JPS63195595A - Nuclear power plant - 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] [Objective of the Invention] (Industrial Application Field) The present invention relates to a nuclear power plant consisting of a plurality of nuclear power plants with different turbine bypass capacities. Accordingly, the present invention relates to a nuclear power plant equipped with a plant output control device that controls the nuclear power plant output within a range that does not shut down the reactor.

(Conventional technology) In recent years, as the proportion of nuclear power plants in power generation facilities has increased, nuclear power plants have been forced to continue operating at their rated output as in the past, and load fluctuations are compensated for by thermal power generation and hydropower generation. In addition to nuclear power plant operations, load following operation is increasingly required for nuclear power plants. In addition, it has great load following performance that corresponds to changes in load size during the day and night, and small vibrations (fluctuations) in the steady frequency at all times.
Various responses are being considered.

In addition to the above-mentioned load fluctuations during normal operation, it is also necessary to consider responses to abnormal situations such as power system accidents. In other words, in the event of a power system accident, the impact appears as a change in the system frequency, but although it is often resolved within a short period of time through system control, the system frequency may transiently increase by 1 to 2H2 within that short period of time. It is conceivable that this could lead to the reactor being shut down.

FIG. 4 is a schematic diagram of a general nuclear power plant 1 and a power supply system.

The nuclear power plant 1 is composed of a plurality of nuclear power plants 2.3.4 having different turbine bypass capacities. Here, for convenience of explanation, it is assumed that the plant is composed of three plants. Each nuclear power plant 2 , 3 . 4 is connected to a power transmission line 8 via an in-station switch 5 . Furthermore, the power transmission line 8 is connected to each external power load 10a, 10 via a substation 9.
Connected to b, 1Qc, and 10d.

FIG. 5 is a schematic configuration diagram of a typical nuclear power plant installed in an atomic saw power plant, in which steam generated in the nuclear reactor 15 passes through a main steam conduit 16, and the steam flow rate is controlled by a steam control valve 17. It is introduced into the steam turbine 18 while being heated. The steam introduced into the steam turbine 18 performs work there, and the power generation Ia 19 directly connected to the steam turbine 18
drive. Electric power generated by driving the generator 19 is sent to an external power system via a circuit breaker 20.

On the other hand, the steam that has performed work in the steam turbine 18 is sent to the condenser 21, where it is condensed and becomes condensed water.

Further, a bypass conduit 23 having a bypass valve 22 is branched out from the main steam conduit 16, and a part of the main steam is routed to the condenser 21 by bypassing the steam turbine 18 as needed.
This is to guide you.

On the other hand, a frequency detector 24 for measuring the power system frequency is provided at the outlet of the external power system interrupter 11i 20,
The frequency signal detected by this frequency detector 24 is input to a comparator 25. The comparator 25 compares the frequency signal with a preset frequency value, and if the frequency signal exceeds the frequency set value, the recirculation pump 26 is decelerated or the control rod 28 is inserted by the control rod part f71 Ill structure 27. This is to reduce the output of the nuclear reactor 15 and reduce the amount of steam generated.

Furthermore, the opening degree of the steam control valve 17 is controlled by the turbine speed control device 29 so that the deviation between the actual turbine speed and the set speed is within a certain range, and the steam inflow M into the steam turbine 18 is adjusted. . Furthermore, in response to the control of the opening direction of the steam control valve 17, the bypass valve 22 is controlled in the opening direction, and excess steam is guided to the condenser 21.

Here, the nuclear power plant 2 in FIG. 4 is a 100% bypass plant that can bypass 100% of the main steam outflow, and the other nuclear power plant 3.4 is a 25% bypass plant that can bypass 25% of the main steam outflow. Assume it is a bypass plant. In addition, the power supplied from the nuclear power plant 1 is 10% to the external power load 10a, and 10% to the external power load 10a.
Assume that the power is supplied to external power load 10C at a rate of 20%, external power load 10C at a rate of 30%, and external power load 10d at a rate of 40%.

