An intelligent insulated oil-immersed transformer and its usage method

Abstract

The present invention discloses an intelligent insulated oil-immersed transformer and its usage method, relating to the technical field of oil-immersed transformers. It includes a transformer body, an oil tank, self-healing microcapsules, an intelligent control unit, and a driving excitation unit. The oil tank installed inside the transformer body is filled with nano-composite insulating oil. In the nano-composite insulating oil, self-healing microcapsules with a diameter of 10-50 μm are dispersed at a mass fraction of 0.5%-2%. The wall material of the self-healing microcapsules is a polyurea-polyurethane copolymer, and it contains an epoxy resin repair agent. By installing the self-healing microcapsules, the present invention realizes the function of automatically filling microcracks, solves the problem that the internal microcracks of traditional transformers cannot be repaired online, greatly reduces the failure rate caused by insulation microcracks, and prolongs the service life of the equipment.

Description

Technical Field

[0001] The present invention relates to the technical field of oil-immersed transformers, and specifically to an oil-immersed transformer with intelligent insulation and its usage method. Background Art

[0002] With the continuous improvement of the requirements of the power system for the reliability and lifespan of transformers, traditional oil-immersed transformers frequently fail due to the aging of insulation media, the development of microcracks, uneven heat dissipation at hot spots, and the accumulation of sediments in the oil. Moreover, most maintenance requires the transformer to be shut down, resulting in high operation and maintenance costs and risks.

[0003] Patent CN114628113B discloses an oil-immersed transformer. The above patent realizes enhancing the insulation and heat dissipation effects of insulating oil and reducing the pressure in the accommodation cavity.

[0004] The above patent reduces the accumulation of gases generated by insulating oil by providing an exhaust pipe on the box body, but it cannot perform real-time online repair when microcracks appear in the transformer.

[0005] Therefore, this application proposes an oil-immersed transformer with intelligent insulation that can perform online repair of microcracks and its usage method. Summary of the Invention

[0006] The purpose of the present invention is to provide an oil-immersed transformer with intelligent insulation and its usage method to solve the technical problems of insulation medium aging and microcrack development causing failures mentioned in the above background art.

[0007] To achieve the above purpose, the present invention provides the following technical solution: An oil-immersed transformer with intelligent insulation, including a transformer body, an oil tank, self-healing microcapsules, an intelligent control unit, and a driving excitation unit. The oil tank installed inside the transformer body is filled with nano-composite insulating oil. In the nano-composite insulating oil, self-healing microcapsules with a diameter of 10 - 50 μm are dispersed at a mass fraction of 0.5% - 2%. The wall material of the self-healing microcapsules is a polyurea-polyurethane copolymer, and it contains an epoxy resin repair agent.

[0008] A data acquisition module and an intelligent control unit are fixedly installed inside the transformer body. The data acquisition module includes a distributed ultrasonic sensor, an infrared temperature sensor, and a triaxial accelerometer, which are used to obtain partial discharge, oil temperature, and vibration signals in real time. The intelligent control unit includes an FPGA and a microcontroller. The FPGA is responsible for high-speed signal preprocessing and feature extraction, and the microcontroller runs a fault diagnosis algorithm that combines a random forest and a self-learning neural network. The driving excitation unit is connected to the intelligent control unit and is used to apply an electric field or ultrasonic waves to the oil medium when the monitored partial discharge intensity exceeds 50 mVpp or the oil temperature exceeds 90 °C, triggering the rupture of the self-healing microcapsules for crack self-healing.

[0009] Preferably, an MRF thermal management unit is also installed in the fuel tank. The MRF thermal management unit includes:

[0010] A section of closed-loop stainless-steel pipe filled with a silicone oil-based magnetorheological fluid containing 40%-60% ferromagnetic particles;

[0011] An electromagnetic coil wound around the outside of the stainless-steel pipe, with the number of turns of the coil being 200-500 turns;

[0012] The intelligent control unit adjusts the current of the electromagnetic coil in a PWM manner according to the hot spot temperature data fed back by the infrared temperature sensor, so that the magnetic field strength varies within the range of 0-200 mT, resulting in a controllable adjustment of the MRF viscosity between 0.1-1 Pa·s, achieving local fixed-point cooling and mechanical vibration suppression.

