A magnetic-rotor type power transformer short-circuit transient oil flow maximum velocity measuring device

Abstract

The application relates to a magnetic-rotation type power transformer short-circuit transient oil flow maximum speed measuring device, which comprises a non-magnetic oil pipe connected in series between two transformer oil pipes, the inner cavity of the non-magnetic oil pipe is provided with an internal magnetic field rotating device, and the outer wall is provided with an inductive detection mechanism and an oscilloscope; the internal magnetic field rotating device comprises a coaxially arranged impeller shaft and an impeller rotatingly arranged on the impeller shaft, the outer circumferential surface of the impeller is provided with blades, and the top is provided with a permanent magnet; the inductive detection mechanism comprises a stator core corresponding to the position of the permanent magnet and a fixed inductive conductor. The oil flow drives the impeller to rotate the permanent magnet to form an alternating magnetic field, the inductive conductor cuts the magnetic induction lines to generate an inductive electric signal, and the oscilloscope collects the signal frequency and converts the signal frequency to obtain the maximum speed of the oil flow. The application has the advantages that the maximum speed of the transformer short-circuit transient oil flow can be accurately captured, the structure is simple, the installation is convenient, the anti-interference performance is high, and reliable data support can be provided for transformer winding state evaluation and fault diagnosis.

Description

Technical Field

[0001] This invention relates to the field of measuring the maximum instantaneous oil flow velocity during a short circuit in large power transformers, and specifically to a device for measuring the maximum instantaneous oil flow velocity during a short circuit in a magnetic rotary power transformer. Background Technology

[0002] Large power transformers, as core hubs for power transmission and transformation, directly impact the safety and stability of the entire power system, serving as crucial support for implementing national energy policies and ensuring efficient energy supply. With the continuous increase in power system capacity, the operating conditions faced by large power transformers are becoming increasingly complex. Sudden short circuits, one of their most destructive faults, not only damage equipment but can also trigger large-scale power outages and significant economic and social losses. Therefore, improving their ability to detect and diagnose sudden short circuit faults is a critical issue for ensuring the safe operation of the power system. When a sudden short circuit fault occurs in a large power transformer, the windings are subjected to a strong electrodynamic impact, and a large amount of heat is rapidly generated at the fault point. This heat is transferred to the insulating oil, causing it to vaporize and expand violently, resulting in a rapid transient change in oil flow within the oil pipe connected to the tank, lasting approximately 200 ms. This transient oil flow signal is directly related to the mechanical state of the windings and the severity of the fault; the higher the maximum oil flow velocity, the greater the mechanical damage to the windings and the more severe the fault. However, currently, there is no mature and reliable dedicated solution for measuring the maximum instantaneous oil flow velocity in large power transformers during a short circuit. Furthermore, existing fault assessment methods for large power transformers are inefficient, costly, and unable to reflect instantaneous damage. Therefore, there is an urgent need to propose a magnetic rotary power transformer short-circuit transient oil flow maximum velocity measurement device. Summary of the Invention

[0003] Purpose of the invention To overcome the shortcomings of existing technologies, this invention provides a magnetic rotary power transformer short-circuit transient oil flow maximum velocity measurement device. Addressing the problem of rapid transient changes and short duration of oil flow during short circuits in large power transformers, this invention utilizes Faraday's principle of electromagnetic induction to design a reasonable measurement structure and device to obtain the maximum oil flow velocity information during short circuits. This allows for accurate assessment of the winding mechanical condition and fault severity, and the use of measured data to optimize transformer operation and maintenance strategies, improve fault diagnosis accuracy, and ensure the safe and stable operation of the power system.

[0004] To achieve the above objectives, the present invention provides the following technical solution: A device for measuring the maximum velocity of transient oil flow during short circuit in a magnetic rotary power transformer includes a non-magnetic oil pipe, an internal magnetic field rotation device, an induction detection mechanism, and an oscilloscope. The non-magnetic oil pipe is connected in series between two sections of transformer oil pipe, and the non-magnetic oil pipe is interconnected with the two sections of transformer oil pipe. The internal magnetic field rotating device is disposed inside the cavity of the non-magnetic oil pipe. The internal magnetic field rotating device includes an impeller shaft, an impeller, a pressure block, and a permanent magnet. The impeller shaft is located inside the non-magnetic oil pipe and is coaxial with the non-magnetic oil pipe. The impeller is rotatably mounted on the impeller shaft and rotates around the axis of the non-magnetic oil pipe. The permanent magnet is fixed to the top of the impeller by the pressure block and rotates synchronously with the impeller. The induction detection mechanism is fixed on the outer wall of the non-magnetic oil pipe; the oscilloscope is electrically connected to the induction detection mechanism; the induction detection mechanism includes a stator core and an induction conductor, the stator core being positioned corresponding to the permanent magnet; the induction conductor passes through the interior of the stator core and is fixed relative to the non-magnetic oil pipe, used to cut the magnetic field lines of the rotating and changing magnetic field to generate an induced electrical signal; the oscilloscope is electrically connected to both ends of the induction conductor, used to collect the frequency parameters of the induced electrical signal, and to obtain the maximum velocity of the oil flow at the moment of transformer short circuit based on a pre-stored flow velocity conversion model.

[0005] As a further description of the above solution, both ends of the non-magnetic oil pipe are provided with flange connection structures and sealing rings. The flange connection structure includes a first screw and a first nut. The non-magnetic oil pipe is coaxially and sealed to the transformer oil pipes on both sides through the first screw and the first nut. The sealing ring includes a first sealing ring and a second sealing ring. The transformer oil pipe includes a left section and a right section. The sealing rings are respectively disposed on the end faces of the non-magnetic oil pipe connected to the transformer oil pipes on both sides.

