JP6366520B2 - Output fluctuation monitoring apparatus and method - Google Patents

Description

  The present invention relates to fluctuation monitoring of generator output in a power generation system such as a nuclear power plant.

  As a power generation system, for example, the mechanism of a nuclear power generation system is as follows.

  The nuclear power generation system in normal operation generates steam using the heat generated by nuclear fission in the nuclear reactor, and the steam is sent to the turbine via the main steam pipe and directly connected to the turbine by rotating the turbine. Electricity is generated by a generator.

  The steam amount to the turbine is controlled by a turbine steam control valve arranged upstream of the turbine, and the power generation amount of the nuclear power plant is controlled by controlling the steam amount sent to the turbine. Steam used in the turbine is recovered by a condenser. The recovered condensate is pressurized by a condensate pump and a feed water pump, and returned to the reactor as feed water via a feed water pipe.

  The heat output generation mechanism in the nuclear reactor is as follows.

  In the boiling water nuclear power generation system, the void reactivity and the like are controlled to control the heat output obtained by nuclear fission in the nuclear reactor. In the case of boiling water nuclear power generation systems, the void reactivity depends on the change in the void ratio (coolant density) of the coolant circulating in the reactor, so it is generated by controlling the void ratio of the coolant circulating in the reactor. The heat output is controlled, that is, the amount of generated steam is controlled.

  From the above, the method for changing the generator output of the boiling water nuclear power generation system is as follows.

  By changing the void ratio of the reactor coolant with a reactor recirculation pump, etc., and changing the heat output obtained by nuclear fission and nuclear fission, the generated steam changes, and the steam control valve opening is generated. The desired generator output can be obtained by setting the opening according to the above.

  In a power plant in a nuclear power plant, it is necessary to detect or predict fatigue and the like of component equipment and to ensure the soundness of the component equipment.

  For example, Patent Document 1 discloses a reactor fuel rod health monitoring device.

  In the technique described in Patent Document 1, when a control rod operation is performed when the reactor power is increased, before the operation is performed, the fuel rod against the fluctuation of the line output of the fuel rod in the fuel assembly adjacent to the control rod to be operated Predict the probability of damage.

  Then, it is determined whether or not the fuel rod damage occurrence probability of the fuel rod with respect to the predicted fluctuation of the line output falls within the range of the set value or less and displayed. The operator can rationally select the control rod operation with reference to the display value.

  JP 59-7295 A

  By the way, in recent years, renewable energy such as wind power generation and solar power generation has been used, but these renewable energy are unstable because the amount of power generation is affected by the weather. For this reason, it is necessary to change the generator output by a power plant such as a nuclear power plant capable of stable power supply, and to balance the demand and supply of power according to the increase or decrease of renewable energy.

  In a nuclear power plant, when changing the generator output, it is necessary to change the amount of steam sent to the turbine. For this purpose, it is necessary to change the amount of steam or water circulating in the nuclear power generation system.

  This changes the stress that occurs in the equipment structure on the steam or water passage that circulates through the nuclear power generation system, but if the stress change is repeated, fatigue accumulates in the equipment structure and the deterioration of the equipment progresses. There is a possibility of acceleration.

  For example, when performing frequency response operation in which the generator output is controlled in response to the system frequency of the power transmission system, the system frequency of the power transmission system is constantly changing. For this reason, the nuclear power generation system needs to repeatedly change the generator output.

  By repeatedly changing the generator output, the amount of steam or water circulating in the nuclear power system changes, and the stress in the equipment structure on the passage path of steam or water circulating in the nuclear power generation system changes repeatedly, There is a possibility that fatigue accumulates in the equipment structure and the progress of deterioration of the equipment structure accelerates.

  In this case, it is necessary to perform maintenance, replacement, etc. of individual equipment for each equipment structure of the power plant in consideration of cumulative fatigue due to changes in the generator output.

  In the technique described in Patent Document 1, it is not considered to change the generator output of a nuclear power plant or the like in accordance with the system frequency that fluctuates due to the increase or decrease in the amount of power generated by renewable energy. It is difficult to manage the equipment taking into account the cumulative fatigue of individual equipment.

  It is an object of the present invention to monitor output fluctuations at a power plant that can perform maintenance, replacement, etc. of individual devices in consideration of cumulative fatigue due to fluctuations in generator output for each of the equipment structures of the power plant. It is to implement the apparatus and method.

