Hydro-generator rack structural damage detection system and method

Abstract

The invention discloses a structural damage detection system and method for a rack of a hydro-generator. The method comprises the following steps: determining a knocking point and a response point on the rack of the hydro-generator; arranging an acceleration sensor at the response point; the knocking point is hammered through an impact force rod; acquiring a signal detected by an acceleration sensor and a signal detected by a force sensor in the impact force bar; fitting according to the signal detected by the acceleration sensor and the signal detected by the force sensor to obtain the inherent frequency, the damping ratio and the vibration mode of the rack; and judging whether the hydraulic generator rack has structural damage according to the inherent frequency, the damping ratio and the vibration mode of the rack. The system and the method can judge whether the hydraulic generator mechanism and the support arm have structural damage.

Description

Technical Field

[0001] The invention belongs to the technical field of structural damage detection of a hydraulic generator frame, and relates to a hydraulic generator frame structural damage detection system and method. Background Art

[0002] The frame is an important supporting component of the hydro-turbine generator set, and the structural safety of the frame affects the safe and stable operation of the unit. As an important load-bearing component of the unit, if the frame is structurally damaged, it will cause the vibration of the unit to increase, and even worse, it will cause unplanned shutdown of the unit or cause a safety accident of the unit. Strengthening the structural damage detection of the unit frame is an effective means to avoid accidents and ensure the safe and stable operation of the unit. Summary of the invention

[0003] The purpose of the present invention is to overcome the above-mentioned shortcomings of the prior art and provide a system and method for detecting structural damage of a hydro-generator frame, which can determine whether structural damage occurs to the mechanism and support arm of the hydro-generator.

[0004] In order to achieve the above object, the present invention adopts the following technical scheme:

[0005] In one aspect, the present invention provides a method for detecting structural damage of a hydro-generator frame, comprising:

[0006] Determine the knocking points and response points on the turbine generator frame;

[0007] Arranging an acceleration sensor at the response point;

[0008] Hammer the striking point with an impact rod;

[0009] Acquire the signal detected by the acceleration sensor and the signal detected by the force sensor in the impact rod;

[0010] Fitting the natural frequency, damping ratio and vibration mode of the frame according to the signal detected by the acceleration sensor and the signal detected by the force sensor;

[0011] Whether the frame of the hydro-generator has structural damage is determined according to the frame natural frequency, damping ratio and frame vibration mode.

[0012] The structural damage detection method of the hydro-generator frame of the present invention is further improved in that:

[0013] Furthermore, it also includes:

[0014] An acceleration sensor is arranged in the axial, tangential and radial directions of one of the arms of the frame, and a hammer is applied at the striking point farthest from the acceleration sensor through an impact rod;

[0015] Determine whether the acceleration sensor is induced to respond. If the acceleration sensor cannot be induced to respond, move the position of the tapping point until the acceleration sensor is induced to respond, so as to test the sensitivity of the acceleration sensor.

[0016] Furthermore, the process of fitting the natural frequency, damping ratio and vibration mode of the frame according to the signal detected by the acceleration sensor and the signal detected by the force sensor is as follows:

[0017] According to the signal detected by the acceleration sensor and the signal detected by the force sensor, the characteristic system is used to implement the algorithm for fitting to obtain the natural frequency, damping ratio and vibration mode of the frame.

[0018] In a second aspect of the present invention, a system for detecting structural damage of a hydro-turbine generator frame is provided, which is used to implement a method for detecting structural damage of a hydro-turbine generator frame, and comprises an acceleration sensor, an impact rod, a data acquisition instrument and a test module, wherein the test module is connected to the data acquisition instrument, and the data acquisition instrument is connected to the acceleration sensor and the impact rod.

[0019] The structural damage detection system for the hydro-generator frame of the present invention is further improved in that:

[0020] Furthermore, the test module is connected to the data acquisition instrument via a data line.

[0021] Furthermore, the data acquisition instrument is connected to the impact rod, the force sensor and the acceleration sensor respectively through connecting cables.

[0022] Furthermore, the data acquisition instrument has multiple input signal channels, and each channel can acquire data without phase difference.

[0023] Furthermore, the data acquisition instrument has the functions of filtering and instantaneous signal capture, signal amplifier, spectrum analysis, frequency response function, phase and coherence function analysis, signal windowing processing and averaging processing of multiple measurement data, raw data storage, and resistance to external electromagnetic interference.

