Electric conductor internal temperature measuring device

Abstract

The invention, which relates to the technical field of the flexible direct-current wall bushing, discloses a temperature measuring device for the interior of an electric conductor, comprising a conducting rod, an insulating rod passing through the hollow inner cavity of the conducting rod, insulating blocks arranged at intervals along the insulating rod, thermocouple wires connected to the insulating blocks, and adjustable supporting seats arranged at the two ends of the conducting rod. The end of the thermocouple wire abuts against the inner wall of the conducting rod and is used for directly measuring the internal temperature. According to the device, high-frequency interference is isolated through the insulating structure, and reliable contact of the temperature measuring contacts is ensured by using the adjustable supporting mechanism, so that the technical problem that the internal temperature of the wall bushing is difficult to accurately measure under the combined action of high-frequency harmonic waves and power frequency current is effectively solved; and a reliable means is provided for evaluating the thermal performance and the safety state of the sleeve in actual operation.

Description

Technical Field

[0001] This invention relates to the field of flexible DC through-wall bushing technology, and more specifically to a temperature measuring device inside a conductor. Background Technology

[0002] Flexible direct current (DC) transmission technology, with its unique advantages in large-scale renewable energy grid integration and inter-regional power exchange, has become a key technological support for new power systems. In recent years, my country has achieved remarkable success in this field, such as the successful commissioning of large-scale projects like the Chongqing-Hubei back-to-back flexible DC interconnection project and the Zhangbei flexible DC project, which have greatly promoted grid interconnection and the efficient consumption of renewable energy.

[0003] However, with the widespread application of flexible DC and other power electronic equipment in new power systems, harmonic problems in the system are becoming increasingly prominent, especially the impact of high-frequency harmonics. High-frequency harmonics of 10kHz and above have been measured on both the AC and DC sides of flexible DC projects, with amplitudes even exceeding design expectations. As a key device connecting the valve hall to the external DC field in flexible DC transmission projects, the through-wall bushing occupies a crucial position in the entire system, and its reliability directly affects the safe and stable operation of the project. It is worth noting that in flexible DC transmission projects, due to the need to control starting overcurrent and suppress three-phase circulating current in the converter, a starting circuit is usually designed between the converter and the connecting transformer, and bridge arm reactors and other equipment are installed. This means that the AC side incoming line to the valve hall cannot be directly introduced through the converter transformer valve side bushing as in conventional DC projects, but must use a through-wall bushing.

[0004] Against this backdrop, gas-insulated flexible DC wall bushings must not only withstand the current-carrying heat generated by power frequency current, but also the dielectric loss heat caused by high-frequency harmonics. Studies have shown that high-frequency harmonics significantly increase the dielectric loss at the interface of insulating materials, further exacerbating the overall temperature rise of the wall bushing. Compared to traditional DC wall bushings, flexible DC wall bushings experience more severe heating problems under the influence of high-frequency harmonics, and the temperature rise increases with the intensity of the harmonic signal.

[0005] Currently, temperature measurement of through-wall bushings faces two main challenges: First, contact-type temperature measuring devices (such as embedded thermocouples) are susceptible to interference in high-frequency voltage environments, generating additional heat and easily damaging the detection circuitry. Second, while non-contact temperature measurement methods (such as infrared thermometry) can measure the external surface temperature, they cannot obtain temperature data for critical internal components (such as conductive rods). Therefore, existing technologies struggle to accurately and comprehensively reflect the temperature rise of the internal and external structures of through-wall bushings under high-frequency harmonic environments, and are even less capable of effectively assessing their thermal performance and safety margins in actual operation.

