Ultrasonic array device for measuring top oil temperature of transformer and measuring method

Abstract

The invention relates to an ultrasonic array device for measuring the top oil temperature of a transformer and a measuring method, the ultrasonic array device comprises an ultrasonic array and a computer processing unit, and the ultrasonic array is composed of an ultrasonic transmitting unit and an ultrasonic receiving and signal conversion unit; the ultrasonic transmitting unit serves as a transmitting array element in the ultrasonic array and is used for receiving excitation parameters and an array element delay table which are transmitted to the ultrasonic transmitting unit by the computer processing unit; the ultrasonic receiving and signal conversion unit serves as a receiving array element in the ultrasonic array and is used for outputting a digital signal after the echo is subjected to amplification, filtering and analog-to-digital conversion; the computer processing unit is used for performing time gating, arrival time extraction and shell section time deduction on the digital signal, and performing inversion according to the sound velocity-temperature relation to obtain and display the oil temperature; the device has the advantages that the structure is simple and reasonable, the body does not need to be transformed, a larger area can be covered, and engineering feasibility is achieved.

Description

Technical Field

[0001] This invention belongs to the technical field of transformer testing equipment, specifically relating to an ultrasonic array device and measurement method for measuring the top oil temperature of a transformer. Background Technology

[0002] During transformer operation, the windings generate heat due to load and electromagnetic losses, causing the transformer oil temperature to rise. If the transformer is exposed to high temperatures for an extended period, the insulation materials and transformer oil will age faster, reducing the transformer's lifespan and potentially posing serious safety hazards. Therefore, transformer oil temperature is a crucial monitoring indicator. However, transformer oil temperature is difficult to monitor and calculate, and current measurement methods have limitations. Built-in temperature sensors can only acquire information from limited points, failing to reflect the overall temperature distribution inside the tank, and the leads and sealing structure affect the integrity of the transformer itself. Infrared thermometry is obstructed by the metal casing, only obtaining surface temperature and making it difficult to pinpoint internal high-temperature points. Numerical calculation or indirect diagnostic methods rely heavily on models and prior knowledge, and lack timeliness. Therefore, it is essential to provide an ultrasonic array device and measurement method for measuring the top-level oil temperature of transformers that is simple and reasonable in structure, requires no modification to the transformer itself, has a wide coverage area, is easy to install, allows for uninterrupted online measurement, has strong noise and multipath resistance capabilities, and is easily maintainable. Summary of the Invention

[0003] (I) Technical Solution

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide an ultrasonic array device and measurement method for measuring the top oil temperature of a transformer, which has a simple and reasonable structure, requires no modification to the main body, has a large coverage area, is easy to install, can perform online measurement without power interruption, has strong noise and multipath resistance capabilities, and is easy to maintain.

[0005] The objective of this invention is achieved as follows: Firstly, an ultrasonic array device for measuring the top-layer oil temperature of a transformer includes an ultrasonic array and a computer processing unit. The ultrasonic array comprises an ultrasonic transmitting unit and an ultrasonic receiving and signal conversion unit. The ultrasonic transmitting unit is electrically connected to the ultrasonic receiving and signal conversion unit, which is also electrically connected to the computer processing unit. The computer processing unit is electrically connected to the ultrasonic transmitting unit. The ultrasonic transmitting unit, as a transmitting element in the ultrasonic array, receives excitation parameters and an array element delay table from the computer processing unit, thereby forming a predetermined directional beam. The ultrasonic receiving and signal conversion unit, as a receiving element in the ultrasonic array, amplifies, filters, and performs analog-to-digital conversion on the echo, outputting it as a digital signal. The computer processing unit performs time gating, arrival time extraction, and shell time subtraction on the digital signal, and retrieves and displays the oil temperature based on the sound velocity-temperature relationship.

[0006] In this invention, the device consists of an ultrasonic transmitting unit, an ultrasonic receiving and signal conversion unit, and a computer processing unit, which are electrically connected in sequence. By controlling the phase and timing of the array element excitation, a directional ultrasonic beam is formed, the echo signal is acquired and processed to obtain the propagation time and sound speed, and the oil temperature is inverted and displayed accordingly.

