Method for judging abnormal output of pressurized water reactor nuclear power unit

Abstract

The present invention discloses a method for determining output anomaly of a pressurized water reactor nuclear power unit, comprising: obtaining output tracking data of a current fuel cycle period and output tracking data of a historical fuel cycle period of the nuclear power unit; calculating, based on the output tracking data, a steam turbine equivalent steam flow rate, electric power converted to rated thermal power, and electric power converted to 104% of a steam flow rate; making four scatter plots based on the output tracking data of the current fuel cycle period and the historical fuel cycle period, with seawater temperature and condenser steam parameters as the X-axis, and electric power converted to rated thermal power and electric power converted to 104% of a steam flow rate as the Y-axis; and conducting longitudinal comparisons individually or jointly based on the four scatter plots with time as the third dimension, thereby determining whether the unit output is abnormal and determining the section in which the abnormality occurs.

Description

Technical Field

[0001] The present invention relates to the field of nuclear power engineering, and in particular to a method for judging abnormal output of a pressurized water reactor nuclear power unit. Background Art

[0002] During routine operation of a pressurized water reactor unit, even if the thermal system and equipment are operating normally, electrical output often fluctuates due to changes in parameters such as seawater temperature, ocean tides, core thermal power, evaporator blowdown flow, and plant steam consumption. Therefore, after unit refueling and maintenance, or during daily production management, unit output must be monitored, known as unit output tracking, to identify whether changes in electrical power are normal. If the cause is uncontrollable factors outside the thermal system boundaries, attention should be paid. If the output change is caused by controllable factors within or outside the thermal system boundaries, the cause should be promptly identified and eliminated to ensure healthy unit operation and maximize its power generation capacity.

[0003] Typically, nuclear power plant technicians use a unit output tracking method: based on the amount of electric power change caused by boundary factors deviating from design conditions, they use the design curves or formulas provided by the equipment manufacturer to perform a correction calculation on the measured electric power, obtaining the electric power corrected to the design conditions (referred to as the corrected electric power). This is then compared with the design value. If the corrected electric power is greater than the design value, the unit output is considered normal; if it is less than the design value, the unit output is considered abnormal. However, there is often a certain deviation between the design curve or formula and the actual thermal characteristics. The correction calculation cannot accurately reflect the amount of electric power change caused by the deviation of the boundary factors from the design conditions. Therefore, the deviation between the corrected electric power and the design value cannot represent the actual performance difference, thus affecting the identification of whether the unit output change is normal or not. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for judging abnormal output of a pressurized water reactor nuclear power unit, abandon the conventional correction calculation method of the measured electric power, and propose a method based on the longitudinal comparison of the actual thermodynamic characteristics of previous fuel cycles to accurately and efficiently identify abnormal output of the nuclear power unit.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A method for determining abnormal output of a pressurized water reactor nuclear power unit is provided, wherein the abnormal output of the nuclear power unit is identified by the following steps:

[0007] Obtain output tracking data of nuclear power units during the current fuel cycle and output tracking data of historical fuel cycles;

[0008] Based on the output tracking data of the nuclear power unit during the current fuel cycle, obtain the current relationship data between the electric power converted to the rated thermal power and the seawater temperature; based on the output tracking data of the nuclear power unit during the historical fuel cycle, obtain the historical relationship data between the electric power converted to the rated thermal power and the seawater temperature;

[0009] If the electric power converted to the rated thermal power corresponding to the seawater temperature in the current relationship data is less than the electric power converted to the rated thermal power corresponding to the same seawater temperature in the historical relationship data, it is determined that the output of the nuclear power unit is abnormal.

[0010] Furthermore, the output tracking data of the current fuel cycle and the output tracking data of the historical fuel cycle are both tracked and obtained when the nuclear power unit is operating at full power, and the tracked data are filtered according to one or more of the following conditions to obtain the output tracking data:

[0011] The thermal power of the steam generator secondary side and its heat balance test system is within the range of 98.5% FP-100% FP; and / or

[0012] The blowdown flow rate of the steam generator blowdown system is about 70t / h, and the cooling water flow rate of APG002RF is greater than or equal to 80t / h, and the outlet temperature of the cooling water side of APG002RF is greater than or equal to 170°C; and / or

[0013] The regulating valve opening of the steam trap is less than or equal to 10%.

