Reactor power determination method and system

Abstract

The invention relates to a reactor power determination method and system. The method comprises the following steps: periodically obtaining a first main feed water flow and a second main feed water flow corresponding to a plurality of steam generators respectively; calculating a deviation coefficient corresponding to each steam generator according to the latest obtained first main feed water flow and second main feed water flow; whether the deviation coefficient of each steam generator is smaller than a set deviation standard value or not is determined; when the deviation coefficient of each steam generator is smaller than the deviation standard value, entering a normal mode; wherein the normal mode comprises the steps that the reactor power is calculated according to the first main feed water flow of each steam generator, and the full power reference value of the reactor is set as a first set value. The measurement uncertainty of the reactor power can be reduced, and the maximum settable power of the reactor and the economical efficiency of the nuclear power plant are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of reactor power detection, and in particular to a method and system for determining reactor power. Background Art

[0002] Reactor power is an important monitoring parameter during the normal operation of a nuclear power plant. Since the reactor power cannot be directly and accurately measured, it can only be calculated by measuring the power of the secondary circuit based on the energy balance principle of the primary and secondary circuits using the test instrument system (KME system for short). Among them, in the reactor power calculation process, the main feed water flow is the dominant factor affecting the uncertainty of reactor power measurement, accounting for up to 80%.

[0003] In the related art, nuclear power plants generally use differential pressure flowmeters to measure the main feed water flow, but differential pressure flowmeters have problems such as large main feed water pressure loss, large maintenance workload, narrow effective flow range (ratio of maximum flow to minimum flow), easy scaling on the orifice surface, or long-term scouring leading to reduced measurement accuracy. Therefore, the assumed value of the measurement uncertainty of the reactor power is relatively high (possibly up to 2%) to sufficiently envelop the actual range of the measurement uncertainty. Based on the assumption of 2% measurement uncertainty, the power level considered in the safety analysis of nuclear power plants is 102% of the designed full power, but in actual operation, the reactor power cannot exceed the full power, that is, the maximum set power of the reactor must not exceed 100%, resulting in the operating power not being utilized to the maximum extent. For a million-kilowatt unit, even if the power generation is lost by 1%, it will bring a lot of negative impact on the economic efficiency of the nuclear power plant. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method and system for determining reactor power.

[0005] The technical solution adopted by the present invention to solve the technical problem is: constructing a method for determining reactor power, comprising:

[0006] Periodically obtaining first main feedwater flow rates and second main feedwater flow rates corresponding to a plurality of steam generators, respectively; wherein the first and second main feedwater flow rates are flow rates output when a preset flow meter and a differential pressure flow meter measure flow rates of corresponding steam generators, respectively, and the measurement uncertainty of the preset flow meter is less than the measurement uncertainty of the differential pressure flow meter;

[0007] Calculating the deviation coefficient corresponding to each of the steam generators according to the first main feed water flow rate and the second main feed water flow rate obtained most recently;

[0008] Determining whether the deviation coefficient of each steam generator is less than a set deviation standard value;

[0009] When the deviation coefficient of each steam generator is less than the deviation standard value, the normal mode is entered; wherein, the normal mode includes: calculating the reactor power according to the first main feed water flow of each steam generator, and setting the full power reference value of the reactor to the first set value.

[0010] Preferably, the reactor power determination method further comprises:

[0011] When there is at least one of the steam generators with a deviation coefficient not less than the deviation standard value, a fault mode is entered; wherein the fault mode includes: calculating the reactor power based on the second main feed water flow of each of the steam generators, and setting the full power reference value to the first set value, and the duration for which the full power reference value is set to the first set value is not greater than the first set time.

[0012] Preferably, the failure mode also includes:

[0013] Determining whether the duration for which the full power reference value is set to the first set value is greater than a first set time;

[0014] When the duration is not greater than the first set time, if the deviation coefficients of the steam generators calculated based on the most recently acquired first main feed water flow and second main feed water flow are both less than the deviation standard value, entering the normal mode;

[0015] When the duration is greater than the first set time, switching from the fault mode to the normal mode is prohibited, and the full power reference value of the reactor is set to a second set value; wherein the first set value is greater than the second set value.

[0016] Preferably, the reactor power determination method further comprises:

[0017] The reactor power measurement uncertainty is calculated according to the maximum measurement uncertainty of the preset flow meter, so as to determine the first set value according to the reactor power measurement uncertainty.