[0013] Preferably, a number of SMA flow guiding plates are installed inside the fuel tank. The material of the SMA flow guiding plates is NiTi alloy, with a thickness of 0.2-0.5 mm and a transformation temperature of 85±2°C; they are in a flat state when the oil temperature is lower than 80°C, automatically bend and deflect 10-30° when the temperature exceeds 85°C, guiding the oil flow to the corresponding hot spot area; the SMA flow guiding plates automatically reset to reconstruct the oil flow channel after the temperature recovers.

[0014] Preferably, the data acquisition module further includes an FBG sensing network. The optical fiber is arranged along the windings inside the fuel tank and the inner wall of the fuel tank, with a node spacing of 0.3-0.7 m, a sensor resolution of ±0.1°C / ±1 με, a sampling speed of ≥500 Hz, and high-speed communication with the intelligent control unit through an optical fiber demodulator to realize on-line monitoring of temperature and strain.

[0015] Preferably, a telescopic soft robot cleaning arm is also installed inside the transformer body. The cleaning arm is composed of medical-grade silicone and a Kevlar fiber core, with an outer diameter of 20 mm and a telescopic length of 500-1500 mm; an ultrasonic vibration cleaning head and a sewage suction nozzle are assembled at the end of the cleaning arm, and it enters and exits through a DN50 quick-connect flange on the side wall of the fuel tank, used to automatically remove metal chips and sediment in the oil during operation.

[0016] Preferably, the winding support structure of the fuel tank adopts a modular quick-disassembly design:

[0017] It is locked with a stainless-steel semi-circular fastener and a positioning pin. An elastic polyester washer is arranged inside the semi-circular fastener to ensure anti-vibration performance;

[0018] The diameter of the positioning pin is 8 mm, the insertion force ≤50 N, and the extraction force ≥200 N;

[0019] The disassembly and assembly of a single-layer winding can be completed within 10 s through a one-key hydraulic locking mechanism.

[0020] Preferably, the inner wall of the oil tank is covered with a polymer-based acoustic metamaterial lining with a periodic cell size of 1.5-3mm and a thickness of 2mm. The metamaterial lining is used to focus the ultrasonic signal generated by local discharge in the frequency band of 100-300kHz to the piezoelectric transducer arranged in the corner of the oil tank cavity, thereby improving the sensing sensitivity by 2-3 times and reducing environmental noise interference.

[0021] Preferably, the intelligent control unit further integrates a remote communication interface, and the remote communication interface supports:

[0022] Switch between three communication modes: Ethernet, WiFi and LoRaWAN;

[0023] Data transmission uses TLS1.2 encryption, and the data packet transmission rate is not less than 10kbps;

[0024] Supports OTA firmware upgrades and MQTT and HTTPS dual protocol reporting.

[0025] Preferably, the method of use comprises the following steps:

[0026] S1. Installation and calibration: Connect the auxiliary power module, execute the self-healing microcapsule trigger threshold and each sensor calibration procedure, and the calibration accuracy is better than ±5%;

[0027] S2. Online monitoring: The intelligent control unit collects sensor data at a frequency of 10 Hz and combines it with a deep learning model to classify fault types and conduct risk assessment;

[0028] S3, self-healing and thermal management: When partial discharge or excessive oil temperature is detected, the control drive excitation unit triggers the microcapsule self-healing; when the oil temperature hot spot exceeds the threshold for 2 minutes, the MRF unit is automatically started to cool down in conjunction with the SMA guide plate;

[0029] S4, online cleaning: If the concentration of suspended particles in the oil exceeds 500ppm, the soft robot cleaning arm is driven to perform ultrasonic cleaning and suction, and each cleaning time is ≤15min;

[0030] S5. Operation and maintenance feedback: All operation and maintenance logs are reported to the cloud platform in real time through the MQTT protocol. The cloud AI system generates operation and maintenance suggestions based on historical data and pushes them in the form of APP messages.

[0031] Preferably, the method of use further comprises the following steps:

[0032] S31, the intelligent control unit combines the high-resolution temperature and strain data fed back by the FBG sensor network to update the local hotspot model in real time at a frequency of 1Hz, and uses the reinforcement learning algorithm to adaptively optimize the fixed-point cooling and self-healing triggering strategy within no less than 100 operating cycles to minimize the transformer insulation aging rate and operating losses.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] 1. By installing self-healing microcapsules, the present invention realizes the function of automatically filling microcracks, solves the problem that the internal microcracks of traditional transformers cannot be repaired online, greatly reduces the failure rate caused by insulation microcracks, and extends the equipment life;

