CN105785145A - DC GIL disc insulator surface charge density measurement and observation platform - Google Patents

Abstract

The invention belongs to the field of surface charge accumulation and surface flashover measurement of high-voltage DC solid insulating materials, and in particular relates to a surface charge density measurement and observation platform of a DC GIL pot insulator. It is characterized in that two insulators are included to divide the sealed metal cavity into three chambers, wherein the left chamber is connected to the outer casing through a flange; the charge measuring device in the upper right chamber is located in the coaxial cylindrical structure test On the top of the device, the turning mechanism is fixed on the wall of the metal cavity. The coaxial cylindrical structure test device is connected to the turning mechanism through a bracket. A quartz window is installed on the top of the chamber, and a high-speed camera is installed on the outside of the top flange cover. Bracket and high-speed camera; each of the three chambers is equipped with a valve with a barometer. The design of the invention is easy to realize, and the operation is simple, and provides a reliable and effective test platform for studying the correlation characteristics of surface charge accumulation and surface flashover of pot insulators in DC GIL.

Description

Surface Charge Density Measurement and Observation Platform for DC GIL Potty Insulators

technical field

The invention belongs to the field of surface charge accumulation and surface flashover measurement of high-voltage DC solid insulating materials, and in particular relates to a surface charge density measurement and observation platform of a DC GIL pot insulator.

Background technique

Gas-insulated metal-enclosed transmission lines (GIL) have the characteristics of large transmission capacity, small loss, small capacitance, small footprint, high reliability, and are suitable for harsh environments. occasions have been widely used. But at present, AC GILs are used for commercial operation, while DC GILs have not been applied on a large scale in actual projects. The main reason is that under the action of DC voltage, the surface charge of the supporting insulator in the DC GIL accumulates seriously, which distorts the electric field distribution along the surface and reduces the withstand voltage of the insulator. Especially when the voltage polarity of DC high-voltage equipment is reversed, the influence of electric field distortion is particularly prominent.

To solve the problem of electric field distortion caused by charge accumulation on the surface of DC GIL, it is first necessary to accurately measure the accumulated charge on the surface of the pot insulator in DC GIL to study the characteristics of charge accumulation. Since the 1980s, scholars from various countries have carried out extensive research on this issue. The current measurement methods of surface charge include: powder layer diagram method, electrostatic capacitance probe method, electro-optic effect method. Among them, the static capacitance probe method is currently the most widely used method in the field of surface charge measurement in the world. Its principle is to pass a miniature metal probe close to the charged insulator surface. Due to electrostatic induction, the probe will also be charged. The surface charge density of the insulator can be calculated by inversion.

However, at present, most researchers only simply measure the surface charge density of DC GIL insulators, and do not conduct quantitative research on the surface flashover characteristics of insulators after surface charge accumulation, and cannot establish the relationship between charge accumulation and insulator surface flashover. Therefore, it cannot provide effective theoretical guidance for the insulation optimization design of DC GIL. Therefore, it is urgent to invent a test platform that can measure the surface charge density of DC GIL pot insulators and observe flashover along the surface.

Contents of the invention

In order to solve the above problems, the present invention proposes a platform for measuring and observing the surface charge density of a DC GIL pot insulator, which is characterized in that the platform includes a metal cavity 12, a coaxial cylindrical structure test device, a charge measuring device, and a Observation window, bushing 14, high-voltage guide rod 13, high-speed camera 17 and turning mechanism 6;

The metal cavity 12 is a U-shaped sealed cavity, which is divided into three chambers by two insulators 11, wherein a coaxial cylindrical structure test device, a charge measuring device and a turning mechanism 6 are installed in the chamber on the upper right side, and the charge The measuring device is located above the coaxial cylindrical structure test device, and the coaxial cylindrical structure test device is connected with the turning mechanism 6 through the bracket 7, and the turning mechanism 6 is fixedly installed on the wall of the metal cavity 12; a quartz window is installed on the top of the cavity 8 is used as a flashover observation window along the surface, and a high-speed camera bracket 9 is installed on the outside of the top flange cover plate 16, and a high-speed camera 17 is installed on the high-speed camera bracket 9; a valve 10 with a barometer is installed in each of the three chambers; One end in the left chamber of the high-voltage guide rod 13 in the metal cavity 12 is connected to the DC voltage generator 15 through the flange and the outer sleeve 14, and the other end in the chamber above the right side of the high-voltage guide rod 13 is connected to To the metal guide rod 3 of the coaxial cylindrical structure test device.

