Generator rotor flexible group copper bar crack detection system and method

Abstract

The invention discloses a system and a method for detecting cracks of a flexible copper bar of a generator rotor. One surface of a welding copper plate is fixedly connected to the outer surface of a flexible copper bar joint of the generator rotor; the vibration sensor is fixedly mounted on the surface of the welding copper plate; a welding copper plate is welded and fixed on the outer surface of a flexible group copper bar joint of a generator rotor; installing at least two vibration sensors on the welding copper plate; impact excitation is applied to the welding copper plate; a vibration response signal is acquired through a vibration sensor and a data acquisition instrument; processing the collected vibration response signal by using a data analyzer to obtain a vibration frequency to be measured; and comparing the obtained vibration frequency to be measured with a pre-stored reference vibration frequency of the intact flexible copper bar, and judging whether the flexible copper bar has cracks or not according to a comparison result. The range of insulating materials needing to be dismantled can be effectively reduced, the construction period is shortened, and the later repair cost is reduced.

Description

Technical Field

[0001] This invention belongs to the field of generator rotor damage detection, and relates to a detection system and method for cracks in the copper busbars of a generator rotor deflector. Background Technology

[0002] As the core component of a generator, the condition of the generator rotor directly affects its performance and safety. If cracks appear in the copper busbars of the generator rotor windings, these cracks can rapidly propagate under the influence of various complex external forces, including electromagnetic forces, centrifugal forces, and thermal stress, during generator operation. If not detected and addressed promptly, these cracks may lead to partial winding fracture, potentially causing faults such as current leakage, short circuits, or open circuits. In severe cases, they could even trigger fires or equipment damage. Therefore, regular crack inspection of the rotor windings is a crucial measure to ensure the safe operation of the equipment.

[0003] The copper busbars of the generator rotor are wrapped with insulating material, making cracks on the busbars impossible to detect directly. Furthermore, since cracks typically occur at the inner corners, even after removing the surface insulation, conventional non-destructive testing methods such as ultrasonic testing and penetrant testing are not feasible. Currently, the traditional method involves destructively disassembling the copper busbars to confirm the presence of internal cracks, followed by repair work to restore the busbars. This process is time-consuming and costly. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a detection system and method for cracks in the copper busbars of a generator rotor flexure, which can effectively reduce the scope of insulation material that needs to be removed, shorten the construction period, and reduce the cost of subsequent repairs.

[0005] To achieve the above objectives, the present invention employs the following technical solution: A detection system for cracks in the copper busbars of a generator rotor deflector includes a welded copper plate, at least two vibration sensors, a data acquisition instrument, and a data analyzer. One side of the welded copper plate is fixedly connected to the outer surface of the deflection copper busbar joint of a generator rotor; the vibration sensor is fixedly installed on the surface of the welded copper plate; the data acquisition instrument is electrically connected to the vibration sensor; and the data analyzer is electrically connected to the data acquisition instrument.

[0006] Preferably, the material of the welding copper plate is the same as the material of the flexible copper busbar joint.

[0007] Preferably, the thickness and width of the welding copper plate are the same as the thickness and width of the flexible copper busbar joint.

[0008] Preferably, one vibration sensor is installed at the end of the welded copper plate away from the copper busbar joint of the flexible assembly, and the other vibration sensor is installed in the middle of the welded copper plate.

[0009] Preferably, the axial direction of the welded copper plate is parallel to the axial direction of the long axis of the generator rotor.

[0010] Preferably, it also includes a connecting cable that connects the vibration sensor and the data acquisition device.

[0011] Preferably, the data acquisition device includes a signal amplifier, a filter, and an analog-to-digital converter.

[0012] Preferably, the data analyzer includes a processor and a memory storing analysis software.

[0013] A method for detecting cracks in the copper busbars of a generator rotor deflector includes the following steps: A copper plate is welded and fixed to the outer surface of the copper busbar joint of a generator rotor. Install at least two vibration sensors on the soldered copper plate; An impact excitation is applied to the copper plate being welded; A vibration response signal is acquired using a vibration sensor and a data acquisition device; The collected vibration response signal is processed using a data analyzer to obtain a vibration frequency to be measured. The obtained vibration frequency to be measured is compared with the reference vibration frequency of the intact flexible copper busbar that has been stored in advance, and the presence of cracks in the flexible copper busbar is determined based on the comparison results.

[0014] Preferably, before obtaining the vibration frequency to be measured, the vibration response signals collected by the two vibration sensors are compared, common-mode interference signals are filtered out, and an effective signal is obtained; the vibration frequency to be measured is obtained by processing the effective signal.