[0035] 2. By installing an MRF thermal management unit, the present invention realizes the functions of local fixed-point cooling and vibration damping adjustment, solves the problems of uneven traditional heat dissipation and difficulty in quickly cooling hot spots, significantly improves the cooling rate of hot spots, and suppresses mechanical vibration by more than 50%;

[0036] 3. By installing an SMA flow deflector, the present invention realizes the function of reconstructing the oil flow channel in the hot spot area, solves the problem of low heat dissipation efficiency caused by uneven oil flow distribution in a passive environment, and improves the local heat dissipation efficiency without an additional driver;

[0037] 4. By installing a soft robot cleaning arm, the present invention realizes the function of automatically removing metal chips and sediment in oil during the moving state, solves the problems of traditional cleaning requiring shutdown, high manual risk, and long duration, and significantly reduces the operation and maintenance cost and risk. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is a schematic diagram of the oil-immersed transformer assembly of the present invention;

[0039] Figure 2 is a schematic diagram of the working process of the oil-immersed transformer of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0040] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0041] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "front end", "rear end", "both ends", "one end", "the other end", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0042] In the description of the present invention, it should be noted that, unless otherwise clearly specified and defined, terms such as "installation", "equipped with", "connection", etc. should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0043] Please refer to Figure 1 and Figure 2 , an embodiment provided by the present invention: an intelligent insulated oil-immersed transformer, including a transformer body, an oil tank, self-healing microcapsules, an intelligent control unit, and a driving excitation unit. The oil tank installed inside the transformer body is filled with nano-composite insulating oil. In the nano-composite insulating oil, self-healing microcapsules with a diameter of 10 - 50 μm are dispersed at a mass fraction of 0.5% - 2%. The wall material of the self-healing microcapsules is a polyurea-polyurethane copolymer, and it contains an epoxy resin repair agent;

[0044] A data acquisition module and an intelligent control unit are fixedly installed inside the transformer body. The data acquisition module includes a distributed ultrasonic sensor, an infrared temperature sensor, and a triaxial accelerometer, which are used to obtain partial discharge, oil temperature, and vibration signals in real time. The intelligent control unit includes an FPGA and a microcontroller. The FPGA is responsible for high-speed signal preprocessing and feature extraction. The microcontroller runs a fault diagnosis algorithm that combines a random forest and a self-learning neural network. The driving excitation unit is connected to the intelligent control unit and is used to apply an electric field or ultrasonic waves to the oil medium when it is detected that the partial discharge intensity exceeds 50 mVpp or the oil temperature exceeds 90 °C, triggering the rupture of the self-healing microcapsules for crack self-healing;

[0045] The data acquisition module further includes an FBG sensing network. The optical fiber is arranged along the windings inside the oil tank and the inner wall of the oil tank, with a node spacing of 0.3 - 0.7 m. The sensor resolution is ±0.1 °C / ±1 με, and the sampling speed is ≥500 Hz. It communicates with the intelligent control unit at high speed through an optical fiber demodulator to realize on-line monitoring of temperature and strain;

[0046] Further, after the transformer is installed, nano-composite insulating oil is filled into the oil tank, where the self-healing microcapsule content is 0.5%-2%, the diameter is 10-50um, and it is stirred in a professional stirring device at 100rpm for 30min to ensure that the microcapsules are evenly dispersed in the oil body without obvious sedimentation or aggregation; the FPGA sends calibration commands to each sensor including ultrasonic sensors, infrared temperature sensors, triaxial accelerometers, and FBGs, samples the baseline signals under no-load, standard temperature of 25°C, and no-vibration conditions respectively, and stores the calibration results in the microcontroller, with the baseline deviation controlled within ±5%;

[0047] The FPGA collects ultrasonic and vibration signals at a frequency of 1kHz, and collects infrared temperature, FBG temperature, and strain data at a frequency of 10Hz. The collected data is sent to the microcontroller through a high-speed bus for real-time analysis and model inference; the microcontroller performs a secondary determination by integrating the random forest algorithm and the self-learning neural network, and outputs "normal" and "abnormal" labels and position coordinates;

[0048] When tiny cracks form in the insulating medium under the action of local electric field stress or thermal stress, accompanied by local discharge and a slight temperature rise; determination threshold: local discharge amplitude ≥ 50mVpp or oil temperature node ≥ 90°C; the intelligent control unit issues a self-healing excitation instruction, and records the trigger time, sensor readings, and position;