[0006] As a further description of the above solution, a first dovetail-shaped assembly groove is provided on the inner wall of the non-magnetic oil pipe; multiple first dovetail-shaped assembly grooves are provided, and multiple first dovetail-shaped assembly grooves are symmetrically arranged on the left and right sides of the non-magnetic oil pipe, and the first dovetail-shaped assembly grooves on each side are evenly arranged circumferentially. The impeller shaft includes a left section and a right section, which are connected by a threaded groove and a thread. The left section of the impeller shaft is provided with a first limiting groove, and the right section of the impeller shaft is provided with a second limiting groove. The internal magnetic field rotating device also includes multiple support rods, which are divided into first-type support rods and second-type support rods. The first-type support rods and second-type support rods are divided into left and right sets of installation units. The number of first-type support rods and second-type support rods in the two sets of installation units is equal, and they respectively support the left section of the impeller shaft and the right section of the impeller shaft. The first type of support rod has a first dovetail-shaped assembly protrusion at one end and a support circular surface at the other end; the second type of support rod has a first dovetail-shaped assembly protrusion at one end and a support circular surface at the other end, with a rectangular assembly protrusion protruding from the center of the support circular surface; the first dovetail-shaped assembly protrusions of the first and second types of support rods are matched and installed with the first dovetail-shaped assembly groove of the non-magnetic oil pipe, so that the support rod is fixedly connected to the non-magnetic oil pipe; The supporting circular surfaces of the first type of support rod and the second type of support rod are tightly fitted to the outer end face of the corresponding impeller shaft section to limit the radial displacement of the impeller shaft; the rectangular mounting protrusion of the second type of support rod is inserted into the corresponding first or second limiting groove to limit the circumferential rotation and axial displacement of the impeller shaft; the impeller shaft is fixed to the center of the inner cavity of the non-magnetic oil pipe by multiple first type of support rods and second type of support rods, and the impeller shaft and the non-magnetic oil pipe are coaxially arranged.

[0007] As a further description of the above scheme, the permanent magnet includes multiple first permanent magnets and second permanent magnets with alternating N and S poles; a third limiting groove is provided on the top of the impeller; the first and second permanent magnets are embedded in the third limiting groove of the impeller; a pressure block is provided between adjacent first and second permanent magnets, the pressure block has a trapezoidal structure that is narrow at the bottom and wide at the top, a first threaded hole is provided on the pressure block, and the pressure block is fixedly connected to the impeller by a second screw; the inclined surface of the pressure block abuts against the side wall of the adjacent first and second permanent magnets, fixing the first and second permanent magnets to the impeller.

[0008] As a further description of the above solution, it also includes multiple snap-fit ​​fasteners; a second dovetail-shaped mounting protrusion is provided at the top of the non-magnetic oil tube; a second dovetail-shaped mounting groove is provided at the bottom of the stator core, the second dovetail-shaped mounting groove and the second dovetail-shaped mounting protrusion are matched and installed to detachably fix the stator core to the outer wall of the non-magnetic oil tube; a through conductor hole is opened inside the stator core; the induction conductor passes through the conductor hole of the stator core; a limiting cylinder is provided at the top of the non-magnetic oil tube, and multiple limiting cylinders are provided; a cylindrical limiting groove is provided inside each snap-fit ​​fastener, the cylindrical limiting groove of the snap-fit ​​fastener is matched and assembled with the limiting cylinder of the non-magnetic oil tube; a second threaded hole is opened in the snap-fit ​​fastener, a third screw passes through the second threaded hole of the snap-fit ​​fastener, and a second nut is used to lock the snap-fit ​​fastener to the outer wall of the non-magnetic oil tube; multiple snap-fit ​​fasteners press and fix the induction conductor to the top of the non-magnetic oil tube.

[0009] As a further description of the above scheme, the oscilloscope has a pre-stored flow rate conversion model, which is: v=k×f / N; v is the maximum velocity of the oil flow at the moment of transformer short circuit; k is a preset flow rate-speed coefficient, which is determined by the impeller model; f is the frequency of the induced electrical signal acquired by the oscilloscope; N is the number of pulses generated by the induced electrical signal in one revolution of the impeller.

[0010] As a further description of the above solution, a ball bearing structure is provided at the contact point between the impeller and the impeller shaft; the impeller rotates around the impeller shaft through the ball bearing structure; a first limiting protrusion is provided on the left section of the impeller shaft; a second limiting protrusion is provided on the right section of the impeller shaft; a first rubber ring is provided between the first limiting protrusion and the left end face of the impeller; a second rubber ring is provided between the second limiting protrusion and the right end face of the impeller.

[0011] As a further description of the above solution, the non-magnetic oil pipe, impeller, first type of support rod and second type of support rod are all made of high-strength non-magnetic engineering plastic by 3D printing. The high-strength non-magnetic engineering plastic is CF-PA12 or PPS-GF20.

[0012] As a further description of the above scheme, a rectangular limiting groove is provided on the top of the stator core; the oscilloscope is fixed in the rectangular limiting groove of the stator core; and the lead wire of the oscilloscope is electrically connected to the two ends of the induction conductor through the connecting terminal.

[0013] Advantages and effects of the present invention: 1. This invention achieves speed measurement by utilizing the principle that oil flow drives the rotation of permanent magnets on the impeller, creating a changing magnetic field, and the conductor cutting magnetic field lines to generate induced current. It can directly capture the maximum oil flow velocity at the moment of a transformer short circuit. This provides important information for accurate diagnosis of sudden short-circuit faults in transformers and subsequent repair decisions, helping to improve transformer fault prevention capabilities and extend equipment lifespan.

[0014] 2. This invention focuses on the transient response design of short-circuit oil flow, eliminating redundant parameter acquisition and focusing on the correlation between maximum oil flow velocity and winding damage and fault level. By capturing the maximum oil flow velocity data, the intensity of the electrodynamic impact on the winding and the severity of the vaporization and expansion of the insulating oil can be directly deduced, thereby determining whether the winding has experienced mechanical faults such as deformation, displacement, or even breakage, as well as the severity of the fault. This provides clear direction for fault diagnosis, significantly improves diagnostic efficiency, and avoids the waste of time and manpower caused by blind troubleshooting.