[0014] Furthermore, under the premise of decomposing the thermodynamic cycle of the pressurized water reactor nuclear power unit into the hot end, the middle section and the cold end, the output improvement contribution of the cold end is calculated according to the following steps:

[0015] According to the relationship data between the electric power converted to the rated thermal power and the seawater temperature, the difference between the current electric power converted to the rated thermal power and the historical electric power converted to the rated thermal power corresponding to the same seawater temperature is calculated to obtain a first converted electric power difference;

[0016] Obtain current relationship data between the electric power converted to the rated thermal power and the condenser steam parameters based on the output tracking data of the current fuel cycle of the nuclear power unit; obtain historical relationship data between the electric power converted to the rated thermal power and the condenser steam parameters based on the output tracking data of the historical fuel cycle of the nuclear power unit; and calculate the difference between the current electric power converted to the rated thermal power and the historical electric power converted to the rated thermal power corresponding to the same condenser steam parameters to obtain a second converted electric power difference;

[0017] The difference between the first converted electric power difference and the second converted electric power difference is calculated as the contribution to the output improvement of the cold end. If the first converted electric power difference is less than the second converted electric power difference, it is determined that the cold end output of the nuclear power unit is abnormal.

[0018] Furthermore, under the premise of decomposing the thermodynamic cycle of the pressurized water reactor nuclear power unit into the hot end, the middle section and the cold end, the output improvement contribution of the hot end is calculated according to the following steps:

[0019] According to the relationship data between the electric power converted to the rated thermal power and the seawater temperature, the difference between the current electric power converted to the rated thermal power and the historical electric power converted to the rated thermal power corresponding to the same seawater temperature is calculated to obtain a first converted electric power difference;

[0020] obtaining, based on output tracking data of the nuclear power unit during a current fuel cycle, current relationship data of the electric power converted to 104% of the steam flow rate and the seawater temperature; obtaining, based on output tracking data of historical fuel cycle periods of the nuclear power unit, historical relationship data of the electric power converted to 104% of the steam flow rate and the seawater temperature; and calculating the difference between the current electric power converted to 104% of the steam flow rate and the historical electric power converted to 104% of the steam flow rate for the same seawater temperature to obtain a third converted electric power difference;

[0021] The difference between the first converted electric power difference and the third converted electric power difference is calculated as the output improvement contribution of the hot end. If the first converted electric power difference is less than the third converted electric power difference, it is determined that the hot end output of the nuclear power unit is abnormal.

[0022] Furthermore, under the premise of decomposing the thermodynamic cycle of the pressurized water reactor nuclear power unit into the hot end, the middle section and the cold end, the output improvement contribution of the middle section is calculated according to the following steps:

[0023] Obtain current relationship data between the electric power converted to 104% steam flow and the condenser steam parameters based on the output tracking data of the current fuel cycle of the nuclear power unit; obtain historical relationship data between the electric power converted to 104% steam flow and the condenser steam parameters based on the output tracking data of the historical fuel cycle of the nuclear power unit; and calculate the difference between the current electric power converted to 104% steam flow and the historical electric power converted to 104% steam flow corresponding to the same condenser steam parameters to obtain a fourth converted electric power difference;

[0024] The fourth converted electric power difference is used as the output improvement contribution of the middle section. If the fourth converted electric power difference is less than 0, it is determined that the output of the middle section of the nuclear power unit is abnormal.

[0025] Furthermore, the statistical calculation of the difference between the current electric power converted to the rated thermal power and the historical electric power converted to the rated thermal power corresponding to the same seawater temperature includes the following steps:

[0026] The relationship data between the electric power converted to the rated thermal power and the seawater temperature is in the form of a scatter plot. The current scatter values and historical scatter values corresponding to multiple seawater temperatures are taken to obtain multiple groups of current scatter values and historical scatter values. The average value of the difference between the current scatter values and the historical scatter values is calculated to obtain the statistical result of the difference between the current electric power converted to the rated thermal power and the historical electric power converted to the rated thermal power corresponding to the same seawater temperature.

[0027] Furthermore, the condenser steam parameter is the condenser steam temperature or the condenser steam pressure.

[0028] Furthermore, the output tracking data of the historical fuel cycle period is output tracking data of multiple cycles, and the historical relationship data of the electric power converted to rated thermal power and the seawater temperature is multiple groups;

[0029] If the electric power converted to the rated thermal power corresponding to the seawater temperature in the current relationship data is less than the electric power converted to the rated thermal power corresponding to the same seawater temperature in any set of historical relationship data, it is determined that the output of the nuclear power unit is abnormal.

[0030] On the other hand, the present invention also provides a method for determining abnormal output of a pressurized water reactor nuclear power unit. Under the premise of decomposing the thermodynamic cycle of the pressurized water reactor nuclear power unit into the hot end, the intermediate section, and the cold end, the method obtains one or more of the following four converted electric power differences to identify abnormal output conditions of the nuclear power unit:

[0031] obtaining current relationship data of the electric power converted to the rated thermal power and the seawater temperature based on output tracking data of the nuclear power unit during the current fuel cycle; obtaining historical relationship data of the electric power converted to the rated thermal power and the seawater temperature based on output tracking data of the nuclear power unit during historical fuel cycles; and calculating the difference between the current electric power converted to the rated thermal power and the historical electric power converted to the rated thermal power corresponding to the same seawater temperature to obtain a first converted electric power difference;

