Fluorescent optical fiber temperature measuring device for transformer winding

Abstract

The invention discloses a fluorescent optical fiber temperature measuring device for a transformer winding. The fluorescent optical fiber temperature measuring device comprises an optical fiber temperature sensor, a control and interaction unit, a transmission and switching unit, a flange fixing unit and a protection unit, through the complete system design of the optical fiber temperature sensor, the control and interaction unit, the transmission and switching unit, the flange fixing unit and the protection unit, a whole-process closed loop from temperature sensing and signal transmission to data processing and alarm control is realized. The optical fiber temperature sensor is in direct contact with a winding hot spot, temperature measurement is performed based on the fluorescence decay time principle, the problems that a traditional indirect calculation method is large in error and an electrical sensor is poor in anti-interference performance are solved, system integration is achieved, and monitoring is more accurate. The optical fiber temperature sensor adopts a polyimide optical fiber core and a polytetrafluoroethylene sheath, has no metal part, is resistant to high pressure, and is completely immune to EMI / RFI; a signal isolation unit of the control and interaction unit further blocks external interference and ensures stable work in a strong electromagnetic environment.

Description

Technical Field

[0001] The present invention relates to the technical field of power equipment temperature monitoring, in particular to a transformer winding fluorescent optical fiber temperature measuring device. Background Art

[0002] In power systems, transformers are core equipment for energy conversion and transmission. The hotspot temperature of their windings is a key parameter affecting insulation life and operational safety. The aging rate of insulation paper is exponentially related to the hotspot temperature of the windings. For every 6-8°C increase in temperature, the insulation life is halved. Therefore, accurate monitoring of hotspot temperature is crucial for transformer life assessment, overload protection, and fault warning.

[0003] In the existing technology, transformer winding temperature monitoring has the following main defects:

[0004] 1. Limitations of traditional electrical temperature measurement methods: When using electrical sensors such as thermocouples and thermal resistors, they are susceptible to strong electromagnetic interference (EMI / RFI) inside the transformer, and the metal material has the risk of high-voltage breakdown and cannot directly contact the winding hot spots.

[0005] 2. Shortcomings of the indirect calculation method: Estimating the winding temperature by combining the top oil temperature with the load factor cannot reflect the actual hot spot temperature and is difficult to meet high-precision monitoring requirements.

[0006] 3. Deficiencies of existing fiber optic temperature measurement technology: Some fluorescent fiber optic temperature measurement devices (such as the fluorescent fiber optic temperature measurement probe and device for oil-immersed transformer windings disclosed in Publication No. CN214096419U) focus only on optimizing the local structure of the probe and lack a complete system design:

[0007] 1. No independent control and interaction unit is integrated, data processing relies on external devices, and the response speed is not timely enough;

[0008] 2. The sealing structure is simple and prone to leakage in a long-term oil immersion environment, resulting in large light loss;

[0009] 3. The protective design is not perfect, the equipment is easily affected by environmental erosion (such as rain and dust), and the maintenance convenience is poor;

[0010] 4. Sensors require regular calibration, increasing operation and maintenance costs. In addition, the multi-channel expansion capability is weak, making it difficult to adapt to transformers of different capacities.

[0011] Therefore, there is an urgent need for an integrated, highly reliable, anti-interference and easy-to-maintain transformer winding fluorescent fiber temperature measurement device to solve the above-mentioned problems of the prior art. Summary of the Invention

[0012] The technical task of the present invention is to address the above shortcomings and provide a transformer winding fluorescent fiber optic temperature measurement device to solve the above problems.

[0013] To achieve the above object, the present invention provides the following technical solutions:

[0014] Transformer winding fluorescent optical fiber temperature measuring device, including:

[0015] Fiber optic temperature sensors, which directly contact the hot spots of transformer windings, receive excitation light and return temperature-related fluorescence signals, enabling temperature sensing without metal intervention.

[0016] The control and interaction unit centrally controls the temperature measurement process of each channel, displays temperature data in real time, and triggers over-temperature alarms;

[0017] The transmission and switching unit is used to achieve sealed switching of optical fibers inside and outside the transformer tank and extend the signal transmission distance, and includes a through-hole assembly and an external optical fiber extension line. The through-hole assembly is connected between the external optical fiber extension line and the optical fiber temperature sensor, and the external optical fiber extension line is connected between the control and interaction unit and the through-hole assembly. The optical fiber temperature sensor is installed in the transformer tank wall through the through-hole assembly.

[0018] A flange fixing unit, which is used to form a mounting base for the through-hole assembly, and the through-hole assembly is arranged on the oil tank through the flange fixing unit;

[0019] A protection unit is used to protect the control and interaction unit, the through-hole assembly and the external optical fiber extension line from damage, and includes a protection box assembly and a protection cover assembly. The protection box assembly is arranged away from the protection cover assembly, and a part of the structure of the control and interaction unit and the external optical fiber extension line is respectively arranged in the protection box assembly, and the other part of the structure of the through-hole assembly and the external optical fiber extension line is respectively arranged in the protection cover assembly.

