Vibration monitoring system for offshore wind turbine generator jacket foundation modal identification

Abstract

The invention relates to the technical field of offshore wind power engineering structure health monitoring, and discloses a vibration monitoring system for offshore wind turbine generator jacket foundation modal identification, which comprises a vibration monitoring device, a data acquisition and analysis device and a modal identification device which are connected in sequence, a plurality of monitoring sections are arranged at each main leg tube of the offshore wind turbine generator jacket, the plurality of monitoring sections are respectively arranged at the top, the middle and the bottom of each main leg tube, the vibration monitoring devices are arranged at the monitoring sections, the data acquisition and analysis device is arranged at the top of the offshore wind turbine generator jacket, and the modal recognition device is arranged on a shore workstation. The offshore wind plant jacket foundation modal identification method fills the blank of offshore wind plant jacket foundation modal identification technology, provides an underwater foundation state for the dynamic response of the whole wind turbine generator, and provides a basis for vibration characteristic analysis, dynamic characteristic optimization, structural damage diagnosis and prediction and the like of a structural system.

Description

Technical Field

[0001] The present invention relates to the technical field of offshore wind power engineering structure health monitoring, and in particular to a vibration monitoring system for modal identification of jacket foundations of offshore wind turbine generator sets. Background Art

[0002] As the development of offshore wind farms advances into deep waters, the height of the jacket platform increases with the operating water depth, resulting in a decrease in structural stiffness. Therefore, in order to timely grasp the dynamic response state of the underwater jacket foundation and fill the monitoring gap, it is necessary to conduct vibration monitoring of the jacket foundation. Modal analysis is used to identify the structural natural frequency and thus assess the damage state of the jacket foundation.

[0003] However, the modal analysis of the jacket foundation of offshore wind turbines mainly focuses on flexible structures such as blades and towers. Vibration monitoring of the underwater jacket foundation has not yet been carried out, and the modal parameters of the jacket foundation cannot be identified. Therefore, the dynamic response state of the jacket foundation cannot be grasped in a timely manner, which has obvious defects. Summary of the Invention

[0004] In view of this, the present invention provides a vibration monitoring system for modal identification of offshore wind turbine jacket foundations to solve the problem that modal analysis of offshore wind turbine jacket foundations does not perform vibration monitoring of the underwater jacket foundations and cannot identify the modal parameters of the jacket foundations.

[0005] In a first aspect, the present invention provides a vibration monitoring system for modal identification of an offshore wind turbine jacket foundation, the system comprising: a vibration monitoring device, a data acquisition and analysis device, and a modal identification device connected in sequence; multiple monitoring sections are provided at each main leg pipe of the offshore wind turbine jacket, the multiple monitoring sections being respectively provided at the top, middle, and bottom of each main leg pipe; the vibration monitoring device is provided at each monitoring section; the data acquisition and analysis device is provided at the top of the offshore wind turbine jacket; and the modal identification device is provided at an onshore workstation;

[0006] A vibration monitoring device is used to monitor the vibration characteristics of the offshore wind turbine jacket and collect structural vibration signals at the monitoring section, and transmit the structural vibration signals at the monitoring section to the modal identification device through the data acquisition and analysis device;

[0007] The modal identification device is used to perform data analysis and modal identification on the structural vibration signal at the monitoring section to obtain the modal parameters of the offshore wind turbine jacket structure.

[0008] The vibration monitoring system for modal identification of the jacket foundation of an offshore wind turbine provided in this embodiment provides multiple monitoring sections at each main leg of the jacket of the offshore wind turbine, and a vibration monitoring device at each monitoring section. The vibration monitoring device comprehensively collects the vibration characteristics of the top, middle, and bottom of each main leg of the jacket of the offshore wind turbine, thereby realizing remote online automated monitoring of the vibration of the jacket foundation structure. The modal parameters of the jacket structure of the offshore wind turbine are then identified by the modal identification device, thus filling the gap in the modal identification technology of the jacket foundation of offshore wind farms, providing the underwater foundation state for the dynamic response of the entire wind turbine, and thus providing a basis for vibration characteristic analysis, dynamic characteristic optimization, structural damage diagnosis and prediction, etc. of the structural system.

[0009] In an optional embodiment, the vibration monitoring device includes: an acceleration sensor installation protection module and a signal transmission protection module arranged at the monitoring section, and the acceleration sensor installation protection module and the signal transmission protection module are connected to each other.

[0010] In an optional embodiment, the signal transmission protection module includes:

[0011] Four-core shielded cable, seamless steel pipe and junction box; the four-core shielded cable is protected by a seamless steel pipe, which is welded to the main structural wall of the conductor frame through a gasket, and four-core shielded cables of multiple sections are collected and led upward through a junction box.