[0015] 3. When using the measurement structure of this invention to measure the maximum oil flow velocity, the measurement structure is directly connected to both sides of the oil pipe via flange connections, eliminating the need for large-scale modifications to the transformer tank and oil pipes. Furthermore, it boasts strong installation adaptability, and the velocity is measured using the waveform of the electrical signal displayed on an oscilloscope. The measurement process does not affect the normal operation of the transformer, significantly reducing the operational difficulty and implementation cost of on-site testing, minimizing measurement time, and significantly improving the on-site feasibility and practical application value of the measurement solution.

[0016] 4. This invention utilizes the principle of electromagnetic induction to design the measurement structure. It only requires capturing the electrical signal waveform using an oscilloscope, eliminating the need for complex sensing and data processing modules. The invention primarily employs mortise and tenon joints to assemble the components and incorporates multiple limiting measures for the components. The structural design is simple and highly resistant to interference, effectively mitigating the influence of the testing environment on the measurement signal. This ensures the stability and accuracy of the oil flow velocity measurement data, providing a reliable guarantee for the precise assessment of the winding's mechanical condition. Attached Figure Description

[0017] Figure 1 This is a left view of the three-dimensional structure of an embodiment of the present invention; Figure 2 This is a front view of the three-dimensional structure of an embodiment of the present invention; Figure 3 This is a right view of the three-dimensional structure of an embodiment of the present invention; Figure 4 This is a side view of the three-dimensional structure of an embodiment of the present invention; Figure 5 This is a schematic diagram of the stator structure of the present invention; Figure 6 This is a schematic diagram of the non-magnetic oil pipe structure of the present invention; Figure 7 This is a schematic diagram of the impeller and pressure block when the permanent magnet of the present invention is hidden; Figure 8 This is a schematic diagram of the left section of the impeller shaft structure of the present invention; Figure 9 This is a schematic diagram of the right section of the impeller shaft of the present invention; Figure 10 This is a schematic diagram of the support rod structure of the present invention; Figure 11 This is a schematic diagram of the assembly of the support rod and the non-magnetic oil pipe of the present invention; Figure 12 This is a schematic diagram of the assembly of the support rod and the impeller shaft of the present invention; Figure 13 This is a schematic diagram showing the connection between the stator core and the partially concealed conductors of the present invention. Figure 14 This is a cross-sectional view of the conductor assembly of the present invention, wherein the upper view is a cross-sectional view of the conductor and the lower view is an assembly view of the conductor; Figure 15 This is a schematic diagram of the stator assembly of the present invention; Figure 16 This is a magnetic field vector distribution diagram of the present invention; Figure 17 This is the magnetic vector potential cloud diagram of the present invention; Figure 18 The image shows the induced voltage waveform displayed on an oscilloscope when the rotational speed is 60 rpm, according to the present invention. Figure 19 This is a partially enlarged view of the snap-fit ​​installation of the present invention; Figure 20 This is a schematic diagram of the impeller structure of the present invention.

[0018] Explanation of reference numerals in the attached drawings: 1-Non-magnetic oil pipe; 2A-First dovetail-shaped assembly groove; 2B-Second dovetail-shaped assembly groove; 3A-First dovetail-shaped assembly protrusion; 3B-Second dovetail-shaped assembly protrusion; 4-Support rod; 4A-First type of support rod; 4B-Second type of support rod; 5-Stator core; 6-Impeller shaft; 6A-Left section of impeller shaft; 6B-Right section of impeller shaft; 7A-Left front buckle; 7B-Left rear buckle; 7C-Right front buckle; 7D-Right rear buckle; 8A-First sealing ring; 8B-Second sealing ring; 9A-Left section of transformer oil pipe; 9B-Right section of transformer oil pipe; 10A-First screw; 10B-Second screw; 10C-Third screw; 11-Pressure block; 12-Impeller; 13A-First limiting groove; 13 B - Second limiting groove; 13C - Third limiting groove; 14A - First limiting protrusion; 14B - Second limiting protrusion; 15A - First rubber ring; 15B - Second rubber ring; 16A - First threaded hole; 16B - Second threaded hole; 16C - Third threaded hole; 17 - Permanent magnet; 17A - First permanent magnet; 17B - Second permanent magnet; 18 - Oscilloscope; 19 - Supporting circular surface; 20 - Rectangular assembly protrusion; 21 - Lead wire; 22 - Threaded groove; 23 - Thread; 24 - Induction conductor; 25 - Limiting cylinder; 26 - Cylindrical limiting groove; 27 - Connecting terminal; 28A - First nut; 28B - Second nut; 29 - Ball bearing structure; 30 - Blade; 31 - Rectangular limiting groove; 32 - Conductor hole. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] A device for measuring the maximum velocity of transient oil flow during short circuit in a magnetic rotary power transformer includes a non-magnetic oil pipe 1, an internal magnetic field rotation device, an induction detection mechanism, and an oscilloscope 18. The non-magnetic oil pipe 1 is connected in series between two sections of transformer oil pipe, and the non-magnetic oil pipe 1 is interconnected with the two sections of transformer oil pipe. An internal magnetic field rotation device is installed inside the non-magnetic oil pipe 1. The internal magnetic field rotation device includes an impeller shaft 6, an impeller 12, a pressure block 11, and a permanent magnet 17. The impeller shaft 6 is located inside the non-magnetic oil pipe 1 and is coaxial with the non-magnetic oil pipe 1. The impeller 12 is rotatably mounted on the impeller shaft 6 and rotates around the axis of the non-magnetic oil pipe 1. The outer circumferential surface of the impeller 12 has blades 30, which are used to drive the impeller 12 to rotate by the impact of the oil flow inside the non-magnetic oil pipe 1. The permanent magnet 17 is fixed in the third limiting groove 13C on the top of the impeller 12 by the pressure block 11, and the permanent magnet 17 rotates synchronously with the impeller 12. The induction detection mechanism is fixed on the outer wall of the non-magnetic oil pipe 1; the oscilloscope 18 is electrically connected to the induction detection mechanism; the induction detection mechanism includes a stator core 5 and an induction conductor 24, the stator core 5 and the permanent magnet 17 are positioned correspondingly; the induction conductor 24 passes through the inside of the stator core 5 and is fixed relative to the non-magnetic oil pipe 1, and is used to cut the magnetic field lines of the rotating and changing magnetic field to generate an induced electrical signal; the oscilloscope 18 is electrically connected to both ends of the induction conductor 24, and is used to collect the frequency parameters of the induced electrical signal, and obtain the maximum velocity of the oil flow at the moment of transformer short circuit based on the pre-stored flow velocity conversion model.