[0018] Preferably, the expression of the reactor power measurement uncertainty is:

[0019]

[0020] Among them, U(W R ) represents the uncertainty of the reactor power measurement, W R Represents the reactor power, U(W SG1 ) represents the measurement uncertainty of the first steam generator, W SG1 represents the thermal power of the first steam generator, U(W SG2) represents the measurement uncertainty of the second steam generator, W SG2 represents the thermal power of the second steam generator, U(W SG3 ) represents the measurement uncertainty of the third steam generator, W SG3 represents the thermal power of the third steam generator, U(W ΔPR ) represents the measurement uncertainty of other heat source input items except the core, W ΔPR Represents the thermal power of the other heat source input.

[0021] Preferably, the first set time ranges from 2 to 3 days.

[0022] Preferably, the first setting value is 101.7% and / or the second setting value is 100%.

[0023] Preferably, the expression of the deviation coefficient is:

[0024]

[0025] Among them, k Q represents the coefficient of deviation, Q CSB represents the first main feedwater flow rate, Q KBF Represents the second main water supply flow rate.

[0026] Preferably, the setting range of the deviation standard value is 0.4% to 0.7%.

[0027] The present invention also constructs a reactor power determination system, comprising:

[0028] Multiple preset flow meters for measuring main feedwater flow to multiple steam generators;

[0029] A plurality of differential pressure flow meters for measuring the main feedwater flow to the plurality of steam generators; and

[0030] A control module comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the steps of the reactor power determination method as described above are implemented when the processor executes the computer program.

[0031] The technical solution of the present invention periodically obtains the first main feed water flow and the second main feed water flow corresponding to multiple steam generators to calculate the deviation coefficient corresponding to each steam generator, and then enters the normal mode when the deviation coefficient of each steam generator is less than the set deviation standard value, thereby calculating the reactor power according to the first main feed water flow of each steam generator, and setting the full power reference value of the reactor to the first set value, so that the reactor can set the maximum settable power to a larger value, which helps to improve the economy of the nuclear power plant. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0033] Figure 1 is a flowchart of a method for determining reactor power in some embodiments of the present invention;

[0034] Figure 2 is a waveform diagram of reactor power in some embodiments of the present invention;

[0035] Figure 3 is a structural block diagram of a reactor power determination system in some embodiments of the present invention. DETAILED DESCRIPTION

[0036] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described in detail with reference to the accompanying drawings.

[0037] It should be noted that the flowcharts shown in the accompanying drawings are only exemplary and do not necessarily include all the contents and operations / steps, nor do they have to be executed in the order described. For example, some operations / steps can be decomposed, while some operations / steps can be combined or partially combined, so the actual execution order may change according to actual conditions.

[0038] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities may be implemented in software form, or in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.

[0039] Figure 1 is a flowchart of a method for determining reactor power in some embodiments of the present invention. The method for determining reactor power improves the measurement accuracy of the main feedwater flow rate and reduces the measurement uncertainty of the reactor power, thereby increasing the maximum settable power of the reactor and helping to improve the economic efficiency of the nuclear power plant. Figure 1 The method may include step S10, step S20, step S30 and step S40.

[0040] Step S10 includes: periodically obtaining the first main feedwater flow and the second main feedwater flow corresponding to the plurality of steam generators; wherein the first and second main feedwater flows are the flow output by the preset flowmeter and the pressure differential flowmeter when measuring the flow of the corresponding steam generator, respectively, and the measurement uncertainty of the preset flowmeter is less than the measurement uncertainty of the pressure differential flowmeter. In a certain nuclear power plant, three steam generators are usually set up to realize the heat exchange between the first and second circuits, and at least one preset flowmeter and at least one pressure differential flowmeter are respectively provided at the water supply port of each steam generator to measure the main feedwater flow of the corresponding steam generator. For the same steam generator, if multiple preset flowmeters and pressure differential flowmeters are set up to measure the main feedwater flow, then the average value of the measured values ​​of each preset flowmeter can be taken as the first main feedwater flow, and the average value of the measured values ​​of each pressure differential flowmeter can be taken as the second main feedwater flow. It can be understood that the embodiment of configuring multiple flowmeters based on the principle of redundancy helps to improve the reliability of the method.

[0041] In addition, the differential pressure flowmeter is an existing flowmeter for measuring the main water flow, while the preset flowmeter is a newly added flowmeter. The preset flowmeter can be an ultrasonic flowmeter of model AH-UFM-1182, and the maximum measurement uncertainty of the ultrasonic flowmeter does not exceed 0.3%. Of course, the preset flowmeter can also be other forms of flowmeters, as long as its measurement uncertainty is lower than the measurement uncertainty of the existing differential pressure flowmeter. The maximum measurement uncertainty of the existing differential pressure flowmeter is generally between 0.7% and 0.8%.

