System and method for detecting structural damage of water turbine generator support

Abstract

A method for detecting structural damage of a water turbine generator support, comprising: determining a knocking point and a response point on a water turbine generator support; arranging an acceleration sensor (7) at the response point; hammering the knocking point by means of an impact force bar (5); acquiring a signal detected by the acceleration sensor (7) and a signal detected by a force sensor (6) in the impact force bar (5); performing fitting on the basis of the signal detected by the acceleration sensor (7) and the signal detected by the force sensor (5), so as to obtain the inherent frequency, damping ratio and vibration mode of the support; and on the basis of the inherent frequency, damping ratio and vibration mode of the support, determining whether structural damage occurs to the water turbine generator support. Further provided is a system for detecting structural damage of a water turbine generator support.

Description

A hydro-generator frame structural damage detection system and method

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] The present application claims priority to the Chinese patent application No. 202411374578.3, filed on September 29, 2024, and entitled "A hydro-generator frame structural damage detection system and method", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0003] The present application belongs to the technical field of hydro-generator frame structural damage detection, and relates to a hydro-generator frame structural damage detection system and method. BACKGROUND

[0004] The frame is an important support component of the hydro-generator unit, and the frame structural safety affects the safe and stable operation of the unit. As an important load-bearing component of the unit, if the frame has structural damage, it will cause the vibration of the unit to increase, and even worse, it will cause the unit to be out of service or cause a safety accident of the unit. Strengthening the structural damage detection of the frame of the unit is an effective means to avoid accidents and ensure the safe and stable operation of the unit. SUMMARY

[0005] The present application aims to overcome the shortcomings of the prior art and provides a hydro-generator frame structural damage detection system and method, which can determine whether the frame and the support arm of the hydro-generator have structural damage.

[0006] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0007] In a first aspect, the present application provides a hydro-generator frame structural damage detection method, comprising:

[0008] determining a knocking point and a response point on the frame of the hydro-generator;

[0009] arranging an acceleration sensor at the response point;

[0010] hammering the knocking point by an impact force rod;

[0011] obtaining signals detected by the acceleration sensor and signals detected by a force sensor in the impact force rod;

[0012] fitting the frame natural frequency, the damping ratio and the frame vibration mode according to the signals detected by the acceleration sensor and the signals detected by the force sensor;

[0013] The method for detecting structural damage of the hydro-generator frame further improves in that:

[0014] The method for detecting structural damage of the hydro-generator frame further improves in that:

[0015] Optionally, the method further comprises:

[0016] Optionally, the method further comprises:

[0017] Optionally, the method further comprises:

[0018] Optionally, the method further comprises:

[0019] Optionally, the method further comprises:

[0020] The second aspect of the present application provides a system for detecting structural damage of a hydro-generator frame, which is used to implement the method for detecting structural damage of a hydro-generator frame, and comprises an acceleration sensor, an impact force rod, a data acquisition instrument and a test module, wherein the test module is connected with the data acquisition instrument, the data acquisition instrument is connected with the acceleration sensor and the impact force rod.

[0021] The system for detecting structural damage of a hydro-generator frame further improves in that:

[0022] Optionally, the test module is connected with the data acquisition instrument through a data line.

[0023] Optionally, the data acquisition instrument is connected with the impact force rod, the force sensor and the acceleration sensor through a connecting cable.

[0024] Optionally, the data acquisition instrument has multiple input signal channels, and can collect signals without phase difference between the channels.

[0025] Optionally, the data acquisition instrument has the functions of filtering, signal instantaneous capture, signal amplifier, spectrum analysis, frequency response function, phase and coherence function analysis, signal windowing processing, multiple measurement data averaging processing, original data storage, and anti-external electromagnetic interference.

[0026] Optionally, the excitation frequency of the impact force rod is selected in a flat range of the force spectrum.

[0027] Optionally, the acceleration sensor is a piezoelectric acceleration sensor.