[0032] Obtain current relationship data between the electric power converted to the rated thermal power and the condenser steam parameters based on the output tracking data of the current fuel cycle of the nuclear power unit; obtain historical relationship data between the electric power converted to the rated thermal power and the condenser steam parameters based on the output tracking data of the historical fuel cycle of the nuclear power unit; and calculate the difference between the current electric power converted to the rated thermal power and the historical electric power converted to the rated thermal power corresponding to the same condenser steam parameters to obtain a second converted electric power difference;

[0033] obtaining, based on output tracking data of the nuclear power unit during a current fuel cycle, current relationship data of the electric power converted to 104% of the steam flow rate and the seawater temperature; obtaining, based on output tracking data of historical fuel cycle periods of the nuclear power unit, historical relationship data of the electric power converted to 104% of the steam flow rate and the seawater temperature; and calculating the difference between the current electric power converted to 104% of the steam flow rate and the historical electric power converted to 104% of the steam flow rate for the same seawater temperature to obtain a third converted electric power difference;

[0034] Based on the output tracking data of the current fuel cycle of the nuclear power unit, the current relationship data between the electric power converted to 104% steam flow and the condenser steam parameters are obtained; based on the output tracking data of the historical fuel cycle of the nuclear power unit, the historical relationship data between the electric power converted to 104% steam flow and the condenser steam parameters are obtained; the difference between the current electric power converted to 104% steam flow and the historical electric power converted to 104% steam flow corresponding to the same condenser steam parameters is statistically calculated to obtain a fourth converted electric power difference.

[0035] Furthermore, abnormal output conditions of nuclear power units are identified through the following conditions:

[0036] If the first converted electric power difference is less than 0, it is determined that the output of the nuclear power unit is abnormal; or,

[0037] If the second converted electric power difference is less than 0, it is determined that the output of the middle section and / or hot end of the nuclear power unit is abnormal; or,

[0038] If the third converted electric power difference is less than 0, it is determined that the output of the middle section and / or cold end of the nuclear power unit is abnormal; or,

[0039] If the fourth converted electric power difference is less than 0, it is determined that the middle section output of the nuclear power unit is abnormal; or,

[0040] Based on at least three of the four converted electric power differences, the output improvement contribution of the hot end, the middle section and the cold end is calculated. If the output improvement contribution of the hot end is a negative value, the hot end output of the nuclear power unit is abnormal; if the output improvement contribution of the middle section is a negative value, the middle section output of the nuclear power unit is abnormal; if the output improvement contribution of the cold end is a negative value, the cold end output of the nuclear power unit is abnormal.

[0041] The beneficial effects brought about by the technical solution provided by the present invention are as follows:

[0042] a. By using the statistical data of nuclear power units' fuel cycles, a scatter plot can be created after converting the electric power. By longitudinally comparing the characteristic trends of previous fuel cycles, it is possible to identify power anomalies and locate the abnormal parts.

[0043] b. There is no need to adopt a corrected calculation method to avoid misjudgment or omission of abnormal unit output due to deviations between the design curve or formula and the actual thermal characteristics of the unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments recorded in this application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0045] Figure 1 This is a schematic diagram of the scattered distribution of the statistical data of the nuclear power unit over the fuel cycles converted to the rated thermal power vs. the seawater temperature provided by an embodiment of the present invention;

[0046] Figure 2 This is a schematic diagram of the scattered distribution of the statistical data of the nuclear power unit over the fuel cycles converted to the rated thermal power VS the condenser steam temperature provided by an embodiment of the present invention;

[0047] Figure 3 This is a schematic diagram of the scattered distribution of the statistical data of the nuclear power unit over the fuel cycles converted to the electric power at 104% steam flow rate vs. seawater temperature provided by an embodiment of the present invention;

[0048] Figure 4 This is a schematic diagram of the scattered distribution of the statistical data of the nuclear power unit over the fuel cycles converted to the electric power at 104% steam flow rate vs. the condenser steam temperature provided by an embodiment of the present invention;

[0049] Figure 5 The present invention provides a logic diagram of a method for determining abnormal output of a pressurized water reactor nuclear power unit. DETAILED DESCRIPTION

[0050] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0051] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, apparatus, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0052] Conventional methods for determining abnormal unit output require the use of design curves or formulas, which often deviate from the actual thermal characteristics of the unit, resulting in misjudgment or omission of abnormal unit output. The present invention abandons conventional correction calculation methods and proposes a method based on longitudinal comparison of actual thermal characteristics of previous fuel cycles. By applying steam turbine principles and related thermodynamic theories, combined with the characteristics of nuclear power units, the method leverages the connection between the reactor thermal power, the first-stage steam pressure before the high-pressure cylinder, and the condenser steam parameters, decomposing the secondary circuit thermal system into three sections. Based on daily unit output tracking statistical data, a simple electric power conversion is performed, which is then classified by fuel cycle and produced into a scatter plot. By longitudinally comparing the characteristic trends of previous fuel cycles, it is possible to accurately and efficiently identify abnormal nuclear power unit output and locate the abnormal section.