[0020] Preferably, the optical fiber temperature sensor includes a polyimide optical fiber core, an exposed temperature probe with built-in rare earth fluorescent material, a first ST connector and a polytetrafluoroethylene sheath, the exposed temperature probe and the first ST connector are respectively connected to the two ends of the polyimide optical fiber core, the polytetrafluoroethylene sheath is sleeved on the surface of the polyimide optical fiber core, and the exposed temperature probe is located at the bottom end of the polytetrafluoroethylene sheath.

[0021] Preferably, the control and interaction unit includes an optical fiber temperature measurement host, a signal processing submodule, and a communication submodule. The signal processing submodule and the communication submodule are integrated inside the optical fiber temperature measurement host, and the three realize electrical connection and data interaction through the PCB circuit board inside the host.

[0022] Preferably, the optical fiber temperature measurement host includes a microprocessor, a liquid crystal display, a 1-8-bit dip switch, two relay output units and a power management unit, the liquid crystal display, the 1-8-bit dip switch, and the two relay output units are electrically connected to the microprocessor respectively, and the microprocessor, the liquid crystal display, the 1-8-bit dip switch, and the two relay output units are electrically connected to the power management unit respectively;

[0023] The signal processing submodule includes a fluorescence signal receiving circuit, a photoelectric conversion unit, a temperature algorithm processor and a multi-channel data acquisition module, the external optical fiber extension line and the photoelectric conversion unit are respectively connected to the fluorescence signal receiving circuit, and the photoelectric conversion unit and the temperature algorithm processor are respectively electrically connected to the multi-channel data acquisition module;

[0024] The communication submodule includes an RS485 interface circuit, a 4-20mA analog output interface circuit, a USB debugging interface circuit and a signal isolation unit. The RS485 interface circuit, the 4-20mA analog output interface circuit and the USB debugging interface circuit are electrically connected to the microprocessor respectively, and the signal isolation unit is connected in series between the microprocessor and the RS485 interface circuit and the 4-20mA analog output interface circuit.

[0025] Preferably, the through-hole assembly includes a through-hole body, a double nut and a first sealing ring. The double nut is threadedly sleeved on the surface of the through-hole body, the top of the double nut is in contact with the flange fixing unit, and the through-hole body is provided with a first groove adapted to the first sealing ring on the side facing the flange fixing unit. The first sealing ring is embedded in the inner cavity of the first groove, and the through-hole body is docked with the first ST connector.

[0026] Preferably, the external optical fiber extension line includes a quartz optical fiber core, a second ST connector with a voltage reducer and a Teflon sheath, the second ST connector is connected to each end of the quartz optical fiber core, the Teflon sheath is sleeved on the surface of the quartz optical fiber core, and the through-hole body and the fluorescent signal receiving circuit are respectively connected to the two second ST connectors.

[0027] Preferably, the flange fixing unit includes a flange ring, a flange plate and a second sealing ring, the flange ring is welded to the inner wall of the transformer box, the flange plate is mounted on the flange ring by screws, a second groove is formed on the side of the flange ring facing the flange plate, the second sealing ring is embedded in the inner cavity of the second groove, and the second sealing ring is in contact with the bottom of the flange plate, wherein:

[0028] The flange is provided with a through hole for the through-device body to pass through, the inner diameter of the through hole is adapted to the outer diameter of the through-device body, and a number of through holes are provided on the flange in a circular shape and at equal intervals. The first sealing ring is fitted with the top of the flange, and the double nut is located in the inner cavity of the flange ring and is in contact with the flange.

[0029] Preferably, the protective box assembly includes a box body and a box door, the control and interaction unit is installed in the inner cavity of the box body, a plurality of first wire threading holes are opened at the bottom of the box body, the box door is hinged to one side of the box body, and a glass observation window is embedded in the surface of the box door.

[0030] Preferably, the protective cover assembly includes a cover body, a cover and a ring gasket. The bottom of the cover body is integrally formed with an outer edge, and the outer edge is mounted on the flange by screws. The top of the cover body is integrally formed with an inner edge, and the cover is mounted on the inner edge by screws. The ring gasket is placed between the cover and the inner edge, and between the outer edge and the flange, respectively. Three second wire threading holes are opened on one side of the surface of the cover body, and the inner cavities of the second wire threading holes and the first wire threading holes are respectively installed with waterproof connectors, and the external optical fiber extension line is passed through the corresponding second wire threading holes and the first wire threading holes in sequence into the box.

[0031] Preferably, the through-hole body, double nuts, flange ring and flange plate are all made of 316 stainless steel, the cover body and cover are all made of 304 stainless steel, the first sealing ring and the second sealing ring are both fluororubber sealing rings, and the ring gasket is a silicone rubber sealing ring gasket.

[0032] Compared with the prior art, the advantages and positive effects of the present invention are:

[0033] 1. This invention, through the complete system design of the fiber optic temperature sensor, control and interaction unit, transmission and adapter unit, flange fixing unit, and protection unit, realizes a closed loop process from temperature sensing and signal transmission to data processing and alarm control. The fiber optic temperature sensor directly contacts the winding hotspot and measures temperature based on the principle of fluorescence decay time (not light intensity). This solves the problems of large errors in traditional indirect calculation methods and poor anti-interference of electrical sensors. The system is integrated and monitoring is more accurate.