In such a power supply system, an external power load of 10 d
In the event of a large load loss, the protection devices in each nuclear power plant 2.3.4 will detect the load loss and trip the circuit breaker 20, disconnecting the generator 19 from the plant switchyard busbar. to protect the plant. in this case,
If the separated plant is a 25% bypass plant, the reactor 15 will be shut down, and if it is a 100% bypass plant, the reactor 15 will not be shut down, but the main steam will be bypassed 100% and the plant will go into independent operation.

On the other hand, in the case of a small load loss such as the external power load 10a, the protection devices of each nuclear power plant 2.3.4 are not activated and the plants are not disconnected. Therefore, the frequency of the power system increases somewhat due to the load loss, and each nuclear power plant 2°3.4 bypasses the steam flowing in the main steam conduit 16 to the bypass conduit 23 by throttling the steam control valve 17 under governor control. to cope with the increase in frequency.

(Problem to be Solved by the Invention) As mentioned above, when a large load loss such as the external power load 10d occurs, the 100% bypass plant does not need to shut down the reactor 15, but the 25% bypass plant does not need to shut down the reactor 15. Nuclear power plants 3 and 4 having a small bypass capacity, such as a nuclear power plant, disconnect the power generation 119 from the external power system and stop the nuclear reactor 15 in order to protect the plant.

On the other hand, in the case of a small loss of load such as the external power load 10a, the protection device does not operate, and the power system frequency increases and the control system of the nuclear power plant 2゜3.4 handles it. do. However, the effect of frequency increase is regardless of the bypass capacity of each nuclear power plant 2, 3.4, so depending on the magnitude of load loss, nuclear power plants 3.4 with small bypass capacity may 15 may stop.

Generally, the steam capacity that can flow through the bypass valve 22 of a 25% bypass plant is about 25% of the 100% capacity of the steam control valve 17. Therefore, when the frequency of the power system increases significantly, when the opening degree of the steam regulating valve 17 is significantly reduced to prevent the rotational speed of the generator 19 from increasing, there is a risk that the steam regulating valve 17 will be throttled down by 25%. If it is within %, it is possible to absorb a cabinet with 25% capacity,
A rise in reactor pressure can be prevented. However, if a frequency increase occurs that causes the steam control valve 17 to be throttled down more than the capacity of the bypass valve 22, the steam control valve 17 will be throttled beyond the capacity of the bypass valve 22, causing an increase in reactor pressure and a reduction in reactor output. The reactor automatically shuts down due to the rise.

The amount of frequency increase and the restriction of the steam control valve 17 are determined by the stray power adjustment rate in the turbine speed control device.
Currently, the speed limit is set at 5%. However, when the actual turbine speed increases by 5%, the steam control valve 17 increases to 10.
It is supposed to be narrowed down by 0%, and the actual turbine speed is 5.
%R is converted to 50 Hz and becomes 52.5 Hz. FIG. 6 is a diagram showing the relationship between the frequency and the opening degree of the steam control valve at a speed regulation rate of 5%. Here, if the upper limit of the frequency that can be absorbed by the bypass valve 22 with a capacity of 25% is determined, it is 50%. It becomes .625Hz.

On the other hand, it is generally said that in the event of a power system failure, it is necessary to consider a maximum frequency increase of about 2H7. Therefore, the current bypass capacity will be insufficient, but increasing the capacity of the bypass valve 22 will require a significant increase in equipment and increase plant construction costs, which is not realistic.

Furthermore, in response to an increase in system frequency due to load loss, by lowering the reactor output, the amount of generated steam can be reduced, making it possible to compensate to some extent for the above-mentioned lack of bypass capacity. In other words, when the frequency is detected by the frequency detector 24 in FIG. A portion of the reactor is inserted to reduce the reactor output.

In this case, if the increase in grid frequency is gradual,
This increase in frequency can be detected to reduce reactor power and reduce steam generation. However, if the system frequency increases rapidly, decelerating the recirculation pump 26 and partially inserting the control rods 28 will not be enough time to reduce the reactor output, and the reactor 15
will stop.

In this way, if the reactor 15 is stopped due to a loss of load on the power system, it will take a lot of effort and time to restart it, and when the power system is restored from an accident, there will be a shortage of power. Become. In general, the operating rates of nuclear power plants and power stations will decline overall.

