An experimental device and method for electro-chemical treeing under constant temperature and hot air in solid dielectrics

Abstract

The present invention relates to an electrical tree experiment device and method for constant-temperature wind heating of solid media. The device includes a pin-type electrical tree specimen, a metal electrode base, a lower electrode, a high-voltage introduction port, an upper electrode, a needle-shaped metal high-voltage bushing, an insulating support column, a constant-temperature wind heating device, an electrical tree detection device, and a metal shell. The left and right sides between the upper and lower electrodes are interconnected by insulating support columns to form an experimental chamber. The high-voltage introduction port is connected to the upper electrode, and the pin-type electrical tree specimen is mounted on top of the lower electrode via the metal electrode base. One end of the needle-shaped metal high-voltage bushing is connected to the upper electrode, and the other end is detachably connected to the pin-type electrical tree specimen. The electrical tree detection device and the constant-temperature wind heating device are installed in the experimental chamber. The lower electrode is connected to the inner bottom of the metal shell. Compared with the prior art, the present invention can more realistically simulate the environment of a solid medium under different temperatures and electric fields, thereby making the electrical tree phenomenon more realistic and improving experimental accuracy.

Description

Technical Field

[0001] The invention relates to the field of electric tree tree experimental devices, in particular to an electric tree tree experimental device and an experimental method for constant-temperature wind heating of a solid medium. Background Art

[0002] With the continuous development of power systems, solid dielectrics, especially cross-linked polyethylene (XLPE), are being widely used in key areas such as DC transmission and insulation. However, solid dielectrics often have to withstand harsh environments such as high temperatures and high voltages during power equipment operation. Over time, due to defects in the production process, external environmental influences, or other factors, the internal electric field of solid insulation materials may be excessively high in some locations, leading to the growth of electrical dendrites.

[0003] The initiation and growth of electrical dendrites will cause the insulation performance of solid insulating materials to gradually decrease. When the electrical dendrites grow to a certain extent, it will cause insulation breakdown and eventually lead to equipment failure.

[0004] Research has shown that the generation and development of electrical treeing is closely related to the electric field strength, the properties of the dielectric itself, and the environment in which the dielectric exists. In particular, the growth rate and characteristics of electrical treeing vary significantly under different temperature conditions. Therefore, research on the initiation and growth characteristics of electrical treeing in solid dielectrics is particularly important. Most existing electrical treeing experimental devices directly connect the ends of the electrical treeing specimen to a high-voltage DC power supply for testing. For example, the low-temperature electrical treeing aging experimental device based on DC superimposed harmonics disclosed in patent application CN110057818A cannot realistically simulate the environment under different temperatures and electric fields when electrical treeing occurs in solid dielectrics. Summary of the Invention

[0005] The purpose of the present invention is to overcome the defect of the above-mentioned prior art that it cannot truly simulate the environment under different temperatures and electric fields when solid media produce electrical treeing phenomenon, and to provide an electrical treeing experimental device and experimental method for constant temperature wind heating of solid media.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] An electrical tree experiment device for constant-temperature wind heating of solid media, comprising a plug-in electrical tree specimen, a metal electrode base, a lower electrode, a high-voltage introduction port, an upper electrode, a needle-shaped metal high-voltage bushing, an insulating support column, a constant-temperature wind heating device, an electrical tree detection device, and a metal casing. The left and right sides between the upper and lower electrodes are interconnected by insulating support columns to form an experimental chamber; the high-voltage introduction port is connected to the upper electrode, the plug-in electrical tree specimen is mounted on top of the lower electrode via the metal electrode base, one end of the needle-shaped metal high-voltage bushing is connected to the upper electrode, and the other end is detachably connected to the plug-in electrical tree specimen; the electrical tree detection device is mounted at the bottom of the upper electrode, facing the plug-in electrical tree specimen, and the constant-temperature wind heating device is mounted within the experimental chamber;

[0008] The lower electrode is connected to the inner bottom of the metal shell. The metal shell is provided with a metal window facing the experimental cavity. The metal window is covered with an insulating and heat-insulating front plate.

[0009] Furthermore, the device also includes a sample fixing rolling belt, and the bottom of the metal electrode base is provided with a mounting groove. The sample fixing rolling belt passes through the outside of the pin electrical tree sample and the mounting groove of the metal electrode base to fix the connection between the pin electrical tree sample and the metal electrode base.

