A method for judging stator waterway blockage fault of a generator based on steady-state and transient characteristics

Abstract

This invention provides a method for judging stator water circuit blockage faults in generators based on steady-state and transient characteristics. First, a simulation database for different blockage conditions is constructed based on the coupling of a fluid network model and a stator local fluid heat transfer model. Second, based on the change in total flow rate and a layered approach, the minimum number of blockages, *m*, is found. When the number of blockages is less than *m*, the blockage condition is judged based on steady-state characteristics. The slot number and the number of blockages can be determined by the position and value of the upper and lower layer outlet water temperatures, and then the process proceeds to a sub-process, where the blockage location is determined based on the interlayer insulation temperature value. When the number of blockages is greater than *m*, the blockage condition is judged based on transient characteristics. The slot number can be determined by the position of the upper and lower layer outlet water temperatures; furthermore, the blockage area can be located based on the transient water temperature rate ratio and the interlayer insulation temperature rate ratio. This invention can accurately assess the local blockage of hollow strands and reliably determine the location of blockages in generator stator strands even with limited experimental data.

Description

Technical Field

[0001] This invention relates to a method for judging stator water circuit blockage faults in generators based on steady-state and transient characteristics, belonging to the field of motor technology. Background Technology

[0002] Nuclear power, as a stable and efficient baseload energy source, is increasingly demonstrating its strategic importance. Large-scale 1100MW nuclear power units are the mainstay of the modern nuclear power industry, and the safe, stable, and efficient operation of their core equipment—the generator—directly affects the reliability and economy of the entire nuclear power plant. The stator winding, as the core component for energy conversion in the generator, bears enormous electromagnetic and thermal loads during operation. To effectively dissipate the Joule heat generated, modern large generators generally employ a "water-hydrogen-hydrogen" cooling method, where high-purity deionized water is directly circulated through the hollow conductors of the stator winding for direct cooling.

[0003] While this internal cooling method is highly efficient, its cooling performance is heavily dependent on the unobstructed flow of cooling water. The stator winding is woven from numerous solid and hollow strands, resulting in a complex structure and narrow flow channels. During long-term operation, due to factors such as water quality control deviations, system corrosion, and foreign object intrusion, copper oxide and impurity particles may gradually accumulate on the inner walls of the hollow strands, causing localized blockages. Even minor and localized blockages can significantly alter the flow distribution of cooling water in parallel branches and among the strands, creating low-velocity zones or even dead zones behind the blockage point. This severely weakens the heat exchange capacity of that area, leading to abnormally high local temperatures in the bars, i.e., "hot spots."

[0004] Localized overheating is the primary factor threatening the lifespan of generator insulation. When epoxy mica insulation systems operate for extended periods at temperatures exceeding their design limits (typically 130°C), their thermal aging process accelerates dramatically, leading to irreversible degradation of insulation properties (such as electrical and mechanical strength). This can ultimately result in catastrophic failures such as inter-turn short circuits or main insulation breakdown. For nuclear power units, the economic losses from such unplanned outages are enormous, reaching millions or even tens of millions of yuan per day, and pose a serious threat to power grid safety. Therefore, accurately assessing localized blockages in hollow-strand wires based on limited experimental data is a critical technical challenge that urgently needs to be addressed to ensure the long-term safe operation of nuclear power units. Summary of the Invention

[0005] The purpose of this invention is to propose a method for judging generator stator water circuit blockage faults, which can ensure sufficient accuracy and facilitate rapid judgment in engineering applications. This provides a precise scientific basis for the formulation of power plant operation and maintenance strategies, avoids reliance on conservative, experience-based periodic flushing, avoids over-maintenance or under-maintenance, and ensures the safe and stable operation of the motor.