[0053] In one embodiment of the present invention, a method for determining abnormal output of a pressurized water reactor nuclear power unit is provided. The method decomposes the thermal cycle of a pressurized water reactor unit into three parts: the hot end, the intermediate section, and the cold end. The hot end includes the systems and equipment through which fresh steam flows, including the steam generator secondary side and its heat balance test system (KME), the auxiliary feedwater pump extraction line (ASG), the main steam pipeline and drain (VVP), the main steam bypass system (GCT), the fresh steam extraction line of the steam-water separator reheat system (GSS), the turbine high-pressure main steam valve and regulating valve (TV&GV), and the steam pipeline (commonly known as the steam guide) connecting to the high-pressure cylinder. The cold end includes the condenser, the circulating water system, the vacuum system, and the vacuum boundary. The intermediate section includes the turbine body and drain, the steam-water separator reheat system, and the regenerative heating system. After completing the three-segment division described above, we first create scatter plots for each fuel cycle of the nuclear power unit, leveraging the interconnectedness of the three parameters: reactor thermal power, steam pressure before the first high-pressure cylinder stage, and condenser steam parameters. These plots are combined using the following combination rules: three segments combined (hot end + middle segment + cold end), two segments combined (hot end + middle segment, middle segment + cold end), and a single segment (middle segment). These plots are then compared longitudinally. By combining one or more scatter plots, we can determine whether the output is normal and infer the segments with abnormal output. The corresponding curves for these scatter plots are: the relationship between the electric power converted to rated thermal power and seawater temperature; the relationship between the electric power converted to rated thermal power and condenser temperature (or condenser pressure, hereinafter using condenser temperature as an example); the relationship between the electric power converted to an equivalent steam flow rate and seawater temperature; and the relationship between the electric power converted to an equivalent steam flow rate and condenser temperature (or condenser pressure, hereinafter using condenser temperature as an example).

[0054] Taking the F1 unit as an example, we analyze the output changes after the F104 overhaul compared to the F103 overhaul and the locations causing the changes. Assuming the F1 unit completed its fourth refueling overhaul (referred to as the F104 overhaul) in mid-September 2021 and subsequently began full power operation during its fifth fuel cycle, we filter the daily output tracking data for the F1 unit's second, third, fourth, and fifth fuel cycles (referred to as F1C02, F1C03, F1C04, and F1C05) according to one or a combination of the following criteria:

[0055] 1) The thermal power of the KME (steam generator secondary side and its heat balance test system) is between 95% FP and 100% FP, more preferably between 98.5% FP and 100% FP;

[0056] 2) The APG (steam generator blowdown system) blowdown flow rate is about 70 t / h, the APG002RF cooling water flow rate is greater than or equal to 80 t / h, more preferably not less than 100 t / h, and the APG002RF cooling water outlet temperature is greater than or equal to 170°C, more preferably not less than 176°C;

[0057] 3) The opening of the STR (plant steam conversion system) fresh steam regulating valve is less than or equal to 10%, and more preferably not more than 5%.

[0058] Based on the filtered data samples, we can make correlation trends and get Figures 1 to 4 The scatter plot shown, Figures 1 to 4 This is for example only and does not limit the actual value and relative size of the data.

[0059] See also Figure 1 , ◇ represents the scatter plot of the electric power converted to the rated thermal power VS seawater temperature during the F1C02 fuel cycle, O represents the scatter plot of the electric power converted to the rated thermal power VS seawater temperature during the F1C03 fuel cycle, △ represents the scatter plot of the electric power converted to the rated thermal power VS seawater temperature during the F1C04 fuel cycle, and □ represents the scatter plot of the electric power converted to the rated thermal power VS seawater temperature during the F1C05 fuel cycle (i.e. the present). Figure 1 It can be seen that under the conditions of rated thermal power and equivalent seawater temperature, the electric power of F1C05 is about 13MW higher than that of F1C04 (at the end of its life) (the calculation method is as follows: first determine the X-axis coordinate, then check the Y-axis coordinate of the trend curves of F1C05 and F1C04 respectively, and subtract the two Y-axis coordinates to get the single-point electric power deviation of F1C05 relative to F1C04 during the fuel cycle. For multiple-point situations, the average value of multiple single-point electric power deviations can be taken). In other words, the output of F104 after overhaul (i.e. F1C05) is about 13MW higher than that before overhaul (i.e. the end of F1C04's life). Figure 1 This represents a 13MW increase in the combined output of the hot, intermediate, and cold ends of the nuclear pressurized water reactor's thermal cycle. Specifically, the electric power converted to rated thermal power is calculated using the formula: "rated thermal power ÷ measured thermal power × electric power."