The present invention has been made in consideration of the above-mentioned circumstances, and it is possible to continue the operation of a nuclear power plant even when a load loss occurs in the power system, and to improve the operating rate of the nuclear power plant. The purpose is to provide a nuclear power plant that can

[Structure of the invention]

(Means for Solving the Problems) A nuclear power plant according to the present invention is composed of a plurality of nuclear power plants having different turbine bypass capacities, and each nuclear power plant has a reactor output that is different from that of a coolant recirculation stream. The output of the turbine generator is controlled by the opening of the main steam control valve of the turbine control 2Il system, and the power of the turbine generator is supplied to the external power system via the station switch. At a nuclear power plant, the power system load fluctuations, the reactor output and turbine generator output of each nuclear power plant are detected, the control ratio of the plant output is calculated, and the control ratio is calculated according to the turbine bypass capacity of each nuclear power plant. The plant is equipped with a plant output control device that controls the reactor output and turbine generator output to the extent that the reactor is not shut down, and this plant output control device maintains harmony between the power system load and the nuclear power plant output. be.

(Function) When an accident or the like occurs in the power system and a loss of load occurs, the plant output control device detects the fluctuation in the power system load. The plant output control device calculates fluctuations in the system frequency, etc. from detected values of the system frequency, etc., and recognizes fluctuations in the power system load. In addition, the plant output control device detects the reactor output and turbine output of each nuclear power plant, and controls the reactor according to the turbine bypass capacity of each nuclear power plant in order to absorb fluctuations in the power system load. Calculate the output control ratio for each nuclear power plant within a range that does not cause shutdown. Then, the plant output control device adjusts the plant output for each nuclear power plant based on the calculation results! control and maintain harmony with power grid loads.

For this reason, the reactors at each nuclear power plant do not shut down,
Continuing operation by flexibly responding to changes in power system load. Therefore, the operating rate of the nuclear power plant is improved.

(Example) The present invention will be explained with reference to the drawings.

FIG. 1 is a schematic diagram of an embodiment of a nuclear power plant 1A and a power supply system according to the present invention.

The nuclear power plant 1A is composed of a plurality of nuclear power plants 2, 3.4 having different turbine bypass capacities. Each nuclear power plant 2, 3.4 is connected to a power transmission line 8 via a station switch 5. Furthermore, the power transmission line 8 is connected to each external power load 10a, 10b, 10c, 1 via a substation 9.
Connected to 0d.

Furthermore, the nuclear power plant 1A is equipped with a system that controls the output of each nuclear power plant 2.3゜4 in response to fluctuations in the power system load.
A plant output control device 30 is provided.

The configuration of each nuclear power plant 2, 3.4 is the same as the conventional one as shown in FIG. 2, so the same parts are given the same reference numerals and the explanation will be omitted.

The plant output control device 30 receives a power system load detection signal 31 from the power system such as the power transmission line 8 and each of the external power loads 10a to 106, and each of the nuclear power plants 2, 3.
The plant output detection signal 32 from 4 is input, and the plant output control signal 33 is input to each nuclear power plant 2.3.4.
It is designed to output .

The power system load detection signal 31 is a detected value of the power system current, voltage, electric energy, system frequency, etc., and the plant output control device 30 inputs the power system load detection signal 31 and calculates the detected values from these detected values. , its absolute amount, magnitude of change rate, and duration are calculated to recognize fluctuations in power system load.

The plant output detection signal 32 is transmitted to each nuclear power plant 2.
These are the detected values of the reactor output and the turbine generator output from the core performance optimization device (not shown) in 3.4, and the plant output control device 30 to which this plant output detection signal 32 is inputted, uses these detected values and the above-mentioned The plant output control ratio and plant output control means according to the turbine bypass capacity of each nuclear power plant 2.3.4 are calculated by comparing the fluctuations in the power system load. This plant output control ratio and plant output control means are determined within a range that does not stop the nuclear reactor 15.

As shown in FIG. 2, plant output control means include control of the opening degree of the main steam control valve 17 by a turbine speed control device 29, control of the coolant recirculation flow rate by a recirculation pump 26, and control by a control rod drive mechanism 27. Control of the control rod 28 position is considered. Further, the plant output control ratio is determined according to the turbine bypass capacity of each nuclear power plant 23.4.