[0034] 2. The fiber optic temperature sensor of the present invention uses a polyimide fiber core and a polytetrafluoroethylene sheath, has no metal parts, can withstand high pressure, and is completely immune to EMI / RFI. The signal isolation unit (optical coupler isolation) of the control and interaction unit further blocks external interference, ensuring stable operation in strong electromagnetic environments. The safety is far superior to existing electrical temperature measurement devices, significantly improving anti-interference and safety.

[0035] 3. The present invention forms a double seal with the double nuts, the first sealing ring, and the second sealing ring to ensure low-loss transmission of optical signals. The flange is made of 316 stainless steel, which is resistant to transformer oil corrosion, solving the problems of sealing failure and optical signal attenuation in existing devices. The sealing performance is adapted to oil-immersion environments.

[0036] 4. The present invention adopts a split structure for the protection unit. The control and interaction unit is installed in the protection box assembly (IP55 protection level), which facilitates remote observation and operation. The protective cover assembly (304 stainless steel) covers the through-hole assembly and the external optical fiber connector, which is rainproof and dustproof. Compared with the single protection structure of the existing technology, the protection design prolongs the equipment life and reduces the maintenance frequency.

[0037] 5. The present invention uses an optical fiber temperature sensor to measure temperature based on fluorescence decay time, which does not require regular calibration and reduces operation and maintenance costs. The flange can be opened with multiple through holes to support multi-channel expansion and adapt to transformers of different capacities. It has better versatility than the existing fixed channel design, is calibration-free, and has strong scalability. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0039] Figure 1 Schematic diagram of the structure of an embodiment of the present invention;

[0040] Figure 2 This is a schematic structural diagram of an optical fiber temperature sensor, a transmission and switching unit, and a flange fixing unit according to an embodiment of the present invention;

[0041] Figure 3 This is an exploded schematic diagram of the structure of the through-hole assembly and the flange fixing unit according to an embodiment of the present invention;

[0042] Figure 4 Schematic diagram of the structure explosion of the flange fixing unit and the protective cover assembly according to the embodiment of the present invention Figure 1 ;

[0043] Figure 5 Schematic diagram of the structure explosion of the flange fixing unit and the protective cover assembly according to the embodiment of the present invention Figure 2 ;

[0044] Figure 6 This is a schematic exploded view of the structure of a through-hole assembly according to an embodiment of the present invention;

[0045] Figure 7This is a schematic structural diagram of an optical fiber temperature sensor according to an embodiment of the present invention;

[0046] Figure 8 This is a schematic structural diagram of an external optical fiber extension cable according to an embodiment of the present invention.

[0047] In the figure: 100, optical fiber temperature sensor; 110, polyimide optical fiber core; 120, exposed temperature probe; 130, first ST connector; 140, polytetrafluoroethylene sheath;

[0048] 200, control and interaction unit;

[0049] 300, transmission and transfer unit; 310, feedthrough assembly; 311, feedthrough body; 3111, first groove; 312, double nut; 313, first sealing ring; 320, external optical fiber extension cable; 321, quartz optical fiber core; 322, second ST connector; 323, Teflon sheath;

[0050] 400, flange fixing unit; 410, flange ring; 411, second groove; 420, flange plate; 421, through hole; 430, second sealing ring;

[0051] 500, protection unit; 510, protection box assembly; 511, box body; 5111, first threading hole; 512, box door; 5121, glass observation window; 520, protection cover assembly; 521, cover body; 5211, outer edge; 5212, inner edge; 5213, second threading hole; 522, cover; 523, ring gasket. DETAILED DESCRIPTION

[0052] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention is further described below in conjunction with the accompanying drawings and embodiments. It should be noted that, in the absence of conflict, the embodiments of the present application and the features therein can be combined with each other.

[0053] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0054] Example 1

[0055] like Figures 1-8 As shown, the transformer winding fluorescent optical fiber temperature measurement device according to an embodiment of the present invention includes an optical fiber temperature sensor 100, a control and interaction unit 200, a transmission and switching unit 300, a flange fixing unit 400 and a protection unit 500, wherein:

[0056] The optical fiber temperature sensor 100 directly contacts the hot spot of the transformer winding, and returns a temperature-related fluorescence signal after receiving the excitation light, realizing temperature perception without metal intervention; the control and interaction unit 200 centrally controls the temperature measurement process of each channel, displays the temperature data in real time, and triggers an over-temperature alarm; the transmission and adapter unit 300 is used to realize the sealed adapter of the optical fiber inside and outside the transformer tank, and extend the signal transmission distance, and includes a through-hole component 310 and an external optical fiber extension line 320. The through-hole component 310 is connected between the external optical fiber extension line 320 and the optical fiber temperature sensor 100, and the external optical fiber extension line 320 is connected between the control and interaction unit 200 and the through-hole component 310. The optical fiber temperature sensor 100 is passed through the transformer tank wall through the through-hole component 310; the flange fixing unit 400 is used to form a mounting base for the through-hole component 310. The through-hole assembly 310 is arranged on the oil tank through the flange fixing unit 400; the protection unit 500 is used to protect the control and interaction unit 200, the through-hole assembly 310 and the external optical fiber extension line 320 to prevent damage, and includes a protection box assembly 510 and a protection cover assembly 520. The protection box assembly 510 is arranged away from the protection cover assembly 520, and part of the structure of the control and interaction unit 200 and the external optical fiber extension line 320 is respectively arranged in the protection box assembly 510, and the other part of the structure of the through-hole assembly 310 and the external optical fiber extension line 320 is respectively arranged in the protection cover assembly 520; an integrated temperature measurement system is provided to solve the problem of functional dispersion and low reliability caused by the existing technology only focusing on local structures such as a single probe, and to achieve full process coverage from temperature perception to alarm control, and adapt to the complex environment of oil immersion, high voltage and strong electromagnetic of transformers.