[0060] See also Figure 2, ◇ represents the scatter points of the electric power converted to the rated thermal power of the F1C02 fuel cycle VS the condenser steam temperature, O represents the scatter points of the electric power converted to the rated thermal power of the F1C03 fuel cycle VS the condenser steam temperature, △ represents the scatter points of the electric power converted to the rated thermal power of the F1C04 fuel cycle VS the condenser steam temperature, and □ represents the scatter points of the electric power converted to the rated thermal power of the F1C05 fuel cycle (i.e. the current) VS the condenser steam temperature; by Figure 2 It can be seen that under the conditions of rated thermal power and the same condenser steam temperature (or equivalent back pressure), the output of F1C05 and F1C04 (end of life) is basically the same (the output increase is 0). Figure 2 It represents the combined output improvement of the hot end and the middle section of the thermal cycle of the nuclear pressurized water reactor unit. Figure 1 and Figure 2 It can be seen that the main contributor to the output increase after the F104 overhaul compared with before the overhaul is the cold end, which is about 13MW.

[0061] See also Figure 3 , ◇ represents the scatter plot of electric power VS seawater temperature under the condition of 104% steam flow rate during the F1C02 fuel cycle, O represents the scatter plot of electric power VS seawater temperature under the condition of 104% steam flow rate during the F1C03 fuel cycle, △ represents the scatter plot of electric power VS seawater temperature under the condition of 104% steam flow rate during the F1C04 fuel cycle, and □ represents the scatter plot of electric power VS seawater temperature under the condition of 104% steam flow rate during the F1C05 fuel cycle (i.e. the present); by Figure 3 It can be seen that under the conditions of equal steam flow and seawater temperature, F1C05 is about 15MW higher than F1C04 (at the end of life) (for the statistical method, please refer to the statistical method of 13MW mentioned above). Figure 3 It represents the combined output improvement of the cold end and the middle section of the thermal cycle of the nuclear pressurized water reactor unit. Figure 1 and Figure 3 It can be seen that after the F104 overhaul, the hot end not only did not bring benefits, but also produced negative effects, resulting in a loss of 2MW of electrical power. Figure 2 It can be seen that the output of the middle section is increased by 2MW (resulting in Figure 2 Specifically, the turbine equivalent flow rate is calculated based on the steam pressure before the first stage of the high-pressure cylinder and the new steam flow rate consumed by the steam-water separator reheater. Then, the electric power converted to 104% steam flow rate is calculated using the formula "104% ÷ turbine equivalent flow rate × electric power".

[0062] See also Figure 4 , ◇ represents the scatter points of the electric power VS condenser steam temperature under the condition of 104% steam flow rate of the F1C02 fuel cycle, O represents the scatter points of the electric power VS condenser steam temperature under the condition of 104% steam flow rate of the F1C03 fuel cycle, △ represents the scatter points of the electric power VS condenser steam temperature under the condition of 104% steam flow rate of the F1C04 fuel cycle, and □ represents the scatter points of the electric power VS condenser steam temperature under the condition of 104% steam flow rate of the F1C05 fuel cycle (i.e. the current period); by Figure 4 It can be seen that under the same steam flow and the same condenser steam temperature (or the same back pressure), F1C05 is 1~2MW higher than F1C04 (end of life), or in other words, F104 after overhaul is 1~2MW higher than F103 after overhaul. Figure 4 It represents the increase in the output of a single part in the middle section of the thermal cycle of a nuclear pressurized water reactor unit.

[0063] In summary, after the F104 overhaul (F1C05 fuel cycle, i.e. the current period) compared with the F103 overhaul (F1C04 fuel cycle), the main contribution to the output increase comes from the cold end, about 13MW; the secondary contributor is the middle section, about 1 to 2MW; but the hot end has a negative effect, offsetting 2MW; after the three sections are superimposed, the output is finally increased by 13MW.

[0064] The above is only for the comparison between F1C05 fuel cycle and F1C04 fuel cycle. The same is true for the comparison between F1C03 fuel cycle and F1C02 fuel cycle. Figures 1 to 4 It can be seen that compared with F1C02 and F1C04, the operating status of F1C03 is relatively optimal. Compared with F1C03, F1C05 gains 7MW of electric power at the cold end, loses 3MW at the hot end, and loses 1MW in the middle section. After the three sections are superimposed, the overall output increases by 3MW.