[0021] The non-magnetic oil pipe 1 of the present invention has flange connection structures and sealing rings at both ends. The flange connection structure includes a first screw 10A, a third threaded hole 16C, and a first nut 28A. The non-magnetic oil pipe 1 is coaxially and sealed to the transformer oil pipes 9 on both sides through the first screw 10A, the third threaded hole 16C, and the first nut 28A. The sealing rings include a first sealing ring 8A and a second sealing ring 8B. The transformer oil pipe includes a left section 9A and a right section 9B. The sealing rings are respectively disposed on the end faces of the non-magnetic oil pipe 1 that connect to the transformer oil pipes on both sides. Specifically, the first sealing ring 8A is disposed at one end of the non-magnetic oil pipe 1, and the second sealing ring 8B is disposed at the other end of the non-magnetic oil pipe 1.

[0022] The non-magnetic oil pipe 1 of the present invention has a first dovetail-shaped assembly groove 2A on its inner wall; there are multiple first dovetail-shaped assembly grooves 2A, and the multiple first dovetail-shaped assembly grooves 2A are symmetrically arranged on the left and right sides of the non-magnetic oil pipe 1, and the first dovetail-shaped assembly grooves 2A on each side are evenly arranged along the circumference. The impeller shaft 6 includes a left section 6A and a right section 6B, which are connected by a threaded groove 22 and a thread 23. The left section 6A is provided with a first limiting groove 13A, and the right section 6B is provided with a second limiting groove 13B. The internal magnetic field rotation device also includes multiple support rods, which are divided into first type support rods 4A and second type support rods 4B. The first type support rods 4A and second type support rods 4B are divided into two sets of installation units, left and right. The number of first type support rods 4A and second type support rods 4B in the two sets of installation units is equal, and they respectively support the left section 6A and the right section 6B of the impeller shaft. The first type of support rod 4A has a first dovetail-shaped mounting protrusion 3A at one end and a support circular surface 19 at the other end; the second type of support rod 4B has a first dovetail-shaped mounting protrusion 3A at one end and a support circular surface 19 at the other end, with a rectangular mounting protrusion 20 protruding from the center of the support circular surface 19; the first dovetail-shaped mounting protrusion 3A of the first type of support rod 4A and the second type of support rod 4B are matched and installed with the first dovetail-shaped mounting groove 2A of the non-magnetic oil pipe 1, so that the support rod is fixedly connected to the non-magnetic oil pipe 1; The supporting circular surfaces 19 of the first type of support rod 4A and the second type of support rod 4B are tightly fitted with the outer end faces of the corresponding impeller shaft sections to limit the radial displacement of the impeller shaft 6. The rectangular mounting protrusion 20 of the second type of support rod 4B is inserted into the corresponding first limiting groove 13A or second limiting groove 13B to limit the circumferential rotation and axial displacement of the impeller shaft 6. The impeller shaft 6 is fixed to the center of the inner cavity of the non-magnetic oil pipe 1 by multiple first type of support rods 4A and second type of support rods 4B, and the impeller shaft 6 and the non-magnetic oil pipe 1 are coaxially arranged.

[0023] The permanent magnet 17 of the present invention includes multiple first permanent magnets 17A and second permanent magnets 17B arranged with alternating N and S poles; a third limiting groove 13C is provided on the top of the impeller 12; the first permanent magnets 17A and second permanent magnets 17B are embedded in the third limiting groove 13C of the impeller 12; a pressure block 11 is provided between adjacent first permanent magnets 17A and second permanent magnets 17B, the pressure block 11 has a trapezoidal structure that is narrow at the bottom and wide at the top, a first threaded hole 16A is provided on the pressure block 11, and the pressure block 11 is fixedly connected to the impeller 12 by a second screw 10B; the inclined surface of the pressure block 11 abuts against the side wall of the adjacent first permanent magnets 17A and second permanent magnets 17B, fixing the first permanent magnets 17A and second permanent magnets 17B to the impeller 12.

[0024] The magnetic rotary power transformer short-circuit transient oil flow maximum velocity measuring device of the present invention further includes a buckle, and multiple buckles are provided; a second dovetail-shaped mounting protrusion 3B is provided at the top of the non-magnetic oil pipe 1; a second dovetail-shaped mounting groove 2B is provided at the bottom of the stator core 5, and the second dovetail-shaped mounting groove 2B matches and is installed with the second dovetail-shaped mounting protrusion 3B to detachably fix the stator core 5 to the outer wall of the non-magnetic oil pipe 1; a through conductor hole 32 is opened inside the stator core 5; an induction conductor 24 passes through the conductor of the stator core 5. Inside the hole 32; a limiting cylinder 25 is provided at the top of the non-magnetic oil tube 1, and multiple limiting cylinders 25 are provided; each buckle has a cylindrical limiting groove 26 inside, and the cylindrical limiting groove 26 of the buckle matches and assembles with the limiting cylinder 25 of the non-magnetic oil tube 1; the buckle has a second threaded hole 16B, and the third screw 10C passes through the second threaded hole 16B of the buckle, and cooperates with the second nut 28B to lock and fix the buckle to the outer wall of the non-magnetic oil tube 1; multiple buckles press and fix the induction conductor 24 to the top of the non-magnetic oil tube 1.