[0012] The vibration monitoring system for modal identification of the jacket foundation of an offshore wind turbine provided in this embodiment ensures the safe transmission of signals between the biaxial acceleration sensor and the data acquisition and analysis device through the signal transmission protection device.

[0013] In an optional embodiment, the acceleration sensor is installed with a protection module, including:

[0014] Two-axis acceleration sensor, bolts, protective steel plate and T-shaped support; the two-axis acceleration sensor is connected to the T-shaped support by bolts, the T-shaped support is installed on the main structural wall of the jacket, the protective steel plate is welded by the side steel plate and the upper cover plate, the protective steel plate is covered on the outside of the two-axis acceleration sensor, and is installed on the main structural wall of the jacket.

[0015] The vibration monitoring system for modal identification of the jacket foundation of an offshore wind turbine provided in this embodiment achieves stable acquisition of voltage signals at the monitoring section by the two-axis acceleration sensor by arranging the two-axis acceleration sensor at the monitoring section and then protecting the two-axis acceleration sensor with a protective steel plate.

[0016] In an optional embodiment, the two-axis acceleration sensor is arranged at a monitoring section of the main leg tube along the main wind direction or perpendicular to the main wind direction.

[0017] In an optional embodiment, the two-axis acceleration sensor transmits the structural vibration signal at the monitoring section through a four-core shielded cable, and the four-core shielded cable is pulled through the holes in the upper cover plate.

[0018] In an optional embodiment, the data acquisition and analysis device includes: a data acquisition module, a ring network switch, a collector line submarine cable, a fiber optic distribution frame panel, a core switch, and a sending submarine cable connected in sequence; the data acquisition module is arranged in a platform monitoring panel cabinet in a jacket of an offshore wind turbine; the fiber optic distribution frame panel and the core switch are connected via a single-mode fiber optic jumper;

[0019] A data acquisition module is used to process the structural vibration signal at the monitoring section and send the processed structural vibration signal at the monitoring section to the ring network switch;

[0020] The ring network switch is used to perform photoelectric conversion on the structural vibration signal at the monitoring section after signal processing, and transmit the structural vibration signal at the monitoring section after photoelectric conversion to the modal recognition device through the collector line submarine cable, optical fiber distribution frame panel, core switch and sending submarine cable.

[0021] In the vibration monitoring system for modal identification of the jacket foundation of an offshore wind turbine provided in this embodiment, the structural vibration signal at the monitoring section is transmitted to a data acquisition module via an electric cable. After the data acquisition module processes the structural vibration signal at the monitoring section, the signal is transmitted to an onshore workstation via an optical cable, thereby ensuring stable transmission of the structural vibration signal at the monitoring section and laying the foundation for subsequent modal identification.

[0022] In an optional embodiment, the data acquisition module includes: a signal amplifier and a filter;

[0023] Signal amplifier, used to amplify the structural vibration signal at the monitoring section;

[0024] The filter is used to filter the amplified structural vibration signal to obtain the structural vibration signal at the monitoring section after signal processing.

[0025] The vibration monitoring system for modal identification of the jacket foundation of an offshore wind turbine provided in this embodiment eliminates rotor rotation noise and environmental noise by amplifying and filtering the structural vibration signal at the monitoring section, making the structural vibration signal at the monitoring section more accurate.

[0026] In an optional embodiment, the modal identification device includes: a signal acquisition module, a time-frequency conversion module, and a parameter identification module connected in sequence;

[0027] The signal acquisition module is used to filter the structural vibration signal at the monitoring section to obtain the effective signal of the offshore wind turbine jacket foundation under random load in the shutdown state, and calculate the real-time acceleration value based on the effective signal;

[0028] The time-frequency conversion module is used to convert the real-time acceleration value into the frequency domain to obtain the structural vibration frequency;

[0029] The parameter identification module is used to calculate the acceleration power spectrum density function based on the structural vibration frequency, and perform modal identification based on the acceleration power spectrum density function to obtain the modal parameters of the offshore wind turbine jacket structure.

[0030] The vibration monitoring system for modal identification of offshore wind turbine jacket foundations provided in this embodiment filters the structural vibration signal at the monitoring section, obtains a frequency domain signal from the filtered data through Fourier transform, and calculates the power spectrum to identify the modal parameters of the offshore wind turbine jacket structure. This system promptly grasps the real-time dynamic response state of the underwater jacket foundation, fills the gap in underwater foundation vibration monitoring, provides measured and effective vibration data for the development of offshore wind farms in deep waters, and provides design guidance for the reduction in jacket stiffness caused by increasing jacket height.