[0006] In summary, accurately and reliably detecting the temperature rise inside (such as the conductive rod) and outside of gas-insulated flexible DC bushings under the combined effect of simulated high-frequency harmonics and actual power frequency current has become a key technical problem that urgently needs to be solved in the condition monitoring and safety assessment of flexible DC transmission equipment. Summary of the Invention

[0007] In view of this, the present invention provides a temperature measuring device inside a conductor, which aims to solve the above-mentioned technical problems.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A temperature measuring device inside a conductor includes a conductive rod and further includes: An insulating rod passes through the hollow inner cavity of the conductive rod, with both ends of the insulating rod penetrating both ends of the conductive rod; Insulating blocks are spaced apart along the length of the insulating rod. Thermocouple wires are connected to the insulating blocks, and the ends of the thermocouple wires abut against the bottom surface of the hollow inner cavity of the conductive rod for detecting the temperature of the conductive rod. Support seats are respectively provided on the outside of both ends of the conductive rod, and the two ends of the insulating rod are respectively adjustablely connected to the support seats.

[0009] Through the above technical solution, this invention achieves direct, reliable and accurate measurement of the temperature of the conductive rod inside the bushing by using an insulating rod that passes through the hollow inner cavity of the conductive rod and an adjustable support structure, and by setting an insulating block with thermocouple wires on the insulating rod. This effectively solves the long-standing technical problem that traditional contact temperature measurement is susceptible to high-frequency interference and non-contact temperature measurement cannot obtain the internal temperature, providing key support for evaluating the thermal performance and safety status of through-wall bushings under the combined conditions of high-frequency harmonics and power frequency current.

[0010] Preferably, in the above-mentioned temperature measuring device inside a conductor, the insulating rod has a plurality of through holes spaced apart along its length, and the insulating block is embedded in the through holes.

[0011] Preferably, in the above-mentioned temperature measuring device inside a conductor, a through hole is provided in the center of the insulating block, the thermocouple wire passes through the through hole, and a contact ball head is welded to the bottom end of the insulating block to abut against the bottom surface of the hollow inner cavity of the conductive rod.

[0012] Preferably, in the above-mentioned internal temperature measuring device for a conductor, the diameter of the contact ball is larger than the diameter of the through hole.

[0013] Preferably, in the above-mentioned internal temperature measuring device for a conductor, the bottom of the insulating block protrudes through the through hole on the insulating rod, and the top of the insulating block has a limiting annular protrusion, which is fixedly connected to the upper surface of the insulating rod by rivets.

[0014] Preferably, in the above-mentioned temperature measuring device inside a conductor, one end of the insulating rod is rotatably connected to a roller, which is used for rolling support when the insulating rod passes through the conductive rod.

[0015] Preferably, in the above-mentioned internal temperature measuring device for a conductor, the insulating rod has light holes at both ends, the support base has threaded holes corresponding to the light holes, and the screw passes through the light holes and connects to the threaded holes on the support base, so that the bolt head of the screw presses down on the insulating rod.

[0016] Preferably, in the above-mentioned conductive body internal temperature measuring device, when the two ends of the insulating rod correspond to the support seats on both sides respectively, the roller is located outside the conductive rod.

[0017] Preferably, in the above-mentioned internal temperature measuring device for a conductor, one end of the thermocouple wire away from the insulating block extends out of the conductive rod and is connected to a measuring instrument for displaying the temperature.

[0018] Preferably, in the above-mentioned temperature measuring device inside a conductor, the insulating rod and the insulating block are made of epoxy resin.

[0019] As can be seen from the above technical solution, compared with the prior art, the present invention discloses a temperature measuring device inside a conductor, which has the following beneficial effects: 1. Achieve direct internal temperature measurement: Through the combination structure of insulating rod and insulating block, the thermocouple can directly and stably contact the inner wall of the conductive rod, solving the industry problem that the key parts inside the wall bushing cannot be directly measured.

[0020] 2. Supports multi-point synchronous monitoring: Multiple temperature measuring points can be set along the length of the insulating rod, which can simultaneously monitor the temperature distribution at different positions of the conductive rod, and more comprehensively reflect its thermal state.