[0007] Furthermore, the ultrasonic transmitting unit includes an array transducer and an excitation circuit, wherein the array transducer is attached to the transformer housing.

[0008] In this invention, the ultrasonic transmitting unit includes an array of transducers and an excitation circuit attached to the transformer housing. The computer processing unit sends excitation parameters and array element delay tables to the transmitting unit to form a beam with a predetermined direction.

[0009] Furthermore, the ultrasonic receiving and signal conversion unit includes a receiving array transducer, a front-end amplification and filtering circuit, and a data acquisition module; the receiving array transducer is externally mounted on the outer wall of the fuel tank.

[0010] In this invention, the ultrasonic receiving and signal conversion unit includes a receiving array transducer, a front-end amplification and filtering circuit, and a data acquisition module, which is used to amplify, filter, and convert the echo into a digital signal; the computer processing unit is used to perform time gating, arrival time extraction, and shell segment time subtraction on the digital signal, and to obtain and display the oil temperature based on the sound speed-temperature relationship.

[0011] Furthermore, both the array transducer and the receiving array transducer are attached to the transformer casing using a regular arrangement of array fixing and coupling components to achieve stable coupling.

[0012] Furthermore, the array transducers and receiving array transducers are arranged in a regular pattern using a linear array or area array installation method.

[0013] In this invention, the array is a linear array or a surface array, with an integrated magnetic fixing structure and a coupling agent attached to the outer shell; the number of array elements, spacing, and aperture can be adjusted according to the size of the device under test; the transmit / receive arrangement can be opposite, on the same side, or crossed to adapt to different installation positions and monitoring ranges.

[0014] Furthermore, the array fixing and coupling component adopts an integrated magnetic fixing structure and is equipped with a component with a replaceable coupling layer.

[0015] Furthermore, the replaceable coupling layer employs a thin layer of high-viscosity coupling agent or a compressible polymer gasket to form a stable interfacial contact and suppress high-frequency scattering.

[0016] Furthermore, the array transducer adopts the NY-90CK type acoustic emission transducer; the receiving array transducer adopts the G80 type transducer.

[0017] Furthermore, the front-end amplification and filtering circuit uses a PXPA3 low-noise preamplifier for gain and preliminary filtering; the data acquisition module uses an SMAQC USB5-1000 data acquisition card and achieves multi-channel synchronous sampling through external triggering.

[0018] In summary, the overall technical solution of this invention is as follows: the ultrasonic array consists of transmitting and receiving elements, with multiple piezoelectric transducers arranged in a linear or planar pattern; the computer-controlled excitation circuit sends amplitude and delay values ​​to each transmitting element to achieve controllable beam shape and direction; the receiving element collects echoes, which are then amplified and filtered before being sent to the acquisition module; the processing unit performs time gating on the echoes, deducts the propagation time of the outer casing section, obtains the propagation time of the oil area and the sound path length, calculates the equivalent sound velocity, and provides the temperature result based on a preset sound velocity-temperature correspondence; scanning measurement is completed by changing the pointing order, without needing to move the position and angle of the array, making it suitable for external online monitoring of the overall oil temperature of transformers.

[0019] Secondly, a measurement method for an ultrasonic array device for measuring the top oil temperature of a transformer, wherein the top oil temperature measurement operation is performed based on the ultrasonic array device for measuring the top oil temperature of a transformer as described above, and the measurement method is as follows:

[0020] Step 1: Set the transmission frequency, amplitude, pulse width, and repetition period in the computer processing unit and send them to the excitation circuit to synchronously trigger transmission and acquisition;

[0021] Step 2: Set the time windows for the inlet section, the direct oil zone section, and the outlet section on the echo signal and complete the noise reduction;

[0022] Step 3: Extract the arrival time of the oil section, subtract the propagation time of the outer shell section, and then calculate the sound velocity in the oil by combining it with the sound path length;

[0023] Step 4: Invert the temperature based on the preset or calibrated sound velocity-temperature relationship;

[0024] Step 5: Execute the preset instructions sequentially to complete the area scan, and output an alarm if an abnormality occurs.