[0024] Furthermore, the excitation frequency of the impact rod is selected within the flat range of the force spectrum.

[0025] Furthermore, the acceleration sensor adopts a piezoelectric acceleration sensor.

[0026] The present invention has the following beneficial effects:

[0027] The system and method for detecting structural damage of a hydro-turbine generator frame of the present invention adopts a hammering method to measure the frame natural frequency, damping ratio and frame vibration mode during specific operation, and then judges whether the hydro-turbine generator frame has structural damage and whether the support arm is firmly connected to the concrete according to the frame natural frequency, damping ratio and frame vibration mode. The system and method are easy to operate and highly practical. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0029] Figure 1 It is a simple three-view drawing of the rack;

[0030] Figure 2 This is a schematic diagram of measuring points of the guide bearing frame of the hydro-turbine generator set;

[0031] Figure 3 It is a schematic diagram of the excitation point and response point of the test system;

[0032] Figure 4 It is the test system diagram;

[0033] Figure 5 It is the time domain diagram of the stimulus and response signal;

[0034] Figure 6 is the vibration mode diagram;

[0035] Among them, 1 is a test module, 2 is a data line, 3 is a data acquisition instrument, 4 is a connecting cable, 5 is an impact rod, 6 is a force sensor, and 7 is an acceleration sensor. DETAILED DESCRIPTION

[0036] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only an embodiment of a part of the present invention, not all embodiments, and is not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concepts disclosed in the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of the present invention.

[0037] The accompanying drawings show schematic diagrams of structures according to embodiments disclosed in the present invention. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0038] Embodiment 1

[0039] The present invention provides a method for detecting structural damage of a hydro-generator frame, comprising:

[0040] Determine the knocking points and response points on the turbine generator frame;

[0041] Arranging an acceleration sensor 7 at the response point;

[0042] Hammering the striking point with the impact rod 5;

[0043] Acquire the signal detected by the acceleration sensor 7 and the signal detected by the force sensor 6 in the impact rod 5;

[0044] The natural frequency, damping ratio and vibration mode of the frame are obtained by fitting the signal detected by the acceleration sensor 7 and the signal detected by the force sensor 6;

[0045] Whether the frame of the hydro-generator has structural damage is determined according to the frame natural frequency, damping ratio and frame vibration mode.

[0046] As an embodiment of the present invention, it also includes:

[0047] An acceleration sensor 7 is arranged in the axial direction, tangential direction and radial direction of one of the arms of the frame, and a hammer is performed at the striking point farthest from the acceleration sensor 7 through an impact force rod 5;

[0048] It is determined whether the acceleration sensor 7 can be stimulated to respond. When the acceleration sensor 7 cannot be stimulated to respond, the position of the tapping point is moved until the acceleration sensor 7 can be stimulated to respond, so as to test the sensitivity of the acceleration sensor 7.

[0049] As an implementation mode of the present invention, the process of fitting the frame natural frequency, damping ratio and frame vibration mode according to the signal detected by the acceleration sensor 7 and the signal detected by the force sensor 6 is as follows:

[0050] According to the signal detected by the acceleration sensor 7 and the signal detected by the force sensor 6, the characteristic system is used to implement the algorithm for fitting to obtain the frame natural frequency, damping ratio and frame vibration mode.

[0051] Embodiment 2

[0052] refer to Figure 4 The structural damage detection system for the turbine generator frame of the present invention comprises an acceleration sensor 7, an impact rod 5, a data acquisition instrument 3 and a test module 1, wherein the test module 1 is connected to the data acquisition instrument 3, and the data acquisition instrument 3 is connected to the acceleration sensor 7 and the impact rod 5.

[0053] As an implementation mode of the present invention, the test module 1 is connected to the data acquisition device 3 via a data line 2 .

[0054] As an implementation mode of the present invention, the data acquisition device 3 is connected to the impact rod 5, the force sensor 6 and the acceleration sensor 7 respectively through the connecting cable 4.

[0055] As an implementation mode of the present invention, the data acquisition device 3 has multiple input signal channels, and each channel can acquire data without phase difference.

[0056] As an embodiment of the present invention, the data acquisition instrument 3 has filtering and signal instantaneous capture, signal amplifier, spectrum analysis, frequency response function, phase and coherence function analysis, signal windowing processing and averaging processing of multiple measurement data, raw data storage function, and the ability to resist external electromagnetic interference.