[0028] The present application has the following beneficial effects:

[0029] The water turbine generator frame structural damage detection system and method described in the present application measures the frame natural frequency, damping ratio and frame vibration mode by using the hammering method in the specific operation, and then judges whether the water turbine generator frame has structural damage, and whether the support arm and the concrete are firmly connected, which is easy to operate and has high practicability. BRIEF DESCRIPTION OF DRAWINGS

[0030] The drawings accompanying the specification of the present application serve to provide a further understanding of the present application, the illustrative embodiments of the present application and their descriptions serve to explain the present application, and do not constitute an improper limitation on the present application. In the drawings:

[0031] Fig. 1 is a simple three-view drawing of the frame;

[0032] Fig. 2 is a schematic diagram of the guide bearing frame measurement point of the water turbine generator set;

[0033] Fig. 3 is a schematic diagram of the excitation point and response point of the test system;

[0034] Fig. 4 is a test system diagram;

[0035] Fig. 5 is a time domain diagram of the excitation and response signals;

[0036] Fig. 6 is a vibration mode diagram.

[0037] In the drawings, 1 is a test module, 2 is a data line, 3 is a data acquisition instrument, 4 is a connection cable, 5 is an impact force rod, 6 is a force sensor, and 7 is an acceleration sensor. DETAILED DESCRIPTION

[0038] In order for those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments, and are not intended to limit the scope of the present application. In addition, in the following description, the description of the known structures and technologies is omitted to avoid unnecessary confusion of the concepts disclosed in the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts should fall within the scope of the present application.

[0039] Structural diagrams according to embodiments of the present disclosure are shown in the accompanying drawings. These drawings are not drawn to scale, in which certain details are exaggerated for clarity and others omitted. The shapes and relative sizes of the various regions, layers, and the relative positions of these in the drawings are shown for example only, and can deviate in actuality due to manufacturing tolerances or technical limitations, and regions / layers with different shapes, sizes, relative positions can be additionally designed by those skilled in the art according to actual needs.

[0040] Embodiment one

[0041] The present application provides a method for detecting structural damage of a hydro-generator frame, comprising:

[0042] Determining a knocking point and a response point on the hydro-generator frame;

[0043] Arranging an acceleration sensor 7 at the response point;

[0044] Hammering the knocking point by an impact force rod 5;

[0045] Obtaining signals detected by the acceleration sensor 7 and signals detected by a force sensor 6 in the impact force rod 5;

[0046] Fitting a frame natural frequency, a damping ratio and a frame vibration mode according to the signals detected by the acceleration sensor 7 and the signals detected by the force sensor 6;

[0047] Judging whether the hydro-generator frame has structural damage according to the frame natural frequency, the damping ratio and the frame vibration mode.

[0048] As an embodiment of the present application, further comprising:

[0049] Arranging one acceleration sensor 7 in the axial, tangential and radial directions of one of the arms of the frame, and hammering at the knocking point farthest from the acceleration sensor 7 by the impact force rod 5;

[0050] Judging whether the response of the acceleration sensor 7 is excited, and when the response of the acceleration sensor 7 cannot be excited, moving the position of the knocking point until the response of the acceleration sensor 7 can be excited, so as to test the sensitivity of the acceleration sensor 7.

[0051] As an embodiment of the present application, the process of fitting the frame natural frequency, the damping ratio and the frame vibration mode according to the signals detected by the acceleration sensor 7 and the signals detected by the force sensor 6 is:

[0052] According to the signals detected by the acceleration sensor 7 and the force sensor 6, the characteristic system algorithm is used for fitting to obtain the inherent frequency, damping ratio and vibration mode of the frame.

[0053] Embodiment two

[0054] Referring to Fig. 4, the structural damage detection system of the water turbine generator frame described in the present application comprises an acceleration sensor 7, an impact force rod 5, a data acquisition instrument 3 and a test module 1, wherein the test module 1 is connected with the data acquisition instrument 3, and the data acquisition instrument 3 is connected with the acceleration sensor 7 and the impact force rod 5.