[0025] (II) Beneficial Effects

[0026] 1. The ultrasonic temperature measurement of the present invention utilizes the physical property that the speed of sound changes with the temperature of the medium. By measuring the propagation time or related characteristics of ultrasound in transformer oil, the equivalent speed of sound in the oil is calculated and the temperature is obtained accordingly.

[0027] 2. The ultrasonic array of the present invention can be externally mounted on the outer wall of the oil tank and stabilized with a coupling agent, without changing the internal structure of the transformer, and can be used for measurement without interrupting power supply;

[0028] 3. This invention, through array pointing control and sequential scanning, can cover multiple directions and regions in a short time, making it easy to obtain the spatiotemporal distribution of oil temperature and use it for trend analysis and anomaly alerts. Attached Figure Description

[0029] Figure 1 This is a block diagram of the overall structure of the present invention.

[0030] Figure 2 This is a schematic diagram illustrating the working principle of the present invention.

[0031] Figure 3 This is a schematic diagram of the ultrasonic transmitting and receiving array used in this invention.

[0032] Figure 4 This is a schematic diagram of the experimental setup and signal link for the present invention.

[0033] In the diagram: 1. Ultrasonic transmitting array; 2. Ultrasonic receiving array; 3. Ultrasonic receiving array; 4. Ultrasonic receiving array; 5. Signal generator; 6. Power amplifier; 7. Preamplifier; 8. Oscilloscope. Detailed Implementation

[0034] The present invention will be further described below with reference to the embodiments and / or accompanying drawings.

[0035] Example 1

[0036] like Figure 1-4 As shown, an ultrasonic array device for measuring the top-layer oil temperature of a transformer includes an ultrasonic array and a computer processing unit. The ultrasonic array consists of an ultrasonic transmitting unit and an ultrasonic receiving and signal conversion unit. The ultrasonic transmitting unit is electrically connected to the ultrasonic receiving and signal conversion unit, which is also electrically connected to the computer processing unit. The computer processing unit is electrically connected to the ultrasonic transmitting unit. The ultrasonic transmitting unit, as the transmitting element in the ultrasonic array, receives excitation parameters and element delay tables from the computer processing unit to form a predetermined beam. The ultrasonic receiving and signal conversion unit, as the receiving element in the ultrasonic array, amplifies, filters, and converts the echo to digital signal. The computer processing unit performs time gating, arrival time extraction, and shell time subtraction on the digital signal, and retrieves and displays the oil temperature based on the sound velocity-temperature relationship.

[0037] As one possible specific implementation, the device consists of a transmitting array, a receiving array, a driving and front-end circuit, a synchronization and data acquisition module, and a computer processing unit. The array is attached to the outer wall of the fuel tank by magnetic attraction and a replaceable coupling layer.

[0038] In specific implementation, the ultrasonic array temperature measurement device of the present invention includes: a transmitting array, a receiving array, an array fixing and coupling component, an excitation and front-end circuit, a data acquisition module, a computer processing unit, and a power supply and synchronization unit; the system signal link is as follows: the computer processing unit generates an array element delay table according to a preset "pointing set" → excitation and acquisition are triggered simultaneously through the synchronization unit → the transmitting array couples ultrasonic waves into the transformer tank wall through the fixing and coupling component → the receiving array acquires the echo and amplifies and filters it through the front-end circuit → the data acquisition module digitizes the data → the computer processing unit completes gating, time extraction, steel shell subtraction, and temperature inversion → outputs the measured temperature value, a two-dimensional temperature heat map, and a status alarm.

[0039] The ultrasonic transmitting unit includes an array transducer and an excitation circuit, wherein the array transducer is attached to the transformer housing.

[0040] The ultrasonic receiving and signal conversion unit includes a receiving array transducer, a front-end amplification and filtering circuit, and a data acquisition module; the receiving array transducer is externally mounted on the outer wall of the fuel tank.