[0025] The oscilloscope 18 of this invention has a pre-stored flow velocity conversion model, which is: v = k × f / N; v is the maximum velocity of the oil flow at the moment of transformer short circuit; k is a preset flow velocity-speed coefficient, which is determined by the model of impeller 12; f is the frequency of the induced electrical signal collected by the oscilloscope 18; N is the number of pulses generated by the induced electrical signal when impeller 12 rotates once, and the value of N in the measurement device of this application embodiment is 5.

[0026] The impeller 12 of the present invention is provided with a ball bearing structure 29 at the contact point with the impeller shaft 6; the impeller 12 rotates around the impeller shaft 6 through the ball bearing structure 29; a first limiting protrusion ring 14A is provided on the left section 6A of the impeller shaft; a second limiting protrusion ring 14B is provided on the right section 6B of the impeller shaft; a first rubber ring 15A is provided between the first limiting protrusion ring 14A and the left end face of the impeller 12; a second rubber ring 15B is provided between the second limiting protrusion ring 14B and the right end face of the impeller 12.

[0027] The non-magnetic oil pipe 1, impeller 12, first type support rod 4A and second type support rod 4B of the present invention are all made of high-strength non-magnetic engineering plastic by 3D printing. The high-strength non-magnetic engineering plastic is CF-PA12 or PPS-GF20.

[0028] The stator core 5 of the present invention is provided with a rectangular limiting groove 31 on its top; the oscilloscope 18 is fixed in the rectangular limiting groove 31 of the stator core 5; and the lead wire 21 of the oscilloscope 18 is electrically connected to both ends of the induction conductor 24 through the connecting terminal 27.

[0029] Specifically, the non-magnetic oil pipe 1 of this application is 3D printed from high-strength engineering plastics such as CF-PA12 and PPS-GF20. The impeller shaft is formed by connecting the left section 6A and the right section 6B of the impeller shaft via threaded grooves 22 and threads 23. The support rod includes a second type of support rod 4B with rectangular mounting protrusions 20 and a first type of support rod 4A without rectangular mounting protrusions 20. Four dovetail-shaped mounting grooves 2A are symmetrically and evenly distributed at both ends of the non-magnetic oil pipe 1 for mounting the support rods. Support rod for impeller shaft; two dovetail-shaped mounting protrusions 3B are opened at the top of non-magnetic oil pipe 1 for mounting stator core 5 for magnetic conduction; the buckles include left front buckle 7A, left rear buckle 7B, right front buckle 7C and right rear buckle 7D, and two limiting cylinders 25 are symmetrically distributed above non-magnetic oil pipe 1 to limit the axial movement of the buckles; its two ends are flanged to the left section 9A and right section 9B of transformer oil pipe via the first sealing ring 8A and the second sealing ring 8B.

[0030] The internal magnetic field rotation device is located inside the non-magnetic oil pipe 1 and mainly consists of two first-type support rods 4A and second-type support rods 4B, impeller shaft 6, pressure block 11, and impeller 12. The first type of support rod 4A and the second type of support rod 4B are 3D printed, totaling 8 rods, divided into two groups of 4 rods each. They are used to connect and fix the non-magnetic oil pipe 1 to the impeller shaft 6. Each group of support rods has two types, two of each type: one type is the first type of support rod 4A with a dovetail-shaped mounting protrusion 3A at one end and a supporting circular surface 19 at the other end; the other type is the second type of support rod 4B with a dovetail-shaped mounting protrusion 3A at one end and a supporting circular surface 19 and a rectangular mounting protrusion 20 integrally formed at the other end. The rectangular mounting protrusion 20 is used to restrict the axial movement of the impeller shaft 6, and the supporting circular surface 19 is used to restrict the radial movement of the impeller shaft 6. The impeller shaft is 3D printed, consisting of the left section 6A and the right section 6B of the impeller shaft connected by threaded grooves 22 and threads 23. The left section 6A of the impeller shaft has a threaded groove 22 at one end and a limiting groove 13A at the other end. The end with the threaded groove has a limiting protrusion ring 14A. The right section 6B of the impeller shaft... One end has a thread 23, and the other end has a limiting groove 13B. The threaded end has a limiting protrusion 14B. When the left and right sections of the impeller shaft are connected as a whole by the thread, the first limiting protrusion 14A and the second limiting protrusion 14B of the left section 6A and the right section 6B of the impeller shaft are engaged with the impeller 12 via the first rubber ring 15A and the second rubber ring 15B, restricting the axial movement of the impeller 12. The pressure block 11 is 3D printed and is narrow at the bottom and wide at the top. The trapezoidal block has a threaded hole 16A at its top, which can be used with screws 10B to fix the permanent magnet 17. The impeller 12 is 3D printed, with a 3D printed ball bearing structure 29 at its bottom, blades 30 in the middle, and a first permanent magnet 17A and a second permanent magnet 17B with a surface-mount structure at its top. The movement of the first permanent magnet 17A and the second permanent magnet 17B is restricted by the limiting groove 13C, the pressure block 11, the screws 10B, and the threaded hole 16A.

[0031] The induction conductor 24, installed on top of the non-magnetic oil tube 1, mainly consists of the induction conductor 24, a left front latch 7A, a left rear latch 7B, a right front latch 7C, and a right rear latch 7D, a stator core 5, and connecting terminals 27. The induction conductor 24 is composed of multiple strands of wire encapsulated in series, and its two ends are connected to the oscilloscope 18 via the connecting terminals 27. The stator core 5 has two dovetail-shaped mounting grooves 2B that match the dovetail-shaped mounting protrusions 3B of the non-magnetic oil tube 1. The stator core 5 is fixedly connected to the non-magnetic oil tube 1 through the mounting grooves 2B. Inside, there is a through conductor hole 32 for placing the induction conductor 24. A trapezoidal slot connected to the conductor hole guides magnetic field lines through the conductor, allowing them to be cut by the conductor. A rectangular limiting groove 31 at the center of its top is used to fix the oscilloscope 18. The latches include a left front latch... The induction conductor 24 passes through the stator core 5 and is fixed to the top of the non-magnetic oil tube 1 by the left front buckle 7A, left rear buckle 7B, right front buckle 7C, and right rear buckle 7D. The buckle has a cylindrical limiting groove 26 that matches the limiting cylinder 25 of the non-magnetic oil tube 1. There are two threaded holes 16B at the bottom of each buckle. The conductor is fixed above the non-magnetic oil tube 1 by the buckle, the non-magnetic oil tube limiting cylinder that matches the cylindrical limiting groove 26 inside the buckle, the threaded hole 16B, the screw 10B, and the nut 28B.