[0006] To achieve the above objectives, the present invention discloses a method for judging generator stator water circuit blockage faults based on steady-state and transient characteristics, characterized by comprising:

[0007] Step S1, stator temperature field data acquisition, further includes: Step S11: Based on the generator ventilation structure and fluid mechanics theory, establish a generator global ventilation network model to obtain the flow distribution and node pressure of each wind zone; Step S12: Based on the circumferential structural symmetry of the generator, establish a stator double half-tooth and one whole slot fluid heat transfer coupling model, and use the stator core airflow and outlet pressure in step S11 as the boundary conditions of this model for iterative calculation. Step S13: After the solution is completed, compare it with the measured interlayer insulation temperature and outlet water temperature to verify the accuracy of the model. If the error requirement is not met, return to steps S11 and S12 to remodel and calculate; If the requirements are met, proceed to step S14; Step S14: Based on steady-state and transient fields, simulate and obtain data including interlayer insulation temperature, outlet water temperature of upper and lower windings, water temperature rise time, and interlayer insulation temperature rise time under different blockage numbers, and construct a simulation database. Step S2, waterway blockage determination based on steady-state characteristics, further includes: Step S21: Measure the steady-state temperature T of the interlayer insulation in step S13. c upper effluent steady-state temperature T u The steady-state temperature T of the lower layer effluent l The measured value of the total cooling water flow rate Q is defined as the reference value. The deviations between the steady-state temperature values ​​in the simulation database constructed in step S14 and the reference values ​​are ΔT respectively. c ΔT u ΔT l Δ Q ; Let the inlet flow rate of a single pipe be x. Determine whether the flow rate deviation ΔQ is less than x: If ΔQ is less than x, then observe ΔT for each slot. u ΔT l Is there any abnormality? If there is no abnormality, the process ends and the stator water circuit is not blocked. If there is an abnormality, the influence of the change in operating conditions must be eliminated and the abnormal tank must be repaired. If ΔQ is greater than x, proceed to step S22.

[0008] Step S22: Determine whether the flow deviation satisfies x < ΔQ ≤ mx, where m is the minimum number of blockages: If so, it is assumed that there are at most m blockages in the stator water circuit. Based on the steady-state characteristics, the judgment is made and the process proceeds to step S23. Otherwise, proceed to step S3; Step S23, if ΔT ui ≥ΔT us ΔT li ≥ΔT ls Then the blocked slot number can be determined according to ΔT. ui / ΔT us ΔT li / ΔT ls The number of blocks in the upper and lower layers of the tank can be approximately calculated, ΔT ui ΔT represents the water temperature rise at the outlet of the i-th water pipe in the upper winding. li ΔT represents the water temperature rise at the outlet of the i-th water pipe in the lower winding. us and ΔT ls These represent the average temperature rise of the upper water layer and the average temperature rise of the lower water layer when a single water pipe is blocked, respectively. Step S24: Based on the interlayer insulation temperature value, proceed to the judgment sub-process to determine the location of the blockage; Step S3, waterway blockage determination based on transient characteristics, further includes: Step S31: If x < ΔQ ≤ mx, it means the number of blocked roots is greater than m. According to ΔT... ui ≥ΔT us ΔT li ≥ΔT ls It can determine the blocked tank number; and determine whether the transient water temperature rate ratio satisfies λ. u >1 or λ l >1, where the transient water temperature rise rate is greater than λ u and λ l Defined as: the ratio of the rate of water temperature rise within 0-10 seconds when blocked to the rate of water temperature rise within 0-10 seconds when not blocked, where the subscripts u and l represent the upper and lower layers respectively. If not satisfied, proceed to step S23; If satisfied, proceed to step S32; Step S32: At least (m+1) water pipes in the upper and lower layers of the tank are blocked. This needs to be determined based on the transient temperature change rate to see if 1 < λ is satisfied. u <1.2 or 1<λ l <1.2: If not, proceed to step S33; If so, based on the data from step S14, it can be determined that at most 20% of the water pipes are blocked, and the interlayer insulation temperature rate ratio λ can be further determined. c : If λ c>1 indicates that the blocked water pipes are mainly located in the area close to the interlayer insulation and within 1 / 3 of the radial height; Otherwise, it indicates that the distribution is located in a region far from interlayer insulation and within 2 / 3 of the radial height. Step S33: Determine whether 1.2 < λ is satisfied. u <1.6 or 1.2 < λ l <1.6: If not, proceed to step S34; If so, based on the data from step S14, it can be determined that at most 37.5% of the water pipes are blocked, and further judgment can be made: If 1.05 < λ c <1.1 indicates that the blocked water pipes are mainly located in the area close to the interlayer insulation and within 1 / 2 of the radial height; Otherwise, it indicates that the distribution is in a region far from the interlayer insulation and within 1 / 2 of the radial height; Step S34: Determine whether 1.6 < λ is satisfied. u <2.0 or 1.6 < λ l <2.0: If not, proceed to step S35; If so, based on the data from step S14, it can be determined that at most 50% of the water pipes are blocked, and further judgment can be made: If 1.1 < λ c <1.2 indicates that the blocked water pipes are mainly located in the area close to the interlayer insulation and within 1 / 2 of the radial height; Otherwise, it indicates that the distribution is in a region far from the interlayer insulation and within 1 / 2 of the radial height; Step S35: Determine whether 2.0 < λ is satisfied. u <2.5 or 2.0 <λ l <2.5: If not, proceed to step S36; If so, based on the data from step S14, it can be determined that at most 60% of the water pipes are blocked, and further judgment can be made: If 1.2 < λ c <1.3 indicates that the blocked water pipes are mainly located in the area close to the interlayer insulation and within 2 / 3 of the radial height; Otherwise, it indicates that the distribution is located in a region far from interlayer insulation and within 2 / 3 of the radial height. Step S36, λ u >2.5 or λ l >2.5. Based on the data in step S14, it can be determined that more than 70% of the water pipes are blocked. The motor cannot be operated at reduced load. There is no need to determine the specific location of the blockage. The machine needs to be stopped and disconnected immediately.

