An oil-immersed transformer health monitoring system and method based on a rotor structure

Abstract

The application discloses a kind of oil-immersed transformer health monitoring system and method based on rotor structure.The system includes sensor and motor.The sensor includes coaxially arranged and can relatively rotate outer ring electrode assembly and inner core electrode assembly.The outer ring electrode assembly is annular structure, and is sleeved on the outside of inner core electrode assembly.Multiple let slots along the circumferential direction of its own central axis are arranged on the outer ring electrode assembly and the inner core electrode assembly in sequence.A comb tooth column is formed between adjacent two let slots.The inner side of outer ring electrode assembly is provided with outer molecular imprinting polymer layer.The outer side of inner core electrode assembly is provided with inner molecular imprinting polymer layer.The application utilizes the stagger and alignment between the combs of the two electrodes, realizes long time sufficient adsorption of furfural during detection process, and short time regular test of furfural concentration, so as to improve the precision of transformer health detection.

Description

Technical Field

[0001] This invention belongs to the field of oil-immersed transformer health monitoring technology; specifically, it relates to an oil-immersed transformer health monitoring system and method based on a rotor structure. Background Technology

[0002] Transformers are critical components in power systems, and their failures can lead to significant economic losses. Oil-immersed transformers, known for their excellent insulation, are widely used in high-voltage power systems. However, over prolonged operation, their internal insulation layers or materials age, necessitating a regular health monitoring system to ensure continued operation. The aging of insulation materials can be determined through their moisture content, dissolved gas analysis, furan content, acidity, and the oil's dissipation coefficient. These parameters, stored in transformer oil, need to be predicted to assess early failures, remaining lifespan, or overall health of the transformer. Therefore, various tests are performed on oil samples to detect insulation degradation in transformers. The 2-furfural molecule content in furans is the optimal parameter for determining the solid insulation material. Currently, most transformer lifespan monitoring technologies utilize optical methods to detect furfural molecule concentrations. While this method is highly sensitive, its detection range is limited, typically below 1 ppm, limiting its application to early warning systems.

[0003] The paper "AComb-TypeCapacitive2-FALSensor for Transformer Oil With Improved Sensitivity" presents a capacitive sensor for oil detection, capable of detecting specific molecules in the oil. However, the variable dielectric layer it detects is the entire external oil, which means that the molecules specifically adsorbed on the outside of the capacitive sensor have little impact on the dielectric coefficient of the sensor's dielectric layer. Consequently, the sensor it provides has low sensitivity and poor stability. Summary of the Invention

[0004] The purpose of this invention is to provide a health monitoring system and monitoring method for oil-immersed transformers based on a rotor structure.

[0005] A health monitoring system for an oil-immersed transformer based on a rotor structure includes a sensor and a motor. The sensor comprises an outer ring electrode assembly and an inner core electrode assembly coaxially arranged and capable of relative rotation. The outer ring electrode assembly has a ring structure and is sleeved outside the inner core electrode assembly. The relative rotation between the outer ring electrode assembly and the inner core electrode assembly is driven by the motor.

[0006] Both the outer ring electrode assembly and the inner core electrode assembly have multiple clearance grooves arranged circumferentially along their central axis. A comb post is formed between two adjacent clearance grooves. The sensor has two states: an adsorption state and a reading state. In the adsorption state, each comb post on the outer ring electrode assembly is aligned with each comb post on the inner core electrode assembly. In the reading state, each comb post on the outer ring electrode assembly is aligned with each comb post on the inner core electrode assembly.

[0007] The outer ring electrode assembly has an outer molecularly imprinted polymer layer on its inner surface. The inner core electrode assembly has an inner molecularly imprinted polymer layer on its outer surface. Both the outer and inner molecularly imprinted polymer layers are capable of adsorbing furfural molecules from the insulating medium of the tested oil-immersed transformer. The outer and inner molecularly imprinted polymer layers are radially spaced along the central axis of the inner core electrode assembly.

[0008] Preferably, the oil-immersed transformer health monitoring system also includes a shielding cage. The shielding cage is placed over the outside of the sensor and the motor.

[0009] Preferably, the shielding cage includes a connecting and fastening structure and two metal hemispherical cages. Each of the two metal hemispherical cages has an aligned mounting plate on its top. Each of the two mounting plates has a semi-groove on its adjacent side. When the two semi-grooves are joined together, they form a rotating locking groove. The connecting and fastening structure is disposed within the rotating locking groove to fix the two metal hemispherical cages together.

[0010] The connection and fastening structure includes a plug-in fastening block, a metal cage, a cage connection hole, and a cage connection rod. The cage connection rod is disposed on one of the metal hemispherical cages; the cage connection hole is disposed on the other metal hemispherical cage. The cage connection rod mates with the cage connection hole. Locking blocks are provided on both sides of the plug-in fastening block. After the plug-in fastening block is inserted into the rotating locking groove formed by the splicing of the two mounting plates and rotated 90°, the locking blocks on both sides of the plug-in fastening block fix the two metal hemispherical cages together.