[0041] Both the array transducer and the receiving array transducer are attached to the transformer shell by regularly arranged array fixing and coupling components to achieve stable coupling.

[0042] The array transducers and receiver array transducers are arranged in a regular pattern using a linear array or area array installation method.

[0043] As one possible specific implementation method, such as Figure 3 As shown, the transmitting and receiving arrays can be linear or area arrays; linear arrays are suitable for directional penetration measurements of narrow fuel tank panels; area arrays facilitate rapid multi-directional coverage; the center distance d between array elements is determined based on the target frequency and the desired beamwidth, preferably d≈(0.5~0.8)·λ 钢 , where λ 钢 λ is the wavelength of the corresponding frequency in the steel shell.

[0044] The array fixing and coupling component adopts an integrated magnetic fixing structure and is equipped with a component with a replaceable coupling layer.

[0045] The replaceable coupling layer uses a thin layer of high-viscosity coupling agent or a compressible polymer gasket to form a stable interfacial contact and suppress high-frequency scattering.

[0046] As a specific implementation method, a magnetic fixing structure and a replaceable coupling layer (such as a thin layer of high-viscosity coupling agent or a compressible polymer gasket) are set at the bottom of the array to form a stable interface contact and suppress high-frequency scattering; the relative arrangement of the transmitting and receiving arrays prioritizes ensuring that the acoustic path passes through the target oil area and avoids strong reflectors such as reinforcing ribs and bolts; the arrangement angle of the array relative to the oil surface satisfies near-normal incidence to reduce dispersion at the inlet / outlet interface.

[0047] The array transducer is an NY-90CK type acoustic emission transducer; the receiving array transducer is a G80 type transducer.

[0048] As a specific feasible implementation, an example of transmitting and receiving transducers is as follows: the transmitting end uses an NY-90CK type acoustic emission transducer (center frequency approximately 80kHz), and the receiving end uses a G80 type transducer (center frequency approximately 80kHz, sensitivity approximately 70dB). Both types of transducers are connected to the front-end circuit via BNC coaxial cables, with the center height kept as consistent as possible to achieve direct acoustic path penetration.

[0049] The front-end amplification and filtering circuit uses a PXPA3 low-noise preamplifier for gain and preliminary filtering; the data acquisition module uses an SMAQC USB5-1000 data acquisition card and achieves multi-channel synchronous sampling through external triggering.

[0050] As a specific implementation example, the front-end and acquisition link are as follows: the excitation uses a CTS-8077PR pulse / echo generator; the receiving end uses a PXPA3 low-noise preamplifier for gain (40dB) and preliminary filtering; the acquisition device uses an SMAQC USB5-1000 data acquisition card, and multi-channel synchronous sampling is achieved by external triggering; the TTL / Sync port of the CTS-8077PR is connected to the Ext-Trig port of the acquisition card as a unified time reference.

[0051] This invention relates to an ultrasonic array device and method for measuring the top-layer oil temperature of a transformer. The device is attached to the outer wall of an oil-immersed transformer. Acoustic parameters in the oil are obtained through array pointing control and echo processing, and the oil temperature is calculated accordingly. This enables online monitoring and anomaly alerts for the top-layer oil temperature of the transformer. In use, this invention employs an external array and beam pointing control to achieve non-invasive, area-coverage measurement of the transformer's top-layer oil temperature. It requires no modification to the main body, simplifying engineering implementation. Combined with time gating and shell time subtraction, it improves the stability and repeatability of the results, facilitating online monitoring and early warning. This invention has the advantages of simple and reasonable structure, no need for main body modification, large coverage area, easy installation, uninterrupted online measurement, strong noise and multipath resistance, and good maintainability.