[0009] Preferably, the principle for determining the minimum number of blocks m is: when m blocks are made, the main insulation temperature is close to the F-class insulation standard; when (m+1) blocks are made, the main insulation temperature just exceeds the F-class insulation standard.

[0010] Preferably, the interlayer insulation temperature rate ratio is λ c Defined as the ratio of the heating rate of the interlayer insulation temperature measurement point within 0-10 seconds when blocked to the heating rate when not blocked.

[0011] Preferably, the judgment threshold used in step S3 is derived from the simulation database constructed in step S14.

[0012] Preferably, for m=4, the decision sub-process includes: R1: In the case of two blocked wires in one tank, if the water temperature in both the upper and lower layers rises, it is determined that one upper wire is blocked and one lower wire is blocked. The reference value ΔT of the interlayer insulation temperature at different blocking locations needs to be found from the database constructed in step S14. ca2 ΔT cb2 ΔT cc2 ΔT cd2 And there is ΔT ca2 <ΔT cb2 <ΔT cc2 <ΔT cd2 : If max{ΔT c}>ΔT cd2 Then it can be determined that the blockage locations are one of the upper U1 row and one of the lower L1 row; If ΔT cc2 <max{ΔT c}<ΔT cd2 Then it can be determined that the blockage locations are one of the lower L1 rows and one of the upper U2-U9 rows; If ΔT cb2 <max{ΔT c}<ΔT cc2 Then it can be determined that the blockage locations are one of the upper U1 rows and one of the lower L2-L6 rows; If ΔT ca2 <max{ΔT c}<ΔT cb2 If the blockage occurs, it can be determined that the blockage location is one of the upper row U2 and one of the lower row L2; otherwise, the blockage location is one of the upper row U3-U9 and one of the lower row L3-L6.

[0013] R2: If the lower layer water temperature remains unchanged and the upper layer water temperature rises, then both wires are located on the upper layer. In a similar manner to R1, the location of the blockage is determined by finding a temperature reference value and comparing it with the maximum interlayer insulation temperature. R3: If the upper water temperature remains unchanged and the lower water temperature increases, then both wires are located in the lower layer. Similar to R1, the location of the blockage is determined by finding a temperature reference value and comparing it with the maximum interlayer insulation temperature.