[0031] In a second aspect, the present invention provides a vibration monitoring method for modal identification of an offshore wind turbine jacket foundation, which is applied to the vibration monitoring system for modal identification of an offshore wind turbine jacket foundation according to the first aspect or any corresponding embodiment thereof, the method comprising:

[0032] The vibration characteristics of the offshore wind turbine jacket are monitored by a vibration monitoring device, and the structural vibration signal at the monitoring section is collected, and the structural vibration signal at the monitoring section is transmitted to the modal identification device through a data acquisition and analysis device;

[0033] The modal identification device is used to perform data analysis and modal identification on the structural vibration signal at the monitoring section to obtain the modal parameters of the offshore wind turbine jacket structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0035] Figure 1 1 is a structural block diagram of a vibration monitoring system for modal identification of an offshore wind turbine jacket foundation according to an embodiment of the present invention;

[0036] Figure 2 2. It is a schematic diagram of the arrangement of a vibration monitoring system for modal identification of an offshore wind turbine jacket foundation according to an embodiment of the present invention;

[0037] Figure 3 is a structural diagram of a signal transmission protection module according to an embodiment of the present invention;

[0038] Figure 4 This is a schematic diagram of four-core shielded cables of multiple cross sections being collected and led upward through a junction box according to an embodiment of the present invention;

[0039] Figure 5 is a schematic structural diagram of a T-shaped support according to an embodiment of the present invention;

[0040] Figure 6 is a schematic structural diagram of a bolt according to an embodiment of the present invention;

[0041] Figure 7 is a schematic structural diagram of a protective steel plate according to an embodiment of the present invention;

[0042] Figure 8 is a schematic diagram of a T-shaped support installed on a main structure wall of a jacket according to an embodiment of the present invention;

[0043] Figure 9 is a structural diagram of a data acquisition and analysis device according to an embodiment of the present invention;

[0044] Figure 10 is a structural block diagram of a data acquisition module according to an embodiment of the present invention;

[0045] Figure 11 is a schematic structural diagram of a modal recognition device according to an embodiment of the present invention;

[0046] Figure 12 The present invention is a flow chart of a vibration monitoring method for modal identification of an offshore wind turbine jacket foundation according to an embodiment of the present invention. DETAILED DESCRIPTION

[0047] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0048] At present, the design method of the jacket foundation of offshore wind turbines mainly simplifies wave loads into static loads and conducts structural analysis based on the principle of static calculation. Dynamic response analysis of the jacket foundation is rarely performed, and the focus is mainly on flexible structures such as blades and towers.

[0049] As offshore wind power projects advance into deep seas, vibration monitoring of jacket foundation structures is imminent. Therefore, a modal identification system suitable for jacket foundations of offshore wind turbines is urgently needed.

[0050] Related vibration monitoring devices include mechanical accelerometers, piezoelectric accelerometers and MEMS accelerometers (micro-electromechanical systems). However, due to the poor low-frequency response of piezoelectric accelerometers, they do not have the ability to perform modal analysis on the basis of the catheter frame; and MEMS accelerometers are affected by the accuracy of the chip and have certain limitations.

[0051] During the modal identification process of the jacket foundation of an offshore wind turbine, modal analysis mainly includes parameters such as natural frequency, damping ratio, and modal vibration shape. The ultimate goal of modal analysis is to identify the modal parameters of the structure and provide a basis for vibration characteristic analysis, dynamic characteristic optimization, structural damage diagnosis and prediction, etc.

[0052] However, the analysis of offshore wind turbine jacket foundations mainly focuses on flexible structures such as blades and towers. Vibration monitoring of underwater jacket foundations has not yet been carried out, and the modal parameters of the jacket foundations cannot be identified. Therefore, the dynamic response state of the jacket foundation cannot be grasped in a timely manner, which has obvious defects.

[0053] To solve the above technical problems, an embodiment of the present invention provides a vibration monitoring system for modal identification of the jacket foundation of an offshore wind turbine. By selecting multiple sections on the jacket foundation of an offshore wind turbine, arranging two-dimensional acceleration sensors, and performing Kalman filtering, the system realizes the identification of modal parameters such as the structural natural frequency, damping ratio, and vibration mode. This system fills the gap in modal identification technology for jacket foundations of offshore wind farms, provides the underwater foundation state for the dynamic response of the entire wind turbine, and thus provides a basis for vibration characteristic analysis, dynamic characteristic optimization, structural damage diagnosis and prediction, etc. of the structural system.

