, a converter that converts the first stage pressure signal detected by the detector into a main steam flow rate signal, and a command value generator that converts the first stage pressure signal detected by the detector into a main steam flow rate signal; an adder for calculating the deviation of the output of the generator, a converter for converting the output of the adder into a speed setpoint request signal for the recirculation pump, a setpoint value generator for generating a final setpoint value for the electrical output of the generator; an arithmetic unit that compares and calculates a final target value and a generator output; a limiter for a deviation between the output of the target value generator and the generator output; and a gate circuit that closes the gate within the limits of the limiter. In order to automatically control the output of the reactor, the main steam flow rate signal obtained by converting the first stage pressure signal is used as the main feedback, and the final target value of the control is sent to the generator. 1. An output control device for a nuclear power plant, characterized in that the reactor output is controlled when the output increases or decreases by making the electric output equal to the electric output, and the final target value is adjusted to match the electric output.