  In order to achieve the above object, the present invention is configured as follows.

In the output fluctuation monitoring device, a plurality of parameter measuring devices for measuring parameters that cause fatigue of the power plant equipment structure, a central control unit for instructing a change in the generator output of the power plant, and a generator from the central control unit An output change instruction is supplied, the output of the generator is changed, and based on the variation of the parameter measured by the parameter measuring instrument, the cumulative fatigue coefficient is calculated for each of the plurality of device structures, and the calculated cumulative Output fluctuation monitoring unit that generates a fatigue warning command for equipment structures for which the fatigue coefficient is determined to be greater than the set value, and a fatigue accumulation alarm that generates a warning according to the fatigue warning command from the output fluctuation monitoring unit A section.

In the output change monitoring process, the parameters for fatigue multiple devices structures of the plant is measured, the generator output change instruction from the central control unit for performing a generator output change instruction of the power plant is issued, the generator of output is changed, the measured based on the variation of the parameters, the plurality of calculating the cumulative fatigue coefficient for each of the equipment structure, the calculated cumulative fatigue coefficients are determined larger than set value equipment structure A fatigue warning is generated for an object.

  To realize an output fluctuation monitoring apparatus and method in a power plant that can perform maintenance, replacement, etc. of individual devices in consideration of cumulative fatigue due to fluctuations in generator output for each of the power plant equipment structures. be able to.

1 is a schematic configuration diagram of a nuclear power generation system to which the present invention is applied. 4 is a flowchart illustrating output fluctuation monitoring according to an embodiment of the present invention. It is a block diagram of an example of logic of an output fluctuation monitoring method according to an embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  A case where the present invention is applied to a nuclear power generation system will be described as an example.

  FIG. 1 is a schematic configuration diagram of a nuclear power generation system to which the present invention is applied.

  In FIG. 1, the nuclear power generation system in normal operation generates steam with the heat output generated by nuclear fission in the reactor pressure vessel 1, and the steam is sent to the turbine 3 via the main steam pipe 2.

  Then, electricity is generated by the generator 4 directly connected to the turbine 3 by rotating the turbine 3 with steam. The amount of steam to the turbine 3 is controlled by a turbine steam control valve 5 disposed upstream of the turbine 3.

  Steam used in the turbine 3 is recovered by the condenser 6. The recovered condensate is pressurized by the condensate pump 7 and the feed water pump 8 and returned to the reactor pressure vessel 1 through the feed water pipe 9 as feed water.

  The pressure in the reactor pressure vessel 1 is measured by a reactor pressure measuring instrument 11. Further, the neutron flux in the reactor pressure vessel 1 is measured by the neutron flux measuring instrument 14. The steam flow rate of the main steam pipe 2, that is, the steam flow rate of the turbine 3 is measured by the steam flow rate measuring device 12. Further, the steam pressure of the turbine 3 is measured by the steam pressure measuring device 13.

  The reactor pressure measuring instrument 11, the neutron flux measuring instrument 14, the steam flow rate measuring instrument 12, and the steam pressure measuring instrument 13 are parameter measuring instruments that measure parameters that cause fatigue of the equipment structure.

  The heat output generation mechanism in the nuclear reactor is as follows.

  In the boiling water nuclear power generation system, heat output by fission is realized by controlling the void reactivity and the like. In the case of boiling water nuclear power generation systems, the void reactivity depends on changes in the void ratio (coolant density), so the generated heat output is controlled by controlling the void ratio of the coolant circulating in the reactor, that is, the generated steam The amount is controlled.

  When it is necessary to reduce the output of the generator 4, that is, the steam consumed by the turbine 3, the void in the reactor pressure vessel 1 is reduced by reducing the reactor recirculation flow rate by the reactor recirculation pump 10. The rate increases and the generated heat output decreases. The generated steam flow is reduced by the reduction of the generated heat output.

  By setting the opening degree of the turbine steam control valve 5 to an opening degree corresponding to the reduced steam quantity, the steam quantity sent to the turbine 3 is reduced, and the generator output of the generator 4 directly connected to the turbine 3 is reduced.