[0054] This embodiment provides a vibration monitoring system for modal identification of jacket foundations of offshore wind turbines. Figure 1 As shown, the system includes: a vibration monitoring device 101, a data acquisition and analysis device 102, and a modal identification device 103 connected in sequence; multiple monitoring sections are set at each main leg pipe of the offshore wind turbine jacket, the vibration monitoring device 101 is set at each monitoring section, and the multiple monitoring sections are respectively set at the top, middle and bottom of each main leg pipe, the data acquisition and analysis device 102 is set at the top of the offshore wind turbine jacket, and the modal identification device 103 is set at an onshore workstation;

[0055] The vibration monitoring device 101 is used to monitor the vibration characteristics of the offshore wind turbine jacket and collect structural vibration signals at the monitoring section, and transmit the structural vibration signals at the monitoring section to the modal identification device 103 through the data acquisition and analysis device 102.

[0056] Specifically, the vibration monitoring device 101 is set on the first to ath monitoring sections of the four main leg pipes of the jacket (four piles) to monitor the vibration characteristics of the jacket, where a is a natural number greater than 1 and less than or equal to N, N represents the preset number of monitoring sections, and each monitoring section consists of 2 monitoring points.

[0057] For example, Figure 2 As shown, monitoring section 1 and monitoring section 2 are arranged at the top and middle of the 1# main leg pipe respectively, and monitoring section 3 and monitoring section 4 are arranged at 1 / 3 and the bottom of the 2# main leg pipe respectively. Vibration monitoring devices 101 are installed at monitoring section 1, monitoring section 2, monitoring section 3 and monitoring section 4.

[0058] The modal identification device 103 is used to perform data analysis and modal identification on the structural vibration signal at the monitoring section to obtain modal parameters of the jacket structure of the offshore wind turbine.

[0059] Specifically, the modal identification device 103 is installed in an onshore workstation and processes the monitoring signal (i.e., the structural vibration signal at the monitoring section) through Kalman filtering. The processed data is subjected to Fourier transform to obtain a frequency domain signal, and the power spectrum is calculated to identify the modal parameters of the jacket structure, mainly the natural frequency.

[0060] The vibration monitoring system for modal identification of the jacket foundation of an offshore wind turbine provided in this embodiment provides multiple monitoring sections at each main leg of the jacket of the offshore wind turbine, and a vibration monitoring device at each monitoring section. The vibration monitoring device comprehensively collects the vibration characteristics of the top, middle, and bottom of each main leg of the jacket of the offshore wind turbine, thereby realizing remote online automated monitoring of the vibration of the jacket foundation structure. The modal parameters of the jacket structure of the offshore wind turbine are then identified by the modal identification device, thus filling the gap in the modal identification technology of the jacket foundation of offshore wind farms, providing the underwater foundation state for the dynamic response of the entire wind turbine, and thus providing a basis for vibration characteristic analysis, dynamic characteristic optimization, structural damage diagnosis and prediction, etc. of the structural system.

[0061] In some optional embodiments, such as Figure 2 As shown, the vibration monitoring device 101 includes: an acceleration sensor installation protection module 1011 and a signal transmission protection module 1012 arranged at the monitoring section, and the acceleration sensor installation protection module 1011 and the signal transmission protection module 1012 are connected to each other.

[0062] In some optional embodiments, such as Figure 3-4 As shown, the signal transmission protection module 1012 includes:

[0063] Four-core shielded cable 10121, seamless steel pipe 10122 and junction box 10123; the four-core shielded cable 10121 is protected by the seamless steel pipe 10122, and the seamless steel pipe 10122 is welded to the main structural wall of the conductor frame through a gasket 10124, and four-core shielded cables 10121 of multiple sections are collected and led upward through the junction box 10123.

[0064] The vibration monitoring system for modal identification of the jacket foundation of an offshore wind turbine provided in this embodiment ensures the safe transmission of signals between the biaxial acceleration sensor and the data acquisition and analysis device through the signal transmission protection device.

[0065] In some optional embodiments, such as Figure 5-7 As shown, the acceleration sensor installation protection module 1011 includes:

[0066] Two-dimensional acceleration sensor 10111, bolt 10112, protective steel plate 10113 and T-shaped support 10114; the two-dimensional acceleration sensor 10111 is connected to the T-shaped support 10114 by bolt 10112, the T-shaped support 10114 is installed on the main structural wall of the conductor frame, the protective steel plate 10113 is welded by the side steel plate 10115 and the upper cover plate 10116, the protective steel plate 10113 is covered on the outside of the two-dimensional acceleration sensor 10111, and is installed on the main structural wall of the conductor frame.

[0067] Specifically, if Figure 8 As shown, the T-shaped support 10114 is installed on the main structure wall of the jacket by full welding, and the T-shaped steel plate is lofted according to the curved surface of the main structure wall of the jacket.