[0011] Preferably, the gap width between the outer molecularly imprinted polymer layer and the inner molecularly imprinted polymer layer along the radial direction of the central axis of the inner core electrode assembly is 0.5 mm.

[0012] Preferably, the outer ring electrode assembly includes an outer skeleton, an outer electrode sheet, and an outer molecularly imprinted polymer layer stacked sequentially from the outside to the inside. The inner core electrode assembly includes an inner skeleton, an inner electrode sheet, and an inner molecularly imprinted polymer layer stacked sequentially from the inside to the outside.

[0013] Preferably, the oil-immersed transformer health monitoring system also includes a fixed frame and a rotating frame. The fixed frame is fixed inside the shielding cage. The motor is fixed to the fixed frame. The rotating frame is coaxially fixed to the output shaft of the motor. The outer ring electrode assembly is fixed to the fixed frame by an external connector fastening block. The inner core electrode assembly is fixed to the rotating frame by an internal connecting rod.

[0014] Preferably, the outer frame is connected to the fixed frame via four external connecting rods. The inner frame is connected to the rotating frame via four internal connecting rods. One end of each of the four external connecting rods is fixed to the fixed frame; the other end of each of the four external connecting rods is detachably connected to the outer frame via a first elastic positioning structure. One end of each of the four internal connecting rods is fixed to the rotating frame; the other end of each of the four internal connecting rods is detachably connected to the inner frame via a second elastic positioning structure.

[0015] The ends of the four external connecting rods are connected to four first positioning holes staggered by 90° along the circumference of the outer frame, which are opened on the outer side of the outer frame. The ends of the four internal connecting rods are connected to four second positioning holes staggered by 90° along the circumference of the inner frame, which are opened on the inner side of the inner frame.

[0016] The first elastic positioning structure includes a first connecting cylinder, a first locking block, and a first spring. The first locking block is fixed to the side of the end of the outer connecting rod. The inner end of the first connecting cylinder is sleeved on the end of the outer connecting rod, forming a cylindrical pair with the outer connecting rod. The axis of the first connecting cylinder is arranged radially along the outer ring electrode assembly. The outer end of the first connecting cylinder is closed. A first spring is provided between the end of the inner cavity of the first connecting cylinder and the end of the outer connecting rod.

[0017] A first constraint groove is formed on the side wall of the first connecting cylinder. The first constraint groove includes a first axial groove segment and a first tangential groove segment connected together. One end of the first axial groove segment communicates with the inner edge of the first connecting cylinder. The other end of the first axial groove segment communicates with the first tangential groove segment. A first locking block is disposed in the first constraint groove. When the first locking block is in the first axial groove segment, the first connecting cylinder extends into the corresponding first positioning hole. When the first locking block is in the first tangential groove segment, the first connecting cylinder retracts from the corresponding first positioning hole.

[0018] The second elastic positioning structure includes a second connecting cylinder, a second locking block, and a second spring. The second locking block is fixed to the side of the end of the inner connecting rod. The inner end of the second connecting cylinder is sleeved on the end of the inner connecting rod, forming a cylindrical pair with the inner connecting rod. The axis of the second connecting cylinder is arranged radially along the inner core electrode assembly. The outer end of the second connecting cylinder is closed. A second spring is provided between the end of the inner cavity of the second connecting cylinder and the end of the inner connecting rod.

[0019] The second connecting cylinder has a second constraint through groove on its side wall. The second constraint through groove includes a second axial groove segment and a second tangential groove segment connected together. One end of the second axial groove segment communicates with the inner edge of the second connecting cylinder. The other end of the second axial groove segment communicates with the second tangential groove segment. A second locking block is disposed in the second constraint through groove. When the second locking block is within the second axial groove segment, the second connecting cylinder extends into the corresponding second positioning hole. When the second locking block is within the second tangential groove segment, the second connecting cylinder retracts from the corresponding second positioning hole.

[0020] Preferably, in the reading state, the smaller the capacitance value of the sensor, the more severe the aging of the insulation medium in the tested oil-immersed transformer.

[0021] Preferably, the angle occupied by the comb post relative to the central axis of the outer ring electrode assembly and the inner core electrode assembly is less than or equal to the angle occupied by the clearance groove relative to the central axis of the outer ring electrode assembly and the inner core electrode assembly.

[0022] Preferably, both the inner molecularly imprinted polymer layer and the outer molecularly imprinted polymer layer are made of polydimethylsiloxane, and each layer has molecular vacancies that are spatially complementary to furfural molecules.

[0023] Preferably, the oil-immersed transformer health monitoring system also includes a data acquisition and control system. The data acquisition and control system includes a signal processing circuit module, a motor control module, and a battery module. The signal processing circuit module is connected to the outer ring electrode assembly and the inner core electrode assembly via wires, and is used to detect the capacitance value between the outer ring electrode assembly and the inner core electrode assembly. The motor control module is used to control the rotation of the motor. The battery module is used to power the signal processing circuit module, the motor control module, and the motor.

[0024] The detection method of this oil-immersed transformer health monitoring system includes the following steps:

[0025] Step 1: Immerse the oil-immersed transformer health monitoring system in the insulating medium being monitored. Set the monitoring cycle. Divide the monitoring cycle into one adsorption period, one reading period, and two switching periods.