In other words, in the case of a 100% bypass plant, even if the main steam control valve 17 is throttled down by 100%, it is possible to bypass the main steam 100% from the bypass conduit 23, so the pressure inside the reactor 15 increases. On the other hand, in the case of a 25% bypass plant, if the main steam control valve 17 is throttled down by 25% or more, the pressure inside the reactor 15 will rise and the reactor 15 will stop. Resulting in. Therefore, it is necessary to suppress the turbine output control ratio of the 25% bypass plant to a level that does not lead to reactor shutdown, and instead, to maximize the bypass capacity a of the 100% bypass plant, the turbine output of the 100% bypass plant is It is necessary to increase the control ratio.

The plant output control signal 33 is output as a result of the above-described operations performed within the plan 1 to the output control device 30. This plant, output control signal 3
3 is output for each nuclear power plant 2, 3, 4, and the plant output control signals 33 include, as shown in FIG. 2, a turbine output control signal 33a, a recirculation side 11 control signal 33b, and a control rod drive signal. A signal 33c is included.

The turbine output control signal 33a is the turbine speed control device e2
The turbine speed control signal 2/9 changes the load setting according to the turbine output control signal @33a. That is, the turbine speed control device ff29 changes the opening degrees of the main steam control valve 17 and the bypass valve 22 to change the rate at which the main steam is bypassed to the bypass conduit 23.

The recirculation flow m control signal 33b is input to the recirculation pump 26, and the recirculation pump 26 receives the recirculation flow control signal 33b.
Depending on the situation, the pump rotation speed is changed and the flow rate of coolant circulated to the core is changed. In addition, t, IJ rod drive signal 3
3c is input to the control rod drive 4i% 27, and the control rod drive v1 mechanism 27 changes the position of the control rod 28 to be inserted into the reactor core in accordance with the control rod drive signal 33c.

These turbine output control signal 833a, recirculation flow rate control signal 33b1, and control rod drive signal 33G are not output in a PA series, but are mutually organic series to change the turbine generator output and the reactor output. death,
It comprehensively controls the output of each nuclear power plant 2, 3.4.

Next, we will specifically discuss the case where a load loss occurs in the power system.

Here, nuclear power plant 2 in Figure 1 is a 100% bypass plant, and other nuclear power plants 3.4 are 2
Assume a 5% bypass plant.

In addition, the power supplied from the nuclear power plant 1A is 10% to the external power load 10a, 20% to the external power load 10b,
30% for external power load 10c, 4 for external power load 10d
Assume that it is supplied at a rate of 0%. Furthermore, although it is possible to recognize fluctuations in power system load by detecting power, current, etc., here, fluctuations in power system load are recognized from detected values of frequency.

In the unlikely event that a power system accident occurs, the external power loads 10a, 10
When a load loss occurs in the power system 1, etc., the system frequency fluctuates, and a detection signal of that frequency is inputted to the plant output control device 30 as the power system load detection signal @31. The plant output control device 30 calculates the absolute value of the frequency and the frequency increase rate from the detected frequency value. The absolute value of these frequencies and the frequency increase rate differ depending on the magnitude of load loss, that is, when load loss occurs at external power load 10a and when load loss occurs at external power load 10b, and are determined by the following three types: A case is possible.

Case 1: When only overfrequency (e.g. 51.5Hz) is detected Case 2: Frequency increase rate "large" (e.g. 1) 1771
Case 3: When only the overfrequency and the frequency increase rate r are detected. FIG. 3 is a logic circuit diagram showing the judgment within the blunt output control device 30 for these three cases. It is.

Case 1 indicates that the frequency has been rising slowly, and if this continues, the frequency will rise further and reach 25
%, the main steam control valve 17 is throttled beyond the bypass capacity M of the bypass plant, the reactor pressure rises, and the reactor 15
will stop.

For this reason, the plant output control device 30 controls the recirculation flow m to the nuclear power plants 3 and 4, which are 25% bypass plants.
Control signal 33b is output to reduce the speed of recirculation pump 26 and reduce reactor power. In this case, it is possible to respond slowly, so the main steam control valve 1
There is no need to narrow it down to 7.