[0015] Compared with the prior art, the present invention has the following beneficial effects: This invention involves welding a copper plate to the joint on the outside of the generator rotor deflector copper busbar and using frequency measurement to detect damage to the busbar. Only the insulation material near the joint on the outside of the busbar needs to be removed, effectively reducing the number of workers and time required for traditional visual inspections. Furthermore, the detection system is simple to operate, stable, and reliable, and can be implemented within the power plant without requiring factory return for testing. This significantly improves the efficiency of generator rotor deflector copper busbar inspection, providing a reliable guarantee for the long-term stable operation of the generator rotor. It can be widely applied to the inspection and maintenance of generator rotor deflector copper busbars in wind turbines, thermal power generators, and other similar applications.

[0016] Furthermore, the welding copper plate uses the same material as the copper busbar of the generator rotor deflector to ensure measurement accuracy.

[0017] Furthermore, by comparing the data from vibration sensors attached to the ends and middle of the welded copper plate, interference signals can be effectively removed, thus improving accuracy. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the generator rotor deflector copper busbar crack detection system of the present invention; Figure 2 This is a partial left view of the detection system for cracks in the copper busbars of the generator rotor deflector according to the present invention.

[0019] Wherein: 1-flexure assembly; 2-flexure assembly copper busbar connector; 3-welded copper plate; 4-vibration sensor; 5-rotor long shaft; 6-connecting cable; 7-data acquisition instrument; 8-data analyzer. Detailed Implementation

[0020] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0021] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terms “installation,” “connection,” and “linkage” should be interpreted broadly, for example, as a fixed connection, a detachable connection, or an integral connection; a mechanical connection, an electrical connection, or a connection that allows communication; a direct connection or an indirect connection via an intermediate medium; or a connection within two elements or an interaction between two elements. The term “and / or” as used herein includes any and all combinations of one or more of the associated listed items. Those skilled in the art will understand the specific meaning of the above terms in this invention according to the specific circumstances. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention.

[0023] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0024] The following disclosure provides many different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0025] Please see Figure 1 and Figure 2 This invention provides a system for detecting cracks in the copper busbars of a generator rotor. The system is constructed around the generator rotor body to be inspected. The generator rotor mainly includes a series of flexible sections 1 evenly distributed along its circumference and copper busbar connectors 2 located at the axial ends of the rotor. The flexible sections 1 and connectors 2 together constitute a key part of the rotor's conductive circuit. The detection system of this invention performs damage detection on this critical component without extensive disassembly of the rotor.

[0026] The detection system mainly consists of a physical sensor section and a data processing section. The physical sensor section includes a welded copper plate 3 that is firmly connected to the flexible copper busbar connector 2, and at least two vibration sensors 4 mounted on the welded copper plate 3. The data processing section includes a data acquisition unit 7 and a data analyzer 8.

[0027] The welded copper plate 3 is fixedly connected to the exposed surface of the flexible copper busbar connector 2 through a welding process, forming a unified vibrating body. To ensure the effectiveness of vibration characteristic transmission, the axial direction of the welded copper plate 3 is kept parallel to the axial direction of the rotor's long shaft 5.

[0028] Vibration sensor 4 is glued or otherwise fixed to the surface of the welding copper plate 3. In this embodiment, it is preferable to provide two vibration sensors 4, one located at the free end of the welding copper plate 3 away from the joint 2, and the other located in the middle of the welding copper plate 3. This arrangement facilitates the effective elimination of interference through subsequent signal comparison.

[0029] Each vibration sensor 4 is connected to the signal input terminal of the data acquisition unit 7 via connecting cables 6. Connecting cables 6 should have good shielding performance to prevent electromagnetic interference from affecting signal quality. The data acquisition unit 7 is responsible for amplifying, filtering, and performing analog-to-digital conversion (A / D conversion) on the analog vibration signals captured by the vibration sensors 4 to form digital signals.

[0030] Finally, the data acquisition unit 7 connects to the data analyzer 8 via wired or wireless means, transmitting the acquired digital vibration signals to the data analyzer 8. The data analyzer 8 can be a computer, industrial control computer, or dedicated device with built-in specific analysis software. Its core function is to perform subsequent signal processing and comparative analysis, ultimately drawing a test conclusion.

[0031] To ensure the accuracy and consistency of the detection, the selection of materials and dimensions of the welding copper plate 3 are crucial. Preferably, the material of the welding copper plate 3 should be exactly the same as that of the generator rotor deflector copper busbar (usually high-conductivity copper or copper alloy) to ensure that they have similar material density and elastic modulus, so that vibration characteristics can be transmitted from the joint 2 to the welding copper plate 3 without damage. In addition, the thickness and width of the welding copper plate 3 are designed to be the same as the corresponding dimensions of the deflector copper busbar joint 2, and its length is determined according to the specific dimensions of the joint and the available operating space, ensuring sufficient length to install the vibration sensor and excite effective vibration.