[0026] Step 2: During the adsorption period, the sensor switches to the adsorption state under the drive of the motor. As the concentration of furfural molecules in the insulating medium increases, the adsorption amount of 2-furfural molecules on the inner and outer molecularly imprinted polymer layers increases.

[0027] Step 3: During the first switching period, the motor drives the inner electrode assembly to rotate, causing the sensor to switch from the adsorption state to the reading state.

[0028] Step 4: During the reading period, detect the capacitance value between the inner core electrode assembly and the outer ring electrode assembly, and determine the health status of the oil-immersed transformer based on the capacitance value.

[0029] Step 5: During the second switching period, the motor drives the inner electrode assembly to rotate, causing the sensor to switch from the reading state to the adsorption state.

[0030] Step 6: Repeat steps 2 to 5 to periodically check the health status of the oil-immersed transformer.

[0031] The beneficial effects of this invention are:

[0032] 1. The sensor proposed in this invention provides two annular, comb-shaped electrodes, inner and outer. By utilizing the staggered and aligned teeth of the inner and outer electrodes, long-term, sufficient adsorption of furfural (adsorption state) is achieved during detection, while short-term, periodic testing of furfural concentration is performed (reading state). In the reading state, the distance between the inner and outer molecularly imprinted polymer layers is relatively short, resulting in a larger capacitance change due to variations in furfural molecule concentration, thereby improving the accuracy of transformer health detection. The combination of these two operating states significantly improves the sensor's sensitivity with low power consumption.

[0033] 2. In this invention, only the molecularly imprinted polymer, furfural molecules, and micro-oil layer between the electrodes serve as the dielectric layer of the capacitor. Because the micro-oil layer and the molecularly imprinted polymer layer are relatively thin, the initial dielectric constant of the dielectric layer is low. Therefore, compared to existing capacitive sensors composed of molecularly imprinted polymers, this invention offers significant advantages in sensitivity and detection range.

[0034] 3. This invention monitors transformer health by detecting the concentration of furfural molecules. Compared to existing technologies that use optical principles to detect furfural molecules, this invention has a relatively high detection capability for furfural molecules at concentrations of 0-100 ppm, thus enabling long-term monitoring and prediction of transformer lifespan. Furthermore, the aging of transformer insulation materials produces various chemical substances. For complex oil sample environments, furfural molecularly imprinted polymers can selectively adsorb single substances from the transformer oil sample; that is, the sensor is only sensitive to the concentration of furfural molecules, effectively improving detection performance.

[0035] 4. This invention uses a polydimethylsiloxane (PDMS)-based polymer with furfural molecular active sites as a molecularly imprinted polymer. The polydimethylsiloxane (PDMS) has effective hydrophobic properties, making the sensor insensitive to changes in humidity in the oil. This allows the sensor's capacitance value to change only with the concentration of furfural molecules in the insulating medium, thereby improving the sensor's stability.

[0036] 5. In view of the characteristics of the sensor, the present invention provides a specific sensor fixing structure and connection method. The connection method is simple and stable, making the sensor easy to remove and install. It can realize the monitoring of the transformer for a longer period of time, and can also reduce the cost and maintenance cycle caused by the replacement of the entire system due to sensor damage. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the overall structure of the oil-immersed transformer health monitoring system provided by the present invention.

[0038] Figure 2 This is a schematic diagram of the internal structure of the oil-immersed transformer health monitoring system provided by the present invention.

[0039] Figure 3 This is a schematic diagram showing the partial structural separation of the sensor in this invention.

[0040] Figure 4 This is a cross-sectional schematic diagram of the sensor in this invention.

[0041] Figure 5 This is a schematic diagram illustrating the state switching process of the sensor in this invention.

[0042] Figure 6 This is a schematic diagram of the shielding cage in this invention.

[0043] Figure 7 This is a schematic diagram of the first elastic positioning structure and the second elastic positioning structure in this invention.

[0044] Figure 8 This is a flowchart illustrating the disassembly process of the present invention. Detailed Implementation

[0045] The present invention will be further described below with reference to the accompanying drawings.

[0046] like Figure 1 and 2 As shown, a health monitoring system for an oil-immersed transformer based on a rotor structure includes a sensor 1, a fixed frame 2, a rotating frame 3, a motor 4, a data acquisition and control system 5, and a shielding cage 6. The shielding cage 6 is a closed wire mesh that utilizes the Faraday cage effect to shield external electric fields, thereby preventing the high-voltage electric field generated by the oil-immersed transformer from affecting the detection accuracy of the sensor 1 and improving the stability of the oil-immersed transformer health monitoring system. The fixed frame 2 is fixed inside the shielding cage 6. The motor 4 and the data acquisition and control system 5 are installed inside the shielding cage 6 and are both fixed to the fixed frame 2. The rotating frame 3 is coaxially fixed to the output shaft of the motor 4. The rotating frame 3 can rotate relative to the fixed frame 2 under the drive of the motor 4.