[0057] Example 2

[0058] like Figures 1-8 As shown, the transformer winding fluorescent optical fiber temperature measurement device provided in this embodiment is different from that in embodiment 1 in that:

[0059] The fiber optic temperature sensor 100 includes a polyimide optical fiber core 110, an exposed temperature probe 120 with a built-in rare earth fluorescent material, a first ST connector 130, and a polytetrafluoroethylene (PTFE) sheath 140. The exposed temperature probe 120 and the first ST connector 130 are respectively connected to the ends of the polyimide optical fiber core 110. The PTFE sheath 140 is sleeved on the surface of the polyimide optical fiber core 110, and the exposed temperature probe 120 is located at the bottom end of the PTFE sheath 140. The fiber optic temperature sensor 100 has no metal components and directly contacts the winding hotspot, is resistant to high pressure and oil immersion corrosion, and is immune to EMI / RFI. The PTFE sheath 140 enhances mechanical protection, and the exposed probe 120 ensures a rapid temperature measurement response, solving the problems of traditional sensors with poor anti-interference and the inability to directly contact the hotspot.

[0060] The control and interaction unit 200 includes a fiber optic temperature measurement host, a signal processing submodule, and a communication submodule. The signal processing submodule and the communication submodule are integrated inside the fiber optic temperature measurement host. The three realize electrical connection and data interaction through the PCB circuit board inside the host; the internal electrical connection and data interaction are realized through the PCB circuit board, which reduces external wiring and improves anti-interference ability; the integrated design reduces the size of the device and facilitates installation, solving the problem that the existing technology requires external equipment to assist in data processing.

[0061] The optical fiber temperature measurement host includes a microprocessor, a liquid crystal display, a 1-8-bit dip switch, two relay output units and a power management unit. The liquid crystal display, the 1-8-bit dip switch and the two relay output units are electrically connected to the microprocessor respectively. The microprocessor, the liquid crystal display, the 1-8-bit dip switch and the two relay output units are electrically connected to the power management unit respectively. The microprocessor and the liquid crystal display are connected through an LVDS low-voltage differential signal interface. The microprocessor outputs temperature data and display control instructions (such as refresh frequency and brightness adjustment) to drive the display to display the temperature value of each channel in real time. The microprocessor and the dip switch are connected through GP The IO general input and output pins are connected, and the 1-8 bit status (on / off) of the dip switch is directly fed back to the microprocessor for reading configuration information such as the communication address; the microprocessor and the relay output unit are connected through a relay drive circuit (such as the ULN2003 chip). The high and low level signals output by the microprocessor are amplified by the drive circuit to control the on and off of the relay contacts, thereby realizing load control during over-temperature alarms; the power management unit converts AC220V into 5V and 3.3V DC power supplies, which are connected to the microprocessor, display screen, relay and other components through fused power cables to provide stable power supply for the entire optical fiber temperature measurement host;

[0062] The signal processing submodule includes a fluorescence signal receiving circuit, a photoelectric conversion unit, a temperature algorithm processor, and a multi-channel data acquisition module. The external optical fiber extension line 320 and the photoelectric conversion unit are respectively connected to the fluorescence signal receiving circuit, and the photoelectric conversion unit and the temperature algorithm processor are respectively electrically connected to the multi-channel data acquisition module; the fluorescence signal receiving circuit is connected to the external optical fiber extension line 320 via a pigtail, and the fluorescence signal transmitted by the external optical fiber is connected to the receiving circuit via a second ST connector 322. The optical lens in the receiving circuit focuses the signal to ensure that the signal is transmitted without attenuation; the fluorescence signal receiving circuit is connected to the photoelectric conversion unit via a coaxial shielded cable, and the fluorescence signal (light signal) captured by the receiving circuit is transmitted to the photosensitive diode of the photoelectric conversion unit and converted into a weak electrical signal (μV level); the photoelectric conversion unit is connected to the multi-channel data acquisition module via an operational amplifier, and the weak electrical signal is amplified and filtered before being input into the ADC (analog-to-digital converter) of the data acquisition module and converted into a digital signal; the multi-channel data acquisition module is connected to the temperature algorithm processor via an SPI bus, and the digital signal is transmitted to the algorithm processor. The processor calculates the temperature value based on the fluorescence decay time algorithm and then transmits the temperature data to the host microprocessor via internal circuits;