[0057] As an implementation mode of the present invention, the excitation frequency of the impact rod 5 is selected within the flat range of the force spectrum, and the acceleration sensor 7 is a piezoelectric acceleration sensor.

[0058] Embodiment 3

[0059] The method for detecting structural damage of a hydro-generator frame of the present invention comprises the following steps:

[0060] 1) Preliminary test

[0061] The impact rod 5, the acceleration sensor 7 and the test module 1 are connected to the data acquisition instrument 3 through the data line 2 respectively, and an acceleration sensor 7 is arranged in the axial, tangential and radial directions of one of the arms of the frame. The impact rod 5 is used to hammer at the excitation point farthest from the acceleration sensor 7. When the acceleration sensor 7 cannot be evoked to respond, the hammering point is moved and hammered again to test the sensitivity of the acceleration sensor 7, until the test module 1 can collect the excitation signal and response signal detected by the acceleration sensor 7 and the force sensor 6 through the data acquisition instrument 3, and the signal can be transmitted normally after three knocks, then the next test work can be carried out.

[0062] 2) Test sampling

[0063] In test module 1, each knocking point is sampled N times according to its number on the frame. After each knocking test, the test data is checked. If the test data cannot meet the expected result, additional testing is required. After the test is completed, modal analysis is performed through test module 1 to determine the structural damage of the turbine generator frame.

[0064] It should be noted that the hammer method is used to obtain the structural excitation signal and response signal, and the transfer function analysis is performed at the same time. From the transfer function curve, it can be seen that better test results can be obtained within the range of 200Hz. Figure 5 shown.

[0065] The test data are fitted using the characteristic system realization algorithm (ERA) to obtain the frame natural frequency, damping ratio and frame vibration mode. The main natural frequency vibration modes are as follows: Figure 6 shown.

[0066] According to the natural frequency of the rack, draw the frequency band that is prone to resonate with the natural frequency of the rack to check the fatigue damage of the unit rack. The closer it is to the natural frequency of the rack, the greater the possibility of resonance of the rack and the more serious the fatigue damage to the rack.

[0067] Embodiment 4

[0068] In this embodiment, a relatively complete test module 1 is selected, which should have multiple coordinate systems, can be customized to establish models according to structures of different shapes and sizes, and has multiple modal fitting methods such as frequency domain method and time domain method related to this field;

[0069] The data acquisition instrument 3 should at least have multiple input signal channels, and each channel should be able to collect data without phase difference. It should have filtering and signal instant capture, signal amplifier, spectrum analysis, frequency response function, phase and coherence function analysis, signal windowing processing and averaging processing of multiple measurement data, raw data storage function, and the ability to resist external electromagnetic interference.

[0070] The excitation frequency of the impact rod 5 is selected within the flat range of the force spectrum, and has the function of changing the hammer head material and the counterweight to change the force pulse width and frequency range.

[0071] The force measuring range of the force sensor 6 is selected to be ±22240N.

[0072] The acceleration sensor 7 is a piezoelectric acceleration sensor.

[0073] like Figure 3 and Figure 4 As shown, 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.

[0074] like Figure 3 As shown, the test module 1 is connected to the data acquisition device 3 through the data line 2, and the data acquisition device 3 is respectively connected to the impact rod 5, the force sensor 6 and the acceleration sensor 7 through the connecting cable 4 to form an experimental test system.

[0075] Then the monitoring is performed using the method described in the present invention.

[0076] It should be noted that the electromagnetic polar frequency vibration range of the unit is: 45Hz~55Hz (1 times the frequency), 90Hz~110Hz (2 times the frequency), 135Hz~165Hz (3 times the frequency), 180Hz~220Hz (4 times the frequency). Among them, the second-order natural frequency of the upper frame is 50.86Hz, the third-order natural frequency is 58.15Hz, and the sixth-order frequency is 145.23Hz, which is close to or overlaps with the polar frequency vibration range, and there is a possibility of resonance. The second-order natural frequency of the small ring of the upper frame is 90.05Hz, and the second-order natural frequency is 153.33Hz, which is close to or overlaps with the polar frequency vibration range, and there is a possibility of resonance. The second-order natural frequency of the lower frame is 58.77Hz, and the third-order natural frequency is 105.93Hz, which is close to or overlaps with the polar frequency vibration range, and there is a possibility of resonance. The remaining frequency bands can be avoided, that is:

[0077] Fc=nc×50(Hz)

[0078] Among them, n C is the frequency multiple, and 50 is the electromagnetic frequency of the unit.