[0047] like Figure 3 and 4As shown, sensor 1 includes an outer ring electrode assembly 1-1 and an inner core electrode assembly 1-2, which are coaxially arranged and rotatable relative to each other. The outer ring electrode assembly 1-1 has a ring structure and is sleeved on the outside of the inner core electrode assembly 1-2. The outer ring electrode assembly 1-1 includes an outer skeleton 1-7, an outer electrode sheet 1-8, and an outer molecularly imprinted polymer layer 1-9, which are stacked sequentially from the outside to the inside. The inner core electrode assembly 1-2 includes an inner skeleton 1-4, an inner electrode sheet 1-5, and an inner molecularly imprinted polymer layer 1-6, which are stacked sequentially from the inside to the outside. The outer molecularly imprinted polymer layer 1-9 and the inner molecularly imprinted polymer layer 1-6 are spaced apart, forming a gap with a width of 0.5 mm.

[0048] The outer frame 1-7 is detachably fixed to the fixed frame 2 via an outer connecting rod 2-1. The inner frame 1-4 is detachably fixed to the rotating frame 3 via an inner connecting rod 3-1; thus, the motor can drive the outer ring electrode assembly 1-1 and the inner core electrode assembly 1-2 to rotate relative to each other. The inner electrode plate 1-5 and the outer electrode plate 1-8 are respectively led out to the acquisition-control system 5 via two wires 3-1.

[0049] A first positioning ring is provided at the end of the inner skeleton 1-4. A second positioning ring is provided at the end of the outer skeleton 1-7. The outer diameter of the first positioning ring is equal to the inner diameter of the second positioning ring. The outer circumferential surface of the first positioning ring contacts the inner circumferential surface of the second positioning ring to form a rotating pair, thereby ensuring that the outer ring electrode assembly 1-1 and the inner core electrode assembly 1-2 remain coaxial, and that the distance between the inner molecularly imprinted polymer layer 1-6 and the outer molecularly imprinted polymer layer 1-9 remains constant.

[0050] When the molecular weight adsorbed on the outer molecular imprinted polymer layer 1-9 and the inner molecular imprinted polymer layer 1-6 changes, the capacitance value between the outer ring electrode assembly 1-1 and the inner core electrode assembly 1-2 will change accordingly. Since the distance between the outer molecular imprinted polymer layer 1-9 and the inner molecular imprinted polymer layer 1-6 decreases, the capacitance change caused by the change in the molecular weight adsorbed on the outer molecular imprinted polymer layer 1-9 and the inner molecular imprinted polymer layer 1-6 is relatively large, which helps to improve the detection accuracy.

[0051] Both the outer ring electrode assembly 1-1 and the inner core electrode assembly 1-2 have multiple circumferentially distributed clearance grooves along their central axes. The number of clearance grooves on the outer ring electrode assembly 1-1 and the inner core electrode assembly 1-2 is the same. A comb-tooth post is formed between two adjacent clearance grooves; each comb-tooth post is connected to the corresponding annular body, thereby making both the outer ring electrode assembly 1-1 and the inner core electrode assembly 1-2 form an annular comb-tooth structure.

[0052] The angle occupied by the comb post relative to the central axis of the outer ring electrode assembly 1-1 and the inner core electrode assembly 1-2 is equal to the angle occupied by the clearance groove relative to the central axis of the outer ring electrode assembly 1-1 and the inner core electrode assembly 1-2, so that each comb post on the outer ring electrode assembly 1-1 and each comb post on the inner core electrode assembly 1-2 can rotate to be aligned or to be staggered.

[0053] Both the inner molecularly imprinted polymer layers 1-6 and the outer molecularly imprinted polymer layers 1-9 are made of polydimethylsiloxane (PDMS), and each layer contains molecular vacancies spatially complementary to the target molecule. These molecular vacancies are formed by pre-assembling the target molecule with a functional monomer through covalent or non-covalent interactions, copolymerizing it with a crosslinking agent, and then removing the target molecule. The molecular vacancies can adsorb the target molecule. The target molecule is furfural, specifically 2-furfural from furan, an organic compound produced during the aging of the insulating medium in oil-immersed transformers, with the molecular formula C5H4O2. The molecular vacancies on the inner molecularly imprinted polymer layers 1-6 and the outer molecularly imprinted polymer layers 1-9 can adsorb 2-furfural molecules from the insulating medium.

[0054] When the comb posts on the outer ring electrode assembly 1-1 are staggered from those on the inner core electrode assembly 1-2, target molecules in the insulating medium can be adsorbed onto the inner molecularly imprinted polymer layer 1-6 and the outer molecularly imprinted polymer layer 1-9, causing a change in the dielectric constant of the outer ring electrode assembly 1-1 and the inner core electrode assembly 1-2. The amount of target molecules adsorbed by the inner molecularly imprinted polymer layer 1-6 and the outer molecularly imprinted polymer layer 1-9 varies with the concentration of target molecules in the insulating medium.