[0010] Furthermore, the needle-shaped metal high-voltage bushing is made of tungsten steel and has a needle-shaped discharge tip.

[0011] Furthermore, the insulating and heat-insulating front plate is made of polytetrafluoroethylene.

[0012] Furthermore, the electrical tree detection device detects the inside of the experimental chamber through ultrasonic waves, and automatically collects the electrical tree morphology when changes in the electrical tree are detected.

[0013] Furthermore, there are multiple constant temperature wind heating devices, which are respectively installed on the insulating support columns on both sides of the experimental chamber.

[0014] Furthermore, the constant temperature wind heating device includes a fan and a heating wire with controllable temperature, and the fan blows the stable hot air generated by the heating wire toward the pin-shaped electrical tree branch sample.

[0015] Furthermore, the device further comprises a base, which is arranged below the lower electrode and is used to balance the lower electrode inside the metal shell.

[0016] Furthermore, the insulating and heat-insulating front plate is welded to the metal shell through a metal window.

[0017] The present invention also provides an experimental method based on the above-mentioned electric tree experiment device for constant-temperature wind heating of solid media, comprising the following steps:

[0018] S1: Clean the surfaces of the various components of the electric tree experiment device and check whether the lower electrode is well grounded;

[0019] S2: Take out the integral connection device of the upper electrode and the lower electrode in the metal shell from the electrical tree experimental device, place the pin electrical tree sample to be tested on the metal electrode base, and fix the pin electrical tree sample and the metal electrode base with a sample fixing rolling belt, put a needle-shaped metal high-voltage bushing on the needle electrode of the pin electrical tree sample, and then put the integral connection device of the upper electrode and the lower electrode back into the metal shell;

[0020] S3: Check and confirm whether the metal connection between the high voltage introduction port and the high voltage power supply is intact, and whether the grounding condition between the lower electrode and the metal shell is good;

[0021] S4: Connect the various components of the constant temperature air heating device through the air duct, and turn on the constant temperature air heating device until the wind speed and temperature in the entire experimental chamber tend to be stable;

[0022] S5: When the temperature in the entire experimental chamber rises to the preset temperature, the high-voltage power supply is started, and the growth of the electrical tree is experimentally recorded by the electrical tree detection device; after the recording is completed, the operation of the high-voltage power supply and the constant temperature air heating device are stopped in sequence;

[0023] S6: Repeat steps S2-S5 to test different plug-in electrical tree specimens until all preset experimental procedures are completed;

[0024] S7: After the experimental procedures are completed, disconnect the metal connecting wire from the high-voltage power supply, wait until the circulating air in the constant temperature wind heating device drops to room temperature, clean the various components of the electric tree experiment device for constant temperature wind heating of solid media, and end the experiment.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] (1) The electric tree experimental device for constant temperature wind heating of solid medium of the present invention is a device that cleverly cooperates with the constant temperature wind heating device, the upper electrode, the lower electrode, the plug-in electric tree specimen and the needle-shaped metal high-voltage bushing. The constant temperature wind heating device provides a stable temperature environment for the plug-in electric tree specimen. The plug-in connection between the plug-in electric tree specimen and the needle-shaped metal high-voltage bushing can provide a precise and stable electric field strength at the discharge tip, and more realistically simulates the environment of the solid medium under different temperatures and electric fields, thereby making the electric tree phenomenon on the sample more realistic and improving the accuracy of the measured results.

[0027] (2) The electric tree experiment device for constant temperature wind heating of solid media of the present invention can effectively reduce the influence of the sample on the flow of circulating insulating oil during the experiment by using a detachable cable tie to fix the pin electric tree specimen and the metal electrode base, so that the efficiency of replacing the sample during the experiment is higher. In addition, the heat-insulating front plate is made of polytetrafluoroethylene. This setting not only ensures the clarity of observation during the experiment, but also has a good insulation effect, which can effectively ensure the safety of the high-speed camera used for observation during the experiment.