The coaxial cylindrical structure test device includes a metal shell 2, a test pot insulator 1 and a metal guide rod 3; the shape of the test pot insulator 1 is a conical shape, and the insulation distances on both sides of the test pot insulator 1 are different. A copper insert with internal thread is installed in the center of 1, and 8 threaded holes are evenly processed on the outside; the metal shell 2 is divided into two sections, which are respectively installed on both sides of the test pot insulator 1 through flanges; the metal guide rod 3 is divided into two sections. The segments are respectively threaded on both sides of the internally threaded copper insert in the center of the test insulator.

The turning mechanism includes a positioning shaft 18, a lifting shaft 19, a cam 20, a turning shaft 21, a lower gear 22, and an upper gear 23, which are used to realize the 180° turning of the coaxial cylindrical structure test device inside the metal cavity 12 to realize static electricity. Capacitance probe 4 measures the surface charge on both sides of the test insulator 1; the cam 20 is installed on the lifting shaft 19; the upper gear (23) is fixed on the turning shaft 21; the middle parts of the lifting shaft 19 and the turning shaft 21 are fixed by flanges Installed on the metal cavity 12, distributed up and down on the same vertical line; the part of the turning shaft 21 located inside the metal cavity 12 is connected to the bracket 7 through the positioning shaft 18; one end of the bracket 7 is installed on the positioning shaft 18 in the form of a slider , the lower gear 22 is fixed on the positioning shaft 18, which can drive the lower gear 22 and the coaxial cylindrical structure test device to slide up and down freely; in the natural state, one end of the bracket 7 is kept horizontally attached to the long side of the cam 20; when the cam 20 When it is rotated to its highest position, the height of the support 7 is just enough to make the lower gear 22 mesh with the upper gear 23, and the upper gear (23) is driven to rotate by turning over the rotating shaft 21, and the lower gear 22 will also rotate accordingly, thereby driving the coaxial The cylindrical structure test device is turned over together.

The charge measurement device includes a static capacitance probe 4 fixed on a three-dimensional motion control mechanism 5 through a pole, and the Z-axis of the three-dimensional motion control mechanism 5 is fixed on the inner wall of the metal cavity 12 .

The metal shell 2 is made of aluminum alloy; the test pot insulator 1 is made of epoxy resin, the shape is a truncated cone, the slope angle is 10°, the center thickness is 5mm, and the bottom surface diameter is 90mm; the internal thread The outer diameter of the copper insert is 20mm.

The metal cavity 12 is made of stainless steel and can withstand an air pressure of up to 0.5Mpa.

The surface flashover observation window is composed of a circular quartz window 8 with a thickness of 20 mm and a diameter of 120 mm. The quartz window 8 is sealed and installed on the upper right side of the metal cavity 12 through a flange cover plate 16 and an O-ring. On the top of the chamber, the center of the quartz window 8 and the center of the test pot insulator 1 are on a vertical line.

The high-speed camera 17 is used to photograph and record the surface flashover process of the test insulator.

The DC voltage generator 15 is a digital DC voltage generator with a maximum output voltage of 200kV, which can stably provide high-voltage DC with a ripple coefficient of <0.3% for a long time.

Beneficial effect

(1) The modular design of the coaxial cylindrical structure test device is conducive to the rapid replacement of the test insulator after the surface flashover experiment research, ensuring the accuracy and reliability of the next measurement data.

(2) The test pot insulator is turned 180° by the turning mechanism, and only one set of measurement system is used to measure the charge density on both sides of the insulator, which can reduce the construction cost of the test platform and avoid different measurement errors due to different measurement systems impact on the analysis results.