[0068] Furthermore, the protective steel plate 10113 is installed on the main structural wall of the conductor frame by full welding.

[0069] The vibration monitoring system for modal identification of the jacket foundation of an offshore wind turbine provided in this embodiment achieves stable acquisition of voltage signals at the monitoring section by the two-axis acceleration sensor by arranging the two-axis acceleration sensor at the monitoring section and then protecting the two-axis acceleration sensor with a protective steel plate.

[0070] In some optional embodiments, such as Figure 2 As shown, the two-way acceleration sensor 10111 is set at the monitoring section of the main leg pipe along the main wind direction or perpendicular to the main wind direction.

[0071] In some optional embodiments, such as Figure 7 As shown, the two-axis acceleration sensor 10111 transmits the structural vibration signal at the monitoring section through the four-core shielded cable 10121, and the four-core shielded cable 10121 is pulled through the hole 10117 at the upper cover plate 10116.

[0072] Specifically, the two-dimensional acceleration sensor 10111 comes with a four-core shielded cable 10121. The four-core shielded cable 10121 is led up through the hole 10117 opened in the upper cover plate 10116 and is protected by a seamless steel pipe 10122. The seamless steel pipe 10122 matches the diameter of the hole 10117 and is sealed and protected by welding.

[0073] In some optional embodiments, such as Figure 9 As shown, the data acquisition and analysis device 102 includes: a data acquisition module 1021, a ring network switch 1022, a collection line submarine cable 1023, a fiber optic distribution frame panel 1024, a core switch 1025, and a sending submarine cable 1026 connected in sequence; the data acquisition module 1021 is set in the platform monitoring panel cabinet inside the offshore wind turbine jacket; the fiber optic distribution frame panel 1024 and the core switch 1025 are connected via a single-mode fiber optic patch cord 1027;

[0074] The data acquisition module 1021 is used to process the structural vibration signal at the monitoring section and send the processed structural vibration signal at the monitoring section to the ring network switch 1022 .

[0075] The ring network switch 1022 is used to perform photoelectric conversion on the structural vibration signal at the monitoring section after signal processing, and transmit the structural vibration signal at the monitoring section after photoelectric conversion to the modal recognition device 103 through the collection line submarine cable 1023, the optical fiber distribution frame panel 1024, the core switch 1025 and the sending submarine cable 1026 in sequence.

[0076] Specifically, after signal processing, the structural vibration signal at the monitoring section is converted into optical fibers by the ring network switch 1022, and transmitted to the optical fiber distribution frame panel 1024 of the booster station through the collector line submarine optical cable 1023. The data processed for the second time by the booster station is transmitted to the onshore workstation through the single-mode optical fiber jumper 1027 and the core switch 1025 via the sending submarine cable 1026 to realize remote online automatic monitoring.

[0077] Furthermore, the onshore workstation is provided with a network switch and an acquisition server to realize photoelectric signal conversion and signal acquisition processing of the structural vibration signal at the monitoring section.

[0078] In the vibration monitoring system for modal identification of the jacket foundation of an offshore wind turbine provided in this embodiment, the structural vibration signal at the monitoring section is transmitted to a data acquisition module via an electric cable. After the data acquisition module processes the structural vibration signal at the monitoring section, the signal is transmitted to an onshore workstation via an optical cable, thereby ensuring stable transmission of the structural vibration signal at the monitoring section and laying the foundation for subsequent modal identification.

[0079] In some optional embodiments, such as Figure 10 As shown, the data acquisition module 1021 includes: a signal amplifier 10211 and a filter 10212;

[0080] The signal amplifier 10211 is used to amplify the structural vibration signal at the monitoring section.

[0081] The filter 10212 is used to filter the amplified structural vibration signal to obtain the structural vibration signal at the monitoring section after signal processing.

[0082] Specifically, the signal amplifier 10211 amplifies the structural vibration signal of the monitoring point, and the filter 10212 filters the wind wheel rotation noise and environmental noise.

[0083] The vibration monitoring system for modal identification of the jacket foundation of an offshore wind turbine provided in this embodiment eliminates rotor rotation noise and environmental noise by amplifying and filtering the structural vibration signal at the monitoring section, making the structural vibration signal at the monitoring section more accurate.

[0084] In some optional embodiments, such as Figure 11 As shown, the modal identification device 103 includes: a signal acquisition module 1031, a time-frequency conversion module 1032 and a parameter identification module 1033 connected in sequence;

[0085] The signal acquisition module 1031 is used to filter the structural vibration signal at the monitoring section to obtain the effective signal of the jacket foundation of the offshore wind turbine under random load in the shutdown state, and calculate the real-time acceleration value based on the effective signal.