[0063] The communication submodule includes an RS485 interface circuit, a 4-20mA analog output interface circuit, a USB debugging interface circuit and a signal isolation unit. The RS485 interface circuit, the 4-20mA analog output interface circuit and the USB debugging interface circuit are electrically connected to the microprocessor respectively. The signal isolation unit is connected in series between the microprocessor and the RS485 interface circuit and the 4-20mA analog output interface circuit. The microprocessor and the RS485 interface circuit are connected through a UART interface. The digital signal output by the microprocessor is converted into an RS485 differential signal by the MAX485 chip and then transmitted through the signal isolation unit (optocoupler). 6N137) after isolation, and output through the RS485 interface (A+ / B-terminal) on the rear panel of the optical fiber temperature measurement host; the microprocessor is connected to the 4~20mA analog output interface circuit through a DAC digital-to-analog converter (such as AD5420), and the temperature digital signal output by the microprocessor is converted into a 4~20mA current signal by the DAC, corresponding to the temperature range of -40℃~200℃, and is led out to the external device through the terminal block; the microprocessor is connected to the USB debugging interface circuit through the CH340 chip (USB to UART), and the microprocessor data is converted into a USB signal by the chip, and is output to the external device through the USB on the side panel of the optical fiber temperature measurement host. The Type-B interface supports local debugging (such as parameter configuration and data reading) via a computer. The signal isolation unit is connected in series between the microprocessor and the RS485 and 4-20mA interfaces, and electrical isolation is achieved through optical coupling (isolation voltage ≥ 2500V) to prevent external high voltage or interference signals from invading the core circuit of the host. The microprocessor of the optical fiber temperature measurement host cooperates with the relay and display screen to achieve real-time display and over-temperature alarm with timely response. The signal processing submodule improves temperature measurement accuracy through the process of fluorescence signal reception, photoelectric conversion, data acquisition, and algorithm processing. The multiple interfaces (RS485 / 4-20mA / USB) and signal isolation design of the communication submodule ensure stable data transmission and adaptability to different monitoring systems.

[0064] The through-hole assembly 310 includes a through-hole body 311, a double nut 312 and a first sealing ring 313. The double nut 312 is threadedly sleeved on the surface of the through-hole body 311, and the top of the double nut 312 is in contact with the flange fixing unit 400. The through-hole body 311 is provided with a first groove 3111 that is adapted to the first sealing ring 313 on the side facing the flange fixing unit 400. The first sealing ring 313 is embedded in the inner cavity of the first groove 3111, and the through-hole body 311 is docked with the first ST connector 130; the double nut 312 realizes mechanical fixation and sealing reinforcement, the first sealing ring 313 can withstand oil pressure, and has low optical loss, thereby solving the problems of sealing failure and optical signal attenuation of existing devices and ensuring long-term reliable operation in an oil-immersed environment.

[0065] The external optical fiber extension cable 320 includes a quartz optical fiber core 321, a second ST connector 322 with a voltage dropper, and a Teflon sheath 323. A second ST connector 322 is connected to each end of the quartz optical fiber core 321. The Teflon sheath 323 is sleeved onto the surface of the quartz optical fiber core 321. The through-hole body 311 and the fluorescent signal receiving circuit are respectively connected to the two second ST connectors 322. The Teflon sheath 323 enhances tensile strength and temperature resistance. The second ST connector 322 with a voltage dropper design reduces signal reflections, extending the transmission distance, and meeting the needs of long-distance signal transmission inside and outside the transformer tank.

[0066] The flange fixing unit 400 includes a flange ring 410, a flange plate 420, and a second sealing ring 430. The flange ring 410 is welded to the inner wall of the transformer box, and the flange plate 420 is mounted on the flange ring 410 with screws. A second groove 411 is formed on the side of the flange ring 410 facing the flange plate 420. The second sealing ring 430 is embedded in the inner cavity of the second groove 411. The second sealing ring 430 is in contact with the bottom of the flange plate 420.

[0067] A through hole 421 is provided on the flange 420 for the through-device body 311 to pass through. The inner diameter of the through hole 421 is adapted to the outer diameter of the through-device body 311. A number of through holes 421 are provided on the flange 420 in a circular shape and at equal intervals. The first sealing ring 313 is fitted with the top of the flange 420. The double nut 312 is located in the inner cavity of the flange ring 410 and in contact with the flange 420. The flange ring 410 is welded and fixed with screws to the flange 420, and combined with the second sealing ring 430 to form a double seal, which is adapted to the modular installation of multiple through-device assemblies 310, meets the requirements of different channel numbers, and solves the problems of poor versatility and insufficient sealing performance of the existing flange structure.

[0068] The protective box assembly 510 includes a box body 511 and a box door 512. The control and interaction unit 200 is installed in the inner cavity of the box body 511. A plurality of first wire threading holes 5111 are provided at the bottom of the box body 511. The box door 512 is hinged to one side of the box body 511. A glass observation window 5121 is embedded on the surface of the box door 512. The box body 511 with an IP55 protection grade protects the control and interaction unit 200 from rain and dust. The glass observation window 5121 facilitates real-time temperature viewing. The first wire threading holes 5111 are adapted for waterproof connectors to improve installation flexibility and solve the problems of inconvenient maintenance and susceptibility to environmental damage of existing devices.