[0049] Drive excitation: Electric field trigger: The drive excitation unit applies a DC electric field of 1kV / cm - 5kV / cm in the oil area near the crack, and the electric field is concentrated at the tip of the microcrack, causing the wall of the self-healing microcapsule to rupture under strong local stress; Ultrasonic trigger: When the ultrasonic mode is adopted, the drive excitation unit generates ultrasonic waves with a frequency of 20kHz - 40kHz and a power of 30W - 60W, which are focused on the target area to cause mechanical vibration and rupture of the microcapsule shell; After the self-healing microcapsule ruptures, it releases epoxy resin repair agent, which automatically flows into the microcrack gap due to the oil-phase interfacial tension and crack capillary action. The repair agent uses the curing agent contained in itself to complete chemical cross-linking and curing within 5min - 15min under the external oil temperature conditions to seal the crack;

[0050] After 5 minutes of repair, start ultrasonic and vibration sampling again to verify whether the local discharge signal disappears and whether the vibration spectrum returns to the baseline range; the FBG sensing network continuously monitors for 10 minutes to confirm that the temperature drop rate of this node matches that of the surrounding area and there are no remaining hot spots; all data is stored in local and cloud logs for subsequent algorithm optimization and operation and maintenance decision-making reference.

[0051] Please refer to Figure 1 and Figure 2 For an embodiment provided by the present invention: an oil-immersed transformer with intelligent insulation, an MRF thermal management unit is also installed in the oil tank, and the MRF thermal management unit includes:

[0052] A section of closed-loop stainless-steel pipeline filled with a silicone oil-based magnetorheological fluid containing 40%-60% ferromagnetic particles;

[0053] An electromagnetic coil wound around the outside of the stainless-steel pipeline, with the number of coil turns being 200 - 500 turns;

[0054] The intelligent control unit adjusts the current of the electromagnetic coil in a PWM manner according to the hot-spot temperature data feedback by the infrared temperature sensor, so that the magnetic field strength varies within the range of 0 - 200 mT, resulting in the viscosity of the MRF being controllably adjustable between 0.1 - 1 Pa·s, achieving local fixed-point cooling and mechanical vibration suppression;

[0055] A number of SMA flow deflectors are installed inside the fuel tank. The material of the SMA flow deflector is NiTi alloy, with a thickness of 0.2 - 0.5 mm and a transformation temperature of 85 ± 2 °C; it is in a flat state when the oil temperature is lower than 80 °C, and automatically bends and deflects by 10 - 30 ° when the temperature exceeds 85 °C, guiding the oil flow to the corresponding hot-spot area; after the temperature recovers, the SMA flow deflector automatically resets to reconstruct the oil flow channel;

[0056] Furthermore, prefabricated magnetorheological fluid is injected into the closed-loop stainless-steel pipeline, and the electromagnetic coil is tested under power. The duty cycle is gradually adjusted from 0 to 100% in a PWM manner to verify that the viscosity of the fluid inside the pipeline can be controllably changed within the range of 0.1 Pa·s to 1 Pa·s. The thermal deformation test of the NiTi flow deflector is carried out in an incubator: its flat state is verified in an 80 °C environment; its bending angle should be between 10 - 30 ° in an 85 °C ± 2 °C environment, and the cooling time required for the flow deflector to reset is recorded; the infrared temperature sensor is arranged in the candidate hot-spot area of the fuel tank, with a calibration accuracy of ±0.5 °C, and the triaxial accelerometer is arranged on the outer shell of the transformer box to calibrate the vibration baseline. The intelligent control unit reads and stores all the baseline data of the sensors, with a cycle period of 10 Hz;

[0057] The intelligent control unit reads the infrared temperature at a frequency of 10 Hz and reads the vibration data of the accelerometer at a frequency of 1 kHz. When the temperature of a certain area exceeds 80 °C for three consecutive sampling periods or the vibration acceleration exceeds 0.5 g, it is marked as a "potential hot spot";

[0058] If the infrared sensor detects T ≥ 85 °C or the accelerometer detects a vibration peak value ≥ 0.8 g, the intelligent control unit switches to the "emergency cooling / vibration suppression" mode; the intelligent control unit adjusts the coil duty cycle through PWM, from 0 - 80%, so that the magnetic field strength ranges from 0 mT - 160 mT, and the viscosity of the MRF increases from 0.1 Pa·s - 0.8 Pa·s with the magnetic field, reducing or enhancing the fluid resistance in the hot-spot area to achieve accelerated cooling and vibration suppression respectively;

[0059] When the local oil temperature ≥ 85°C, the SMA flow guide plate near this area crosses the phase change point due to heat, and automatically bends 15 - 25° within 30 s. The bent flow guide plate redirects the original channel parallel to the oil flow, transports more oil to the hot spot, and enhances the directional cooling. When the hot spot temperature drops to ≤ 80°C, the flow guide plate automatically cools and resets within 2 min, restoring the full-field average flow channel.