[0065] In summary, the present invention utilizes the connection effect of the three parameters of reactor thermal power, high pressure cylinder first stage steam pressure and condenser steam parameters, see Figure 5, obtain the output tracking data of the nuclear power unit in the current fuel cycle period and the output tracking data of the historical fuel cycle period; based on the output tracking data, calculate the turbine equivalent steam flow rate, the electric power converted to the rated thermal power, and the electric power converted to 104% of the steam flow rate; based on the output tracking data of the current fuel cycle period and the historical fuel cycle period, make four scatter plots with seawater temperature and condenser steam parameters as the X-axis, and the electric power converted to the rated thermal power and the electric power converted to 104% of the steam flow rate as the Y-axis; based on the four scatter plots, with time as the third dimension, conduct longitudinal comparisons individually or jointly to determine whether there is any abnormality in the unit output and determine the section where the abnormality occurs. According to the combination rules of three sections in one (hot end + middle section + cold end), two sections in one (hot end + middle section, middle section + cold end), and a single section only (middle section), with the help of the statistical data of the nuclear power unit's previous fuel cycles, it is only necessary to convert the electric power and then make a scatter plot, namely: the relationship curve between the electric power converted to the rated thermal power and the seawater temperature, the relationship curve between the electric power converted to the rated thermal power and the condenser temperature (or condenser pressure), the relationship curve between the electric power converted to the same steam flow and the seawater temperature, and the relationship curve between the electric power converted to the same steam flow and the condenser temperature (or condenser pressure). Then, the scatter plots are compared vertically. Based on these four scatter plots, using thermodynamic knowledge, it is possible to judge whether the output is normal and infer the sections with abnormal output, for example:

[0066] like Figure 1 As shown, based on the output tracking data of the nuclear power unit during the current fuel cycle, current relationship data of the electric power converted to the rated thermal power and the seawater temperature are obtained; based on the output tracking data of the nuclear power unit during the historical fuel cycle, historical relationship data of the electric power converted to the rated thermal power and the seawater temperature are obtained; and the difference between the current electric power converted to the rated thermal power and the historical electric power converted to the rated thermal power corresponding to the same seawater temperature is calculated to obtain a first converted electric power difference;

[0067] like Figure 2 As shown, based on the output tracking data of the current fuel cycle of the nuclear power unit, the current relationship data of the electric power converted to the rated thermal power and the condenser steam parameters are obtained; based on the output tracking data of the historical fuel cycle of the nuclear power unit, the historical relationship data of the electric power converted to the rated thermal power and the condenser steam parameters are obtained; the difference between the current electric power converted to the rated thermal power and the historical electric power converted to the rated thermal power corresponding to the same condenser steam parameters is calculated to obtain a second converted electric power difference;

[0068] like Figure 3As shown, based on the output tracking data of the nuclear power unit during the current fuel cycle, current relationship data of the electric power converted to 104% steam flow rate and the seawater temperature are obtained; based on the output tracking data of the nuclear power unit during the historical fuel cycle, historical relationship data of the electric power converted to 104% steam flow rate and the seawater temperature are obtained; and the difference between the current electric power converted to 104% steam flow rate and the historical electric power converted to 104% steam flow rate corresponding to the same seawater temperature is calculated to obtain a third converted electric power difference;

[0069] like Figure 4 As shown, according to the output tracking data of the current fuel cycle of the nuclear power unit, the current relationship data of the electric power converted to 104% steam flow and the condenser steam parameters are obtained; according to the output tracking data of the historical fuel cycle of the nuclear power unit, the historical relationship data of the electric power converted to 104% steam flow and the condenser steam parameters are obtained; the difference between the current electric power converted to 104% steam flow and the historical electric power converted to 104% steam flow corresponding to the same condenser steam parameters is calculated to obtain a fourth converted electric power difference;

[0070] Abnormal output of nuclear power units can be identified through the following conditions:

[0071] If the first converted electric power difference is less than 0, it is determined that the output of the nuclear power unit is abnormal; or,

[0072] If the second converted electric power difference is less than 0, it is determined that the output of the middle section and / or hot end of the nuclear power unit is abnormal; or,

[0073] If the third converted electric power difference is less than 0, it is determined that the output of the middle section and / or cold end of the nuclear power unit is abnormal; or,

[0074] If the fourth converted electric power difference is less than 0, it is determined that the middle section output of the nuclear power unit is abnormal; or,

[0075] Based on at least three of the four converted electric power differences, the output improvement contribution of the hot end, the middle section and the cold end is calculated. If the output improvement contribution of the hot end is a negative value, the hot end output of the nuclear power unit is abnormal; if the output improvement contribution of the middle section is a negative value, the middle section output of the nuclear power unit is abnormal; if the output improvement contribution of the cold end is a negative value, the cold end output of the nuclear power unit is abnormal.

[0076] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0077] The above is only a specific implementation method of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A method for determining abnormal output of a pressurized water reactor nuclear power unit, characterized in that: Identify abnormal output conditions of nuclear power units through the following steps: Obtain output tracking data of nuclear power units during the current fuel cycle and output tracking data of historical fuel cycles; Based on the output tracking data of the nuclear power unit during the current fuel cycle, the current corresponding relationship data of the electric power converted to the rated thermal power and the seawater temperature are obtained; based on the output tracking data of the nuclear power unit during the historical fuel cycle, the historical corresponding relationship data of the electric power converted to the rated thermal power and the seawater temperature are obtained; If the electric power converted to the rated thermal power corresponding to the seawater temperature in the current correspondence data is less than the electric power converted to the rated thermal power corresponding to the same seawater temperature in the historical correspondence data, it is determined that the output of the nuclear power unit is abnormal.