[0069] The protective cover assembly 520 includes a cover body 521, a cover 522 and a ring gasket 523. The bottom of the cover body 521 is integrally formed with an outer edge 5211, and the outer edge 5211 is mounted on the flange 420 by screws. The top of the cover body 521 is integrally formed with an inner edge 5212, and the cover 522 is mounted on the inner edge 5212 by screws. The ring gasket 523 is placed between the cover 522 and the inner edge 5212, and between the outer edge 5211 and the flange 420. One side of the surface of the cover body 521 is provided with three A second threading hole 5213 is provided, and waterproof connectors are installed in the inner cavities of the second threading hole 5213 and the first threading hole 5111 respectively. The external optical fiber extension line 320 passes through the corresponding second threading hole 5213 and the first threading hole 5111 into the box body 511 in turn; the 304 stainless steel cover body 521 and the silicone rubber ring gasket form a sealing protection to protect the through-device assembly 310 and the second ST connector 322. The waterproof connector of the second threading hole 5213 prevents water from entering the cable entrance, with a high protection level, thereby extending the life of the equipment.

[0070] The through-hole body 311, double nut 312, flange ring 410, and flange plate 420 are all made of 316 stainless steel, the cover body 521 and cover cap 522 are both made of 304 stainless steel, the first sealing ring 313 and the second sealing ring 430 are both fluororubber O-rings, and the ring gasket 523 is a silicone rubber sealing ring gasket. The cover body 521, cover cap 522 and ring gasket 523 all have special-shaped structures, which are composed of a part of circular arc structure and another part of flat structure. The second threading hole 5213 is opened on the flat structure; 316 stainless steel is resistant to transformer oil corrosion, 304 stainless steel takes into account both protection and cost, the fluororubber sealing ring is resistant to oil temperature, and the silicone rubber ring gasket enhances the sealing elasticity, ensuring the material stability of the device in long-term high temperature and oil-immersion environment, and solving the problem of short life caused by the corrosion resistance of the existing material.

[0071] The temperature algorithm processor performs a weighted least squares fitting algorithm for the fluorescence decay time, and its objective function is defined as:

[0072]

[0073] Among them, the weight factor w i Dynamically adjusted to:

[0074] Where:

[0075] I(t i ):t i Fluorescence intensity sampling value at the moment;

[0076] A: fluorescence signal amplitude, B: background noise offset;

[0077] τ: Fluorescence lifetime to be solved (with a temperature dependence) linear inverse relationship);

[0078] SNR(t i ): signal-to-noise ratio at time ti (calculated in real time by the multi-channel data acquisition module);

[0079] Measurement variance (system preset);

[0080] k: Noise immunity coefficient (configured by 1 to 8-bit DIP switches, k∈{1,2,3})

[0081] Technical principle of the equation:

[0082] 1. Dynamic weight design

[0083] Disadvantages of traditional methods: Existing technologies (such as CN214096419U) use fixed-weight least squares fitting, which is prone to τ calculation deviation due to noise under strong electromagnetic interference.

[0084] Innovations of this solution:

[0085] Weight w i and signal-to-noise ratio SNR(t i ) is proportional to the k-th power, and high signal-to-noise ratio time periods are given higher weights (such as Figure 1 Initial decay phase after the excitation light is turned off) to enhance the effective signal;

[0086] When SNR(t i ) is lower than the threshold (such as the late attenuation signal), the weight is automatically reduced to suppress noise interference.

[0087] Adaptability of parameter k: The anti-noise strength is set by the DIP switch (for example, when the transformer is unloaded, set k = 1 to maintain sensitivity, and when the load suddenly changes, set k = 3 to enhance the anti-noise.

[0088] 2. Multi-channel collaborative calibration

[0089] After calculating τ independently for each channel, cross-validation is performed using the temperature consistency constraint:

[0090]

[0091] T j : jth channel temperature, The mean temperature of all channels;

[0092] ΔT th : Threshold (default 5℃), exceeding the limit channel automatically triggers resampling;

[0093] Solve the pain points of existing technologies: avoid single point failure and reduce the frequency of manual calibration (the background technology in the manual points out that existing devices need to be calibrated regularly).

[0094] Implementation examples and effects:

[0095] Workflow:

[0096] 1. Signal acquisition: The photoelectric conversion unit outputs the fluorescence intensity sequence I(t1), I(t2),…, I(t N )(N=200 sampling points).

[0097] 2. Dynamic weight calculation:

[0098] Real-time computing (σ noise taken from the background noise in the absence of excitation);

[0099] according to Generate weight sequence ( preset by the system noise model).

[0100] 3. Fluorescence lifetime calculation:

[0101] Solve the objective function minimization problem and obtain the optimal τ value;

[0102] Substitute into the calibration formula Output temperature (a, b are probe calibration parameters).

[0103] 4. Multi-channel verification:

[0104] If a channel The microprocessor controls the channel to resample and give an alarm.

[0105] Technical Effect Table:

[0106]

[0107]

[0108] Differences from existing technologies:

[0109] 1. Non-universal formula: Existing fluorescence lifetime temperature measurement only uses I(t) = Ae -tτ , no dynamic weight mechanism is introduced; this equation combines the time-varying signal-to-noise ratio with the adjustable anti-noise strength, which is the first of its kind.

[0110] 2. Technical synergy: weight factor w i Rely on the real-time noise analysis function of the multi-channel data acquisition module;

[0111] The k value is configured through a patented 1 to 8 position DIP switch.