[0014] Preferably, the selection of the interlayer insulation temperature reference value depends on the data in the database constructed in step S14.

[0015] Compared with existing technical solutions, the present invention has the following beneficial effects: This invention solves the problem of accurately assessing the local blockage of hollow strands in an environment with limited experimental data and monitoring methods, while ensuring sufficient accuracy and facilitating engineering applications. It reliably determines the location of blockage in the generator stator strands through measured data, which facilitates timely development of maintenance plans and operating schedules by operation and maintenance personnel, and ensures the long-term safe operation of nuclear power units. Attached Figure Description

[0016] Figure 1 A flowchart of a generator stator water circuit blockage fault judgment method based on steady-state and transient characteristics provided in an embodiment of the present invention; Figure 2 This is a diagram of the generator global ventilation network provided in an embodiment of the present invention; Figure 3 This is a diagram of a local fluid heat transfer coupling model of a generator stator provided in an embodiment of the present invention; Figure 4 A flowchart for judging generator stator water circuit blockage fault based on steady-state and transient characteristics (taking m=4 as an example) is provided for an embodiment of the present invention. Detailed Implementation

[0017] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0018] Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the term “comprising” as used in this specification means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It should be understood that when we say an element is “connected” or “coupled” to another element, it can be directly connected or coupled to the other element, or there may be intermediate elements. Furthermore, “connected” or “coupled” as used herein can include wireless connections or couplings. The term “and / or” as used herein includes any and all combinations of one or more of the associated listed items.

[0019] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless defined as herein.

[0020] To facilitate understanding of the embodiments of the present invention, the following will provide further explanation and description with reference to the accompanying drawings and several specific embodiments. These embodiments do not constitute a limitation on the embodiments of the present invention.

[0021] This invention discloses a method for determining generator stator water circuit blockage faults based on steady-state and transient characteristics, as follows: Figure 1 As shown, it includes: Step 1: Stator temperature field data acquisition step, water circuit blockage judgment step based on steady-state characteristics, and water circuit blockage judgment step based on transient characteristics.

[0022] Step 2: Based on the generator's ventilation structure and fluid mechanics theory, establish a global ventilation network model for the generator, such as... Figure 2 As shown, the flow distribution and node pressure of each wind zone are obtained. In the figure, Z1 to Z23 represent the wind resistance of each node, and P f Indicates fan voltage rise, P r This indicates the centrifugal pressure rise caused by the rotation of the rotor.

[0023] Step 3: Based on the circumferential structural symmetry of the generator, establish a coupled fluid heat transfer model for the stator with two half-tooth stators and one full-slot structure, such as... Figure 3As shown in the figure, S1 represents the end face of the excitation-end stator core, S2 represents the end section of the excitation-end stator winding and insulation, S3 represents the end face of the steam-end stator core, S4 represents the end section of the steam-end stator winding and insulation, S5 represents the outer circular surface of the stator yoke, S6 represents the central tangent of the stator teeth, and S7 represents the inner circular surface of the stator. The flow rate and outlet pressure of the stator core airflow zone in step 2 are used as the boundary conditions for this model, and iterative calculations are performed.

[0024] Step 4: After the solution is completed, compare it with the measured interlayer insulation temperature and outlet water temperature to verify the accuracy of the model. If the 5% error requirement is not met, return to steps 2 and 3 to re-model and calculate. If the requirement is met, proceed to step 5.

[0025] Step 5: Based on steady-state and transient fields, simulate and obtain the interlayer insulation temperature, upper and lower winding outlet water temperature, water temperature rise time, and interlayer insulation temperature rise time under different blockage numbers, and construct a simulation database.

[0026] Step 6: Determine if the flow deviation ΔQ is less than x: If ΔQ is less than x, then observe ΔT for each slot. u ΔT l Is there any abnormality? If there is no abnormality, the process ends and the stator water circuit is not blocked. If there is an abnormality, the influence of the change in operating conditions must be eliminated and the abnormal tank must be repaired. If ΔQ is greater than x, proceed to step 7.