[0021] 3. Ensure measurement reliability in high-frequency environments: The fully insulated structure and adjustable pressure design ensure good contact and minimal damage to the thermocouple under high voltage and high-frequency harmonic conditions, resulting in accurate and reliable measurement results.

[0022] 4. Simple structure and convenient operation: The device has a modular design. During installation, it is easy to insert with the help of rollers and fix with the screw for fine adjustment. It is suitable for laboratory and field testing and has strong practicality. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0024] Figure 1 The attached figure is a schematic diagram of the internal temperature measuring device of the conductor provided by the present invention. Figure 2 The attached figure is a schematic diagram of the insulating block provided by the present invention.

[0025] in: 1-Support base; 2-Roller; 3-Insulating rod; 4-Conductive rod; 5-Thermocouple wire; 6-Insulating block; 7-Contact ball head; 8-Screw; 9-Measuring instrument; 61 - Threading hole; 62 - Annular flange. Detailed Implementation

[0026] 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.

[0027] See appendix Figure 1 This invention discloses a temperature measuring device inside a conductor, including a conductive rod 4, and further comprising: An insulating rod 3 passes through the hollow inner cavity of the conductive rod 4, with both ends of the insulating rod 3 penetrating both ends of the conductive rod 4; Insulating blocks 6 are arranged at intervals along the length of the insulating rod 3. Thermocouple wires 5 are connected to the insulating blocks 6. The ends of the thermocouple wires 5 abut against the bottom surface of the hollow inner cavity of the conductive rod 4 to detect the temperature of the conductive rod 4. Support bases 1 are respectively provided on the outside of both ends of the conductive rod 4, and the two ends of the insulating rod 3 are respectively adjustablely connected to the support bases 1.

[0028] To further optimize the above technical solution, multiple through holes are provided on the insulating rod 3 at intervals along its length, and the insulating block 6 is embedded in the through holes.

[0029] See appendix Figure 2 An insulating block 6 has a through hole 61 in the center, through which the thermocouple wire 5 passes. A contact ball head 7 is welded to the bottom of the insulating block 6 to abut against the bottom surface of the hollow inner cavity of the conductive rod 4.

[0030] To further optimize the above technical solution, the diameter of the contact ball head 7 is larger than the diameter of the thread hole 61.

[0031] To further optimize the above technical solution, the bottom of the insulating block 6 protrudes through the through hole on the insulating rod 3, and the top of the insulating block 6 has a limiting annular protrusion 62, which is fixedly connected to the upper surface of the insulating rod 3 by rivets.

[0032] To further optimize the above technical solution, a roller 2 is rotatably connected to one end of the insulating rod 3. The roller 2 is used for rolling support when the insulating rod 3 passes through the conductive rod 4.

[0033] To further optimize the above technical solution, light holes are provided at both ends of the insulating rod 3, and threaded holes corresponding to the light holes are provided on the support base 1. The screw 8 passes through the light holes and connects with the threaded holes on the support base 1, so that the bolt head of the screw 8 presses down on the insulating rod 3.

[0034] To further optimize the above technical solution, when the two ends of the insulating rod 3 correspond to the support seats 1 on both sides respectively, the roller 2 is located outside the conductive rod 4.

[0035] To further optimize the above technical solution, when the end of the thermocouple wire 5 has poor contact with the bottom surface of the hollow inner cavity of the conductive rod 4, the adjusting screw 8 increases the pressure of the bolt head of the screw 8 on the insulating rod 3.

[0036] To further optimize the above technical solution, the end of the thermocouple wire 5 away from the insulating block 6 is led out of the conductive rod 4 and connected to the measuring instrument 9 for displaying the temperature.

[0037] To further optimize the above technical solution, the insulating rod 3 and the insulating block 6 are made of epoxy resin.