2. The method for determining abnormal output of a pressurized water reactor nuclear power unit according to claim 1, wherein: The output tracking data of the current fuel cycle and the output tracking data of the historical fuel cycle are both obtained by tracking when the nuclear power unit is operating at full power, and the output tracking data are obtained by filtering the tracked data according to one or more of the following conditions: The thermal power of the steam generator secondary side and its heat balance test system is within the range of 98.5% FP-100% FP; and / or, The blowdown flow rate of the steam generator blowdown system is approximately 70 t / h, the cooling water flow rate of the blowdown heat recovery heat exchanger is greater than or equal to 80 t / h, and the outlet temperature of the cooling water side of the blowdown heat recovery heat exchanger is greater than or equal to 170°C; and / or, The opening of the new steam regulating valve of the plant steam conversion system is less than or equal to 10%.

3. The method for determining abnormal output of a pressurized water reactor nuclear power unit according to claim 1, wherein: Under the premise of decomposing the thermodynamic cycle of a pressurized water reactor nuclear power unit into the hot end, the intermediate section, and the cold end, the output improvement contribution of the cold end is calculated according to the following steps: According to the corresponding relationship data between the electric power converted to the rated thermal power and the seawater temperature, the difference between the current electric power converted to the rated thermal power and the historical electric power converted to the rated thermal power corresponding to the same seawater temperature is calculated to obtain a first converted electric power difference; Based on the output tracking data of the nuclear power unit during the current fuel cycle, the current corresponding relationship data between the electric power converted to the rated thermal power and the condenser steam parameters are obtained; based on the output tracking data of the nuclear power unit during the historical fuel cycle, the historical corresponding relationship data between the electric power converted to the rated thermal power and the condenser steam parameters are obtained; Counting the difference between the current electric power converted to the rated thermal power and the historical electric power converted to the rated thermal power corresponding to the same condenser steam parameters to obtain a second converted electric power difference; The difference between the first converted electric power difference and the second converted electric power difference is calculated as the contribution to the output improvement of the cold end. If the first converted electric power difference is less than the second converted electric power difference, it is determined that the cold end output of the nuclear power unit is abnormal.

4. The method for determining abnormal output of a pressurized water reactor nuclear power unit according to claim 1, wherein: Under the premise of decomposing the thermodynamic cycle of a pressurized water reactor nuclear power unit into the hot end, the intermediate section, and the cold end, the output improvement contribution of the hot end is calculated according to the following steps: According to the corresponding relationship data between the electric power converted to the rated thermal power and the seawater temperature, the difference between the current electric power converted to the rated thermal power and the historical electric power converted to the rated thermal power corresponding to the same seawater temperature is calculated to obtain a first converted electric power difference; obtaining, based on output tracking data of the nuclear power unit during a current fuel cycle, current corresponding relationship data of the electric power converted to 104% of the steam flow rate and the seawater temperature; obtaining, based on output tracking data of historical fuel cycle periods of the nuclear power unit, historical corresponding relationship data of the electric power converted to 104% of the steam flow rate and the seawater temperature; and calculating the difference between the current electric power converted to 104% of the steam flow rate and the historical electric power converted to 104% of the steam flow rate for the same seawater temperature to obtain a third converted electric power difference; The difference between the first converted electric power difference and the third converted electric power difference is calculated as the output improvement contribution of the hot end. If the first converted electric power difference is less than the third converted electric power difference, it is determined that the hot end output of the nuclear power unit is abnormal.

5. The method for determining abnormal output of a pressurized water reactor nuclear power unit according to claim 1, wherein: Under the premise of decomposing the thermodynamic cycle of a pressurized water reactor nuclear power unit into the hot end, the middle section, and the cold end, the output improvement contribution of the middle section is calculated according to the following steps: Obtain current correspondence data between the electric power converted to 104% steam flow and the condenser steam parameters based on the output tracking data of the current fuel cycle of the nuclear power unit; obtain historical correspondence data between the electric power converted to 104% steam flow and the condenser steam parameters based on the output tracking data of the historical fuel cycle of the nuclear power unit; and calculate the difference between the current electric power converted to 104% steam flow and the historical electric power converted to 104% steam flow corresponding to the same condenser steam parameters to obtain a fourth converted electric power difference; The fourth converted electric power difference is used as the output improvement contribution of the middle section. If the fourth converted electric power difference is less than 0, it is determined that the output of the middle section of the nuclear power unit is abnormal.