[0028] (3) The electric tree experiment device for solid medium constant temperature wind heating of the present invention improves the overall complexity of the experimental process and simplifies the connection method between the sample and the electrode. The form of the sleeve allows the sample to be inserted in advance, and the presence of the rolling strip can effectively reduce the impact of the sample on the flow of circulating insulating oil during the experiment. In addition, the detachable device can be disassembled after the test to replace the sample, which to a certain extent reduces the time for the constant temperature wind heating machine to open and close the cooling and heating processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of the internal structure of an electric tree experiment device for constant-temperature wind heating of solid media provided in an embodiment of the present invention;

[0030] Figure 2 Schematic diagram of the overall structure of an electric tree experiment device for constant-temperature wind heating of solid media provided in an embodiment of the present invention;

[0031] 1. Pin-inserted electric tree specimen, 2. Specimen fixing strip, 3. Metal electrode base, 4. Lower electrode, 5. High-voltage introduction port, 6. Upper electrode, 7. Needle-shaped metal high-voltage bushing, 8. Insulating support column, 9. Constant temperature air heating device, 10. Electric tree detection device, 11. Metal window, 12. Insulating and heat-insulating front plate, 13. Metal casing. DETAILED DESCRIPTION

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0033] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0034] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0035] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, or are the orientation or position relationship in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limiting the present invention.

[0036] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0037] Furthermore, terms such as "horizontal" and "vertical" do not necessarily mean that a component must be absolutely horizontal or overhanging, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but rather that it can be slightly tilted.

[0038] Example 1

[0039] like Figure 1 As shown, this embodiment provides an electric tree experimental device for constant temperature wind heating of solid media, including a pin electric tree sample 1, a metal electrode base 3, a lower electrode 4, a high voltage introduction port 5, an upper electrode 6, a needle-shaped metal high voltage bushing 7, an insulating support column 8, a constant temperature wind heating device 9, an electric tree detection device 10 and a metal shell 13. The left and right sides between the upper electrode 6 and the lower electrode 4 are interconnected through the insulating support column 8 to form an experimental cavity; the high voltage introduction port 5 is connected to the upper electrode 6, the pin electric tree sample 1 is installed on the top of the lower electrode 4 through the metal electrode base 3, one end of the needle-shaped metal high voltage bushing 7 is connected to the upper electrode 6, and the other end is detachably connected to the pin electric tree sample 1; the electric tree detection device 10 is installed at the bottom of the upper electrode 6 and is directly opposite to the pin electric tree sample 1, and the constant temperature wind heating device 9 is installed in the experimental cavity, as shown in FIG. Figure 2 As shown;

[0040] The lower electrode 4 is connected to the inner bottom of the metal shell 13 . The metal shell 13 is provided with a metal window 11 facing the experimental cavity. The metal window 11 is covered with an insulating and heat-insulating front plate 12 .

[0041] The insulating and heat-insulating front plate 12 is welded to the metal shell 13 through the metal window 11, thereby ensuring the sealing of the entire constant temperature wind heating device without affecting observation.

[0042] The electrical tree detection device 10 detects the inside of the experimental chamber through ultrasonic waves and collects the real-time electrical tree morphology. When changes in electrical trees are detected, the electrical tree morphology is automatically collected.

[0043] There are multiple constant temperature wind heating devices 9, which are respectively installed on the insulating support columns 8 on both sides of the experimental chamber. In this embodiment, a corresponding constant temperature wind heating device 9 is provided on both sides of the electric tree fixed structure. This arrangement facilitates the circulating wind heating mechanism to form a stable air path inside the metal shell 13, thereby ensuring that the solid electric tree sample is at a stable temperature and improving the accuracy of the results obtained by the solid dielectric electric tree experimental device.

[0044] The constant temperature wind heating device 9 includes a fan and a heating wire with controllable temperature. The fan blows the stable hot air generated by the heating wire toward the pin-shaped electrical tree branch sample 1.

[0045] Preferably, the device also includes a sample fixing rolling belt 2, and a mounting groove is provided at the bottom of the metal electrode base 3. The sample fixing rolling belt 2 passes through the outside of the pin electric tree sample 1 and the mounting groove of the metal electrode base 3 to fix the connection between the pin electric tree sample 1 and the metal electrode base 3.