[0060] Please refer to Figure 1 and Figure 2 For an embodiment provided by the present invention: an oil-immersed transformer with intelligent insulation, a telescopic soft robotic cleaning arm is also installed inside the transformer body. The cleaning arm is composed of medical-grade silicone and a Kevlar fiber core, with an outer diameter of 20 mm and a retractable length of 500 - 1500 mm; an ultrasonic vibration cleaning head and a dirt suction nozzle are assembled at the end of the cleaning arm, and it enters and exits through a DN50 quick-connect flange on the side wall of the fuel tank, and is used to automatically remove metal chips and sediment in the oil during the operation state;

[0061] Furthermore, the system reads the data of the oil turbidity sensor and the particle counter at a frequency of 1 kHz. When the concentration of suspended solid particles in the oil exceeds 500 ppm or the metal chip content exceeds 200 mg / L, the intelligent control unit determines that "cleaning is required" and starts the cleaning process;

[0062] The intelligent control unit first closes the corresponding oil circuit isolation valve, opens the DN50 quick-connect flange valve, maintains the internal pressure balance of the fuel tank, issues an "extend" command, and the cleaning arm enters the fuel tank from the flange at a speed of 50 mm / s, extends to the predetermined depth, and the position is confirmed by the feedback of the travel sensor. The micro magnetic positioning ring continuously sends position and direction information on the arm body, and the intelligent control unit performs spatial positioning in combination with the CAD model of the fuel tank;

[0063] The vibration head at the end of the cleaning arm vibrates continuously at 25 kHz and 50 W. The microbubbles generated by the ultrasonic waves and the high-frequency vibration cause the sediment and particles in the oil to desorb and form microemulsions, which is convenient for subsequent suction. In the vibration mode, the cleaning arm slowly sweeps along the preset trajectory at a speed of 10 mm / s to ensure that the vibration energy acts evenly on each treatment surface;

[0064] During the vibration cleaning, the dirt suction nozzle sucks out the mixture of suspended particles and oil with a vacuum degree of 0.3 bar. The sucked oil first enters the external microfilter. After separating the metal chips and large particles, the clean oil returns to the fuel tank through the return pipe. The filtered metal chips and sediment accumulate in the detachable collection tank, and about 100 g of particles are collected after a 15-min cleaning cycle;

[0065] The above-mentioned ultrasonic vibration and dirt suction process lasts for 5 minutes as a cycle, and is executed for 3-5 rounds by default until the oil turbidity drops to <300ppm; at the end of each round, the cleaning arm is retracted 20cm, and the turbidity sensor and particle counter re-measure and upload the results to the intelligent control unit to decide whether to continue or end the cleaning.

[0066] See also Figure 1 and Figure 2 , an embodiment provided by the present invention: an intelligent insulated oil-immersed transformer, the oil tank winding support structure adopts a modular quick-disassembly design:

[0067] Stainless steel half-ring fasteners are used to lock with positioning pins, and elastic polyester washers are installed inside the half-ring fasteners to ensure vibration resistance;

[0068] The diameter of the positioning pin is 8mm, the insertion force is ≤50N, and the extraction force is ≥200N;

[0069] The one-touch hydraulic locking mechanism can complete the disassembly and assembly of single-layer windings within 10 seconds;

[0070] Furthermore, a semi-circular stainless steel fastener (with an inner diameter matching the outer diameter of the winding bracket) is matched with the corresponding positioning pin, and an elastic polyester gasket is pre-installed on the inner side of the fastener to ensure vibration isolation between the fastener and the winding bracket after fastening; the prefabricated winding bracket is inserted into the reserved guide groove of the oil tank, and the positioning pin is inserted into the alignment hole of the fastener and the bracket. It can be smoothly positioned when the insertion force is ≤50N; the hydraulic locking mechanism is started: the hydraulic cylinder pushes the semi-circular fastener to close and clamp the positioning pin under a driving pressure of 0.5MPa, and the locking completion time is ≤1 0s, the pull-out force of the locating pin is ≥200N to ensure that the winding does not loosen under high vibration conditions; apply ±1g, 5Hz-500Hz sinusoidal sweep vibration table test, there is no looseness or resonance peak superposition between the winding bracket and the oil tank, and after the hydraulic locking mechanism is cycled for ≥100 times, repeat the above vibration test to ensure the life and reliability of the mechanism; drive the hydraulic cylinder in reverse to quickly release the clamping force of the fastener. The locating pin can be easily removed when the pull-out force is ≤50N, and the winding bracket can be pulled out as a whole for inspection or replacement.