[0112] This equation perfectly matches the advantages of "anti-interference", "calibration-free" and "multi-channel expansion".

[0113] The workflow of the present invention is based on fluorescent fiber optic sensing technology and system collaborative design, and is as follows:

[0114] Temperature signal sensing: The signal processing submodule of the control and interaction unit 200 emits excitation light of a specific wavelength, which is transmitted via the external optical fiber extension cable 320 and the through-hole assembly 310 to the exposed temperature sensing probe 120 (with a built-in rare earth fluorescent material) of the optical fiber temperature sensor 100. The excitation light excites the fluorescent material and then turns off. The fluorescent material releases a fluorescent signal (afterglow) related to the ambient temperature, which is then returned along the original path.

[0115] Signal transmission and conversion: The fluorescence signal is transmitted to the fluorescence signal receiving circuit of the signal processing submodule via the optical fiber temperature sensor 100, the feedthrough assembly 310, and the external optical fiber extension cable 320. After being focused by the optical lens, it is transmitted to the photoelectric conversion unit and converted into a weak electrical signal. The multi-channel data acquisition module amplifies and filters the electrical signal and converts it into a digital signal through the ADC (analog-to-digital converter).

[0116] Temperature data processing: The temperature algorithm processor calculates the actual temperature value based on the fluorescence decay time (which is linearly related to temperature) and transmits it to the microprocessor of the control and interaction unit via the SPI bus. The microprocessor integrates multi-channel data, drives the LCD screen to display the temperature in real time, and compares it with the preset threshold value.

[0117] Alarm and data interaction: If the temperature exceeds the threshold, the microprocessor triggers the relay output through the relay drive circuit to implement an over-temperature alarm (such as cutting off the load). At the same time, the communication submodule transmits data to the host computer through the RS485 interface (Modbus protocol) and 4-20mA analog interface, or through the USB interface for local debugging. The signal isolation unit ensures that data transmission is not affected by external interference.

[0118] System protection and sealing guarantee: The flange fixing unit 400 prevents transformer oil leakage through double sealing (first sealing ring 313, second sealing ring 430), ensuring the sealing of the signal transmission path; the protective box assembly 510 and the protective cover 520 assembly respectively protect the control and interaction unit 200, the through-hole assembly 310 and the second ST connector, avoiding the influence of environmental factors (rain, dust), and ensuring the long-term stable operation of the system.

[0119] The above specific embodiments will allow those skilled in the art to easily implement the present invention. However, it should be understood that the present invention is not limited to the above specific embodiments. Based on the disclosed embodiments, those skilled in the art can arbitrarily combine different technical features to implement different technical solutions.

Claims

1. Transformer winding fluorescent optical fiber temperature measuring device, characterized in that: include: An optical fiber temperature sensor (100) directly contacts the hot spot of the transformer winding, receives excitation light, and returns a fluorescence signal related to temperature, thereby realizing temperature sensing without metal intervention; A control and interaction unit (200) centrally controls the temperature measurement process of each channel, displays temperature data in real time, and triggers an over-temperature alarm; A transmission and switching unit (300) is used to achieve sealed switching of optical fibers inside and outside a transformer oil tank and to extend the signal transmission distance, and comprises a through-hole assembly (310) and an external optical fiber extension line (320), wherein the through-hole assembly (310) is connected between the external optical fiber extension line (320) and an optical fiber temperature sensor (100), and the external optical fiber extension line (320) is connected between a control and interaction unit (200) and the through-hole assembly (310), and the optical fiber temperature sensor (100) is penetrated through the wall of the transformer oil tank through the through-hole assembly (310); A flange fixing unit (400) is used to form a mounting base for the through-hole assembly (310), wherein the through-hole assembly (310) is mounted on the oil tank via the flange fixing unit (400); A protection unit (500) is used to protect a control and interaction unit (200), a through-hole assembly (310) and an external optical fiber extension line (320) from damage, and comprises a protection box assembly (510) and a protection cover assembly (520). The protection box assembly (510) is arranged away from the protection cover assembly (520), a part of the structure of the control and interaction unit (200) and the external optical fiber extension line (320) is respectively arranged in the protection box assembly (510), and another part of the structure of the through-hole assembly (310) and the external optical fiber extension line (320) is respectively arranged in the protection cover assembly (520).

2. The transformer winding fluorescent optical fiber temperature measurement device according to claim 1, characterized in that: The optical fiber temperature sensor (100) comprises a polyimide optical fiber core (110), a bare temperature sensing probe (120) with a built-in rare earth fluorescent material, a first ST connector (130) and a polytetrafluoroethylene sheath (140), wherein the bare temperature sensing probe (120) and the first ST connector (130) are respectively connected to two ends of the polyimide optical fiber core (110), the polytetrafluoroethylene sheath (140) is sleeved on the surface of the polyimide optical fiber core (110), and the bare temperature sensing probe (120) is located at the bottom end of the polytetrafluoroethylene sheath (140).

3. The transformer winding fluorescent optical fiber temperature measurement device according to claim 2, characterized in that: The control and interaction unit (200) comprises an optical fiber temperature measurement host, a signal processing submodule, and a communication submodule. The signal processing submodule and the communication submodule are both integrated inside the optical fiber temperature measurement host. The three realize electrical connection and data interaction through a PCB circuit board inside the host.