[0038] The specific structural design of the conductive internal temperature measuring device provided in this embodiment includes: (1) Embed the measuring end of the thermocouple wire 5 into the insulating block 6, such as Figure 2 As shown. The measuring end of the thermocouple wire 5 passes through the inside of the insulating block 6, and then the thermocouple wire 5 is welded into a relatively large sphere, so that the welded contact ball head 7 cannot pass through the insulating block 6, which facilitates the fixation of the thermocouple wire 5. The other end of the thermocouple wire 5 is connected to the measuring instrument 9 to display the temperature.

[0039] (2) For example Figure 2 As shown, an epoxy resin insulating rod 3, longer than the sleeve test sample, is drilled with a through hole at the required temperature measurement position of the conductive rod 4. The size of the through hole is consistent with that of the insulating block 6. Then, the insulating block 6 is connected to the insulating rod 3 by rivets.

[0040] (3) such as Figure 1As shown, a roller 2 is added to one end of the insulating rod 3 to facilitate the smooth passage of the insulating rod 3 through the interior of the conductive rod 4 and to protect the interior of the conductive rod 4 from scratches and damage.

[0041] (4) such as Figure 1 As shown, there are light holes at both ends of the insulating rod 3, and the screw 8 passes through the light holes and connects to the threaded hole. After the insulating rod 3 passes through the hollow conductive rod 4, it is fixed to the support base 1 by the screw 8. When the contact ball 7 and the inside of the conductive rod 4 have poor contact due to the process level, the screw 8 is adjusted to press down the insulating rod 3, so that the contact ball 7 and the conductive rod 4 have a tighter contact.

[0042] The method for measuring the temperature rise of the through-wall bushing in this embodiment is as follows: (1) Apply power frequency to both ends of the bushing sample. Measure the surface temperature of the bushing outside using an infrared thermometer. On the inside of the bushing, pass the internal temperature measuring fixture through roller 2 and conductive rod 4, and fix the temperature measuring fixture with screw 8. Check whether the thermocouple wire 5 is in good contact. If the contact is poor, adjust screw 8. Then monitor the temperature in real time until it stabilizes. Record the temperature and duration, and denote the time as t1.

[0043] (2) Apply both the power frequency power supply and the high frequency high voltage source to both ends of the bushing sample. Measure the surface temperature of the bushing using an infrared thermometer and record the time it takes for the temperature to stabilize, denoted as t2. Select the larger of t1 and t2 as the current-carrying time. When the current-carrying time is reached, immediately disconnect the high frequency voltage source. Then, insert the internal temperature measuring fixture into the conductive rod 4 to measure the temperature rise.

[0044] Example 1: The structure provided in this embodiment is applied to a gas-insulated flexible DC through-wall bushing under high-frequency harmonics. Specifically, in this embodiment: 1. Insulating rod 3 and its connecting structure: Insulating rod 3 is a cylindrical long rod, the length of which must be greater than the length of the conductive rod 4 of the through-wall bushing to be tested. It is made of epoxy resin, which has excellent mechanical strength and electrical insulation properties. Multiple through holes are arranged along its axis at preset temperature measurement points at equal intervals or according to the focus of thermal field analysis.

[0045] The holes at both ends of the insulating rod 3 are either oblong or round holes with a diameter slightly larger than that of the screw rod 8, allowing the insulating rod 3 to have a small range of vertical movement after the screw rod 8 is initially tightened, which facilitates subsequent fine-tuning of the contact pressure.

[0046] The screw 8 mates with the threaded hole of the support base 1. The support base 1 is preferably made of insulating material or has an insulating gasket at the contact point with the insulating rod 3 to prevent leakage or induced current path. When the screw 8 is turned, its bolt head acts directly on the upper surface of the end of the insulating rod 3, and the resulting downward pressure causes the insulating rod 3 to undergo slight elastic deformation, thereby uniformly transmitting the pressure to each insulating block 6.