[0052] Example 2

[0053] like Figure 1-4 As shown, a measurement method for an ultrasonic array device for measuring the top oil temperature of a transformer is described above. The method involves using the ultrasonic array device described above to measure the top oil temperature of the transformer. The measurement method is as follows:

[0054] Step 1: Set the transmission frequency, amplitude, pulse width, and repetition period in the computer processing unit and send them to the excitation circuit to synchronously trigger transmission and acquisition;

[0055] Step 2: Set the time windows for the inlet section, the direct oil zone section, and the outlet section on the echo signal and complete the noise reduction;

[0056] Step 3: Extract the arrival time of the oil section, subtract the propagation time of the outer shell section, and then calculate the sound velocity in the oil by combining it with the sound path length;

[0057] Step 4: Invert the temperature based on the preset or calibrated sound velocity-temperature relationship;

[0058] Step 5: Execute the preset instructions sequentially to complete the area scan, and output an alarm if an abnormality occurs.

[0059] As one feasible implementation method, the measurement method includes:

[0060] A directional beam is formed by generating an array element delay table based on the pointing angle set;

[0061] The host computer triggers the synchronous acquisition of signals from each channel.

[0062] Zero-phase bandpass / wavelet threshold denoising, DC removal, and alignment are performed on the gated signal;

[0063] The total arrival time is obtained by cross-correlation within the oilfield time window, and the signal-to-noise ratio (SNR) and sidelobe ratio (PPR) are calculated as quality indicators.

[0064] The oil travel time is obtained by subtracting the propagation time into / out of the shell from the sound velocity in the steel and the shell thickness. The sound velocity is then calculated by combining the net path length in the oil. Finally, the sound velocity-temperature relationship is obtained by using two-point / multi-point calibration to output the top layer oil temperature.

[0065] Multi-directional / multi-path results are weighted and fused according to SNR, PPR and path length, and can be repeated M times and averaged to improve stability.

[0066] This invention eliminates the need for sensors inside the oil tank, enabling online measurement of the top oil temperature without power interruption. It offers advantages such as easy installation, wide coverage, strong noise and multipath resistance, and good maintainability.

[0067] In terms of specific implementation, ① Preliminary installation and parameter settings: 1) The system operates in the low ultrasonic frequency band of 40 to 150 kHz to take into account the attenuation characteristics in transformer oil and engineering adaptability; the preferred center frequency is f0≈80 kHz; all channels share a unified time base and trigger source to ensure the consistency of time measurement.

[0068] 2) The array is a linear array or a surface array: the array elements use contact piezoelectric transducers, and the center frequency is preferably 40-150kHz (approximately 80kHz in the example); a magnetic structure is set on the bottom surface of the array and coated with a coupling agent; during installation, the transmitting and receiving centers are aligned at the same height and avoid external accessories; the cables are BNC coaxial and reliably grounded.

[0069] The array is attached to the outer wall by a magnetic structure and coated with a coupling agent to form a stable acoustic contact; the excitation, front-end and acquisition equipment are arranged with uniform grounding and safe distance, and the wiring is kept away from high-voltage leads to meet insulation requirements;

[0070] Each of the two outer walls is equipped with a transmitter array and a receiver array. Common combinations are 1→3, 1→4, 2→3, and 2→4 (1 is the left array (TX), 2 is the top array (RX), 3 is the right array (RX), and 4 is the bottom array (RX), representing the acoustic path combination of the transmitter array → receiver array. For example, "1→3" is a direct path to the opposite side with left-side transmission and right-side reception). This is suitable for situations where there is no obstruction on the opposite side of the enclosure, providing a large coverage area and very clear direct transmission.

[0071] 3) After installation, record the shortest distance from the array to the cabinet boundary, the straight-line distance between arrays, and the estimated spacing D between the inner walls as geometric priors, and obtain the inner and outer shell thickness h from the equipment nameplate or on-site thickness measurement. in h out This is for subsequent steel shell removal.

[0072] 4) Transmission parameter settings: The host computer sets the transmission frequency, amplitude, pulse width and repetition period on the interface, and the parameters are sent to the CTS-8077PR to generate waveforms; for example, the frequency is set near the transducer resonance (about 80kHz); the number of pulse trains and the repetition period are matched with the target echo window.