[0071] See also Figure 1 and Figure 2 , an embodiment provided by the present invention: an intelligent insulated oil-immersed transformer, wherein the inner wall of the oil tank is covered with a polymer-based acoustic metamaterial lining with a periodic cell size of 1.5-3mm and a thickness of 2mm, the metamaterial lining is used to focus the ultrasonic signal generated by partial discharge in the frequency band of 100-300kHz to the piezoelectric transducer arranged at the corner of the oil tank cavity, thereby improving the sensing sensitivity by 2-3 times and reducing the interference of environmental noise;

[0072] Furthermore, a periodic metamaterial plate with a thickness of 2 mm and a cell size of 1.5 mm × 1.5 mm - 3 mm × 3 mm is prepared by polymer-based materials such as PDMS micro-injection. After the inner wall surface of the fuel tank is roughened by sandblasting, the metamaterial plates are respectively attached using oil-resistant silicone adhesives, ensuring no air bubbles and warping. The phonon bandgap and refractive characteristics formed by the metamaterial cells cause ultrasonic waves in the frequency band of 100 kHz - 300 kHz to undergo secondary diffraction and focusing on the plate surface. The focusing target is located at the center of the piezoelectric transducer array at a corner of the fuel tank, increasing the sound pressure level received by the sensor by approximately 6 dB. Four piezoelectric transducers are arranged to receive ultrasonic signals released by partial discharges in real time. The intelligent control unit triggers broadband amplification and FFT spectrum analysis at a sampling frequency of 1 MHz, effectively distinguishing the focused signals from environmental noise and increasing the signal-to-noise ratio by ≥10 dB. Under the artificial discharge simulation conditions in the laboratory, the traditional point sensor can minimally detect a discharge time of 20 nJ. After installing the metamaterial lining, a single discharge energy of 10 nJ can be stably captured, and the detection success rate is increased from 60% to 95%. The metamaterial is assembled modularly and can be locally replaced when contaminated or damaged. An ultrasonic sensor calibration test is carried out once a year, and the bonding integrity of the lining is checked.

[0073] Please refer to Figure 1 and Figure 2 , an embodiment provided by the present invention: an oil-immersed transformer with intelligent insulation, the intelligent control unit is further integrated with a remote communication interface, and the remote communication interface supports:

[0074] Switching among three communication methods: Ethernet, WiFi, and LoRaWAN;

[0075] Data transmission uses TLS1.2 encryption, and the data packet transmission rate is not less than 10 kbps;

[0076] Supports OTA firmware upgrade and reporting using both MQTT and HTTPS protocols;

[0077] Furthermore, three PHY chips are integrated on the main board of the intelligent control unit: 100Base-TX Ethernet, 802.11n WIFI, and 868MHz LoRaWAN. The driver software is based on RTOS, and multi-threads manage the three network interfaces. By default, Ethernet has the highest priority, followed by WiFi, and then LoRaWAN. Power-on self-test: Detect the physical connectivity of each interface. If the Ethernet link is normal, it will be enabled. During operation: If the Ethernet connection is interrupted for ≥30s, it will automatically switch to WiFi. If the WiFi connection fails for ≥60s, it will switch to LoRaWAN. During the switching process, data caching and ordered retransmission are maintained, without packet loss and interruption. All TCP / IP links use TLS1.2 handshake and data encryption. The integer is based on the ECC algorithm, and the handshake time ≤200ms. The upload protocol supports MQTT and HTTPS, which are backed up by each other. The packet size is controlled between 512B - 1KB, and the transmission rate is not less than 10kbps to ensure that key monitoring data and warning information arrive in real time. After receiving the OTA instruction through MQTT, the device automatically downloads the encrypted firmware package, verifies the SHA-256 integrity, switches to the backup partition to write the new firmware, and performs a CRC self-test after writing. If it passes, it will restart and switch partitions. Otherwise, it will roll back to the original firmware and report a failure. The entire upgrade process ≤3min, and the upgrade success rate ≥99.5%. The intelligent control unit reports a heartbeat packet every 60s, including the current network mode, signal strength, and error count. When there are multiple handshake failures or the packet loss rate >5%, a local alarm will be triggered and it will simultaneously switch to the next available interface.