[0047] 2. Assembly structure of insulating block 6 and thermocouple: The insulating block 6 is a cylinder or square prism, and its outer diameter is interference-fitted or tight-fitted with the through hole on the insulating rod 3 to ensure a firm fit. The diameter of the annular protrusion 62 at the top is larger than that of the through hole, and it is fixed to the upper surface of the insulating rod 3 by riveting, bonding or small screws to prevent it from falling downwards.

[0048] The wire hole 61 is a thin straight hole that passes through the upper and lower end faces of the insulating block 6. Its diameter is slightly larger than the outer diameter of the thermocouple wire 5 but much smaller than the diameter of the contact ball 7, ensuring that the thermocouple wire 5 can pass through flexibly and the contact ball 7 can be reliably locked in place.

[0049] The contact ball 7 is formed by welding the measuring end wire of the thermocouple wire 5 to form a spherical solder joint. Its material is the same as that of the thermocouple wire, such as the nickel-chromium-nickel-silicon of a type K thermocouple. The diameter of the ball is more than 1.5 times the diameter of the through hole 61 to ensure that it is reliably limited at the bottom of the insulating block 6 and to directly expose the thermocouple junction to the contact surface with the inner wall of the conductive rod 4.

[0050] 3. Roller assembly 2 structure: The roller 2 is rotatably connected to the end of the insulating rod 3 via a wheel frame and a pin. The roller 2 itself is preferably made of engineering plastics with low coefficient of friction and high insulation strength, such as nylon and polytetrafluoroethylene. Its outer circumferential surface is smooth arc-shaped to ensure rolling contact with the inner wall of the conductive rod 4 during insertion, minimizing scratches and resistance.

[0051] 4. Temperature measurement system: After the multiple thermocouple wires 5 are led out of the conductive rod 4, they can be connected to a multi-channel temperature measuring instrument 9, such as a multi-channel temperature recorder or data acquisition system, either individually or through a multiplexer switch, to achieve synchronous real-time display, recording and analysis of the temperature at each point.

[0052] The overall solution in this embodiment achieves accurate, reliable, and direct measurement of the temperature of the conductive rod 4 inside the wall bushing under combined high-frequency harmonics and power frequency current conditions through the following synergistic effects: Direct internal temperature measurement and high-frequency interference isolation: The core temperature measurement function of the device is achieved by an insulating rod 3 passing through the hollow inner cavity of the conductive rod 4 and multiple insulating blocks 6 fixed thereon. Thermocouple wires 5 are led out through the wire holes 61 of the insulating blocks 6, and the contact ball heads 7 formed by welding their ends directly abut against the inner wall of the conductive rod 4. Both the insulating rod 3 and the insulating blocks 6 are made of high-insulation-strength materials such as epoxy resin, forming a fully insulating barrier that runs through the measurement path. This structure allows the contact ball heads 7 of the thermocouple wires 5 to directly sense the body temperature of the conductive rod 4; on the other hand, it effectively isolates the electromagnetic interference and capacitive coupling of the high-frequency voltage and harmonic current carried on the conductive rod 4 to the temperature measurement signal transmission path, prevents the generation of additional thermoelectric potential, and ensures the purity and accuracy of the temperature measurement signal.

[0053] Reliable Contact and Adaptive Pressure Adjustment: The device utilizes a unique adjustable support mechanism to ensure the reliability of the temperature sensing contacts during long-term operation or under varying operating conditions. The insulating rod 3 is supported at both ends by support bases 1 and is adjustable via screws 8. When screws 8 are tightened, the bolt heads press downwards against both ends of the insulating rod 3. This pressure is transmitted through the insulating rod 3 to each insulating block 6, ultimately transforming into a positive clamping force between all contact balls 7 and the inner wall of the conductive rod 4. This design allows for easy restoration and maintenance of optimal contact even if initial contact is poor due to machining tolerances or thermal expansion and contraction, by finely adjusting the screws 8, avoiding measurement errors introduced by changes in contact resistance.