[0079] The flow vibration caused by the blades is mainly caused by uneven flow or Karman vortex. The blade number frequency (number of blades × rotation frequency) is 7.692Hz. The test results avoid 6.92Hz~8.46Hz (1 times frequency), 13.84Hz~16.92Hz (2 times frequency), 20.76Hz~25.38Hz (3 times frequency), 27.69Hz~33.84Hz (4 times frequency); the first-order natural frequency of the upper frame is 22.36Hz, and the first-order natural frequency of the upper frame ring is 27.26Hz, which is close to or coincides with the blade flow vibration range, and there is a possibility of resonance, that is:

[0080] F Y =n Y ×fn×Y0(Hz)

[0081] Among them, n Y is the frequency multiple, and Y0 is the number of blades.

[0082] The uneven flow field of water formed by the guide vanes is the main cause of water flow excitation, and has a greater impact on the units with a long distance between the guide vane outlet and the runner inlet. The guide vane frequency (number of guide vanes × rotation frequency) is 41.53Hz~50.76Hz (1st frequency), 83.07Hz~101.53Hz (2nd frequency), 124.59Hz~152.28Hz (3rd frequency), 166.14Hz~203.06Hz (4th frequency), among which the second-order natural frequency of the upper frame is 50.86Hz, the first-order natural frequency of the lower frame is 43.810Hz, and the sixth-order natural frequency of the small ring of the upper frame is 176.018Hz, which is close to or coincides with the vibration range of the guide vane flow pattern, and there is a possibility of resonance, that is:

[0083] F D =n D ×fn×Z0(Hz)

[0084] Among them, n D is the frequency multiple, and Z0 is the number of guide vanes.

[0085] Uneven thrust bearings can cause obvious vibrations in vertical turbine generator sets. The matching relationship between the thrust head and the thrust bearing is the main factor causing the vibration. The thrust bearing frequency (thrust bearing × rotation frequency) is 24.23Hz-29.61Hz (1 frequency), 48.46Hz-59.23Hz (2 frequency), 72.69Hz~88.84Hz (3 frequency), 96.92Hz-118.45Hz (4 frequency), among which the second-order and third-order modal natural frequencies of the upper frame are 50.864Hz and 58.152Hz, which coincide with the 2 frequency vibration range of the thrust bearing of the unit, and there is a possibility of resonance, namely:

[0086] F T =n T×fn×T0(Hz)

[0087] Among them, n T is the frequency multiple, T0 is the thrust wattage.

[0088] The tailwater vortex will cause certain vibrations in the unit in some load sections, mainly due to the runner outlet circulation. Generally, it gradually disappears after the unit load section is increased by 70%. The test results are all greater than the tailwater pipe pressure pulsation frequency section, and will not cause resonance to the frame, that is:

[0089] F W =1 / 3×fn(Hz)

[0090] In summary, the present invention first obtains the modal characteristics of the frame from the upper frame modal test, the upper frame ring modal test, and the lower frame single-arm test. And construct an evaluation system to distinguish the interval segments where frequency resonance is prone to occur, such as hydraulic factors, mechanical factors, and electromagnetic factors, and extract the frequency segments and vibration characteristics that are prone to cause unit resonance. In the subsequent operation process, the frequency segments that are prone to resonance should be continuously monitored, and the vibration conditions of the upper frame should be continuously paid attention to. Modal tests should be carried out on the characteristic points before and after the shutdown and maintenance, and the data changes during the maintenance period should be compared to evaluate the actual comprehensive service status of the unit.

[0091] Table 1

[0092]

[0093]

[0094] Embodiment 5

[0095] A computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the method for detecting structural damage to a frame of a hydro-turbine generator are implemented, for example, including: determining a knocking point and a response point on the frame of the hydro-turbine generator; arranging an acceleration sensor at the response point; hammering the knocking point with an impact rod; acquiring a signal detected by the acceleration sensor and a signal detected by a force sensor in the impact rod; fitting the frame natural frequency, damping ratio and frame vibration mode according to the signal detected by the acceleration sensor and the signal detected by the force sensor; judging whether the frame of the hydro-turbine generator has structural damage according to the frame natural frequency, damping ratio and frame vibration mode. The memory may include a memory, such as a high-speed random access memory, and may also include a non-volatile memory, such as at least one disk memory, etc. The processor, the network interface, and the memory are interconnected through an internal bus, and the internal bus may be an industrial standard architecture bus, a peripheral component interconnection standard bus, an extended industrial standard architecture bus, etc. The bus may be divided into an address bus, a data bus, a control bus, etc. The memory is used to store programs, specifically, the programs may include program codes, and the program codes include computer operation instructions. The memory may include internal memory and non-volatile memory, and provide instructions and data to the processor.