[0046] Preferably, the needle-shaped metal high-voltage bushing 7 is made of tungsten steel and has a needle-shaped discharge tip. Because tungsten steel has the characteristics of high hardness, corrosion resistance, and wear resistance, this configuration facilitates improving the stability and durability of the needle-shaped metal high-voltage bushing 7 during the test process, reducing the risk of errors in the experimental results due to wear of the needle-shaped metal high-voltage bushing 7. In addition, during the test, the needle-shaped metal high-voltage bushing 7 can work in conjunction with the lower electrode 4 to form a high-voltage to low-voltage DC voltage environment. This configuration also ensures that the electric field strength at the discharge tip of the needle-shaped metal high-voltage bushing 7 can accurately meet the requirements of the experiment, improving the flexibility of the test operation, and thus improving the accuracy of the results obtained by the electrical tree test device for solid dielectrics.

[0047] Preferably, the lower electrode 4 and the upper electrode 6 are made of a low-resistance conductive material; the insulating and heat-insulating front plate 12 is made of polytetrafluoroethylene, polychlorotetrafluoroethylene (Polytetrafluoroethylene, abbreviated as PTFE), which is known for its excellent mechanical strength, electrical insulation performance, high resistance to acids and alkalis, and chemical stability. This setting ensures the necessary heat dissipation of the wind-removal heat trough part, and also realizes thermal isolation of the remaining parts, thereby effectively reducing errors in the test process and improving the accuracy and reliability of the test data.

[0048] Preferably, the device further comprises a base, which is arranged below the lower electrode 4 so that the entire Figure 1 The device shown is capable of balancing the Figure 2 The interior of the device shown can also ensure that the device can remain stable in the circulating oil circuit composed of the circulating air heater, making it easier for experimenters to better observe the samples.

[0049] Example 2

[0050] This embodiment provides an experimental method for an electric tree experiment device for constant-temperature wind heating of a solid medium based on the embodiment 1, including the following steps:

[0051] S1: Clean the surfaces of various components of the electric tree experiment device, that is, sweep and wipe them to keep them clean, and check whether the lower electrode 4 is well grounded;

[0052] S2: Take out the integral connection device of the upper electrode 6 and the lower electrode 4 in the metal shell 13 from the electrical tree experimental device, place the pin electrical tree sample 1 to be tested on the metal electrode base 3, and fix the pin electrical tree sample 1 and the metal electrode base 3 with the sample fixing rolling belt 2, put the needle-shaped metal high-voltage bushing 7 on the needle electrode of the pin electrical tree sample 1, and ensure that the needle-shaped metal high-voltage bushing 7 is tightly connected to the pin electrical tree sample 1, and then put the integral connection device of the upper electrode 6 and the lower electrode 4 back to the middle position in the metal shell 13;

[0053] S3: Check and determine whether the metal connection between the high voltage introduction port 5 and the high voltage power supply is intact, and whether the grounding condition between the lower electrode 4 and the metal shell 13 is good;

[0054] S4: Connect the various components of the constant temperature wind heating device 9 through the air duct, and turn on the constant temperature wind heating device 9 until the wind speed and temperature in the entire experimental chamber tend to be stable;

[0055] S5: When the temperature in the entire experimental chamber rises to a preset temperature, the high-voltage power supply is started, and the growth of electrical trees is experimentally recorded by the electrical tree detection device 10. After the recording is completed, the high-voltage power supply and the constant temperature wind heating device 9 are stopped in sequence.

[0056] S6: Repeat steps S2-S5 to test different plug-in electrical tree specimens 1 until all preset experimental procedures are completed;

[0057] S7: After the experimental procedures are completed, disconnect the metal connecting wire from the high-voltage power supply. When the circulating air in the constant-temperature wind heating device 9 drops to room temperature, clean the various components of the electric tree experiment device for constant-temperature wind heating of solid media and end the experiment.

[0058] Specifically, the voltage value provided by the high-voltage power supply and the preset temperature are both selected according to the insulation characteristics of the sample to be tested.