  In addition, the amount of steam recovered from the condenser 6 after working in the turbine 3 is reduced. The recovered condensate is pressurized by the condensate pump 7 and the feed water pump 8 and returned to the reactor pressure vessel 1 through the feed water pipe 9 as feed water. However, since the amount of generated steam decreases, the reactor pressure vessel The amount of water supplied back to 1 also decreases.

  On the other hand, when it is necessary to increase the output of the generator 4, when the generated steam flow rate is increased, the steam flow rate sent to the turbine 3 is increased, and the generator output is increased. Furthermore, the amount of steam recovered into the condenser 6 also increases. In addition, the amount of water supplied to the reactor pressure vessel 1 increases.

  In other words, since the amount of steam or water that circulates increases or decreases by increasing or decreasing the generator output, the stress generated in all equipment structures through which the steam or water circulating in the nuclear power generation system passes changes.

  For example, when the frequency response operation is performed, by repeatedly changing the generator output, fatigue may accumulate in these equipment structures, and deterioration may progress.

  Monitor the fatigue accumulated in the equipment structure for possible deterioration of the equipment structure due to the change in the generator output, and the operator will keep the generator output constant before the equipment structure deteriorates and cannot perform its original function. By switching to operation or newly exchanging the equipment structure, the progress of deterioration of the equipment structure can be suppressed.

  FIG. 2 is an output fluctuation monitoring flowchart of the output fluctuation monitoring system in the embodiment of the present invention.

  In FIG. 2, the change of the stress which arises in each apparatus structure (for example, the reactor pressure vessel 1, the turbine 3) is calculated from the parameter which fluctuates by the change of a generator output (step S1).

  Here, in the case of the reactor pressure vessel 1, the parameters are the pressure in the reactor pressure vessel 1 measured by the pressure measuring instrument 11 and the neutron flux measured by the neutron flux measuring instrument 14.

  In the case of the turbine 3, the steam flow rate of the turbine 3 measured by the steam flow meter 12 and the steam pressure of the turbine 3 measured by the steam pressure meter 13.

  Next, a cumulative fatigue coefficient (calculation formula will be described later) obtained from the stress amplitude calculated in step S1 is calculated (step S2), and the cumulative fatigue coefficient calculated for each device is set in advance. The cumulative fatigue coefficient set values are compared (step S3).

  If the calculated cumulative fatigue coefficient falls below the cumulative fatigue coefficient set value as a result of comparison between the calculated cumulative fatigue coefficient and a preset cumulative fatigue coefficient set value (for example, 0.9), the generator It is determined that the output can be changed. Then, the output of the generator is changed to the output required at that time.

  On the other hand, in step S3, when the calculated cumulative fatigue coefficient is equal to or greater than the cumulative fatigue coefficient set value, the deterioration progress of the equipment structure may be accelerated by changing the generator output (possibility of impairing soundness). The equipment structure is displayed to the operator that the equipment structure with the calculated cumulative fatigue coefficient exceeding the cumulative fatigue coefficient setting value may impair the soundness. (Step 4).

  When the equipment structure is replaced, the cumulative fatigue coefficient of the replaced equipment structure is initialized by a reset signal. However, the cumulative fatigue coefficient of the device structure other than the replaced device structure is held without being reset.

  FIG. 3 is a block diagram of a logic example of the output fluctuation monitoring method.

  In FIG. 3, the output fluctuation monitoring logic unit (output fluctuation monitoring unit) 15 includes a switch unit 16, a memory 17, a cumulative fatigue calculation unit 22, a fatigue accumulation state determination unit 23, and an OR circuit unit 24. Yes.

  During the generator output changing operation, the generator output changing operation signal 20 transmitted from the central control unit (central control room) 18 becomes a trigger, the switch unit 16 as a function is turned on, and the measurement signal 21 of the measured parameter is accumulated. The fatigue coefficient calculation unit 22 is supplied to calculate the cumulative fatigue coefficient.

The cumulative fatigue coefficient is also called a cumulative fatigue index, and is calculated by the following equation (1).
f = Σ (n (σ) / N _F (σ)) (1)

In the above formula (1), f is a cumulative fatigue coefficient, n (σ) is the number of stress cycles of the stress σ of the equipment structure (number of generator output fluctuations), and N _F (σ) is This is the number of stress cycles when the equipment structure is damaged by the stress cycle of stress σ. Whether or not the equipment structure has been damaged can be determined based on the value set for each equipment structure from the magnitude of the output fluctuation, which is the number of stress cycles, and the years of use.