[0032] The oscilloscope 18 is fixed to the top of the non-magnetic oil tube 1 by a rectangular limiting groove 31, and the leads of the oscilloscope 18 are connected to the induction conductor 24 via two pairs of connecting terminals 27 on both sides.

[0033] The above measuring device can measure the maximum oil flow velocity at the moment of a short circuit in a large power transformer using Faraday's law of electromagnetic induction. The principle is as follows: When a large power transformer experiences a sudden short-circuit fault, the windings are subjected to a strong electrodynamic impact, instantly generating a large amount of heat. This causes the insulating oil to vaporize and expand violently, resulting in a rapid transient change in oil flow within the oil pipe connected to the tank, lasting approximately 200 ms. This device utilizes the oil flow to drive the blades 30 on the impeller 12 to rotate. The rotation of the blades 30 drives the permanent magnet to rotate, thereby creating a rotating magnetic field. This causes the induction conductor connected to the oscilloscope 18 to cut magnetic field lines, inducing an electrical signal. The waveform of this electrical signal in the oscilloscope 18 is then used to detect the instantaneous maximum oil flow velocity in the oil pipe.

[0034] This application achieves speed measurement by utilizing the principle that oil flow drives the rotation of permanent magnets on the impeller, creating a changing magnetic field, and the conductor cutting magnetic field lines to generate an induced electrical signal. This allows for the direct capture of the maximum oil flow velocity at the moment of a transformer short circuit. It provides crucial information for accurate diagnosis and subsequent repair decisions regarding sudden short-circuit faults in transformers, contributing to improved transformer fault prevention capabilities and extended equipment lifespan.

[0035] This application focuses on the transient response design of short-circuit oil flow, abandoning redundant parameter acquisition and focusing on the correlation between maximum oil flow velocity and winding damage and fault level. By capturing the maximum oil flow velocity data, the intensity of the electrodynamic impact on the winding and the severity of the vaporization and expansion of the insulating oil can be directly deduced, thereby determining whether the winding has undergone mechanical faults such as deformation, displacement, or even breakage, as well as the severity of the fault. This provides clear direction for fault diagnosis, significantly improves diagnostic efficiency, and avoids the waste of time and manpower caused by blind troubleshooting.

[0036] When individual components are damaged, the device can be directly disassembled and the damaged component replaced, greatly saving maintenance costs. The installation steps for each part are as follows: First, place the first permanent magnet 17A and the second permanent magnet 17B in the third limiting groove 13C on the top of the impeller 12 with the N poles and S poles alternating. Then, place the pressure block 11 in the middle of the first permanent magnet 17A and the second permanent magnet 17B in a narrow-at-the-bottom-wide-at-the-top form. Screw the second screw 10B into the threaded hole 16A to fix the first permanent magnet 17A and the second permanent magnet 17B.

[0037] The impeller 12 with a permanent magnet is placed between the left section 6A and the right section 6B of the impeller shaft. The two sections of the impeller shaft are fastened together by the threaded groove 22 and the thread 23. The first limiting protrusion 14A and the second limiting protrusion 14B of the left section 6A and the right section 6B of the impeller shaft are fastened to the impeller 12 via the first rubber ring 15A and the second rubber ring 15B, thereby restricting the axial movement of the impeller 12.

[0038] Four second-type support rods 4B with rectangular mounting protrusions 20 are installed on both sides of the non-magnetic oil pipe 1 via dovetail mounting grooves 2A and matching dovetail mounting protrusions 3A, with two rods installed at the lower end of each side, serving to fix and limit the impeller shaft. Then, the first limiting grooves 13A and second limiting grooves 13B of the left section 6A and right section 6B of the impeller shaft are assembled with the rectangular mounting protrusions 20 of the second-type support rods 4B. Finally, four first-type support rods 4A without rectangular limiting protrusions 20 are installed on both sides of the non-magnetic oil pipe 1 via dovetail mounting grooves 2A and matching dovetail mounting protrusions 3A, thus fixing the left section 6A and right section 6B of the impeller shaft.

[0039] Insert the induction conductor 24 into the conductor hole 32 of the stator core 5. Install the stator core with the conductor inserted at the top of the non-magnetic oil pipe 1 through the dovetail mounting groove 2B and the matching dovetail mounting protrusion 3B. Then, assemble the left front buckle 7A, left rear buckle 7B, right front buckle 7C and right rear buckle 7D together through the internal cylindrical limiting groove 26 and the matching non-magnetic oil pipe limiting cylinder 25. After passing the screw 10C through the threaded hole 16B, fix it with the nut 28B.

[0040] Place the oscilloscope 18 in the rectangular limiting groove of the stator core, and connect the leads 21 at both ends of the oscilloscope 18 to the conductor through the connecting terminals.

[0041] When using the measurement structure of this application to measure the maximum oil flow velocity, the measurement structure of this invention is directly connected to both sides of the oil pipe via flange connection, without the need for large-scale modification of the transformer tank and oil pipe. Furthermore, it has strong installation adaptability, and the velocity is measured by the waveform of the electrical signal displayed on an oscilloscope. The measurement process does not affect the normal operation of the transformer, significantly reducing the operational difficulty and implementation cost of on-site testing, reducing measurement time, and significantly improving the on-site feasibility and practical application value of the measurement scheme.