[0059] The above describes in detail the preferred embodiments of the present invention. It should be understood that those skilled in the art can make numerous modifications and variations based on the concepts of the present invention without inventive effort. Therefore, any technical solutions that can be derived by those skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. An experimental method for an electric tree experiment device for constant temperature wind heating of a solid medium, characterized in that: The device comprises a plug-in electric tree specimen (1), a metal electrode base (3), a lower electrode (4), a high-voltage introduction port (5), an upper electrode (6), a needle-shaped metal high-voltage bushing (7), an insulating support column (8), a constant-temperature wind-heating device (9), an electric tree detection device (10) and a metal shell (13), wherein the left and right sides between the upper electrode (6) and the lower electrode (4) are connected to each other through the insulating support column (8) to form an experimental cavity; the high-voltage introduction port (5) is connected to the upper electrode (6), the plug-in electric tree specimen (1) is installed on the top of the lower electrode (4) through the metal electrode base (3), one end of the needle-shaped metal bushing is connected to the upper electrode (6), and the other end is detachably connected to the plug-in electric tree specimen (1); the electric tree detection device (10) is installed at the bottom of the lower electrode (4) and is directly opposite to the plug-in electric tree specimen (1), and the constant-temperature wind-heating device (9) is installed in the experimental cavity; The lower electrode (4) is connected to the inner bottom of the metal shell (13), and the metal shell (13) is provided with a metal window (11) facing the experimental cavity, and the metal window (11) is covered with an insulating and heat-insulating front plate (12); The electrical tree branch detection device (10) detects the interior of the experimental chamber through ultrasonic waves, and automatically collects the electrical tree branch morphology when changes in the electrical tree branches are detected; The needle-shaped metal high-voltage bushing (7) is made of tungsten steel and has a needle-shaped discharge tip; The constant temperature wind heating device (9) comprises a fan and a heating wire capable of controlling the temperature, and the fan blows the stable hot air generated by the heating wire toward the pin-shaped electrical tree branch sample (1); The experimental method comprises the following steps: S1: Clean the surfaces of the various components of the electric tree experiment device and check whether the lower electrode (4) is well grounded; S2: Take out the integral connection device of the upper electrode (6) and the lower electrode (4) in the metal shell (13) from the electric tree experimental device, place the plug-in electric tree sample (1) to be tested on the metal electrode base (3), and fix the plug-in electric tree sample (1) and the metal electrode base (3) with the sample fixing rolling belt (2), put the needle-shaped metal high-voltage bushing (7) on the needle electrode of the plug-in electric tree sample (1), and then put the integral connection device of the upper electrode (6) and the lower electrode (4) back into the metal shell (13); S3: Check and confirm whether the metal connection between the high voltage introduction port (5) and the high voltage power supply is intact, and whether the grounding condition between the lower electrode (4) and the metal shell (13) is good; S4: Connect the various components of the constant temperature wind heating device (9) through the air duct, and turn on the constant temperature wind heating device (9) until the wind speed and temperature in the entire experimental chamber tend to be stable; S5: When the temperature in the entire experimental chamber rises to a preset temperature, the high-voltage power supply is started, and the growth of the electrical tree branches is experimentally recorded by the electrical tree branch detection device (10); after the recording is completed, the operation of the high-voltage power supply and the constant temperature wind heating device (9) are stopped in sequence; S6: Repeat steps S2-S5 to test different plug-in electrical tree specimens (1) until all preset experimental procedures are completed; S7: After the experimental procedures are completed, disconnect the metal connecting wire from the high-voltage power supply, wait until the circulating air in the constant temperature wind heating device (9) drops to room temperature, clean the various components of the electric tree experimental device for constant temperature wind heating of solid media, and end the experiment.

2. The method according to claim 1, characterized in that The device further comprises a sample fixing rolling belt (2), the bottom of the metal electrode base (3) is provided with a mounting groove, and the sample fixing rolling belt (2) passes through the outside of the pin-type electrical tree specimen (1) and the mounting groove of the metal electrode base (3), thereby fixedly connecting the pin-type electrical tree specimen (1) and the metal electrode base (3).

3. The method according to claim 1, characterized in that The insulating and heat-insulating front plate (12) is made of polytetrafluoroethylene.

4. The method according to claim 1, wherein There are multiple constant temperature wind heating devices (9), which are respectively installed on the insulating support columns (8) on both sides of the experimental chamber.

5. The method according to claim 1, wherein The device further comprises a base, which is arranged below the lower electrode (4) and is used to balance the lower electrode (4) inside the metal shell (13).

6. The method according to claim 1, characterized in that The insulating and heat-insulating front plate (12) is welded to the metal shell (13) in conjunction with the metal window (11).

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