[0055] As an embodiment of the present application, the test module 1 is connected with the data acquisition instrument 3 through the data line 2.

[0056] As an embodiment of the present application, the data acquisition instrument 3 is connected with the impact force rod 5, the force sensor 6 and the acceleration sensor 7 through the connecting cable 4 respectively.

[0057] As an embodiment of the present application, the data acquisition instrument 3 has multiple input signal channels, and can collect signals without phase difference between channels.

[0058] As an embodiment of the present application, the data acquisition instrument 3 has the functions of filtering, signal instantaneous capture, signal amplifier, frequency spectrum analysis, frequency response function, phase and coherence function analysis, signal windowing processing, multiple measurement data averaging processing, original data storage function and anti-external electromagnetic interference capability.

[0059] As an embodiment of the present application, the excitation frequency of the impact force rod 5 is selected in the flat range of the force spectrum, and the acceleration sensor 7 adopts a piezoelectric acceleration sensor.

[0060] Embodiment three

[0061] The structural damage detection method of the water turbine generator frame described in the present application comprises the following steps:

[0062] 1) Pre-test

[0063] The impact force rod 5, the acceleration sensor 7 and the test module 1 are connected with the data acquisition instrument 3 through the data line 2 respectively, one acceleration sensor 7 is arranged in the axial direction, the tangential direction and the radial direction of one arm of the frame, and the impact force rod 5 is used to hammer at the farthest excitation point from the acceleration sensor 7, when the acceleration sensor 7 cannot be excited, the hammering point is moved and the hammering is performed again to test the sensitivity of the acceleration sensor 7, until the test module 1 can collect the excitation signals and response signals detected by the acceleration sensor 7 and the force sensor 6 through the data acquisition instrument 3, and the signals can be normally transmitted after three times of hammering, and then the next test work can be performed.

[0064] 2) Test sampling

[0065] In the test module 1, N qualified samples are taken for each knocking point according to the number of each knocking point on the rack, wherein, after each knocking test collection is completed, the test data is checked, if the test data cannot reach the expected value, the test needs to be supplemented, after the test is completed, modal analysis is carried out through the test module 1 to judge the structural damage of the hydro-generator rack.

[0066] It should be noted that the structural excitation signal and response signal are obtained by hammering method, and the transfer function analysis is carried out at the same time, and it can be known from the transfer function curve that better test results can be obtained within the range of 200Hz. As shown in Figure 5.

[0067] The test data is fitted, and the characteristic system realization algorithm (ERA) is used for fitting to obtain the natural frequency, damping ratio and rack vibration mode of the rack, wherein, the main natural frequency vibration mode is shown in Figure 6.

[0068] According to the natural frequency of the rack, the frequency band which is easy to resonate with the natural frequency of the rack is drawn, and the fatigue damage of the rack of the unit is checked, and the closer the natural frequency of the rack is, the greater the possibility of resonance of the rack is, and the more serious the fatigue damage of the rack is.

[0069] Example four

[0070] In this embodiment, a test module 1 with relatively perfect test function is selected, which should have multiple coordinate systems, be able to establish a model according to different shapes and sizes of structures, and have multiple modal fitting methods related to the field, such as frequency domain method and time domain method;

[0071] The data acquisition instrument 3 should have at least multiple input signal channels, and should be able to collect without phase difference between channels, and should have the functions of filtering, signal instantaneous capture, signal amplifier, frequency spectrum analysis, frequency response function, phase and coherence function analysis, signal windowing processing, multiple measurement data averaging processing, original data storage function, and anti-external electromagnetic interference ability.

[0072] The excitation frequency of the impact force rod 5 is selected in the flat range of the force spectrum, and the force rod 5 has the functions of replacing the hammer head material and counterweight, changing the force pulse width and frequency range.