  That is, the pressure in the reactor pressure vessel 1 measured by the reactor pressure measuring instrument 11, the neutron flux in the reactor pressure vessel 1 measured by the neutron flux measuring instrument 14, and the main measured by the steam flow measuring instrument 12. The value set for each equipment structure from the amount of change, the years of use, etc. of the parameters that cause the equipment structure to be fatigued, such as the steam flow of the steam pipe 2 and the steam pressure measuring device 13 and the steam flow of the turbine 3 Thus, it can be determined whether or not the equipment structure has been damaged.

  Further, Σ is the sum total for the stress cycle.

  If the cumulative fatigue coefficient f exceeds 1, the probability that the equipment structure is damaged is high, and if the cumulative fatigue coefficient f is less than 1, the probability that the equipment structure is damaged is low.

  The stress σ and the stress cycle number of each device structure are stored in the memory 17, and the stress cycle number is added every time stress is applied, that is, every time there is output fluctuation. The memory 17 is also configured to store and update, for each device structure, the number of times it is determined that the device structure has been damaged.

  As will be described later, the reset signal 25 resets the number of stress cycles of the corresponding equipment structure to the initial number.

  The cumulative fatigue coefficient calculated by the cumulative fatigue coefficient calculator 22 is supplied to the cumulative fatigue coefficient determiner 23. The fatigue accumulation state determination unit 23 compares the cumulative fatigue calculated by the cumulative fatigue coefficient calculation unit 22 with the set value stored in the memory 17 in advance.

  When the cumulative fatigue coefficient calculated by the cumulative fatigue coefficient calculation unit 22 exceeds the set value, the fatigue accumulation state determination unit 23 outputs a signal “1” to the OR circuit unit 24.

  At this time, the OR condition is satisfied, and an alarm signal is supplied from the OR circuit unit 24 to the fatigue failure alarm generating unit 19, whereby a fatigue failure alarm is issued.

  The fatigue breakage alarm generation unit 19 includes a display unit. The display unit displays a corresponding equipment structure name and also displays a fatigue breakage alarm.

  Further, when the equipment structure is newly replaced, the reset signal 25 is supplied from the central control unit 18 to the cumulative fatigue coefficient calculation unit 22. The cumulative fatigue coefficient calculation unit 22 resets the number of stress cycles stored in the memory 17 for the newly replaced equipment structure to the initial value. Thereby, the cumulative fatigue coefficient is initialized. The reset signal is generated when the operator manually operates the operation unit of the central control unit 18.

  As described above, according to the embodiment of the present invention, when a change in the generator output of the nuclear power plant is requested, the cumulative fatigue coefficient due to the output fluctuation is calculated for each component of the nuclear power plant. When the calculated cumulative fatigue coefficient exceeds the set value, the device structure is warned of the possibility of damage and the generator output is not changed.

  As a result, for each of the equipment structures of the nuclear power plant, it is possible to perform maintenance, replacement, etc. of individual devices in consideration of cumulative fatigue due to fluctuations in generator output. A method can be realized.

  In addition, it is possible to prevent the deterioration of the equipment structure due to the change in the generator output and prevent the damage.

  In addition, when the equipment structure is replaced, the cumulative fatigue coefficient of the replaced equipment structure is reset. For this reason, it is possible to appropriately monitor the state of the equipment structure throughout the lifetime of the nuclear power generation system.

  In addition, although the example mentioned above is an example at the time of applying this invention to a nuclear power plant, this invention is applicable not only to a nuclear power plant but other power plants, such as a thermal power plant.

  1: Reactor pressure vessel, 2: Main steam pipe, 3: Turbine, 4: Generator, 5: Turbine steam control valve, 6: Condenser, 7: Condensate pump, 8: Feed water pump, 9: Feed water pipe 10: Recirculation pump, 11: Reactor pressure measuring instrument, 12: Steam flow measuring instrument, 13: Steam pressure measuring instrument, 14: Neutron flux measuring instrument, 15: Output fluctuation monitoring logic section (output fluctuation monitoring section), 16: switch unit, 17: memory, 18: central control unit, 19: fatigue accumulation alarm generation unit, 20: generator output change operation signal, 21: measurement parameter signal, 22: cumulative fatigue coefficient calculation unit, 23: fatigue accumulation State determination unit, 24: OR circuit unit, 25: reset signal