[0096] Embodiment 6

[0097] A computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the method for detecting structural damage of a hydro-turbine generator frame are implemented, for example, including: determining a knocking point and a response point on the hydro-turbine generator frame; arranging an acceleration sensor at the response point; hammering the knocking point with an impact rod; acquiring a signal detected by the acceleration sensor and a signal detected by a force sensor in the impact rod; fitting the frame natural frequency, damping ratio and frame vibration mode according to the signal detected by the acceleration sensor and the signal detected by the force sensor; judging whether the hydro-turbine generator frame has structural damage according to the frame natural frequency, damping ratio and 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 may include a random access memory (RAM) and / or a cache memory (cache), etc. The non-volatile memory may include a read-only memory (ROM), a hard disk, a flash memory, an optical disk, a magnetic disk, etc.

[0098] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0099] 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 process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, 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 device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0100] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0101] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0102] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for detecting structural damage of a hydro-generator frame, characterized in that: include: Determine the knocking points and response points on the turbine generator frame; Arranging an acceleration sensor (7) at the response point; Hammering the striking point with an impact rod (5); Acquire a signal detected by an acceleration sensor (7) and a signal detected by a force sensor (6) in an impact force rod (5); Fitting the natural frequency, damping ratio and vibration mode of the frame according to the signal detected by the acceleration sensor (7) and the signal detected by the force sensor (6); Whether the frame of the hydro-generator has structural damage is determined according to the frame natural frequency, damping ratio and frame vibration mode.

2. The method for detecting structural damage of a hydro-generator frame according to claim 1, characterized in that: Also includes: An acceleration sensor (7) is arranged in the axial direction, tangential direction and radial direction of one of the arms of the frame, and a hammer is performed at a striking point farthest from the acceleration sensor (7) through an impact force rod (5); It is determined whether the acceleration sensor (7) is stimulated to respond. If the acceleration sensor (7) cannot be stimulated to respond, the position of the striking point is moved until the acceleration sensor (7) can be stimulated to respond, so as to test the sensitivity of the acceleration sensor (7).

3. The method for detecting structural damage of a hydro-generator frame according to claim 1, characterized in that: The process of fitting the natural frequency, damping ratio and vibration mode of the frame according to the signal detected by the acceleration sensor (7) and the signal detected by the force sensor (6) is as follows: According to the signal detected by the acceleration sensor (7) and the signal detected by the force sensor (6), a characteristic system is used to implement an algorithm for fitting to obtain the natural frequency, damping ratio and vibration mode of the frame.

4. A structural damage detection system for a hydro-generator frame, characterized in that: The method for detecting structural damage of a hydro-turbine generator frame according to claims 1 to 3 comprises an acceleration sensor (7), an impact rod (5), a data acquisition device (3) and a test module (1), wherein the test module (1) is connected to the data acquisition device (3), and the data acquisition device (3) is connected to the acceleration sensor (7) and the impact rod (5).

5. The structural damage detection system for a hydro-generator frame according to claim 4, characterized in that: The test module 1 is connected to a data acquisition device (3) via a data line (2).

6. The structural damage detection system for a hydro-generator frame according to claim 4, characterized in that: The data acquisition instrument (3) is respectively connected to the impact force rod (5), the force sensor (6) and the acceleration sensor (7) via a connecting cable (4).

7. The structural damage detection system for a hydro-generator frame according to claim 4, characterized in that: The data acquisition device (3) has multiple input signal channels, and each channel can acquire data without phase difference.

8. The structural damage detection system for a hydro-generator frame according to claim 4, characterized in that: The data acquisition instrument (3) has the functions of filtering and instantaneous signal capture, signal amplifier, spectrum analysis, frequency response function, phase and coherence function analysis, signal windowing processing and average processing of multiple measurement data, raw data storage, and the ability to resist external electromagnetic interference.

9. The structural damage detection system for a hydro-generator frame according to claim 4, characterized in that: The excitation frequency of the impact force rod (5) is selected within the flat range of the force spectrum.

10. The structural damage detection system for a hydro-generator frame according to claim 4, characterized in that: The acceleration sensor (7) adopts a piezoelectric acceleration sensor.

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