[0073] The transmission parameters include the center frequency f0 and the peak-to-peak amplitude A. pp The pulse width τ, repetition period PRF, and number of pulse trains N; the computer processing unit uses the "pointing angle set" {θ} k}Generate array element delay table {△t k ,i}(θ k Let Δt be the expected main lobe pointing angle; k To make the main lobe point to θ kWhen the relative transmission delay is applied to the i-th array element (i is the array element number), the desired main lobe pointing is achieved; each pointing is repeatedly transmitted M times and averaged in the time domain to improve the signal-to-noise ratio.

[0074] ② Adopt a unified time base: such as Figure 4 As shown, the TTL trigger signal of the excitation device is at system zero time t=0; the data acquisition module performs multi-channel synchronous sampling with rising edge trigger; the sampling rate f s To meet bandwidth and time resolution requirements, f is preferred. s ≥500kSa / s; Single recording duration T rec Covering the intake window, oil access window, and exhaust window, T is preferred. rec ≥50ms.

[0075] ③ Synchronization and Acquisition: The host computer issues a measurement trigger, and the signal generator synchronously outputs excitation and TTL trigger; the acquisition card starts synchronous sampling of each channel when the rising edge of the trigger is zero. For example, the sampling rate is set to ≥500kSa / s and the recording time is ≥50ms to fully cover the echo window.

[0076] ④ Based on the layout geometry and estimated time delay, three time windows are set on the waveform: the shell entry segment, the oil zone direct arrival segment, and the shell exit segment. Only the arrival time and amplitude-frequency characteristics of the oil zone direct arrival segment are calculated, while the shell entry / exit segments are used for steel shell time estimation and quality determination.

[0077] ⑤ Perform zero-phase bandpass or wavelet threshold denoising on the signal within the window to suppress power frequency and its harmonics, low-frequency drift and high-frequency noise dispersion; then perform DC removal, amplitude normalization and sampling point alignment to obtain comparable gated waveforms.

[0078] ⑥ The entry window covers 0-t1 after launch, the direct access window in the oil zone covers t1-t2, and the exit window covers t2-t3; t1, t2, and t3 are determined by geometric sound path and empirical margin; the data outside the window are used for noise estimation and quality control.

[0079] Within the oilfield time window, the peak time of the echo envelope or the peak time of the cross-correlation is taken as the estimate of the total arrival time t; at the same time, the signal-to-noise ratio (SNR) and sidelobe ratio (PPR) are calculated as quality indicators for subsequent screening and weighting.

[0080] Within the time window W = [t1, t2] in the oil zone, use the emission template S tx (t) and received echo S rx (t) Perform a sliding cross-correlation and find the time shift that maximizes the correlation value, which is taken as the total arrival time: Among them, S tx (t) is the launch template; S rx (t) represents the received signal after gating / DC removal / bandpass.

[0081] The signal-to-noise ratio (SNR) is calculated by default using the energy method. For the received signal x(t) after removing the DC component: The signal-to-noise ratio SNR is then obtained:

[0082] For the peak-to-peak ratio (PPR), take the position of its maximum value as the main peak position, and define the main peak amplitude: The sidelobe amplitude: Outside the main peak guard band (to avoid taking the shoulder of the main peak), search for the second maximum peak: where g is the guard band width (empirically taken as 1.5 - 2 carrier periods or half of an envelope width); then the PPR is defined as: If the SNR < S0 or the PPR < P0 for a sound path, the sound path is invalidated / downweighted; the rest are processed according to the fusion temperature.

[0083] ⑦ After the acquisition card completes a triggered sampling, it transmits the digital waveforms of each channel back to the computer; the data frame contains the channel identifier and the time stamp; the computer then completes multi-channel time alignment and integrity verification, and marks the abnormal frames as pending remeasurement.

[0084] The host computer synchronously saves the original waveform, the gated waveform, the features, and the temperature / interval results, and uses the oil temperature measured by the thermocouple as the reference value.