[0055] Each comb post on the outer ring electrode assembly 1-1 is aligned with each comb post on the inner core electrode assembly 1-2, enabling the detection of the capacitance value between the outer ring electrode assembly 1-1 and the inner core electrode assembly 1-2. This capacitance value changes with the amount of target molecules adsorbed in the inner molecular imprinted polymer layer 1-6 and the outer molecular imprinted polymer layer 1-9. Therefore, the concentration of target molecules in the insulating medium can be determined based on the measured capacitance value, thereby determining the degree of aging of the insulating medium in the oil-immersed transformer.

[0056] Sensor 1 has two states: adsorption state and reading state. In the adsorption state, the comb teeth on the outer ring electrode assembly 1-1 are aligned with the comb teeth on the inner core electrode assembly 1-2, allowing both the inner molecularly imprinted polymer layer 1-6 and the outer molecularly imprinted polymer layer 1-9 to fully contact the insulating medium in the oil-immersed transformer. This enables the inner and outer molecularly imprinted polymer layers 1-6 and 1-9 to effectively adsorb target molecules as the concentration of target molecules in the insulating medium increases. In the reading state, the comb teeth on the outer ring electrode assembly 1-1 are aligned with the comb teeth on the inner core electrode assembly 1-2. At this time, the concentration of target molecules corresponding to the adsorbed molecular weight can be determined by reading the capacitance value between the outer ring electrode assembly 1-1 and the inner core electrode assembly 1-2, thereby determining the degree of aging of the insulating medium in the oil-immersed transformer.

[0057] The rotation of motor 4 is used to switch sensor 1 between the adsorption state and the reading state. The switching process is as follows: Figure 5 As shown, sensor 1 is in the adsorption state most of the time, only switching from the adsorption state to the reading state to read the capacitance value after a preset time interval. After reading, it returns to the adsorption state. This ensures that the inner molecular imprinted polymer layers 1-6 and the outer molecular imprinted polymer layers 1-9 are in full contact with the insulating medium in the oil-immersed transformer most of the time, thus improving the accuracy of detection.

[0058] The acquisition-control system 5 includes a signal processing circuit module, a motor control module, and a battery module. The signal processing circuit module is connected to the outer ring electrode assembly 1-1 and the inner core electrode assembly 1-2 via wires 1-3, and is used to detect the capacitance value between the outer ring electrode assembly 1-1 and the inner core electrode assembly 1-2. The motor control module controls the rotation of the motor 4, enabling the sensor 1 to switch between the adsorption state and the reading state. The battery module supplies power to the signal processing circuit module, the motor control module, and the motor 4.

[0059] To facilitate disassembly and replacement of sensor 1 separately, this embodiment provides a preferred, non-essential technical solution: such as... Figure 6 As shown, the shielding cage includes a connecting and fastening structure and two metal hemispherical cages. Each of the two metal hemispherical cages has a semi-circular mounting plate aligned with each other on its top. Each adjacent side of the two mounting plates has a semi-groove. When the two semi-grooves are joined together, they form a rotating locking groove. The semi-grooves on the two mounting plates are connected together by the connecting and fastening structure.

[0060] The fastening structure includes a connecting fastening block 6-2, a metal cage 6-1, a cage connecting hole 6-3, and a cage connecting rod 6-4. The cage connecting rod 6-4 is located on one of the metal hemispherical cages; the cage connecting hole 6-3 is located on the other metal hemispherical cage. The cage connecting rod 6-4 and the cage connecting hole 6-3 mate together to form a tenon connection structure. Locking blocks are provided on both sides of the connecting fastening block 6-2. After the connecting fastening block 6-2 is inserted into the rotating locking groove formed by the splicing of the two mounting plates and rotated 90°, the two metal hemispherical cages are fixed together.

[0061] Four external connecting rods 2-1 are provided between the outer frame 1-7 and the fixed frame 2. Four internal connecting rods 3-1 are provided between the inner frame 1-4 and the rotating frame 3. One end of each of the four external connecting rods 2-1 is fixed to the fixed frame 2; the other end of each of the four external connecting rods 2-1 is connected to the outer frame 1-7 through a first elastic positioning structure 2-2. One end of each of the four internal connecting rods 3-1 is fixed to the rotating frame 3; the other end of each of the four internal connecting rods 3-1 is connected to the inner frame 1-4 through a second elastic positioning structure 3-2.

[0062] The ends of the four outer connecting rods 2-1 are connected to the four first positioning holes 1-10 on the outer frame 1-7, which are staggered by 90° along the circumference of the axis. The ends of the four inner connecting rods 3-1 are connected to the four second positioning holes 1-11 on the inner frame 1-4, which are staggered by 90° along the circumference of the axis.

[0063] The first elastic positioning structure 2-2 and the second elastic positioning structure 3-2 have the same structure, as detailed below:

[0064] like Figure 7 As shown, the first elastic positioning structure 2-2 includes a first connecting cylinder, a first locking block, and a first spring. The first locking block is fixed to the side of the end of the outer connecting rod 2-1. The inner end of the first connecting cylinder is sleeved on the end of the outer connecting rod 2-1, forming a cylindrical pair with the outer connecting rod 2-1. The axis of the first connecting cylinder is arranged radially along the outer ring electrode assembly 1-1. The outer end of the first connecting cylinder is closed. A first spring is provided between the end of the inner cavity of the first connecting cylinder and the end of the outer connecting rod 2-1. The first spring applies an outward thrust to the first connecting cylinder.