[0027] Step 7: Determine if the flow deviation satisfies x < ΔQ ≤ mx, where m is the minimum number of blockages: If so, it is assumed that there are at most m blockages in the stator water circuit. Based on the steady-state characteristics, the judgment is made and proceeds to step 8. Otherwise, proceed with the waterway blockage judgment step based on transient characteristics.

[0028] Step 8, if ΔT ui ≥ΔT us ΔT li ≥ΔT ls Then the blocked slot number can be determined according to ΔT. ui / ΔT us ΔT li / ΔT ls The number of blocks in the upper and lower layers of the tank can be approximately calculated, ΔT ui ΔT represents the water temperature rise at the outlet of the i-th water pipe in the upper winding. li This indicates the water temperature rise at the outlet of the i-th water pipe in the lower winding.

[0029] Step 9: Based on the interlayer insulation temperature value, proceed to the judgment sub-process to determine the location of the blockage.

[0030] Step 10: If x < ΔQ ≤ mx, it means the number of blocked roots is greater than m. Based on ΔT... ui ≥ΔT us ΔT li ≥ΔT ls This allows us to determine the blocked tank number. We also determine if the transient water temperature rate ratio satisfies λ. u >1 or λ l If the condition is not met, proceed to step 8. If the condition is met, proceed to step 11.

[0031] Step 11: At least (m+1) water pipes in the upper and lower layers of the tank are blocked, which needs to be determined based on the transient temperature change rate. Determine if 1 < λ. u <1.2 or 1<λ l <1.2: If not, proceed to step 12; If so, based on the data from step 4, it can be determined that at most 20% of the water pipes are blocked. Continue to determine the interlayer insulation temperature rate ratio λ. c If λ c A value >1 indicates that the blocked water pipe is mainly located in the area close to the interlayer insulation and within 1 / 3 of the radial height; otherwise, it indicates that it is located in the area far from the interlayer insulation and within 2 / 3 of the radial height.

[0032] Step 12: Determine if 1.2 < λ is satisfied. u <1.6 or 1.2 < λ l <1.6: If not, proceed to step 13; If so, based on the data from step 4, it can be determined that at most 37.5% of the water pipes are blocked. Further assessment: If 1.05 < λ c If the value is less than 1.1, it indicates that the blocked water pipe is mainly located in the area close to the interlayer insulation and within 1 / 2 of the radial height; otherwise, it indicates that it is located in the area far from the interlayer insulation and within 1 / 2 of the radial height.

[0033] Step 13: Determine if 1.6 < λ is satisfied. u <2.0 or 1.6 < λ l <2.0: If not, proceed to step 14; If so, based on the data from step 4, it can be determined that at most 50% of the water pipes are blocked. Continue the assessment: if 1.1 < λ c If the value is less than 1.2, it indicates that the blocked water pipe is mainly located in the area close to the interlayer insulation and within 1 / 2 of the radial height; otherwise, it indicates that it is located in the area far from the interlayer insulation and within 1 / 2 of the radial height.

[0034] Step 14: Determine if 2.0 < λ is satisfied. u<2.5 or 2.0 <λ l <2.5: If not, proceed to step 15; If so, based on the data from step 4, it can be determined that at most 60% of the water pipes are blocked. Continue the assessment: if 1.2 < λ c If the value is less than 1.3, it indicates that the blocked water pipe is mainly located in the area close to the interlayer insulation and within 2 / 3 of the radial height; otherwise, it indicates that it is located in the area far from the interlayer insulation and within 2 / 3 of the radial height.

[0035] Step 15, λ u >2.5 or λ l >2.5, based on the data in step 4, it can be determined that more than 70% of the water pipes are blocked. The motor should not be operated at reduced load. There is no need to determine the specific location of the blockage; the machine must be stopped and disconnected immediately.

[0036] The principle for determining the minimum number of blocks m is: when m blocks are made, the main insulation temperature is close to the F-class insulation standard; when (m+1) blocks are made, the main insulation temperature just exceeds the F-class insulation standard. In this embodiment, m=4.