(3) Through the integrated design, the surface charge measurement and surface flashover observation of DC GIL pot insulators are realized, which is conducive to establishing the correlation characteristics between insulator surface charge accumulation and surface flashover.

(4) The platform design of the present invention is easy to realize and simple to operate, and provides a reliable and effective test platform for studying the correlation characteristics of surface charge accumulation and surface flashover of pot insulators in DC GIL.

Description of drawings

Fig. 1 is a schematic diagram of a DC GIL pot insulator surface charge density measurement and surface flashover observation platform provided by the present invention;

Fig. 2 is a schematic diagram of an overturning mechanism in a surface charge density measurement and surface flashover observation platform of a DC GIL pot insulator provided by the present invention.

1-test pot insulator; 2-metal shell; 3-metal guide rod; 4-static capacitance probe; 5-three-dimensional motion control mechanism; 6-turning mechanism; 7-bracket; 8-quartz window; Bracket; 10-valve with barometer; 11-insulator; 12-metal cavity; 13-high voltage guide rod; 14-sleeve; 15-DC voltage generator; 16-flange cover; 17-high-speed camera; 18-positioning shaft; 19-promoting rotating shaft; 20-cam; 21-overturning rotating shaft; 22-lower gear; 23-upper gear.

detailed description

The present invention will be described in detail below in conjunction with the accompanying drawings. Fig. 1 is a schematic diagram of a DC GIL pot insulator surface charge density measurement and surface flashover observation platform provided by the present invention; the platform includes a metal cavity 12, a coaxial cylindrical structure test device, a charge measurement device, and a surface flashover observation window , bushing 14, high-voltage guide rod 13, high-speed camera 17 and turning mechanism 6. It is characterized in that: the metal cavity 12 is divided into three chambers by the insulator 11, a quartz window 8 is installed on the top of the right chamber, and a high-speed camera bracket 9 is installed on the flange cover plate 16 outside the cavity. Two sections of metal shell 2 are installed on the test basin insulator 1 through flanges, and two sections of metal guide rod 3 are installed on the center of the test basin insulator 1 through threaded inserts, which jointly constitute a coaxial cylindrical structure test device. The coaxial cylindrical structure test device is connected to the turning mechanism 6 through the support rod 7, and the turning mechanism 6 is fixedly installed on the wall of the metal cavity 12. In the static state, the metal guide rod 3 in the test device and the high-voltage guide rod 13 in the metal cavity 12 are in good condition. touch. The static capacitance probe 4 is fixed on the three-dimensional motion control mechanism 5 through the support rod 7 , and the Z-axis of the three-dimensional motion control mechanism 5 is fixedly installed on the inner wall of the metal cavity 12 . The high-voltage guide rod 13 is fixed in the center of the metal cavity 12 through the insulator 11 ; the DC voltage generator 15 applies a DC voltage to the high-voltage guide rod 13 through the bushing 14 .

The metal cavity 12 is made of stainless steel and can withstand up to 0.5Mpa air pressure. The metal cavity 12 is divided into three chambers by an insulator 11 , wherein the left chamber is connected to an outer sleeve 14 through a flange. The coaxial cylindrical structure test device, the electric charge measurement device, the turning mechanism 6 and the corresponding auxiliary connection parts are installed in the right chamber. Each chamber is equipped with a valve 10 with a barometer, which can fill the metal chamber with 0.5Mpa SF6 to simulate the insulation conditions of a real GIL.

The coaxial cylindrical structure test device includes a metal shell 2 , a test pot insulator 1 and a metal guide rod 2 . The metal shell 2 is made of aluminum alloy. The test pot insulator 1 is made of epoxy resin and is in the shape of a truncated cone with a slope angle of 10°, a center thickness of 5mm, and a bottom diameter of 90mm. The insulation distance on both sides of the test pot insulator 1 is different to ensure that flashover along the surface only occurs on the fixed side. An internally threaded copper insert with an outer diameter of 20mm is installed in the center of the insulator 1, and 8 threaded holes are uniformly processed on the outside. The metal shell 2 is divided into two sections, which are respectively installed on both sides of the test pot insulator 1 through flanges. The metal guide rod 3 is divided into two sections, which are installed on the copper inserts at the center of both sides of the test insulator 1 respectively.