[0065] A first constraint through groove is formed on the side wall of the first connecting cylinder. The first constraint through groove includes a first axial groove segment and a first tangential groove segment connected together. One end of the first axial groove segment communicates with the inner edge of the first connecting cylinder. The other end of the first axial groove segment communicates with the first tangential groove segment. A first locking block is disposed in the first constraint through groove. When the first locking block is in the first axial groove segment, the first connecting cylinder can only slide axially with the outer connecting rod 2-1, and the first connecting cylinder extends into the corresponding first positioning hole 1-10. When the first locking block is in the first tangential groove segment, the first connecting cylinder can only rotate circumferentially with the outer connecting rod 2-1, and the first connecting cylinder exits the corresponding first positioning hole 1-10.

[0066] The second elastic positioning structure 2-2 includes a second connecting cylinder, a second locking block, and a second spring. The second locking block is fixed to the side of the end of the inner connecting rod 3-1. The inner end of the second connecting cylinder is sleeved on the end of the inner connecting rod 3-1, forming a cylindrical pair with the inner connecting rod 3-1. The axis of the second connecting cylinder is arranged radially along the inner core electrode assembly 1-2. The outer end of the second connecting cylinder is closed. A second spring is provided between the end of the inner cavity of the second connecting cylinder and the end of the inner connecting rod 3-1. The second spring applies an outward thrust to the second connecting cylinder.

[0067] A second constraint through groove is formed on the side wall of the second connecting cylinder. The second constraint through groove includes a second axial groove section and a second tangential groove section connected together. One end of the second axial groove section communicates with the inner edge of the second connecting cylinder. The other end of the second axial groove section communicates with the second tangential groove section. A second locking block is disposed in the second constraint through groove. When the second locking block is in the second axial groove section, the second connecting cylinder can only slide axially with the inner connecting rod 3-1, and the second connecting cylinder extends into the corresponding second positioning hole 1-11. When the second locking block is in the second tangential groove section, the second connecting cylinder can only rotate circumferentially with the inner connecting rod 3-1, and the second connecting cylinder exits the corresponding second positioning hole 1-11.

[0068] Therefore, the outer ring electrode assembly 1-1 and the inner core electrode assembly 1-2 can be disassembled by sliding the first connecting cylinder and the second connecting cylinder in sequence and rotating them.

[0069] This embodiment provides a non-essential technical solution: the materials of the outer skeleton 1-7 and the inner skeleton 1-4 are both photosensitive resin materials, printed by a photopolymerization 3D printer, and have a high dielectric constant.

[0070] The detection method for the health monitoring system of this oil-immersed transformer is as follows:

[0071] Step 1: Immerse the oil-immersed transformer health monitoring system in the insulating medium being monitored. Set the monitoring cycle to 1 hour. The monitoring cycle consists of one adsorption period, one reading period, and two switching periods. The adsorption period lasts 55 minutes; the reading period lasts 1 minute; and the switching period lasts 2 minutes. The order of the four periods is: adsorption period → first switching period → reading period → second switching period.

[0072] Step 2: During the adsorption period, sensor 1 switches to the adsorption state under the drive of motor 4. As the concentration of 2-furfural molecules in the insulating medium increases, the adsorption amount of 2-furfural molecules on the inner molecular imprinted polymer layer 1-6 and the outer molecular imprinted polymer layer 1-9 increases.

[0073] Step 3: During the first switching period, motor 4 drives the inner core electrode assembly 1-2 to rotate, so that sensor 1 switches from the adsorption state to the reading state.

[0074] Step 4: During the reading period, the signal processing circuit module detects the capacitance value between the inner core electrode assembly 1-2 and the outer ring electrode assembly 1-1, and judges the health status of the oil-immersed transformer based on the capacitance value.

[0075] Step 5: During the second switching period, motor 4 drives the inner core electrode assembly 1-2 to rotate, causing sensor 1 to switch from the reading state to the adsorption state.

[0076] Step 6: Repeat steps 2 to 5 to periodically check the health status of the oil-immersed transformer.

[0077] like Figure 8 As shown, during the oil monitoring process, for sensor 1 of the present invention, this embodiment provides a simple replacement and installation method as follows:

[0078] ①. Rotate the fastening block 6-2. Pull the fastening block 6-2 out of the rotating locking groove of the metal cage 6-1. Then separate the cage connecting hole 6-3 from the cage connecting rod 6-4, thereby opening the shielding cage.

[0079] ②. Separate the inner core electrode assembly 1-2 from the inner connecting rod 3-1. First, pull the second connecting cylinder outward to completely disengage the outer connecting cylinder 3-2 from the second positioning hole 1-11. Then, rotate the second connecting cylinder to lock it in place.

[0080] ③. Separate the outer core electrode assembly 1-1 from the outer connecting rod 2-1. First, pull the first connecting cylinder outward to completely disengage it from the first positioning hole 1-10; then, rotate the first connecting cylinder 2-2 to lock it in place.

[0081] The installation of the new sensor 1 can be achieved by following the reverse steps described above.