[0085] For the temperatures of multiple sound paths in the same grid / area, fuse them according to the quality weights: the weights are positively correlated with the SNR and PPR, and moderately decay with the path length L; the final temperature and the heat map are output, and the original results of each sound path are retained for traceability; L is determined by the array geometry / direction, and can be approximately taken as L ≈ D (the distance between the transmitting transducer and the receiving transducer) according to the near-normal method.

[0086] ⑧ For the first deployment, calibrate the sound speed - temperature at two or three temperature points to obtain a linear model: c(T) = a0 + a1(T - T0). Suppose that at two known temperatures T1 and T2, the sound speeds in the oil are measured as c1 and c2 respectively, then: a0 = c1 - a1(T1 - T0). At temperature T, the corresponding geometric length of the sound path is L, and the total arrival time t is synchronously measured.

[0087] The in-shell / out-shell section times are respectively: Then, after deducting the steel shell section, the propagation time in the oil area is obtained: t oil = t - t in - t out , and the equivalent sound speed in the oil is calculated as: Substitute at T = T1 and T2 respectively to obtain c1 and c2; to improve stability, the same direction can be repeatedly transmitted multiple times and averaged before calculating c.

[0088] ⑨ The calibration steps are: constant temperature control of oil temperature → acquisition of travel time → calculation of sound velocity → least squares calculation of a0, a1; if necessary, piecewise linear processing is performed according to low / medium / high temperature.

[0089] When oil is changed, array position is adjusted, or there are significant seasonal changes, a0, a1, and the steel shell thickness and sound velocity c in the steel are updated by single-point or double-point recalibration. steel The difference in sound velocity in the same direction before and after recalibration should be less than the set threshold.

[0090] The embodiment uses the literature parameter: c(T)=1420-3.3693(T-293.15). The Celsius temperature obtained by inverse solving the above formula is mapped to a preset temperature range (such as normal, high, overheated, severe overheated) and displayed on the interface as a numerical / thermal map. An alarm is triggered when the temperature enters the overheated range or above. For the temperature obtained from multiple acoustic paths in the same grid, the range is determined by weighted fusion according to SNR / sidelobe ratio / path length.

[0091] ⑩ Precautions: 1) The device casing and grounding must comply with high-voltage electrical safety regulations; signal cables should be laid away from high-voltage leads and shielded and properly routed; the array fixing magnetic attraction force should meet the anti-vibration requirements; the coupling agent material should meet the requirements of temperature resistance, oil resistance and dielectric safety.

[0092] 2) The system has breakpoint continuation test and self-test functions: After power-on, it performs channel consistency and self-noise detection; when channel drift is detected to exceed the set threshold, it prompts for calibration.

[0093] 3) In terms of data management, the system archives the original waveform, gated waveform, characteristic parameters, temperature results, calibration curves and equipment attitude information according to the measurement number; it supports exporting to engineering reports and audit traceability.

[0094] It should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, enabling those skilled in the art to implement it, and do not limit the scope of protection of the present invention in any way. For those skilled in the art, equivalent substitutions or obvious modifications made without departing from the spirit and substance of the present invention should all fall within the scope of protection of the present invention.

[0095] This invention relates to an ultrasonic array device and method for measuring the top-layer oil temperature of a transformer. The device is attached to the outer wall of an oil-immersed transformer. It acquires acoustic parameters in the oil through array pointing control and echo processing, and calculates the oil temperature accordingly. This enables online monitoring and anomaly alerts for the top-layer oil temperature of the transformer. In use, this invention employs an external array and beam pointing control to achieve non-invasive, area-coverage measurement of the transformer's top-layer oil temperature. It requires no modification to the main body, simplifying engineering implementation. Combined with time gating and shell time subtraction, it improves the stability and repeatability of the results, facilitating online monitoring and early warning. This invention has the advantages of simple and reasonable structure, no need for main body modification, large coverage area, easy installation, uninterrupted online measurement, strong noise and multipath resistance, and good maintainability.