[0042] This application utilizes the principle of electromagnetic induction to design a measurement structure. It only requires capturing the electrical signal waveform using an oscilloscope, eliminating the need for complex sensing and data processing modules. The invention primarily employs mortise and tenon joints to assemble the components and incorporates multiple limiting measures for the components. The structural design is simple and highly resistant to interference, effectively mitigating the influence of the testing environment on the measurement signal. This ensures the stability and accuracy of the oil flow velocity measurement data, providing a reliable guarantee for the precise assessment of the winding's mechanical condition. As can be seen from the above measurement principle, this invention provides a measuring device for the maximum oil flow velocity at the moment of a short circuit in a large power transformer. It achieves the measurement of the maximum oil flow velocity at the moment of a short circuit in a large power transformer by applying the principle of electromagnetic induction. The measuring device mainly consists of a non-magnetic oil pipe (…). Figures 1-4 , Figure 6 , Figure 11 , Figure 13 , Figure 15 ), inductive conductor ( Figures 1-4 , Figures 13-15 ), and internal magnetic field rotation device ( Figures 1-4 , Figures 7-12 The device is constructed using an oscilloscope 18, which detects the instantaneous maximum oil flow velocity in the oil pipe by measuring the current waveform in the oscilloscope 18. Therefore, this measuring device can measure the maximum oil flow velocity at the moment of a short circuit in a large power transformer, providing direct and reliable measured data support for the assessment of the mechanical condition of transformer windings and the accurate diagnosis of sudden short circuit faults.

[0043] formula: (1), Where v is the oil flow velocity, k is the velocity-speed coefficient, n is the impeller speed, and K is determined by the impeller model and specified by the impeller manufacturer. (2), Where f is the frequency, and N is the number of pulses generated by one revolution of the impeller. In this device, N=5. From (1) and (2), we get .

[0044] like Figure 16 The figure shows the finite element simulation results of the two-dimensional magnetic field in this design. The blue magnetic block represents the N-pole permanent magnet, and the red magnetic block represents the S-pole permanent magnet. The figure illustrates the spatial distribution of the magnetic induction intensity B and the direction of the magnetic field vector. The magnetic field originates from the N-pole of the permanent magnet, passes through the air gap into the stator core, and then returns to the S-pole through the other air gap, forming a complete magnetic circuit. As can be seen from the figure, when the impeller drives the permanent magnet to rotate, the conductor located in the green area will cut the magnetic field lines, thereby generating an electrical signal.

[0045] like Figure 17 As shown, this figure displays a simulated contour plot of the magnetic vector potential A corresponding to the previous figure (magnetic induction intensity B). The phenomenon of magnetic field lines being cut by the conductor can be clearly seen.

[0046] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A device for measuring the maximum velocity of transient oil flow during a short circuit in a magnetic rotary power transformer, characterized in that, It includes a non-magnetic oil pipe (1), an internal magnetic field rotation device, an induction detection mechanism and an oscilloscope (18). The non-magnetic oil pipe (1) is connected in series between two sections of transformer oil pipe, and the non-magnetic oil pipe (1) is interconnected with the two sections of transformer oil pipe. The internal magnetic field rotating device is located inside the non-magnetic oil pipe (1). The internal magnetic field rotating device includes an impeller shaft (6), an impeller (12), a pressure block (11), and a permanent magnet (17). The impeller shaft (6) is located inside the non-magnetic oil pipe (1) and is coaxial with the non-magnetic oil pipe (1). The impeller (12) is rotatably mounted on the impeller shaft (6) and rotates around the axis of the non-magnetic oil pipe (1). The permanent magnet (17) is fixed to the top of the impeller (12) by the pressure block (11) and rotates synchronously with the impeller (12). The induction detection mechanism is fixed on the outer wall of the non-magnetic oil pipe (1); the oscilloscope (18) is electrically connected to the induction detection mechanism; the induction detection mechanism includes a stator core (5) and an induction conductor (24), the stator core (5) and the permanent magnet (17) are positioned correspondingly; the induction conductor (24) passes through the inside of the stator core (5), and the induction conductor (24) is fixed relative to the non-magnetic oil pipe (1), used to cut the magnetic field lines of the rotating and changing magnetic field to generate an induced electric signal; the oscilloscope (18) is electrically connected to both ends of the induction conductor (24), used to collect the frequency parameters of the induced electric signal, and obtain the maximum velocity of the oil flow at the moment of transformer short circuit based on the pre-stored flow velocity conversion model.

2. The device for measuring the maximum velocity of transient oil flow during short circuit in a magnetic rotary power transformer according to claim 1, characterized in that, The non-magnetic oil pipe (1) is provided with flange connection structure and sealing ring at both ends. The flange connection structure includes a first screw (10A) and a first nut (28A). The non-magnetic oil pipe (1) is coaxially and sealed to the transformer oil pipes (9) on both sides through the first screw (10A) and the first nut (28A). The sealing ring includes a first sealing ring (8A) and a second sealing ring (8B). The transformer oil pipe includes a left section (9A) and a right section (9B). The sealing rings are respectively provided on the end face of the non-magnetic oil pipe (1) connected to the transformer oil pipes on both sides.