[0073] The force sensor 6 selects the force measurement range of ±22240N.

[0074] The acceleration sensor 7 adopts a piezoelectric acceleration sensor.

[0075] As shown in Figures 3 and 4, the rack to be tested is modeled, a three-dimensional schematic diagram of the rack is established, and the excitation points and response points required in the test are determined.

[0076] As shown in Fig. 3, the test module 1 is connected with the data acquisition instrument 3 through the data line 2, the data acquisition instrument 3 is connected with the impact force rod 5, the force sensor 6 and the acceleration sensor 7 through the connecting cable 4, and a test test system is formed.

[0077] Then the method described in the application is used for monitoring.

[0078] It should be noted that the electromagnetic pole frequency vibration range of the unit is: 45Hz-55Hz (1 times frequency), 90Hz-110Hz (2 times frequency), 135Hz-165Hz (3 times frequency), 180Hz-220Hz (4 times frequency). Among them, the second order natural frequency of the upper rack is 50.86Hz, the third order natural frequency is 58.15Hz, and the sixth order frequency is 145.23Hz, which is close to or coincides with the pole frequency vibration range, and resonance is possible. The second order natural frequency of the small ring of the upper rack is 90.05Hz, and the second order natural frequency is 153.33Hz, which is close to or coincides with the pole frequency vibration range, and resonance is possible. The second order natural frequency of the lower rack is 58.77Hz, and the third order natural frequency is 105.93Hz, which is close to or coincides with the pole frequency vibration range, and resonance is possible. The remaining frequency bands can be avoided, that is: Fc=ncx50(Hz)

[0079] Among them, n C is the frequency number, and 50 is the electromagnetic rotation frequency of the unit.

[0080] The flow state vibration caused by the blade is mainly caused by uneven flow state or karman vortex. The blade number times frequency (blade number x rotation frequency) is 7.692Hz, and the test results all avoid 6.92Hz-8.46Hz (1 times frequency), 13.84Hz-16.92Hz (2 times frequency), 20.76Hz-25.38Hz (3 times frequency), and 27.69Hz-33.84Hz (4 times frequency). The first order natural frequency of the upper rack is 22.36Hz, and the first order natural frequency of the ring of the upper rack is 27.26Hz, which is close to or coincides with the blade flow state vibration range, and resonance is possible, that is: F Y =n Y x fnx Y0(Hz)

[0081] Among them, n Y is the frequency number, and Y0 is the blade number.

[0082] The uneven flow field formed by the guide vane is the main cause of the water flow vibration, and has a greater impact on the unit with a long distance between the guide vane outlet and the runner inlet. The guide vane multiple frequency (guide vane number x rotation frequency) is 41.53 Hz-50.76 Hz (1 multiple frequency), 83.07 Hz-101.53 Hz (2 multiple frequency), 124.59 Hz-152.28 Hz (3 multiple frequency), and 166.14 Hz-203.06 Hz (4 multiple frequency), wherein the second order natural frequency of the upper bracket is 50.86 Hz, the first order natural frequency of the lower bracket is 43.810 Hz, and the sixth order natural frequency of the small ring of the upper bracket is 176.018 Hz, which is close to or coincides with the guide vane flow state vibration range, and has the possibility of resonance, that is: F D = n D x fn x Z0 (Hz)

[0083] wherein, n D is the multiple frequency, and Z0 is the guide vane number.

[0084] The uneven thrust pad will cause the vertical hydroelectric generating unit to produce obvious vibration phenomenon, and the matching relationship between the thrust head and the thrust pad is the main factor causing the vibration, the thrust pad multiple frequency (thrust pad x rotation frequency) is 24.23 Hz-29.61 Hz (1 multiple frequency), 48.46 Hz-59.23 Hz (2 multiple frequency), 72.69 Hz-88.84 Hz (3 multiple frequency), and 96.92 Hz-118.45 Hz (4 multiple frequency), wherein the second order and third order modal natural frequency of the upper bracket is 50.864 Hz and 58.152 Hz, which coincides with the 2 multiple frequency vibration range of the unit thrust pad, and has the possibility of resonance, that is: F T = n T x fn x T0 (Hz)

[0085] wherein, n T is the multiple frequency, and T0 is the thrust pad number.