Claims

1. An oil-immersed transformer health monitoring system based on a rotor structure, comprising a sensor (1); characterized in that: It also includes a motor (4); the sensor (1) includes coaxially arranged and relatively rotatable outer ring electrode assembly (1-1) and inner core electrode assembly (1-2); the outer ring electrode assembly (1-1) is annular structure, and is sleeved on the outside of the inner core electrode assembly (1-2); the relative rotation between the outer ring electrode assembly (1-1) and the inner core electrode assembly (1-2) is driven by the motor (4); The outer ring electrode assembly (1-1) and the inner core electrode assembly (1-2) are provided with a plurality of circumferential slots along the central axis of the outer ring electrode assembly (1-1) and the inner core electrode assembly (1-2), respectively; adjacent two slots form a comb tooth column; the sensor (1) has two states, respectively, adsorption state and reading state; in the adsorption state, the comb tooth columns on the outer ring electrode assembly (1-1) and the comb tooth columns on the inner core electrode assembly (1-2) are staggered, respectively; in the reading state, the comb tooth columns on the outer ring electrode assembly (1-1) and the comb tooth columns on the inner core electrode assembly (1-2) are aligned, respectively; The inner side of the outer ring electrode assembly (1-1) is provided with an outer molecular imprinting polymer layer (1-9); the outer side of the inner core electrode assembly (1-2) is provided with an inner molecular imprinting polymer layer (1-6); the outer molecular imprinting polymer layer (1-9) and the inner molecular imprinting polymer layer (1-6) can adsorb the furfural molecules in the insulating medium of the measured oil immersed transformer; the outer molecular imprinting polymer layer (1-9) and the inner molecular imprinting polymer layer (1-6) are radially spaced along the central axis of the inner core electrode assembly (1-2); The outer ring electrode assembly (1-1) includes an outer skeleton (1-7), an outer electrode sheet (1-8) and an outer molecular imprinting polymer layer (1-9) which are sequentially stacked from outside to inside; the inner core electrode assembly (1-2) includes an inner skeleton (1-4), an inner electrode sheet (1-5) and an inner molecular imprinting polymer layer (1-6) which are sequentially stacked from inside to outside; The angle of the comb tooth column relative to the central axis of the outer ring electrode assembly (1-1) and the inner core electrode assembly (1-2) is less than or equal to the angle of the slot relative to the central axis of the outer ring electrode assembly (1-1) and the inner core electrode assembly (1-2).

2. The oil-immersed transformer health monitoring system based on a rotor structure according to claim 1, characterized in that: It also includes a shielding cage (6); the shielding cage (6) is sleeved on the outside of the sensor (1) and the motor (4).

3. The oil-immersed transformer health monitoring system based on a rotor structure according to claim 2, characterized in that: The shielding cage includes a connecting fastening structure and two metal hemisphere cage bodies; the top of each of the two metal hemisphere cage bodies is provided with a mounting plate aligned with each other; a half slot is formed on the adjacent side surface of the two mounting plates; the two half slots are spliced together to form a rotary locking slot; the connecting fastening structure is arranged in the rotary locking slot to fix the two metal hemisphere cage bodies together; The connecting fastening structure comprises a connector fastening block (6-2), a metal cage (6-1), a cage connecting hole (6-3) and a cage connecting rod (6-4); the cage connecting rod (6-4) is arranged on one of the metal hemispherical cages; the cage connecting hole (6-3) is arranged on the other metal hemispherical cage; the cage connecting rod (6-4) is matched with the cage connecting hole (6-3); the connector fastening block (6-2) is provided with locking blocks on both sides; after the connector fastening block (6-2) is inserted into the rotating locking slot formed by the half-slot splicing on the two mounting plates and rotated by 90°, the locking blocks on both sides of the connector fastening block (6-2) fix the two metal hemispherical cages together.

4. The oil-immersed transformer health monitoring system based on a rotor structure according to claim 1, characterized in that: The gap width of the outer molecular imprinting polymer layer (1-9) and the inner molecular imprinting polymer layer (1-6) along the radial direction of the central axis of the inner core electrode assembly (1-2) is 0.5 mm.

5. The oil-immersed transformer health monitoring system based on a rotor structure according to claim 2, characterized in that: The fixed frame (2) is fixed in the shielding cage (6); the motor (4) is fixed with the fixed frame (2); the rotating frame (3) is coaxially fixed with the output shaft of the motor (4); the outer ring electrode assembly (1-1) is fixed with the fixed frame (2) through the outer connecting rod (2-1); and the inner core electrode assembly (1-2) is fixed with the rotating frame (3) through the inner connecting rod (3-1).