[0032] The working principle of this invention is based on structural modal analysis and vibration characteristic comparison. Every mechanical structure has its inherent vibration frequency (i.e., natural frequency) and mode shape. When the inside of the flexible copper busbar is intact, the overall stiffness and mass distribution of the composite vibration system composed of the joint 2 and the welded copper plate 3 are determined. Therefore, when it is subjected to external impact excitation, it will vibrate at a specific set of natural frequencies. This set of frequency signals can serve as a reference fingerprint of its health.

[0033] When cracks develop inside the copper busbar of the flexural assembly (especially at stress concentration corners), their presence alters the local cross-sectional properties of the busbar, leading to a decrease in the effective stiffness of the entire vibration system. According to vibration theory, a reduction in structural stiffness directly results in a decrease in its natural frequency. Furthermore, the cracks may open and close during vibration, introducing nonlinear damping, which also changes the amplitude and energy attenuation characteristics of the vibration response.

[0034] Therefore, by comparing the vibration frequency of the rotor under test joint 2-welded copper plate 3 system with the vibration frequency of the pre-measured healthy rotor reference fingerprint, it can be determined whether there are cracks in the deflection coil copper busbar. A significant drop in frequency or abnormal changes in amplitude indicate a high probability of damage.

[0035] The detailed implementation process of the method for detecting cracks in the copper busbars of the generator rotor deflector using the above-mentioned detection system is as follows: Step 1: Establish a health baseline database (baseline fingerprint collection).

[0036] Select a new generator rotor, or one whose flexural busbars are confirmed to be intact through other reliable means (such as destructive testing), as the reference component.

[0037] Preparation: Carefully remove a small area of ​​insulation material near joint 2 on the outside of the copper busbar of the flexible assembly to expose a clean, flat metal surface for welding.

[0038] Install the copper plate and sensor: Use a welding copper plate 3 of the same specifications as described above, and firmly fix it to the exposed surface of the joint 2 using a reliable welding process (such as argon arc welding) to ensure a rigid connection between the two without any relative displacement. Subsequently, attach vibration sensors 4 to the ends and middle of the welding copper plate 3, and connect them to the data acquisition instrument 7.

[0039] Excitation and Data Acquisition: Apply a momentary impact excitation to the welded copper plate 3 using a non-metallic striking tool (such as a wooden stick or rubber mallet). The striking point should be consistent to ensure the comparability of the excitation energy. Simultaneously, start the data acquisition instrument 7 to record the vibration response signals of the two vibration sensors 4 for a period of time after the impact.

[0040] Analysis and Storage: The acquired time-domain signal is transmitted to the data analyzer 8. The analysis software performs a Fast Fourier Transform (FFT) on the signal to obtain its spectrum. The first three or several significant intrinsic frequencies of the healthy sample and their corresponding amplitudes are identified and recorded from the spectrum, forming a complete set of "baseline fingerprint" data, which is then stored in the database.

[0041] Step 2: Conduct on-site testing of the rotor to be tested.

[0042] On-site preparation: For the generator rotor that needs to be tested, remove the local insulation material at the same location as the copper busbar joint 2 of the deflector.

[0043] Installation and Configuration: Using the same welding copper plate 3 of the same size and material as that used for acquiring the reference data, and employing the same welding process and position, fix it to the connector 2 of the rotor to be tested. Install the vibration sensor 4 in the same position and connect it to the data acquisition instrument 7 and the data analyzer 8.

[0044] Data Acquisition: Using the same striking tools and methods as in the first step, apply impact excitation to the welding copper plate 3 and simultaneously collect vibration response data. To reduce random errors, multiple strikes can be performed and the average value taken.

[0045] Step 3: Data comparison and analysis and damage assessment.

[0046] Signal preprocessing and interference elimination: First, compare the measurement results of two sensors at the upper and middle parts of the same welded copper plate 3. Since environmental vibration or low-frequency vibration (rotor fundamental frequency) of the entire rotor support system can be captured by both sensors simultaneously, forming a common-mode signal, these global interference frequencies can be effectively filtered out by performing differential or correlation analysis on the two signals, extracting the effective signal generated only by the vibration of the welded copper plate itself, thus improving the signal-to-noise ratio and analysis accuracy.

[0047] Frequency comparison: The vibration frequency of the rotor to be tested after preprocessing (focusing on the first three frequencies) is accurately compared with the benchmark fingerprint in the database.

[0048] If the measured frequency is basically consistent with the reference frequency (within the allowable error range), the copper busbar can be considered intact. If the measured frequency, especially the lower-order frequencies, is significantly lower than the reference frequency, it is highly suspected that there is a crack inside the copper busbar. The magnitude of the frequency drop is usually related to the severity of the crack.