[0086] The tail water vortex belt will cause the unit to vibrate at some load section, which is mainly caused by the runner outlet circulation, and generally disappears gradually after the load section of the unit is raised by 70%, and the test results are all greater than the tail water pipe pressure pulsation frequency section, which will not have resonance effect on the bracket, that is: F W = 1 / 3 x fn (Hz)

[0087] In summary, the application firstly obtains the modal characteristics of the rack from the upper rack modal test, the upper rack ring modal test, and the lower rack single-arm test. An evaluation system is constructed to distinguish the frequency resonance prone intervals of hydraulic factors, mechanical factors, electromagnetic factors, and the like, and to extract the frequency intervals and vibration characteristics prone to causing unit resonance. In the subsequent operation process, the frequency intervals prone to resonance should be continuously monitored, and the vibration condition of the upper rack should be continuously monitored. Modal tests should be performed on the characteristic points before and after shutdown maintenance, and the data changes over the maintenance period are compared to evaluate the actual service comprehensive state of the unit.

[0088] Table 1

[0089] Example Five

[0090] A computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements the steps of the water turbine generator rack structural damage detection method when executing the computer program, for example, including: determining a knocking point and a response point on the water turbine generator rack; arranging an acceleration sensor at the response point; hammering the knocking point by an impact force rod; acquiring signals detected by the acceleration sensor and signals detected by a force sensor in the impact force rod; fitting the natural frequency, damping ratio, and rack vibration mode according to the signals detected by the acceleration sensor and the signals detected by the force sensor; and judging whether the water turbine generator rack has structural damage according to the natural frequency, damping ratio, and rack vibration mode. The memory can include an internal memory, such as a high-speed random memory, and can also include a non-volatile memory, such as at least one disk memory; the processor, network interface, and memory are connected to each other through an internal bus, which can be an industry standard architecture bus, a peripheral component interconnect standard bus, an extended industry standard structure bus, etc., and the bus can be divided into an address bus, a data bus, a control bus, etc. The memory is used to store programs, specifically, the programs can include program codes, and the program codes include computer operation instructions. The memory can include an internal memory and a non-volatile memory, and provide instructions and data to the processor.

[0091] Example Six

[0092] A computer readable storage medium stores a computer program, which, when executed by a processor, implements steps of the water turbine generator frame structural damage detection method, for example, including: determining a knocking point and a response point on the water turbine generator frame; arranging an acceleration sensor at the response point; hammering the knocking point by an impact force rod; acquiring signals detected by the acceleration sensor and signals detected by a force sensor in the impact force rod; fitting a frame natural frequency, a damping ratio, and a frame vibration mode according to the signals detected by the acceleration sensor and the signals detected by the force sensor; and judging whether the water turbine generator frame has structural damage according to the frame natural frequency, the damping ratio, and the frame vibration mode. Specifically, the computer readable storage medium includes, but is not limited to, for example, a volatile memory and / or a non-volatile memory. The volatile memory can include a random access memory (RAM) and / or a cache memory, etc. The non-volatile memory can include a read-only memory (ROM), a hard disk, a flash memory, an optical disc, a magnetic disc, etc.

[0093] Those skilled in the art will appreciate that embodiments of the present application can be supplied as a method, a system, or a computer program product. Therefore, the present application can take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROMs, optical storage, etc.) having computer usable program code embodied therein.

[0094] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and combinations of flows and / or blocks in the flowcharts and / or block diagrams can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing apparatus to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing apparatus produce the functions specified in the flowchart one or more flows and / or block diagram one or more blocks.