In case 2, there is a possibility of overfrequency if left as is, so the plant output control device 30 outputs the turbine output control signal 33a to the nuclear power plant 3.4, which is a 25% bypass plant, to take a rapid response. For example, lower the load set point from 100% to 80% and set it to 80%.
maintain the turbine generator output. Any further increase in frequency will be left to the automatic control of the nuclear power plant 2, which is a 100% bypass plant, and case 3 will be used if an overfrequency is detected.

Case 3 is the worst case, and for all nuclear power plants 2.3.4, the plant output control device 30
From recirculation flow rate control signal 33b1 control rod drive signal 33c
, which reduces the speed of the recirculation pump and inserts a portion of the control rods to reduce reactor power.

Afterwards, when the power system load is increased due to recovery from the power system accident, etc., the plant output control 2II device 30 inputs the power system load detection signal 31 and calculates the absolute value of the frequency and the rate of frequency decrease. Then, the plant output control device 30 outputs the plant output a, II control signal 33, and the nuclear R
Increase the output of ffj plants 2 and 3.4 and restore normal operation.

As described above, according to this embodiment, even if a load loss occurs due to an accident in the power system, the nuclear reactor 15 will not be stopped and the operation can be continued.

Therefore, there is no need for labor and time to restart the reactor 15 when it is stopped, and even if the power system is overloaded after the power system accident is restored, the nuclear power plant 2°3.4 You can increase the output and never run out of power. Therefore, the operating rate of the atomic J power plant 1A can be improved.

In the above embodiment, only the case where the plant output control device 30 was installed in the nuclear power plant 1A was explained, but the plant output control device 30 was installed in the central power supply station (control center that monitors and controls the entire system). You may.

〔Effect of the invention〕

The nuclear power plant according to the present invention is characterized by changes in power system load,
The reactor output and turbine generator output of each nuclear power plant are detected, and the control ratio of the plant output is calculated. According to the turbine bypass capacity of each nuclear power plant, the reactor output is determined within the range that does not shut down the reactor. and a plant output control device that controls the turbine generator output, and this plant output control device maintains harmony between the power system load and the nuclear power plant output.
Even if a power system load loss occurs, the nuclear power plant can continue operating by maintaining a balance between the power system load and the nuclear power plant capacity, improving the operating rate of the nuclear power plant. It has the effect of being able to

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an embodiment of a nuclear power plant and an electric power supply system according to the present invention, FIG. 2 is a schematic configuration diagram of a nuclear power plant according to the above embodiment, and FIG. A logic circuit diagram showing the judgment when the control device detects overfrequency and frequency increase seriousness, Figure 4 is a schematic configuration diagram of a general nuclear power plant and power supply system,
Figure 5 is a schematic diagram of a general nuclear power generation system.
FIG. 6 is a graph showing the relationship between frequency and steam control valve opening at a speed regulation rate of 5%. 1,1A... Nuclear power plant, 2.3.4... Nuclear power plant, 5... Station switch, 8... Power transmission line, 9... Substation, 10a, 10b, 10c , 10d
-・・Outside i! iIl power load, 31... Power system load detection signal, 32... Plant output detection signal, 33...
- Plant output control signal, 33a... Turbine output control signal, 33b... Recirculation flow rate control signal, 33G...
・Patent attorney representing control rod drive unit Noriyuki Chika Yudo Hiroshi Mitsumata Figure 5 Figure 6

Claims (1)

[Claims] Consisting of multiple nuclear power plants with different turbine bypass capacities, each nuclear power plant has reactor output controlled by the coolant recirculation flow rate and core control rod position, and turbine generator output controlled by the main turbine control system. In a nuclear power plant where power from the above turbine generator is supplied to the external power system via an on-site switch controlled by the opening of the steam control valve, fluctuations in the power system load and reactor output of each nuclear power plant are controlled by the opening of the steam control valve. and a plant that detects the turbine generator output and calculates the control ratio of the plant output, and controls the reactor output and turbine generator output according to the turbine bypass capacity of each nuclear power plant to the extent that the reactor is not shut down. Equipped with an output control device,
A nuclear power plant characterized by maintaining harmony between the power system load and the nuclear power plant output using this plant output control device.