6. The oil-immersed transformer health monitoring system based on a rotor structure according to claim 5, characterized in that: The outer frame (1-7) and the fixed frame (2) are connected through four outer connecting rods (2-1); the inner frame (1-4) and the rotating frame (3) are connected through four inner connecting rods (3-1); one end of each of the four outer connecting rods (2-1) is fixed with the fixed frame (2); the other end of each of the four outer connecting rods (2-1) is detachably connected with the outer frame (1-7) through the first elastic positioning structure (2-2); one end of each of the four inner connecting rods (3-1) is fixed with the rotating frame (3); the other end of each of the four inner connecting rods (3-1) is detachably connected with the inner frame (1-4) through the second elastic positioning structure (3-2); The end of each of the four outer connecting rods (2-1) is connected with the four first positioning holes (1-10) which are sequentially staggered by 90° along the circumferential direction and are arranged on the outer side surface of the outer frame (1-7); the end of each of the four inner connecting rods (3-1) is connected with the four second positioning holes (1-11) which are sequentially staggered by 90° along the circumferential direction and are arranged on the inner side surface of the inner frame (1-4); The first elastic positioning structure (2-2) comprises a first connecting cylinder, a first locking block and a first spring; the first locking block is fixed on the side surface of the end of the outer connecting rod (2-1); the inner end of the first connecting cylinder is sleeved on the end of the outer connecting rod (2-1) and forms a cylindrical pair with the outer connecting rod (2-1); the axis of the first connecting cylinder is arranged along the radial direction of the outer ring electrode assembly (1-1); the outer end of the first connecting cylinder is closed; and the first spring is arranged between the end of the inner cavity of the first connecting cylinder and the end of the outer connecting rod (2-1); The side wall of the first connecting barrel is provided with a first restriction through slot; the first restriction through slot comprises a first axial slot section and a first tangential slot section connected together; one end of the first axial slot section is communicated with the inner end edge of the first connecting barrel; the other end of the first axial slot section is communicated with the first tangential slot section; the first locking block is arranged in the first restriction through slot; When the first locking block is in the first axial slot section, the first connecting barrel extends into the corresponding first positioning hole (1-10); when the first locking block is in the first tangential slot section, the first connecting barrel exits the corresponding first positioning hole (1-10); The second elastic positioning structure (3-2) comprises a second connecting barrel, a second locking block and a second spring; the second locking block is fixed to the side surface of the end of the inner connecting rod (3-1); the inner end of the second connecting barrel is sleeved on the end of the inner connecting rod (3-1) and forms a cylindrical pair with the inner connecting rod (3-1); the axis of the second connecting barrel is arranged along the radial direction of the inner core electrode assembly (1-2); the outer end of the second connecting barrel is closed; the second spring is arranged between the end of the inner cavity of the second connecting barrel and the end of the inner connecting rod (3-1); The side wall of the second connecting barrel is provided with a second restriction through slot; the second restriction through slot comprises a second axial slot section and a second tangential slot section connected together; one end of the second axial slot section is communicated with the inner end edge of the second connecting barrel; the other end of the second axial slot section is communicated with the second tangential slot section; the second locking block is arranged in the second restriction through slot; when the second locking block is in the second axial slot section, the second connecting barrel extends into the corresponding second positioning hole (1-11); when the second locking block is in the second tangential slot section, the second connecting barrel exits the corresponding second positioning hole (1-11).

7. The oil-immersed transformer health monitoring system based on a rotor structure according to claim 1, characterized in that: The materials of the inner molecular imprinting polymer layer (1-6) and the outer molecular imprinting polymer layer (1-9) are both polydimethylsiloxane, and both are provided with molecular cavities which are spatially complementary to the furfural molecules.

8. The oil-immersed transformer health monitoring system based on a rotor structure according to claim 1, characterized in that: Further comprising a collection-control system (5); the collection-control system (5) comprises a signal processing circuit module, a motor control module and a battery module; the signal processing circuit module is connected with the outer ring electrode assembly (1-1) and the inner core electrode assembly (1-2) through wires (1-3) respectively, for detecting the capacitance value between the outer ring electrode assembly (1-1) and the inner core electrode assembly (1-2); the motor control module is used for controlling the rotation of the motor (4); the battery module is used for supplying power to the signal processing circuit module, the motor control module and the motor (4).

9. A method for health monitoring of an oil-immersed transformer based on a rotor structure, characterized by: The oil-immersed transformer health monitoring system provided by claim 1 is used; the oil-immersed transformer health monitoring method comprises the following steps: Step one, immerse the oil-immersed transformer health monitoring system in the monitored insulating medium; set the monitoring period; divide the monitoring period into an adsorption period, a reading period and two switching periods; Step two, in the adsorption period, the sensor (1) is switched to the adsorption state under the driving of the motor (4), and as the concentration of furfural molecules in the insulating medium increases, the adsorption amount of 2-furfural molecules on the inner molecular imprinting polymer layer (1-6) and the outer molecular imprinting polymer layer (1-9) increases; Step three, in the first switching period, the motor (4) drives the inner core electrode assembly (1-2) to rotate, so that the sensor (1) is switched from the adsorption state to the reading state; Step four, in the reading period, the capacitance value between the inner core electrode assembly (1-2) and the outer ring electrode assembly (1-1) is detected, and the health degree of the oil-immersed transformer is judged according to the capacitance value; Step five, in the second switching period, the motor (4) drives the inner core electrode assembly (1-2) to rotate, so that the sensor (1) is switched from the reading state to the adsorption state; Step six, repeat steps two to five to periodically detect the health degree of the oil-immersed transformer.

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