3. The device for measuring the maximum velocity of transient oil flow during short circuit in a magnetic rotary power transformer according to claim 1, characterized in that, The inner wall of the non-magnetic oil pipe (1) is provided with a first dovetail-shaped assembly groove (2A); there are multiple first dovetail-shaped assembly grooves (2A), and multiple first dovetail-shaped assembly grooves (2A) are symmetrically arranged on the left and right sides of the non-magnetic oil pipe (1), and the first dovetail-shaped assembly grooves (2A) on each side are evenly arranged along the circumference. The impeller shaft (6) includes a left section (6A) and a right section (6B), which are connected by a threaded groove (22) and a thread (23). The left section (6A) is provided with a first limiting groove (13A), and the right section (6B) is provided with a second limiting groove (13B). The internal magnetic field rotation device also includes multiple support rods, which are divided into first type support rods (4A) and second type support rods (4B). The first type support rods (4A) and second type support rods (4B) are divided into left and right sets of installation units. The number of first type support rods (4A) and second type support rods (4B) in the two sets of installation units is equal, and they respectively support the left section (6A) and the right section (6B) of the impeller shaft. One end of the first type of support rod (4A) is provided with a first dovetail-shaped assembly protrusion (3A), and the other end of the first type of support rod (4A) is a support circular surface (19); one end of the second type of support rod (4B) is provided with a first dovetail-shaped assembly protrusion (3A), and the other end of the second type of support rod (4B) is provided with a support circular surface (19), and a rectangular assembly protrusion (20) protrudes from the center of the support circular surface (19); the first dovetail-shaped assembly protrusion (3A) of the first type of support rod (4A) and the second type of support rod (4B) are matched and installed with the first dovetail-shaped assembly groove (2A) of the non-magnetic oil pipe (1), so that the support rod is fixedly connected to the non-magnetic oil pipe (1); The support circular surfaces (19) of the first type of support rod (4A) and the second type of support rod (4B) are closely fitted with the outer end face of the corresponding impeller shaft section to limit the radial displacement of the impeller shaft (6); the rectangular mounting protrusion (20) of the second type of support rod (4B) is inserted into the corresponding first limiting groove (13A) or second limiting groove (13B) to limit the circumferential rotation and axial displacement of the impeller shaft (6); the impeller shaft (6) is fixed to the center of the inner cavity of the non-magnetic oil pipe (1) by multiple first type of support rods (4A) and second type of support rods (4B), and the impeller shaft (6) and the non-magnetic oil pipe (1) are coaxially arranged.

4. The device for measuring the maximum velocity of transient oil flow during short circuit in a magnetic rotary power transformer according to claim 1, characterized in that, The permanent magnet (17) includes multiple first permanent magnets (17A) and second permanent magnets (17B) with alternating N and S poles; a third limiting groove (13C) is provided on the top of the impeller (12); the first permanent magnets (17A) and second permanent magnets (17B) are embedded in the third limiting groove (13C) of the impeller (12); a pressure block is provided between adjacent first permanent magnets (17A) and second permanent magnets (17B). 11), the pressure block (11) is a trapezoidal structure that is narrow at the bottom and wide at the top. A first threaded hole (16A) is provided on the pressure block (11). The pressure block (11) is fixedly connected to the impeller (12) by a second screw (10B). The inclined surface of the pressure block (11) abuts against the side wall of the adjacent first permanent magnet (17A) and second permanent magnet (17B) to fix the first permanent magnet (17A) and the second permanent magnet (17B) on the impeller (12).

5. The device for measuring the maximum velocity of transient oil flow during short circuit in a magnetic rotary power transformer according to claim 3, characterized in that, It also includes a buckle, of which multiple buckles are provided; the top of the non-magnetic oil pipe (1) is provided with a second dovetail-shaped mounting protrusion (3B); the bottom of the stator core (5) is provided with a second dovetail-shaped mounting groove (2B), which matches and is installed with the second dovetail-shaped mounting protrusion (3B) to detachably fix the stator core (5) to the outer wall of the non-magnetic oil pipe (1); the stator core (5) has a through conductor hole (32) inside; the induction conductor (24) passes through the conductor hole (32) of the stator core (5); the non-magnetic oil pipe (1) The top of the buckle is provided with a limiting cylinder (25), and there are multiple limiting cylinders (25); each buckle is provided with a cylindrical limiting groove (26) inside, and the cylindrical limiting groove (26) of the buckle matches and assembles with the limiting cylinder (25) of the non-magnetic oil pipe (1); the buckle is provided with a second threaded hole (16B), and a third screw (10C) passes through the second threaded hole (16B) of the buckle, and cooperates with the second nut (28B) to lock and fix the buckle to the outer wall of the non-magnetic oil pipe (1); multiple buckles press and fix the induction conductor (24) to the top of the non-magnetic oil pipe (1).

6. The device for measuring the maximum velocity of transient oil flow during short circuit in a magnetic rotary power transformer according to claim 1, characterized in that, The oscilloscope (18) has a pre-stored flow rate conversion model, which is: v = k × f / N; v is the maximum speed of the oil flow at the moment of transformer short circuit; k is the preset flow rate-speed coefficient, which is determined by the model of impeller (12); f is the frequency of the induced electrical signal collected by the oscilloscope (18); N is the number of pulses generated by the induced electrical signal when the impeller (12) rotates one revolution.

7. The device for measuring the maximum velocity of transient oil flow during short circuit in a magnetic rotary power transformer according to claim 1, characterized in that, A ball bearing structure (29) is provided at the contact point between the impeller (12) and the impeller shaft (6); the impeller (12) rotates around the impeller shaft (6) through the ball bearing structure (29); a first limiting protrusion ring (14A) is provided on the left section (6A) of the impeller shaft; a second limiting protrusion ring (14B) is provided on the right section (6B) of the impeller shaft; a first rubber ring (15A) is provided between the first limiting protrusion ring (14A) and the left end face of the impeller (12); a second rubber ring (15B) is provided between the second limiting protrusion ring (14B) and the right end face of the impeller (12).

8. The device for measuring the maximum velocity of transient oil flow during short circuit in a magnetic rotary power transformer according to claim 1, characterized in that, The non-magnetic oil pipe (1), impeller (12), first type support rod (4A) and second type support rod (4B) are all made of high-strength non-magnetic engineering plastic by 3D printing. The high-strength non-magnetic engineering plastic is CF-PA12 or PPS-GF20.

9. The device for measuring the maximum velocity of transient oil flow during short circuit in a magnetic rotary power transformer according to claim 1, characterized in that, The top of the stator core (5) is provided with a rectangular limiting groove (31); the oscilloscope (18) is fixed in the rectangular limiting groove (31) of the stator core (5); and the lead wire (21) of the oscilloscope (18) is electrically connected to both ends of the induction conductor (24) through the connecting terminal (27).

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