[0095] These computer program instructions can also be stored in a computer readable memory that can direct a computer or other programmable data processing apparatus to work in a specific manner, so that the instructions stored in the computer readable memory produce a manufactured product including instruction means, which implements the functions specified in the flowchart one or more flows and / or block diagram one or more blocks.

[0096] These computer program instructions can also be loaded into a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart and / or block diagram block or blocks.

[0097] Finally, it should be noted that the above-mentioned embodiments are merely used to illustrate the technical solutions of the present application, rather than limit the technical solutions of the present application. Although the present application has been described in detail with reference to the above-mentioned embodiments, those skilled in the art should understand that the specific embodiments of the present application can be modified or equivalent replacements without departing from the spirit and scope of the present application. Any modification or equivalent replacement without departing from the spirit and scope of the present application should be covered in the protection scope of the claims of the present application.

Claims

1. A method of detecting structural damage of a hydroelectric generator frame, characterized by, The method comprises the following steps: determining the knocking point and the response point on the water turbine generator frame; arranging an acceleration sensor (7) at the response point; hammering the knocking point by the impact force rod (5); obtaining the signals detected by the acceleration sensor (7) and the force sensor (6) in the impact force rod (5); fitting the natural frequency, damping ratio and frame vibration mode according to the signals detected by the acceleration sensor (7) and the force sensor (6); judging whether the water turbine generator frame has structural damage according to the natural frequency, damping ratio and frame vibration mode.

2. The method of claim 1, wherein The method further comprises the following steps: arranging an acceleration sensor (7) on the shaft, tangent and radial of one arm of the frame, and hammering the knocking point farthest from the acceleration sensor (7) by the impact force rod (5); judging whether the response of the acceleration sensor (7) is excited, and moving the position of the knocking point when the response of the acceleration sensor (7) cannot be excited until the response of the acceleration sensor (7) is excited to test the sensitivity of the acceleration sensor (7).

3. The method of claim 1, wherein The process of fitting the natural frequency, damping ratio and frame vibration mode according to the signals detected by the acceleration sensor (7) and the force sensor (6) is as follows: fitting the natural frequency, damping ratio and frame vibration mode according to the signals detected by the acceleration sensor (7) and the force sensor (6) by using the characteristic system realization algorithm.

4. A structural damage detection system for a hydroelectric generator frame, comprising: The method for detecting the structural damage of the water turbine generator frame according to claims 1-3 comprises an acceleration sensor (7), an impact force rod (5), a data acquisition instrument (3) and a test module (1), wherein the test module (1) is connected with the data acquisition instrument (3), and the data acquisition instrument (3) is connected with the acceleration sensor (7) and the impact force rod (5).

5. The hydroelectric generator frame structural damage detection system of claim 4, wherein, The test module (1) is connected with the data acquisition instrument (3) through a data line (2).

6. The hydroelectric generator frame structural damage detection system of claim 4, wherein, The data acquisition instrument (3) is connected with the impact force rod (5), the force sensor (6) and the acceleration sensor (7) through a connection cable (4).

7. The hydroelectric generator frame structural damage detection system of claim 4, wherein, The data acquisition instrument (3) has multiple input signal channels, and can collect signals without phase difference between channels.

8. The hydroelectric generator frame structural damage detection system of claim 4, wherein, The data acquisition instrument (3) has the functions of filtering, signal instantaneous capture, signal amplifier, spectrum analysis, frequency response function, phase and coherence function analysis, signal windowing processing, multiple measurement data averaging processing, original data storage function and anti-external electromagnetic interference capability.

9. The hydroelectric generator frame structural damage detection system of claim 4, wherein, The excitation frequency of the impact force rod (5) is selected in the flat range of the force spectrum.

10. The hydroelectric generator frame structural damage detection system of claim 4, wherein, The acceleration sensor (7) is a piezoelectric acceleration sensor.

Images