[0086] Specifically, the signal acquisition module 1031 collects voltage signals (i.e., structural vibration signals at the monitoring section) through an acceleration sensor at a sampling frequency of 50 Hz, and eliminates interference from simple harmonics through Kalman filtering to obtain the effective signal of the wind turbine jacket foundation under random loads in the shutdown state. The real-time acceleration value is then calculated using the following formula:

[0087] a (t) =V (t) / S

[0088] In the above formula, a (t) is the current acceleration value (i.e. the real-time acceleration value), V (t) is the real-time output voltage of the acceleration sensor (i.e., the effective signal), and S is the sensitivity coefficient of the acceleration sensor.

[0089] The time-frequency conversion module 1032 is used to perform frequency domain conversion on the real-time acceleration value to obtain the structural vibration frequency.

[0090] Specifically, the time-frequency transformation module 1032 obtains the real-time value of continuous acceleration through a 50 Hz sampling frequency, and transforms it from the time domain to the frequency domain through Fourier transformation to extract the structural vibration frequency. The formula is as follows:

[0091]

[0092] In the above formula, F(ω) is the Fourier transform of a single time point, i is an imaginary number, ω is the frequency variable, t is the time point of each acceleration real-time value, f(t) is the acceleration real-time value at time point t, is the structural vibration frequency.

[0093] The parameter identification module 1033 is used to calculate the acceleration power spectrum density function based on the structural vibration frequency, and perform modal identification based on the acceleration power spectrum density function to obtain the modal parameters of the offshore wind turbine jacket structure.

[0094] Specifically, the parameter identification module 1033 obtains a frequency domain signal by Fourier transforming the structural vibration frequency, and then calculates the acceleration power spectrum density corresponding to each frequency through power spectrum calculation. The calculation formula of the acceleration power spectrum density function is as follows:

[0095]

[0096] In the above formula, T is the time interval for taking values, F T (ω) is the Fourier transform of the entire time interval, and S(ω) is the acceleration power spectral density function.

[0097] Furthermore, based on the rule that the acceleration power spectrum density function will show a significant increase near the natural frequency of the structure, modal identification is performed to obtain the modal parameters of the jacket structure, such as the natural frequency, damping ratio and vibration mode.

[0098] The vibration monitoring system for modal identification of offshore wind turbine jacket foundations provided in this embodiment filters the structural vibration signal at the monitoring section, obtains a frequency domain signal from the filtered data through Fourier transform, and calculates the power spectrum to identify the modal parameters of the offshore wind turbine jacket structure. This system promptly grasps the real-time dynamic response state of the underwater jacket foundation, fills the gap in underwater foundation vibration monitoring, provides measured and effective vibration data for the development of offshore wind farms in deep waters, and provides design guidance for the reduction in jacket stiffness caused by increasing jacket height.

[0099] The following describes the workflow of a vibration monitoring system for modal identification of an offshore wind turbine jacket foundation through a specific embodiment.

[0100] Example 1:

[0101] The workflow of the vibration monitoring system for modal identification of offshore wind turbine jacket foundations includes:

[0102] S1. Select 8 vibration monitoring sections on each main leg of the jacket. Monitoring section 1 and monitoring section 2 are both arranged on the 1# main leg, and one two-axis acceleration sensor 10111 is arranged at the top and middle of the main leg respectively along the main wind direction and perpendicular to the main wind direction; monitoring section 3 and monitoring section 4 are arranged on the 2# main leg, and one two-axis acceleration sensor 10111 is arranged at the top and middle of the main leg respectively along the main wind direction and perpendicular to the main wind direction; monitoring section 5 and monitoring section 6 are arranged on the 3# main leg, and one two-axis acceleration sensor 10111 is arranged at 1 / 3 and the bottom of the main leg respectively along the main wind direction and perpendicular to the main wind direction; monitoring section 7 and monitoring section 8 are both arranged on the 4# main leg, and one two-axis acceleration sensor 10111 is arranged at 1 / 3 and the bottom of the main leg respectively along the main wind direction and perpendicular to the main wind direction.

[0103] S2. Fix the two-dimensional acceleration sensor 10111 on each monitoring section to the T-shaped support 10114 with bolts 10112. The T-shaped support 10114 is fixed to the structural wall of the conductor frame by welding. The side steel plate 10115 of the protective steel plate 10113 is welded to the T-shaped support 10114 and the structural wall of the conductor frame, and is covered around the two-dimensional acceleration sensor 10111.