Claims (8)

A plurality of parameter measuring device for measuring the parameters for fatigue equipment structures of the plant, and a central control unit for generator output change instruction of the power station, the generator output change instruction from the central control unit is supplied The output of the generator is changed, and based on the variation of the parameter measured by the parameter measuring instrument, the cumulative fatigue coefficient is calculated for each of the plurality of device structures, and the calculated cumulative fatigue coefficient is calculated from the set value. An output fluctuation monitoring unit that generates a fatigue warning command and a fatigue accumulation alarm generation unit that generates a warning according to the fatigue warning command from the output fluctuation monitoring unit for a device structure that is determined to be large Output fluctuation monitoring device characterized by. In the output fluctuation monitoring device as claimed in claim 1, said output change monitoring unit for each of the plurality of devices configured creation, output and variable Dokai speed of the generator, and damage occurs to the device structure a memory for storing the number of times that is determined, based on the upper Symbol memory the output variable Dokai amount stored in, and the number of stress cycles is determined that damage to the device structure occurs, said plurality of devices the cumulative fatigue coefficient calculation unit for calculating the cumulative fatigue coefficient for each structure creation, cumulative fatigue factor the accumulated fatigue coefficient calculation unit has calculated that determines whether large or not than the set value, the calculated cumulative fatigue coefficient is set A fatigue accumulation state determination unit that generates a fatigue warning command for the equipment structure determined to be larger than the value, and the fatigue alarm command is generated from the fatigue accumulation state determination unit, and the fatigue accumulation alarm generation unit generates fatigue. alarm Output fluctuation monitoring device, characterized in that it comprises an OR circuit, the outputs of the decree. In the output fluctuation monitoring device according to claim 2, when the fatigue accumulation state determination unit of the output fluctuation monitoring unit outputs a reset signal for any of the plurality of device structures from the central control unit, the device structure reset signal is outputted, stored in the memory, the output change monitoring apparatus characterized by resetting the initial value the number of the output variables Dokai.   4. The output fluctuation monitoring apparatus according to claim 3, wherein the power plant is a nuclear power plant, and the parameter measuring device includes, for example, a pressure measuring device that measures a pressure in a reactor pressure vessel, and a reactor pressure vessel. A neutron flux measuring device for measuring the neutron flux in the inside, a steam flow measuring device for measuring the steam flow rate of the turbine, a steam pressure measuring device for measuring the steam pressure of the turbine, and the like. The parameters for fatigue multiple devices structures of the plant is measured, the generator output change instruction from the central control unit for performing a generator output change instruction of the power plant is issued, the output of the generator is changed, based on the variation of the measured the parameters for the plurality of respective devices structures to calculate the cumulative fatigue coefficient, device structures accumulated fatigue coefficient is determined larger than set value calculated, fatigue alarm The output fluctuation monitoring method characterized by generating. In the output change monitoring method according to claim 5, for each of the plurality of devices configured creation, output and variable Dokai speed of the generator, the number of damage to the device structure is determined to have occurred in the memory store, and the upper Symbol memory the output variable Dokai amount stored in, based on the number of stress cycles is determined that damage to the device structure is generated, the cumulative fatigue for each of the plurality of devices configured creation Calculates the coefficient, determines whether the calculated cumulative fatigue coefficient is greater than the set value, and generates a fatigue warning command for equipment structures for which the calculated cumulative fatigue coefficient is determined to be greater than the set value An output fluctuation monitoring method characterized by outputting a fatigue warning when the fatigue warning command is generated. 7. The output fluctuation monitoring method according to claim 6, wherein when the reset signal for any of the plurality of device structures is output from the central control unit, the reset signal stored in the memory is output. the device structures, the output change monitoring method characterized by resetting the number of the output variable Dokai to the initial value.   The output fluctuation monitoring method according to claim 7, wherein the power plant is a nuclear power plant, and the parameter measuring instrument for measuring the parameter includes, for example, a pressure measuring instrument for measuring a pressure in a reactor pressure vessel, An output characterized by a neutron flux measuring instrument for measuring the neutron flux in the reactor pressure vessel, a steam flow measuring instrument for measuring the steam flow of the turbine, a steam pressure measuring instrument for measuring the steam pressure of the turbine, etc. Fluctuation monitoring method.

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