The charge measuring device includes a capacitance probe 4, a coaxial cable, a three-dimensional motion control mechanism 5 and its connectors. One end of the coaxial cable is connected to the static capacitance probe 4 through a BNC connector, and the other end is installed on the wall of the metal cavity through a sealed BNC connector with a flange, so that the measurement signal of the static capacitance probe 4 is transmitted to the detection instrument outside the cavity. The static capacitance probe 4 is fixedly installed under the three-dimensional motion control mechanism 5 through a support rod, and the control mechanism can drive the static capacitance probe 4 to measure the charge density on the surface of the test insulator.

The surface flashover observation window is composed of a circular quartz window 8 with a thickness of 20mm and a diameter of 120mm. The quartz window 8 is sealed and mounted on the top of the chamber above the right side of the metal chamber 12 through a flange and an O-ring. When installing, ensure that the center of circle of the quartz window 8 and the center of circle of the test pot insulator 1 are on the same line. A high-speed camera bracket 9 is installed on the top of the quartz window 8, so that the high-speed camera 17 can be fixed to take pictures and record the surface flashover process of the test insulator.

The bushing 14 is installed above the cavity on the left side of the metal cavity 1 , and is used for safely introducing high-voltage power into the metal guide rod 3 .

The high-voltage guide rod 13 is installed in the center of the metal cavity 12 by being fixed on the insulator 11 . One end of the high-voltage guide rod 13 is connected with the casing 14, and the other end of the high-voltage guide rod 13 is connected with the metal guide rod 3 in the coaxial cylindrical device.

The high-speed camera 17 is fixed on the top of the quartz window through the high-speed camera bracket 9, which is convenient for photographing the flashover process on the upper surface of the test pot insulator.

In the schematic diagram of the overturning mechanism shown in Figure 2, the overturning mechanism includes a positioning shaft 18, a cam 20, a lifting shaft 19, an upper gear 23, a lower gear 22 and an overturning shaft 21, which are used to realize the simultaneous installation of test pot insulators. The 180° rotation of the axial cylinder structure test device inside the metal cavity allows the electrostatic capacity probe 4 to measure the surface charge on the other side of the test insulator 1 . Wherein the cam 20 and the lifting rotating shaft 19 are used to realize the position promotion before the coaxial cylindrical device is overturned, ensuring that there are no other devices hindering the overturning path; the positioning shaft 18 is used to ensure that the coaxial cylindrical structure test device maintains a vertical state during the lifting process; The upper gear 23, the lower gear 22 and the turning shaft 21 are used to realize the 180° turning of the test device after being promoted to the turning point. One end of the lifting rotating shaft 19 is connected with the cam 20, one end of the turning rotating shaft 21 is connected with the upper gear 23, and the other ends of the two rotating shafts extend out of the cavity through the flange respectively, so as to facilitate external manual operation. The overturning mechanism 6 is fixedly installed on the inner wall of the metal cavity, and the coaxial cylindrical structure test device is fixed on the overturning mechanism 6 through the bracket 7 .

The specific operation steps of the platform provided by the present invention are as follows:

1. Under the condition of not applying DC voltage, connect the vacuum pumps to the valves 10 with barometers respectively, and evacuate the three chambers until the vacuum degree reaches -50Kpa. Then fill the chamber with 0.5Mpa of SF6 respectively.

2. Turn on the power switch, increase the output voltage of the DC voltage generator 15 to +60kV, until the charge accumulation saturation time on the surface of the insulator.

3. Disconnect the DC voltage generator 15.

4. Start the three-dimensional motion control mechanism 5 to drive the static capacitance probe 4 close to the surface of the test pot insulator 1 at 2 mm to measure the surface charge density. Based on the programmable function of the three-dimensional motion control mechanism 5, the charge density on the upper side of the test insulator 1 is measured on the entire surface according to the preset path, and the measurement data are recorded and saved.

5. Start the three-dimensional motion control mechanism 5, and move the static capacitance probe 4 out of the coaxial cylindrical structure test device.