[0054] Multi-point synchronous monitoring and comprehensive thermal assessment: By arranging multiple temperature measuring units consisting of insulating blocks 6, thermocouple wires 5, and contact ball heads 7 at intervals along the length of the insulating rod 3, the device can simultaneously acquire temperature data at different axial positions of the conductive rod 4, such as the high-voltage end, the middle, and the grounding end. This helps to construct an axial temperature distribution map of the conductive rod 4, providing crucial data support for analyzing the spatial distribution of additional losses caused by high-frequency harmonics, assessing the overall thermal balance of the bushing, and locating potential hot spots, overcoming the limitations of single-point temperature measurement.

[0055] Easy installation and versatility: The roller 2 at one end of the insulating rod 3 greatly reduces the frictional resistance and operational difficulty when inserting the entire temperature measuring component into the inner cavity of the conductive rod 4 with a large length-to-diameter ratio, protecting the smoothness of the inner wall of the sleeve. The modular design allows the device to adapt to conductive rods with different lengths and inner diameters for through-wall sleeves, possessing good versatility and engineering practicality.

[0056] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0057] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A temperature measuring device inside a conductive body, comprising a conductive rod (4), characterized in that, Also includes: An insulating rod (3) passes through the hollow inner cavity of the conductive rod (4), with both ends of the insulating rod (3) penetrating both ends of the conductive rod (4); Insulating blocks (6) are arranged at intervals along the length of the insulating rod (3) on the insulating rod (3). Thermocouple wires (5) are connected to the insulating blocks (6). The end of the thermocouple wires (5) abuts against the bottom surface of the hollow inner cavity of the conductive rod (4) to detect the temperature of the conductive rod (4). Support seats (1) are respectively provided on the outside of both ends of the conductive rod (4), and the two ends of the insulating rod (3) are respectively adjustablely connected to the support seats (1).

2. The internal temperature measuring device of a conductive body according to claim 1, characterized in that, The insulating rod (3) has multiple through holes spaced apart along its length, and the insulating block (6) is embedded in the through holes.

3. The internal temperature measuring device of a conductive body according to claim 2, characterized in that, The insulating block (6) has a through hole (61) in the center, through which the thermocouple wire (5) passes. A contact ball head (7) is welded to the bottom of the insulating block (6) to abut against the bottom surface of the hollow cavity of the conductive rod (4).

4. The internal temperature measuring device of a conductive body according to claim 3, characterized in that, The diameter of the contact ball (7) is larger than the diameter of the thread hole (61).

5. A temperature measuring device for the interior of a conductive body according to any one of claims 1-4, characterized in that, The bottom of the insulating block (6) extends through the through hole on the insulating rod (3), and the top of the insulating block (6) has a limiting annular protrusion (62). The annular protrusion (62) is fixedly connected to the upper surface of the insulating rod (3) by rivets.

6. The internal temperature measuring device of a conductive body according to claim 1, characterized in that, One end of the insulating rod (3) is rotatably connected to a roller (2), which is used for rolling support when the insulating rod (3) passes through the conductive rod (4).

7. The internal temperature measuring device of a conductive body according to claim 6, characterized in that, The insulating rod (3) has light holes at both ends, and the support base (1) has threaded holes corresponding to the light holes. The screw (8) passes through the light holes and connects to the threaded holes on the support base (1), so that the bolt head of the screw (8) presses down on the insulating rod (3).

8. The internal temperature measuring device of a conductive body according to claim 7, characterized in that, When the two ends of the insulating rod (3) correspond to the support seats (1) on both sides respectively, the roller (2) is located outside the conductive rod (4).

9. The internal temperature measuring device of a conductive body according to claim 7, characterized in that, One end of the thermocouple wire (5) away from the insulating block (6) is led out of the outside of the conductive rod (4) and connected to a measuring instrument (9) for displaying the temperature.

10. The internal temperature measuring device of a conductive body according to claim 1, characterized in that, The insulating rod (3) and the insulating block (6) are made of epoxy resin.

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