[0078] Working principle: The transformer is built-in with multiple sensors: distributed ultrasonic sensors, infrared temperature sensors, triaxial accelerometers, and FBG fiber grating networks. The FPGA collects partial discharge, temperature, and vibration strain data in parallel at 1 kHz / 500 Hz and sends the characteristic information to the microcontroller in real time.

[0079] The microcontroller runs random forest and self-learning neural network fault diagnosis algorithms to perform online analysis on the monitored data. Once it detects that the discharge intensity exceeds 50 mVpp or the oil temperature and strain exceed the threshold, it immediately triggers the corresponding driving excitation unit for the electric field or ultrasonic wave, and starts the MRF thermal management, SMA deflector deformation, or microcapsule self-healing repair mechanism.

[0080] The self-healing microcapsules rupture under the excitation of the electric field and ultrasonic waves, releasing epoxy resin repair agents to fill the microcracks and cure. The MRF thermal management unit + SMA deflector work together to achieve fixed-point cooling of hot spots and vibration suppression. The cleaning arm of the soft robot extends and retracts in the oil, vibrates ultrasonically, and aspirates suspended particles to automatically remove sediments.

[0081] At the same time, all operation and maintenance logs are reported to the cloud through TLS1.2 encryption, MQTT / HTTPS, supporting OTA upgrade and operation and maintenance guidance.

[0082] It will be apparent to those skilled in the art that the present invention is not limited to the details of the above-described exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, in any regard, the embodiments should be regarded as exemplary and non-limiting, and the scope of the present invention is defined by the appended claims rather than the above description. Accordingly, all changes that fall within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention. Any reference signs in the claims should not be construed as limiting the claims concerned.

Claims

1. An intelligent insulated oil-immersed transformer, comprising a transformer body, an oil tank, self-healing microcapsules, an intelligent control unit and a driving excitation unit, characterized in that: The oil tank installed inside the transformer body is filled with nano-composite insulating oil. In the nano-composite insulating oil, self-healing microcapsules with a diameter of 10 - 50 μm are dispersed at a mass fraction of 0.5% - 2%. The wall material of the self-healing microcapsules is a polyurea-polyurethane copolymer, and it contains an epoxy resin repair agent. A data acquisition module and an intelligent control unit are fixedly installed inside the transformer body. The data acquisition module includes a distributed ultrasonic sensor, an infrared temperature sensor, and a triaxial accelerometer, which are used to obtain partial discharge, oil temperature, and vibration signals in real time. The intelligent control unit includes an FPGA and a microcontroller. The FPGA is responsible for high-speed signal preprocessing and feature extraction. The microcontroller runs a fault diagnosis algorithm that combines random forest and self-learning neural network. The drive excitation unit is connected to the intelligent control unit and is used to apply an electric field or ultrasonic waves to the oil medium when the monitored partial discharge intensity exceeds 50 mVpp or the oil temperature exceeds 90 °C, triggering the rupture of the self-healing microcapsules for crack self-healing.

2. The intelligent insulated oil-immersed transformer according to claim 1, wherein: An MRF thermal management unit is also installed inside the oil tank. The MRF thermal management unit includes: A section of closed-loop stainless steel pipe filled with a silicone oil-based magnetorheological fluid containing 40% - 60% ferromagnetic particles; An electromagnetic coil wound around the outside of the stainless steel pipe, with the number of coil turns being 200 - 500 turns; The intelligent control unit adjusts the current of the electromagnetic coil in a PWM manner according to the hot spot temperature data fed back by the infrared temperature sensor, so that the magnetic field strength changes within the range of 0 - 200 mT, resulting in the controllable adjustment of the MRF viscosity between 0.1 - 1 Pa·s, achieving local fixed-point temperature reduction and mechanical vibration suppression.

3. An intelligent insulated oil-immersed transformer according to claim 1, characterized in that: Several SMA flow guiding plates are installed inside the oil tank. The material of the SMA flow guiding plates is NiTi alloy, with a thickness of 0.2 - 0.5 mm and a transformation temperature of 85 ± 2 °C. When the oil temperature is lower than 80 °C, it is in a flat state. When the temperature exceeds 85 °C, it automatically bends and deflects by 10 - 30 °, guiding the oil flow to the corresponding hot spot area. After the temperature recovers, the SMA flow guiding plates automatically reset to reconstruct the oil flow channel.