Claims

1. An ultrasonic array device for transformer top layer oil temperature measurement, comprising an ultrasonic array and a computer processing unit, characterized in that: The ultrasonic array is composed of an ultrasonic transmitting unit, an ultrasonic receiving and signal converting unit, the ultrasonic transmitting unit is electrically connected with the ultrasonic receiving and signal converting unit, the ultrasonic receiving and signal converting unit is electrically connected with a computer processing unit, the computer processing unit is electrically connected with the ultrasonic transmitting unit, and the ultrasonic transmitting unit serves as a transmitting array element in the ultrasonic array and is used for receiving excitation parameters and array element delay tables sent by the computer processing unit, so as to form a beam with a predetermined direction; the ultrasonic receiving and signal converting unit serves as a receiving array element in the ultrasonic array and is used for amplifying, filtering and analog-digital converting echo signals and then outputting the signals as digital signals; and the computer processing unit is used for time gating, arrival time extraction and shell segment time deduction of the digital signals and inversely calculating oil temperature according to a sound speed-temperature relationship and displaying the oil temperature.

2. An ultrasonic array device for transformer top oil temperature measurement as claimed in claim 1, characterized in that: The ultrasonic transmitting unit comprises an array transducer and an excitation circuit, and the array transducer is attached to the transformer shell.

3. An ultrasonic array device for transformer top oil temperature measurement as claimed in claim 2, characterized in that: The ultrasonic receiving and signal converting unit comprises a receiving array transducer, a front-end amplification and filtering circuit and a data acquisition module, and the receiving array transducer is externally attached to the outer wall of the oil tank.

4. An ultrasonic array apparatus for transformer top oil temperature measurement as claimed in claim 3, wherein: The array transducer and the receiving array transducer are regularly arranged and attached to the transformer shell by using an array fixing and coupling assembly, so that stable coupling is achieved.

5. An ultrasonic array apparatus for transformer top oil temperature measurement as claimed in claim 4, characterized in that: The array transducer and the receiving array transducer are regularly arranged and arranged in a linear array or a surface array, and the array transducer and the receiving array transducer are arranged in an opposite, same side or cross arrangement to adapt to different installation positions and monitoring ranges.

6. An ultrasonic array apparatus for transformer top oil temperature measurement as claimed in claim 4, wherein: The array fixing and coupling assembly adopts an integrated magnetic attraction fixing structure and cooperates with a replaceable coupling layer assembly.

7. An ultrasonic array apparatus for transformer top oil temperature measurement as claimed in claim 6, characterized in that: The replaceable coupling layer adopts a thin layer of high-viscosity coupling agent or a compressible polymer gasket to form stable interface contact and suppress high-frequency scattering.

8. An ultrasonic array apparatus for transformer top oil temperature measurement as claimed in claim 5, wherein: The array transducer adopts an NY-90CK acoustic emission transducer, and the receiving array transducer adopts a G80 transducer.

9. An ultrasonic array apparatus for transformer top oil temperature measurement as claimed in claim 2, wherein: The front-end amplification and filtering circuit adopts a PXPA3 low-noise preamplifier for gain and preliminary filtering, and the data acquisition module adopts an SMAQC USB5-1000 data acquisition card and realizes multi-channel synchronous sampling in an external trigger mode.

10. A measuring method for transformer top oil temperature measurement with an ultrasonic array device, based on the ultrasonic array device for transformer top oil temperature measurement according to any one of claims 1-9, for implementing transformer top oil temperature measurement operation, characterized in that: The measurement method is as follows: Step 1: set the transmitting frequency, amplitude, pulse width and repetition period in the computer processing unit and send them to the excitation circuit, and synchronously trigger the transmitting and collecting; Step 2: set the time windows of the shell entering segment, the oil zone direct segment and the shell exiting segment on the echo signal and complete the denoising; Step 3: extract the arrival time of the oil zone segment, deduct the shell segment propagation time, combine the sound path length to obtain the sound speed in the oil; Step 4: inversely calculate the temperature according to the preset or calibrated sound speed-temperature relationship; Step 5: sequentially execute according to the preset direction to complete the area scanning, and output an alarm when an abnormality occurs.

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