[0037] The m=4 conditional subprocess is as follows: Figure 4 As shown, it includes: 9-1: In the case of two blocked wires in one tank, if the water temperature in both the upper and lower layers rises, it is determined that one wire in the upper layer is blocked and one wire in the lower layer is blocked. From the database in step 4, find the reference values ​​for interlayer insulation temperature (1.3℃, 10℃, 13℃, 19℃) for different blocking locations. If max{ΔT c If the temperature is >19℃, then the blockage locations can be determined to be one of the upper U1 row and one of the lower L1 rows. If 13℃ <max{ΔT c If the temperature is less than 19℃, then the blockage locations can be determined to be one of the bars in the lower L1 row and one of the bars in the upper U2-U9 rows. If 10℃ <max{ΔT c If the temperature is less than 13℃, then the blockage locations can be determined to be one of the upper U1 rows and one of the lower L2-L6 rows. If 1.3℃ <max{ΔT c If the temperature is less than 10℃, then the blockage locations can be determined to be one of the upper U2 rows and one of the lower L2 rows. Otherwise, the blockage location is one of the upper-level rows U3-U9 and one of the lower-level rows L3-L6.

[0038] 9-2: If the lower layer water temperature remains constant while the upper layer water temperature rises, then both wires are located on the upper layer. From the database in step 4, find the reference values ​​for interlayer insulation temperature (10℃, 11.3℃, 18℃) for different blockage locations. If max{ΔT c If the temperature is >18℃, then the blockage location can be determined to be the upper U1 row; If 11.3℃ <max{ΔT c If the temperature is less than 18℃, then the blockage locations can be determined to be one of the bars in row U1 and one of the bars in row U2. If 10℃ <max{ΔT c If the temperature is less than 11.3℃, then the blockage locations can be determined to be one of the bars in row U2 and one of the bars in row U2-U9. Otherwise, the blockage will occur at the two roots in rows U2-U9.

[0039] 9-3: If the upper water temperature remains constant while the lower water temperature rises, then both wires are located in the lower layer. From the database in step 4, find the reference values ​​for interlayer insulation temperature at different blockage locations: 13℃, 14.3℃, and 23℃. If max{ΔT c If the temperature is greater than 23℃, then the blockage location can be determined to be row L1; If 14.3℃ <max{ΔT c If the temperature is less than 23℃, then the blockage locations can be determined to be one of the bars in row L1 and one of the bars in row L2. If 13℃ <max{ΔT c If the temperature is less than 14.3℃, then the blockage locations can be determined to be one of the bars in row L1 and one of the bars in rows L2-L6. Otherwise, the blockage will occur at the two roots in rows L2-L6.

[0040] The embodiments of the present invention solve the problem of accurately assessing the local blockage of hollow strands in an environment with limited experimental data and monitoring methods, while ensuring sufficient accuracy and facilitating engineering applications. The invention reliably determines the location of blockage in the generator stator strands through measured data, which facilitates timely development of maintenance plans and operation schedules by the operation and maintenance team, and ensures the long-term safe operation of nuclear power units.

[0041] The embodiments of the present invention have been described above. However, these embodiments are merely illustrative and not intended to limit the scope of this disclosure. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. The scope of the present invention is defined by the appended claims and their equivalents. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of the present invention, and all such substitutions and modifications should fall within the scope of this disclosure.