4. The transformer winding fluorescent optical fiber temperature measurement device according to claim 3, characterized in that: The optical fiber temperature measurement host includes a microprocessor, a liquid crystal display, a 1-8-bit dial switch, two relay output units and a power management unit. The liquid crystal display, the 1-8-bit dial switch, and the two relay output units are electrically connected to the microprocessor respectively. The microprocessor, the liquid crystal display, the 1-8-bit dial switch, and the two relay output units are electrically connected to the power management unit respectively; The signal processing submodule comprises a fluorescence signal receiving circuit, a photoelectric conversion unit, a temperature algorithm processor and a multi-channel data acquisition module, the external optical fiber extension line (320) and the photoelectric conversion unit are respectively connected to the fluorescence signal receiving circuit, and the photoelectric conversion unit and the temperature algorithm processor are respectively electrically connected to the multi-channel data acquisition module; The communication submodule includes an RS485 interface circuit, a 4-20mA analog output interface circuit, a USB debugging interface circuit and a signal isolation unit. The RS485 interface circuit, the 4-20mA analog output interface circuit and the USB debugging interface circuit are electrically connected to the microprocessor respectively, and the signal isolation unit is connected in series between the microprocessor and the RS485 interface circuit and the 4-20mA analog output interface circuit.

5. The transformer winding fluorescent optical fiber temperature measurement device according to claim 4, characterized in that: The through-hole assembly (310) includes a through-hole body (311), a double nut (312) and a first sealing ring (313), wherein the double nut (312) is threadedly sleeved on the surface of the through-hole body (311), and the top of the double nut (312) contacts the flange fixing unit (400), and the through-hole body (311) is provided with a first groove (3111) adapted to the first sealing ring (313) on the side facing the flange fixing unit (400), and the first sealing ring (313) is embedded in the inner cavity of the first groove (3111), and the through-hole body (311) is docked with the first ST connector (130).

6. The transformer winding fluorescent optical fiber temperature measurement device according to claim 5, characterized in that: The external optical fiber extension line (320) comprises a quartz optical fiber core (321), a second ST connector (322) with a voltage reducer, and a Teflon sheath (323); the second ST connector (322) is connected to one of the two ends of the quartz optical fiber core (321); the Teflon sheath (323) is sleeved on the surface of the quartz optical fiber core (321); the through-hole body (311) and the fluorescent signal receiving circuit are respectively connected to the two second ST connectors (322).

7. The transformer winding fluorescent optical fiber temperature measurement device according to claim 6, characterized in that: The flange fixing unit (400) includes a flange ring (410), a flange plate (420) and a second sealing ring (430). The flange ring (410) is welded to the inner wall of the transformer box. The flange plate (420) is mounted on the flange ring (410) by screws. A second groove (411) is provided on the side of the flange ring (410) facing the flange plate (420). The second sealing ring (430) is embedded in the inner cavity of the second groove (411). The second sealing ring (430) is in contact with the bottom of the flange plate (420), wherein: The flange (420) is provided with a through hole (421) for the through-device body (311) to pass through. The inner diameter of the through hole (421) is adapted to the outer diameter of the through-device body (311). A plurality of through holes (421) are provided in an annular shape and equidistantly on the flange (420). The first sealing ring (313) is fitted with the top of the flange (420). The double nut (312) is located in the inner cavity of the flange ring (410) and is in contact with the flange (420).

8. The transformer winding fluorescent optical fiber temperature measurement device according to claim 7, characterized in that: The protective box assembly (510) includes a box body (511) and a box door (512), the control and interaction unit (200) is installed in the inner cavity of the box body (511), a plurality of first threading holes (5111) are opened at the bottom of the box body (511), the box door (512) is hinged to one side of the box body (511), and a glass observation window (5121) is embedded on the surface of the box door (512).

9. The transformer winding fluorescent optical fiber temperature measurement device according to claim 8, characterized in that: The protective cover assembly (520) includes a cover body (521), a cover (522) and a ring gasket (523). The bottom of the cover body (521) is integrally formed with an outer edge (5211), and the outer edge (5211) is mounted on the flange (420) by screws. The top of the cover body (521) is integrally formed with an inner edge (5212), and the cover (522) is mounted on the inner edge (5212) by screws. The ring gasket (523) is mounted on the cover (521). 2) and one is placed between the inner edge (5212), the outer edge (5211) and the flange (420), respectively; one side of the surface of the cover body (521) is provided with three second threading holes (5213); the inner cavities of the second threading holes (5213) and the first threading holes (5111) are respectively installed with waterproof connectors; the external optical fiber extension line (320) passes through the corresponding second threading holes (5213) and the first threading holes (5111) in sequence and passes into the box body (511).

10. The transformer winding fluorescent optical fiber temperature measurement device according to claim 9, characterized in that: The through-hole body (311), double nut (312), flange ring (410), and flange plate (420) are all made of 316 stainless steel, the cover body (521) and cover (522) are all made of 304 stainless steel, the first sealing ring (313) and the second sealing ring (430) are both fluororubber sealing rings, and the ring gasket (523) is a silicone rubber sealing ring gasket.

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