4. An intelligent insulated oil-immersed transformer according to claim 1, characterized in that: The data acquisition module further includes an FBG sensing network. The optical fiber is arranged along the inner wall of the winding and the oil tank wall inside the oil tank, with a node spacing of 0.3 - 0.7 m. The sensor resolution is ±0.1 °C / ±1 με, and the sampling speed is ≥500 Hz. It communicates with the intelligent control unit at high speed through an optical fiber demodulator to achieve on-line monitoring of temperature and strain.

5. An intelligent insulated oil-immersed transformer according to claim 1, characterized in that: A telescopic soft robot cleaning arm is also installed inside the transformer body. The cleaning arm is composed of medical-grade silicone and a Kevlar fiber core, with an outer diameter of 20 mm and a telescopic length of 500 - 1500 mm. An ultrasonic vibration cleaning head and a sewage suction nozzle are assembled at the end of the cleaning arm, and it enters and exits through a DN50 quick-connect flange on the side wall of the oil tank, which is used to automatically remove metal chips and sediment in the oil during operation.

6. An intelligent insulated oil-immersed transformer according to claim 4, characterized in that: The winding support structure of the oil tank adopts a modular quick-disassembly design: It is locked with a stainless steel semi-ring fastener and a positioning pin. An elastic polyester washer is equipped on the inner side of the semi-ring fastener to ensure anti-vibration performance; The diameter of the positioning pin is 8 mm, the insertion force ≤50 N, and the extraction force ≥200 N; The disassembly and assembly of a single-layer winding can be completed within 10 s through a one-key hydraulic locking mechanism.

7. An intelligent insulated oil-immersed transformer according to claim 1, characterized in that: The inner wall of the oil tank is covered with a polymer-based acoustic metamaterial lining with a periodic cell size of 1.5-3mm and a thickness of 2mm. The metamaterial lining is used to focus the ultrasonic signal generated by local discharge in the 100-300kHz frequency band to the piezoelectric transducer arranged in the corner of the oil tank cavity, thereby improving the sensing sensitivity by 2-3 times and reducing environmental noise interference.

8. An intelligent insulated oil-immersed transformer according to claim 1, characterized in that: The intelligent control unit further integrates a remote communication interface, which supports: Switch between three communication modes: Ethernet, WiFi and LoRaWAN; Data transmission uses TLS1.2 encryption, and the data packet transmission rate is not less than 10kbps; Supports OTA firmware upgrades and MQTT and HTTPS dual protocol reporting.

9. A method for using an intelligent-insulated oil-immersed transformer, applicable to an intelligent-insulated oil-immersed transformer described in any one of claims 1-8, characterized in that: The method of use comprises the following steps: S1. Installation and calibration: Connect the auxiliary power module, execute the self-healing microcapsule trigger threshold and each sensor calibration procedure, and the calibration accuracy is better than ±5%; S2. Online monitoring: The intelligent control unit collects sensor data at a frequency of 10 Hz and combines it with a deep learning model to classify fault types and conduct risk assessment; S3, self-healing and thermal management: When partial discharge or excessive oil temperature is detected, the control drive excitation unit triggers the microcapsule self-healing; when the oil temperature hot spot exceeds the threshold for 2 minutes, the MRF unit is automatically started to cool down in conjunction with the SMA guide plate; S4, online cleaning: If the concentration of suspended particles in the oil exceeds 500ppm, the soft robot cleaning arm is driven to perform ultrasonic cleaning and suction, and each cleaning time is ≤15min; S5. Operation and maintenance feedback: All operation and maintenance logs are reported to the cloud platform in real time through the MQTT protocol. The cloud AI system generates operation and maintenance suggestions based on historical data and pushes them in the form of APP messages.

10. The usage method of an intelligent insulated oil-immersed transformer according to claim 9, characterized in that: The method of use also includes the following steps: S31, the intelligent control unit combines the high-resolution temperature and strain data fed back by the FBG sensor network to update the local hotspot model in real time at a frequency of 1Hz, and uses the reinforcement learning algorithm to adaptively optimize the fixed-point cooling and self-healing triggering strategy within no less than 100 operating cycles to minimize the transformer insulation aging rate and operating losses.

Images