Claims

1. A method for judging generator stator water circuit blockage faults based on steady-state and transient characteristics, characterized in that, include: Step S1, stator temperature field data acquisition, further includes: Step S11: Based on the generator ventilation structure and fluid mechanics theory, establish a generator global ventilation network model to obtain the flow distribution and node pressure of each wind zone; Step S12: Based on the circumferential structural symmetry of the generator, establish a stator double half-tooth and one whole slot fluid heat transfer coupling model, and use the stator core airflow and outlet pressure in step S11 as the boundary conditions of this model for iterative calculation. Step S13: After the solution is completed, compare it with the measured interlayer insulation temperature and outlet water temperature to verify the accuracy of the model. If the error requirement is not met, return to steps S11 and S12 to remodel and calculate; If the requirements are met, proceed to step S14; Step S14: Based on steady-state and transient fields, simulate and obtain data including interlayer insulation temperature, outlet water temperature of upper and lower windings, water temperature rise time, and interlayer insulation temperature rise time under different blockage numbers, and construct a simulation database. Step S2, waterway blockage determination based on steady-state characteristics, further includes: Step S21: Measure the steady-state temperature T of the interlayer insulation in step S13. c upper effluent steady-state temperature T u The steady-state temperature T of the lower layer effluent l The measured value of the total cooling water flow rate Q is defined as the reference value. The deviations between the steady-state temperature values ​​in the simulation database constructed in step S14 and the reference values ​​are ΔT respectively. c ΔT u ΔT l Δ Q ; Let the inlet flow rate of a single pipe be x. Determine whether the flow rate deviation ΔQ is less than x: If ΔQ is less than x, then observe ΔT for each slot. u ΔT l Is there any abnormality? If there is no abnormality, the process ends and the stator water circuit is not blocked. If there is an abnormality, the influence of the change in operating conditions must be eliminated and the abnormal tank must be repaired. If ΔQ is greater than x, proceed to step S22. Step S22: Determine whether the flow deviation satisfies x < ΔQ ≤ mx, where m is the minimum number of blockages: If so, it is assumed that there are at most m blockages in the stator water circuit. Based on the steady-state characteristics, the judgment is made and the process proceeds to step S23. Otherwise, proceed to step S3; Step S23, if ΔT ui ≥ΔT us ΔT li ≥ΔT ls Then the blocked slot number can be determined according to ΔT. ui / ΔT us ΔT li / ΔT ls The number of blocks in the upper and lower layers of the tank can be approximately calculated, ΔT ui ΔT represents the water temperature rise at the outlet of the i-th water pipe in the upper winding. li ΔT represents the water temperature rise at the outlet of the i-th water pipe in the lower winding. us and ΔT ls These represent the average temperature rise of the upper water layer and the average temperature rise of the lower water layer when a single water pipe is blocked, respectively. Step S24: Based on the interlayer insulation temperature value, proceed to the judgment sub-process to determine the location of the blockage; Step S3, waterway blockage determination based on transient characteristics, further includes: Step S31: If x < ΔQ ≤ mx, it means the number of blocked roots is greater than m. According to ΔT... ui ≥ΔT us ΔT li ≥ΔT ls It can determine the blocked tank number; and determine whether the transient water temperature rate ratio satisfies λ. u >1 or λ l >1, where the transient water temperature rise rate is greater than λ u and λ l Defined as: the ratio of the rate of water temperature rise within 0-10 seconds when blocked to the rate of water temperature rise within 0-10 seconds when not blocked, where the subscripts u and l represent the upper and lower layers respectively. If not satisfied, proceed to step S23; If satisfied, proceed to step S32; Step S32: At least (m+1) water pipes in the upper and lower layers of the tank are blocked. This needs to be determined based on the transient temperature change rate to see if 1 < λ is satisfied. u <1.2 or 1<λ l <1.2: If not, proceed to step S33; If so, based on the data from step S14, it can be determined that at most 20% of the water pipes are blocked, and the interlayer insulation temperature rate ratio λ can be further determined. c : If λ c >1 indicates that the blocked water pipes are mainly located in the area close to the interlayer insulation and within 1 / 3 of the radial height; Otherwise, it indicates that the distribution is located in a region far from interlayer insulation and within 2 / 3 of the radial height. Step S33: Determine whether 1.2 < λ is satisfied. u <1.6 or 1.2 < λ l <1.6: If not, proceed to step S34; If so, based on the data from step S14, it can be determined that at most 37.5% of the water pipes are blocked, and further judgment can be made: If 1.05 < λ c <1.1 indicates that the blocked water pipes are mainly located in the area close to the interlayer insulation and within 1 / 2 of the radial height; Otherwise, it indicates that the distribution is in a region far from the interlayer insulation and within 1 / 2 of the radial height; Step S34: Determine whether 1.6 < λ is satisfied. u <2.0 or 1.6 < λ l <2.0: If not, proceed to step S35; If so, based on the data from step S14, it can be determined that at most 50% of the water pipes are blocked, and further judgment can be made: If 1.1 < λ c <1.2 indicates that the blocked water pipes are mainly located in the area close to the interlayer insulation and within 1 / 2 of the radial height; Otherwise, it indicates that the distribution is in a region far from the interlayer insulation and within 1 / 2 of the radial height; Step S35: Determine whether 2.0 < λ is satisfied. u <2.5 or 2.0 <λ l <2.5: If not, proceed to step S36; If so, based on the data from step S14, it can be determined that at most 60% of the water pipes are blocked, and further judgment can be made: If 1.2 < λ c <1.3 indicates that the blocked water pipes are mainly located in the area close to the interlayer insulation and within 2 / 3 of the radial height; Otherwise, it indicates that the distribution is located in a region far from interlayer insulation and within 2 / 3 of the radial height. Step S36, λ u >2.5 or λ l >2.