[0042] Furthermore, in order to ensure that the measurement environment of the two flow meters is consistent, the preset flow meter accuracy is preferably set at a similar or even the same position as the differential pressure flow meter with the same measurement target (i.e., measuring the main feed water flow of the same steam generator) to avoid flow measurement errors due to different measurement environments, which may have an adverse effect on subsequent steps and help improve the reliability of the present invention.

[0043] In some embodiments, the reactor power determination method may further include: obtaining a cycle setting instruction to set the acquisition cycle of the first main feedwater flow rate and the second main feedwater flow rate according to the cycle setting instruction. In this embodiment, the user can input the cycle setting instruction through the human-computer interaction unit according to the needs, so as to realize the customized setting of the acquisition cycle.

[0044] Step S20 includes: calculating the deviation coefficient corresponding to each steam generator according to the most recently acquired first main feedwater flow and second main feedwater flow. In this step, after each new first main feedwater flow and second main feedwater flow are acquired, the most recent deviation coefficient corresponding to each steam generator is calculated according to the most recently acquired first main feedwater flow and second main feedwater flow, and step S30 is executed based on the most recently calculated deviation coefficient.

[0045] In some embodiments, the deviation coefficient can be calculated by the following expression: Among them, k Q Denotes the coefficient of deviation, Q CSB Indicates the first main water supply flow, Q KBF Indicates the second main water supply flow.

[0046] Step S30 includes: determining whether the deviation coefficient of each steam generator is less than the set deviation standard value. In this step, the user can input the setting instruction through the human-computer interaction unit according to the needs, so as to customize the deviation standard value. Generally, the deviation standard value can be determined by the measurement uncertainty of the preset flow meter and the differential pressure flow meter. The smaller the deviation standard value is set, the more conservative the maximum settable power of the reactor is, which is more conducive to ensuring the safety of the nuclear power plant, but not conducive to improving the economic efficiency of the nuclear power plant. Therefore, in order to maximize the economic efficiency of the nuclear power plant while ensuring safety as much as possible, the setting range of the deviation standard value can be 0.4% to 0.7%.

[0047] Step S40 includes: when the deviation coefficient of each steam generator is less than the deviation standard value, entering the normal mode; wherein the normal mode includes: calculating the reactor power according to the first main feedwater flow of each steam generator, and setting the full power reference value of the reactor to the first set value. In this step, based on the conservative principle, it is necessary to ensure that the deviation coefficient corresponding to each steam generator is less than the deviation standard value before entering the normal mode. Wherein, the first set value is greater than 100%, which is equivalent to being able to set the full power reference value of the reactor to a higher power, that is, increasing the maximum settable power of the reactor, which helps to improve the economy of the nuclear power plant.

[0048] In some embodiments, the reactor power can be calculated by the following expression:

[0049]

[0050] Among them, H vi represents the wet steam enthalpy of the i-th steam generator, H ei represents the feed water enthalpy of the i-th steam generator, Q ei represents the main feedwater flow rate of the i-th steam generator, Hpi represents the blowdown enthalpy of the i-th steam generator, Q pi represents the blowdown flow of the i-th steam generator, W ΔPR Thermal power of other heat source input items except the core; where i = (1, 2, 3). In addition, H vi , H ei and W ΔPR All of them can be obtained through existing technologies and will not be described in detail here.

[0051] In some embodiments, the reactor power determination method may further include step S50.

[0052] Step S50 includes: when there is at least one steam generator whose deviation coefficient is not less than the deviation standard value, entering the fault mode; wherein the fault mode includes: calculating the reactor power according to the second main feedwater flow of each steam generator, and setting the full power reference value to the first set value, and the duration of the full power reference value being set to the first set value is not greater than the first set time. Since the existing differential pressure flowmeter is a pure mechanical component, the failure rate is lower than the failure rate of the preset flowmeter. When the deviation coefficient corresponding to a steam generator is greater than the deviation standard value, it is inferred that the preset flowmeter has a fault, and the reactor power is jointly affected by the three steam generators, and based on the conservative principle, it will enter the fault mode.