[0104] S3. The two-dimensional acceleration sensor 10111 comes with a four-core shielded cable 10121. The four-core shielded cable 10121 is led up through the hole 10117 opened in the upper cover 10116 and is protected by a seamless steel pipe 10122. The seamless steel pipe 10122 matches the diameter of the hole 10117 and is sealed and protected by welding.

[0105] S4. The seamless steel pipe 10122 is welded to the main structural wall of the conduit frame through a gasket 10124. Multiple four-core shielded cables 10121 are collected and led upward through the circular holes opened on the junction box 10123. The junction box 10123 is welded to the main structural wall of the conduit frame by full welding.

[0106] S5. The data acquisition module 1021 is installed in the platform monitoring panel cabinet inside the jacket. Each biaxial acceleration sensor 10111 needs to use two data acquisition channels to perform data acquisition.

[0107] S6. The data acquisition module 1021 contains a signal amplifier 10211 and a filter 10212; the signal amplifier 10211 amplifies the structural vibration signal of the measured point, and the filter 10212 filters the wind wheel rotation noise and environmental noise; the filtered signal is photoelectrically converted through the ring network switch 1022, and is transmitted to the optical fiber distribution frame panel 1024 of the booster station through the collector line submarine cable 1023. The data processed for the second time at the booster station is transmitted to the onshore workstation through the single-mode optical fiber jumper 1027 and the core switch 1025 via the sending submarine cable 1026 to realize remote online automatic monitoring.

[0108] S7. The modal identification device 103 is installed in the onshore workstation and has a built-in relevant algorithm to process the monitoring signal, thereby identifying the modal parameters such as the natural frequency, damping ratio and vibration mode of the jacket structure.

[0109] S8. Repeat S2-S4 to complete the construction process of strain monitoring and installation of transmission devices for several other monitoring sections in sequence.

[0110] In the above-mentioned embodiment 1, by selecting multiple sections on the jacket foundation and arranging biaxial acceleration sensors, the modal parameters such as the structural natural frequency, damping ratio and vibration mode are identified. First, biaxial acceleration sensors are arranged at predetermined test points of the jacket corresponding to the first to a sections. The biaxial acceleration sensors are then protected. The measured signals are transmitted to a data acquisition module via a cable. The data acquisition module includes a signal amplifier and a filter. The processed data is transmitted to an onshore workstation via an optical cable. The workstation is equipped with a modal analysis algorithm based on time domain and frequency domain, thereby realizing the modal identification of the jacket foundation structure. The offshore wind turbine jacket foundation modal identification system based on vibration monitoring identifies the jacket foundation mode, timely grasps the real-time dynamic response state of the underwater jacket foundation, fills the gap in underwater foundation vibration monitoring, provides measured and effective vibration data for the development of offshore wind farms in deep waters, and provides a design guidance basis for the reduction in jacket stiffness caused by increasing jacket height.

[0111] The embodiment of the present invention also provides a vibration monitoring method for modal identification of jacket foundation of offshore wind turbine generator set, which is applied to a vibration monitoring system for modal identification of jacket foundation of offshore wind turbine generator set, such as Figure 12 As shown, the method includes:

[0112] Step S1201 , monitoring the vibration characteristics of the offshore wind turbine jacket through a vibration monitoring device, collecting structural vibration signals at the monitoring section, and transmitting the structural vibration signals at the monitoring section to a modal identification device through a data acquisition and analysis device.

[0113] Step S1202 : performing data analysis and modal identification on the structural vibration signal at the monitoring section by a modal identification device to obtain modal parameters of the jacket structure of the offshore wind turbine.

[0114] The vibration monitoring method for modal identification of the jacket foundation of an offshore wind turbine generator system according to this embodiment is applied to the following situations: Figure 1 In the embodiment shown, a vibration monitoring system for modal identification of an offshore wind turbine jacket foundation is provided. Therefore, the specific implementation of steps S1201 and S1202 can refer to the above description. Figure 1 The corresponding description of the illustrated embodiment will not be repeated here.

[0115] It is understood that the effects and beneficial effects of the method of this embodiment are similar to those of Figure 1 The functions and beneficial effects of a vibration monitoring system for modal identification of an offshore wind turbine jacket foundation in the illustrated embodiment correspond to each other and are not described in detail here.

[0116] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the embodiments of this application.