5. Based on the data in step S14, it can be determined that more than 70% of the water pipes are blocked. The motor cannot be operated at reduced load. There is no need to determine the specific location of the blockage. The machine needs to be stopped and disconnected immediately.

2. The generator stator water circuit blockage fault judgment method based on steady-state and transient characteristics according to claim 1, characterized in that, The principle for determining the minimum number of blocks m is as follows: when m blocks are made, the main insulation temperature is close to the F-class insulation standard; when (m+1) blocks are made, the main insulation temperature just exceeds the F-class insulation standard.

3. The generator stator water circuit blockage fault judgment method based on steady-state and transient characteristics according to claim 1, characterized in that, The interlayer insulation temperature rate ratio λ c Defined as the ratio of the heating rate of the interlayer insulation temperature measurement point within 0-10 seconds when blocked to the heating rate when not blocked.

4. The generator stator water circuit blockage fault judgment method based on steady-state and transient characteristics according to claim 1, characterized in that, The judgment threshold used in step S3 is derived from the simulation database constructed in step S14.

5. The generator stator water circuit blockage fault judgment method based on steady-state and transient characteristics according to claim 1, characterized in that, For m=4, the decision sub-process includes: R1: In the case of two blocked wires in one tank, if the water temperature in both the upper and lower layers rises, it is determined that one upper wire is blocked and one lower wire is blocked. The reference value ΔT of the interlayer insulation temperature at different blocking locations needs to be found from the database constructed in step S14. ca2 ΔT cb2 ΔT cc2 ΔT cd2 And there is ΔT ca2 <ΔT cb2 <ΔT cc2 <ΔT cd2 : If max{ΔT c }>ΔT cd2 Then it can be determined that the blockage locations are one of the upper U1 row and one of the lower L1 row; If ΔT cc2 <max{ΔT c }<ΔT cd2 Then it can be determined that the blockage locations are one of the lower L1 rows and one of the upper U2-U9 rows; If ΔT cb2 <max{ΔT c }<ΔT cc2 Then it can be determined that the blockage locations are one of the upper U1 rows and one of the lower L2-L6 rows; If ΔT ca2 <max{ΔT c }<ΔT cb2 If the blockage occurs, it can be determined that the blockage location is one of the upper row U2 and one of the lower row L2; otherwise, the blockage location is one of the upper row U3-U9 and one of the lower row L3-L6. R2: If the lower layer water temperature remains unchanged and the upper layer water temperature rises, then both wires are located on the upper layer. In a similar manner to R1, the location of the blockage is determined by finding a temperature reference value and comparing it with the maximum interlayer insulation temperature. R3: If the upper water temperature remains unchanged and the lower water temperature increases, then both wires are located in the lower layer. Similar to R1, the location of the blockage is determined by finding a temperature reference value and comparing it with the maximum interlayer insulation temperature.

6. The generator stator water circuit blockage fault judgment method based on steady-state and transient characteristics according to claim 5, characterized in that, The selection of the interlayer insulation temperature reference value depends on the data in the database constructed in step S14.

Images