[0053] Taking into account that the measurement values ​​of the preset flow meter and the differential pressure flow meter may experience short-term non-recurring fluctuations due to external factors, thereby causing the fault mode to be mistakenly entered, in this regard, in some embodiments, the fault mode may also include: determining whether the duration for which the full power reference value is set to the first set value is greater than the first set time; when the duration is not greater than the first set time, if the deviation coefficients of each steam generator calculated based on the most recently acquired first main feed water flow and second main feed water flow are less than the deviation standard value, entering the normal mode; when the duration is greater than the first set time, switching from the fault mode to the normal mode is prohibited, and the full power reference value of the reactor is set to the second set value; wherein the first set value is greater than the second set value. In this embodiment, when the duration of entering the fault mode does not exceed the first set time, as long as the most recently calculated deviation coefficients of each steam generator are less than the deviation standard value, it will be considered that it is caused by a short-term fluctuation of the flow meter, and thus the fault mode can be switched back to the normal mode; and when there is always at least one steam generator with a deviation coefficient not less than the deviation standard value within the first set time, it will be inferred that the preset flow meter and the differential pressure flow meter corresponding to the steam generator are faulty, and therefore switching back to the normal mode from the fault mode is prohibited. Only after confirming that the flow meter fault has been eliminated can the user manually switch back to the normal mode.

[0054] In some embodiments, the first set time may range from 2 to 3 days.

[0055] In some embodiments, the first set value may be determined in the following manner: a reactor power measurement uncertainty is calculated based on a maximum measurement uncertainty of a preset flow meter to determine the first set value based on the reactor power measurement uncertainty.

[0056] In some embodiments, the reactor power measurement uncertainty can be calculated by the following expression: Among them, U(W R ) represents the uncertainty of reactor power measurement, W R Represents the reactor power, U(W SG1 ) represents the measurement uncertainty of the first steam generator, W SG1 represents the thermal power of the first steam generator, U(W SG2 ) represents the measurement uncertainty of the second steam generator, W SG2 represents the thermal power of the second steam generator, U(W SG3 ) represents the measurement uncertainty of the third steam generator, W SG3 represents the thermal power of the third steam generator, U(W ΔPR ) represents the measurement uncertainty of other heat source input items except the core, W ΔPR represents the thermal power of other heat source input items. In addition, U(W ΔPR ) and W ΔPR It can be determined by existing technology or by taking empirical values.

[0057] Furthermore, the thermal power of the steam generator can be calculated by the following expression (this formula is applicable to each steam generator): W SG =(H v ―H e )Q e ―(H v ―H p )Q p ; Among them, W SG Indicates the thermal power of the steam generator, H v Indicates the wet steam enthalpy of the steam generator, H e represents the feed water enthalpy of the steam generator, Q e Indicates the feed water flow rate of the steam generator, H p represents the blowdown enthalpy of the steam generator, Q p Indicates the blowdown flow of the steam generator. In addition, the measurement uncertainty of each steam generator (including U(W SG1 )、U(W SG2 )、U(W SG3))After determining the thermal power of the steam generator, it can be obtained through existing algorithm technology and is not limited here.

[0058] Since the reactor power is calculated based on the measured value of the differential pressure flowmeter, the second set value can use the existing set value, that is, the second set value can be set to 100%. For the preset flowmeter, since the measurement uncertainty of the preset flowmeter is smaller than the measurement uncertainty of the differential pressure flowmeter, the reactor power measurement uncertainty is lower, so the first set value can be set to a higher value, for example, some embodiments set the first set value to 101.7%. Please refer to Figure 2 It should be noted that Figure 2 The displayed fault mode (calculating reactor power using the measured values ​​of the differential pressure flowmeter) is a waveform diagram of the change in reactor power after the fault mode lasts for more than the first set time, with an amplitude of up to 4%. To ensure safety, the reactor's full-power reference value can only be set to a maximum of 100%. In normal mode (calculating reactor power using the preset flowmeter measured values), the amplitude is only 0.6%, so the reactor's full-power reference value can be set to a maximum of 101.7%.

[0059] It can be understood that the technical solution of the present invention is implemented by periodically obtaining the first main feed water flow rates and the second main feed water flow rates corresponding to multiple steam generators, respectively, to calculate the deviation coefficient corresponding to each steam generator, and then entering the normal mode when the deviation coefficient of each steam generator is less than the set deviation standard value, thereby calculating the reactor power according to the first main feed water flow rate of each steam generator, and setting the full power reference value of the reactor to the first set value, so that the reactor can set the maximum settable power to a larger value, which helps to improve the economy of the nuclear power plant.

[0060] like Figure 3 As shown, the present invention also provides a reactor power determination system, including a plurality of preset flow meters 1, a plurality of differential pressure flow meters 2, and a control module 3.

[0061] Multiple preset flowmeters 1 are used to measure the main feedwater flow of multiple steam generators. Each steam generator is provided with at least one preset flowmeter 1, so as to measure the feedwater flow of the corresponding steam generator and obtain the corresponding first main feedwater flow.

[0062] Multiple differential pressure flowmeters 2 are used to measure the main feedwater flow of multiple steam generators. Each steam generator is provided with at least one differential pressure flowmeter 2, so as to measure the feedwater flow of the corresponding steam generator and obtain the corresponding second main feedwater flow.