6. The method for determining abnormal output of a pressurized water reactor nuclear power unit according to claim 3 or 4, characterized in that: The statistical calculation of the difference between the current electric power converted to the rated thermal power and the historical electric power converted to the rated thermal power corresponding to the same seawater temperature comprises the following steps: The data on the correspondence between the electric power converted to the rated thermal power and the seawater temperature is in the form of a scatter plot. The current scatter values and historical scatter values corresponding to multiple seawater temperatures are taken to obtain multiple groups of current scatter values and historical scatter values. The average value of the difference between the current scatter values and the historical scatter values is calculated to obtain the statistical result of the difference between the current electric power converted to the rated thermal power and the historical electric power converted to the rated thermal power corresponding to the same seawater temperature.

7. The method for determining abnormal output of a pressurized water reactor nuclear power unit according to claim 3 or 5, characterized in that: The condenser steam parameter is the condenser steam pressure or the condenser steam temperature.

8. The method for determining abnormal output of a pressurized water reactor nuclear power unit according to any one of claims 3 to 5, characterized in that: The output tracking data of the historical fuel cycle period is output tracking data of multiple cycles, and the historical corresponding relationship data of the electric power converted to the rated thermal power and the seawater temperature are multiple groups; If the electric power converted to the rated thermal power corresponding to the seawater temperature in the current correspondence data is less than the electric power converted to the rated thermal power corresponding to the same seawater temperature in any set of historical correspondence data, it is determined that the output of the nuclear power unit is abnormal.

9. A method for determining abnormal output of a pressurized water reactor nuclear power unit, characterized in that: Under the premise of decomposing the thermodynamic cycle of a pressurized water reactor nuclear power unit into the hot end, the intermediate section, and the cold end, abnormal output conditions of the nuclear power unit can be identified by obtaining one or more of the following four converted electric power differences: Based on the output tracking data of the nuclear power unit during the current fuel cycle, the current corresponding relationship data of the electric power converted to the rated thermal power and the seawater temperature are obtained; based on the output tracking data of the nuclear power unit during the historical fuel cycle, the historical corresponding relationship data of the electric power converted to the rated thermal power and the seawater temperature are obtained; Counting the difference between the current electric power converted to the rated thermal power and the historical electric power converted to the rated thermal power corresponding to the same seawater temperature to obtain a first converted electric power difference; Based on the output tracking data of the nuclear power unit during the current fuel cycle, the current corresponding relationship data between the electric power converted to the rated thermal power and the condenser steam parameters are obtained; based on the output tracking data of the nuclear power unit during the historical fuel cycle, the historical corresponding relationship data between the electric power converted to the rated thermal power and the condenser steam parameters are obtained; Counting the difference between the current electric power converted to the rated thermal power and the historical electric power converted to the rated thermal power corresponding to the same condenser steam parameters to obtain a second converted electric power difference; obtaining, based on output tracking data of the nuclear power unit during a current fuel cycle, current corresponding relationship data of the electric power converted to 104% of the steam flow rate and the seawater temperature; obtaining, based on output tracking data of historical fuel cycle periods of the nuclear power unit, historical corresponding relationship data of the electric power converted to 104% of the steam flow rate and the seawater temperature; and calculating the difference between the current electric power converted to 104% of the steam flow rate and the historical electric power converted to 104% of the steam flow rate for the same seawater temperature to obtain a third converted electric power difference; Obtain current correspondence data between the electric power converted to 104% steam flow and the condenser steam parameters based on the output tracking data of the current fuel cycle of the nuclear power unit; obtain historical correspondence data between the electric power converted to 104% steam flow and the condenser steam parameters based on the output tracking data of the historical fuel cycle of the nuclear power unit; and calculate the difference between the current electric power converted to 104% steam flow and the historical electric power converted to 104% steam flow corresponding to the same condenser steam parameters to obtain a fourth converted electric power difference; Abnormal output of nuclear power units can be identified through the following conditions: If the first converted electric power difference is less than 0, it is determined that the output of the nuclear power unit is abnormal; or, If the second converted electric power difference is less than 0, it is determined that the output of the middle section and / or the hot end of the nuclear power unit is abnormal; or, If the third converted electric power difference is less than 0, it is determined that the output of the middle section and / or the cold end of the nuclear power unit is abnormal; or, If the fourth converted electric power difference is less than 0, it is determined that the output of the middle section of the nuclear power unit is abnormal; or, Calculating the output improvement contribution of the hot end, the middle section, and the cold end based on at least three of the four converted electric power differences; if the output improvement contribution of the hot end is negative, the hot end output of the nuclear power unit is abnormal; If the output improvement contribution of the middle section is a negative value, the output of the middle section of the nuclear power unit is abnormal; if the output improvement contribution of the cold end is a negative value, the output of the cold end of the nuclear power unit is abnormal.

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