[0049] Amplitude Comparison: Simultaneously, analyze the changes in vibration amplitude. The presence of cracks may alter the energy transfer and dissipation paths, leading to abnormal increases or decreases in amplitude at certain frequencies. Changes in amplitude can serve as an auxiliary basis for judging frequency changes.

[0050] Conclusion: Based on the changes in frequency and amplitude, it was finally determined whether there was damage to the copper busbar of the generator rotor deflector and the approximate extent of the damage.

[0051] In summary, this invention, through an innovative approach of adding an additional oscillator, transforms the problem of internal damage to copper busbars, which is difficult to measure directly, into a problem of easily measurable vibration characteristic changes in an additional welded copper plate. The entire system is simple to operate, requiring only local insulation removal, which greatly reduces the workload of inspection and repair costs. Furthermore, it can be quickly implemented on-site at power plants, providing strong and efficient technical support for the safe and stable operation of generators.

[0052] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0053] In the above embodiments of this application, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0054] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. The device embodiments described above are merely illustrative; for example, the division of units can be a logical functional division, and in actual implementation, there may be other division methods. For instance, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual coupling, direct coupling, or communication connection may be through some interfaces; the indirect coupling or communication connection between units or modules may be electrical or other forms.

[0055] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0056] The above description is only a preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

[0057] It should be understood that the above description is for illustrative purposes and not for limitation. Many embodiments and applications beyond the provided examples will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of this patent should not be determined by reference to the above description, but rather by reference to the foregoing claims and the full scope of their equivalents. For purposes of completeness, all articles and references, including patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the foregoing claims is not intended as a waiver of that subject matter, nor should it be construed as an indication that the applicant has not considered that subject matter as part of the disclosed inventive subject matter.

Claims

1. A detection system for cracks in the copper busbars of a generator rotor deflector, characterized in that, Includes a welded copper plate (3), at least two vibration sensors (4), a data acquisition instrument (7), and a data analyzer (8); One side of the welded copper plate (3) is fixedly connected to the outer surface of the deflection copper busbar joint (2) of a generator rotor; the vibration sensor (4) is fixedly installed on the surface of the welded copper plate (3); the data acquisition instrument (7) is electrically connected to the vibration sensor (4); the data analyzer (8) is electrically connected to the data acquisition instrument (7).

2. The detection system for cracks in the copper busbars of the generator rotor deflector according to claim 1, characterized in that, The material of the welding copper plate (3) is the same as that of the flexible copper busbar connector (2).

3. The detection system for cracks in the copper busbars of the generator rotor deflector according to claim 1, characterized in that, The thickness and width of the welded copper plate (3) are the same as the thickness and width of the flexible copper busbar joint (2).

4. The detection system for cracks in the copper busbars of the generator rotor deflector according to claim 1, characterized in that, One vibration sensor (4) is installed at the end of the welded copper plate (3) away from the flexible copper busbar connector (2), and the other vibration sensor (4) is installed in the middle of the welded copper plate (3).

5. The detection system for cracks in the copper busbars of the generator rotor deflector according to claim 1, characterized in that, The axial direction of the welded copper plate (3) is parallel to the axial direction of the rotor long axis (5) of the generator rotor.

6. The detection system for cracks in the copper busbars of the generator rotor deflector according to claim 1, characterized in that, It also includes a connecting cable (6), which connects the vibration sensor (4) and the data acquisition instrument (7).

7. The detection system for cracks in the copper busbars of the generator rotor deflector according to claim 1, characterized in that, The data acquisition unit (7) includes a signal amplifier, a filter and an analog-to-digital converter.

8. The detection system for cracks in the copper busbars of the generator rotor deflector according to claim 1, characterized in that, The data analyzer (8) includes a processor and a memory storing analysis software.

9. A method for detecting cracks in the copper busbars of a generator rotor based on the system described in any one of claims 1-8, characterized in that, Includes the following steps: A copper plate is welded and fixed to the outer surface of the copper busbar joint of a generator rotor. Install at least two vibration sensors (4) on the welded copper plate (3); An impact excitation is applied to the welded copper plate (3); A vibration response signal is acquired by a vibration sensor (4) and a data acquisition instrument (7); The collected vibration response signal is processed using a data analyzer (8) to obtain a vibration frequency to be measured; The obtained vibration frequency to be measured is compared with the reference vibration frequency of the intact flexible copper busbar that has been stored in advance, and the presence of cracks in the flexible copper busbar is determined based on the comparison results.

10. The method for detecting cracks in the copper busbars of the generator rotor according to claim 1, characterized in that, Before obtaining the vibration frequency to be measured, the vibration response signals collected by the two vibration sensors (4) are compared, the common-mode interference signal is filtered out, and an effective signal is obtained; the vibration frequency to be measured is obtained by processing the effective signal.

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