[0063] The control module 3 includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the method for determining reactor power provided in the embodiment of the present invention are implemented.

[0064] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0065] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0066] The steps of the method or algorithm described in conjunction with the embodiments disclosed herein may be implemented directly using hardware, a software module executed by a processor, or a combination of the two. The software module may be placed in a random access memory (RAM), a memory, a read-only memory (ROM), an electrically programmable ROM, an electrically erasable programmable ROM, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.

[0067] It can be understood that the above embodiments only express the preferred implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the patent scope of the present invention. It should be pointed out that, for ordinary technicians in this field, the above technical features can be freely combined without departing from the concept of the present invention, and several deformations and improvements can be made, which all belong to the protection scope of the present invention. Therefore, all equivalent changes and modifications made to the scope of the claims of the present invention should belong to the coverage of the claims of the present invention.

Claims

1. A method for determining reactor power, characterized in that: include: Periodically obtaining first main feedwater flow rates and second main feedwater flow rates corresponding to a plurality of steam generators, respectively; wherein the first and second main feedwater flow rates are flow rates output when a preset flow meter and a differential pressure flow meter measure flow rates of corresponding steam generators, respectively, and the measurement uncertainty of the preset flow meter is less than the measurement uncertainty of the differential pressure flow meter; Calculating the deviation coefficient corresponding to each of the steam generators according to the first main feed water flow rate and the second main feed water flow rate obtained most recently; Determining whether the deviation coefficient of each steam generator is less than a set deviation standard value; When the deviation coefficient of each steam generator is less than the deviation standard value, the normal mode is entered; wherein, the normal mode includes: calculating the reactor power according to the first main feed water flow of each steam generator, and setting the full power reference value of the reactor to the first set value.

2. The method for determining reactor power according to claim 1, characterized in that: Also includes: When there is at least one of the steam generators with a deviation coefficient not less than the deviation standard value, a fault mode is entered; wherein the fault mode includes: calculating the reactor power based on the second main feed water flow of each of the steam generators, and setting the full power reference value to the first set value, and the duration for which the full power reference value is set to the first set value is not greater than the first set time.

3. The method for determining reactor power according to claim 2, characterized in that: The failure modes also include: Determining whether the duration for which the full power reference value is set to the first set value is greater than a first set time; When the duration is not greater than the first set time, if the deviation coefficients of the steam generators calculated based on the most recently acquired first main feed water flow and second main feed water flow are both less than the deviation standard value, entering the normal mode; When the duration is greater than the first set time, switching from the fault mode to the normal mode is prohibited, and the full power reference value of the reactor is set to a second set value; wherein the first set value is greater than the second set value.

4. The method for determining reactor power according to claim 3, characterized in that: Also includes: The reactor power measurement uncertainty is calculated according to the maximum measurement uncertainty of the preset flow meter, so as to determine the first set value according to the reactor power measurement uncertainty.

5. The method for determining reactor power according to claim 3, characterized in that: The expression of the reactor power measurement uncertainty is: Among them, U(W R ) represents the reactor power measurement uncertainty, W R Represents the reactor power, U(W SG1 ) represents the measurement uncertainty of the first steam generator, W SG1 represents the thermal power of the first steam generator, U(W SG2 ) represents the measurement uncertainty of the second steam generator, W SG2 represents the thermal power of the second steam generator, U(W SG3 ) represents the measurement uncertainty of the third steam generator, W SG3 represents the thermal power of the third steam generator, U(W ΔPR ) represents the measurement uncertainty of other heat source input items except the core, W ΔPR Represents the thermal power of the other heat source input.

6. The method for determining reactor power according to any one of claims 2 to 5, characterized in that: The first set time ranges from 2 to 3 days.

7. The method for determining reactor power according to any one of claims 2 to 5, characterized in that: The first setting value is 101.7% and / or the second setting value is 100%.

8. The method for determining reactor power according to claim 1, characterized in that: The expression of the deviation coefficient is: Among them, k Q represents the coefficient of deviation, Q CSB represents the first main feedwater flow rate, Q KBF Represents the second main water supply flow rate.

9. The method for determining reactor power according to claim 1, characterized in that: The deviation standard value is set in the range of 0.4% to 0.7%.

10. A reactor power determination system, characterized in that: include: Multiple preset flow meters for measuring main feedwater flow to multiple steam generators; Multiple differential pressure flow meters for measuring main feedwater flow rates of multiple steam generators; as well as A control module, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the reactor power determination method as described in any one of claims 1 to 8 when executing the computer program.

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