[0117] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0118] In the several embodiments provided in the embodiments of the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0119] Units described as separate components may or may not be physically separate, and components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0120] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0121] If the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the embodiment of the present application, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, which is stored in a storage medium and includes a number of instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the various embodiments of the present application. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0122] Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention. Such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A vibration monitoring system for modal identification of offshore wind turbine jacket foundations, characterized in that: The system includes: a vibration monitoring device, a data acquisition and analysis device, and a modal identification device connected in sequence; multiple monitoring sections are provided at each main leg pipe of the offshore wind turbine jacket, and the multiple monitoring sections are respectively provided at the top, middle and bottom of each main leg pipe; the vibration monitoring device is provided at each monitoring section, the data acquisition and analysis device is provided at the top of the offshore wind turbine jacket, and the modal identification device is provided at an onshore workstation; The vibration monitoring device is used to monitor the vibration characteristics of the offshore wind turbine jacket and collect structural vibration signals at the monitoring section, and transmit the structural vibration signals at the monitoring section to the modal identification device through the data acquisition and analysis device; The modal identification device is used to perform data analysis and modal identification on the structural vibration signal at the monitoring section to obtain modal parameters of the jacket structure of the offshore wind turbine.

2. The system according to claim 1, wherein: The vibration monitoring device includes: an acceleration sensor installation protection module and a signal transmission protection module arranged at the monitoring section, and the acceleration sensor installation protection module and the signal transmission protection module are connected to each other.

3. The system according to claim 2, characterized in that The signal transmission protection module includes: Four-core shielded cable, seamless steel pipe and junction box; the four-core shielded cable is protected by the seamless steel pipe, the seamless steel pipe is welded to the main structural wall of the conductor frame through a gasket, and the four-core shielded cable of multiple sections is collected and led upward through the junction box.

4. The system according to claim 3, characterized in that The acceleration sensor installation protection module includes: A two-dimensional acceleration sensor, a bolt, a protective steel plate and a T-shaped support; the two-dimensional acceleration sensor is connected to the T-shaped support through the bolt, the T-shaped support is installed on the main structural wall of the jacket, the protective steel plate is welded by a side steel plate and an upper cover plate, the protective steel plate covers the outside of the two-dimensional acceleration sensor and is installed on the main structural wall of the jacket.

5. The system according to claim 4, characterized in that The two-way acceleration sensor is arranged at the monitoring section of the main leg pipe along the main wind direction or perpendicular to the main wind direction.

6. The system according to claim 4, characterized in that The two-axis acceleration sensor transmits the structural vibration signal at the monitoring section through the four-core shielded cable, and the four-core shielded cable is pulled through the hole at the upper cover plate.

7. The system according to claim 1, wherein: The data acquisition and analysis device includes: a data acquisition module, a ring network switch, a collector line submarine cable, a fiber optic distribution frame panel, a core switch, and a sending submarine cable connected in sequence; the data acquisition module is arranged in a platform monitoring panel cabinet inside the offshore wind turbine jacket; the fiber optic distribution frame panel and the core switch are connected via a single-mode fiber optic jumper; The data acquisition module is used to process the structural vibration signal at the monitoring section and send the processed structural vibration signal at the monitoring section to the ring network switch; The ring network switch is used to perform photoelectric conversion on the structural vibration signal at the monitoring section after the signal processing, and transmit the structural vibration signal at the monitoring section after the photoelectric conversion to the modal recognition device in sequence through the collector line submarine cable, the optical fiber distribution frame screen, the core switch and the sending submarine cable.

8. The system according to claim 7, characterized in that The data acquisition module includes: a signal amplifier and a filter; The signal amplifier is used to amplify the structural vibration signal at the monitoring section; The filter is used to filter the amplified structural vibration signal to obtain the structural vibration signal at the monitoring section after signal processing.

9. The system according to claim 1, wherein: The modal identification device comprises: a signal acquisition module, a time-frequency conversion module and a parameter identification module connected in sequence; The signal acquisition module is used to filter the structural vibration signal at the monitoring section to obtain an effective signal of the jacket foundation of the offshore wind turbine under random load in a shutdown state, and calculate the real-time acceleration value based on the effective signal; The time-frequency conversion module is used to perform frequency domain conversion on the real-time acceleration value to obtain the structural vibration frequency; The parameter identification module is used to calculate the acceleration power spectrum density function based on the structural vibration frequency, and perform modal identification based on the acceleration power spectrum density function to obtain the modal parameters of the offshore wind turbine jacket structure.

10. A vibration monitoring method for modal identification of an offshore wind turbine jacket foundation, characterized in that: A vibration monitoring system for modal identification of an offshore wind turbine jacket foundation according to any one of claims 1 to 9, the method comprising: The vibration characteristics of the jacket of the offshore wind turbine are monitored by a vibration monitoring device, and a structural vibration signal at a monitoring section is collected, and the structural vibration signal at the monitoring section is transmitted to a modal identification device through a data acquisition and analysis device; The modal identification device performs data analysis and modal identification on the structural vibration signal at the monitoring section to obtain the modal parameters of the jacket structure of the offshore wind turbine.

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