6. Rotate the cam 20 by rotating the lifting shaft 19 so as to jack up the coaxial cylindrical structure test device and move upward along the positioning shaft 18 . When promoted to the preset position, the lower gear 22 and the upper gear 23 just mesh.

7. Rotate the turning shaft 21 to drive the upper gear 23 to rotate to realize the turning of the test insulator 1 . Then rely on self-gravity to make the test device descend voluntarily along the positioning axis 18.

8. Start the three-dimensional motion control mechanism 5, and repeat the fourth and fifth steps in sequence.

9. Start the high-speed camera 17 and adjust to the automatic trigger mode.

10. Turn on the power switch, and rapidly increase the output voltage of the DC voltage generator 15 until the surface flashover of the test pot insulator 1 occurs.

11. Record the flashover voltage, and save the images taken by the high-speed camera 17 during the flashover process along the surface.

Claims (9)

1. A DC GIL pot insulator surface charge density measurement and observation platform is characterized in that the platform includes a metal cavity (12), a coaxial cylindrical structure test device, a charge measurement device, a flashover observation window along the surface, and a bushing (14), high-voltage guide rod (13), high-speed camera (17) and turning mechanism (6); The metal cavity (12) is a U-shaped sealed cavity, which is divided into three chambers by two insulators (11), wherein the upper right chamber is equipped with a coaxial cylindrical structure test device, a charge measurement device and a flipping chamber. Mechanism (6), the charge measurement device is located above the coaxial cylindrical structure test device, the coaxial cylindrical structure test device is connected with the turning mechanism (6) through the bracket (7), and the turning mechanism (6) is fixedly installed in the metal cavity (12 ) wall; a quartz window (8) is installed on the top of the chamber as a surface flashover observation window, and a high-speed camera bracket (9) is installed on the outside of the top flange cover (16), and the high-speed camera (17) is installed On the high-speed camera bracket (9); the three chambers are respectively equipped with a valve (10) with an air pressure gauge; one end of the left chamber of the high-pressure guide rod (13) in the metal chamber (12) It is connected to the DC voltage generator (15) through the flange and the outer bushing (14), and the other end in the chamber above the right side of the high-voltage guide rod (13) is connected to the metal guide rod (3) of the coaxial cylindrical structure test device superior. 2. The surface charge density measurement and surface flashover observation platform of a DC GIL pot insulator according to claim 1, wherein the coaxial cylindrical structure test device includes a metal shell (2), a test pot insulator (1) and metal guide rods (3); the shape of the test pot insulator (1) is a circular truncated shape, and the insulation distances on both sides of the test pot insulator (1) are different, and the center of the test pot insulator (1) is installed with an internal thread Copper insert, with 8 threaded holes evenly processed on the outside; the metal shell (2) is divided into two sections, which are respectively installed on both sides of the test pot insulator (1) through flanges; the metal guide rod (3) is divided into two sections , respectively installed on both sides of the inner threaded copper insert in the center of the test insulator through threads. 3. The surface charge density measurement and observation platform of a DC GIL pot insulator according to claim 1, wherein the turning mechanism includes a positioning shaft (18), a lifting shaft (19), a cam (20), Flip the rotating shaft (21), the lower gear (22) and the upper gear (23), used to realize the 180° flip of the coaxial cylindrical structure test device inside the metal cavity (12), and realize the static capacitance probe (4) to test the insulator (1) surface charge measurement on both sides; wherein the cam (20) is installed on the lifting shaft (19); the upper gear (23) is fixed on the turning shaft (21); the lifting shaft (19) and the turning shaft (21) The middle part is fixedly installed on the metal cavity (12) through the flange, distributed up and down on the same vertical line; the part of the turning shaft (21) located inside the metal cavity (12) is connected to the bracket (7) through the positioning shaft (18) One end of the support (7) is installed on the positioning shaft (18) in the form of a slide block, and the positioning shaft (18) is fixed with the lower gear (22), which can drive the lower gear (22) and the coaxial cylindrical structure test device freely Slide up and down; in the natural state, one end of the support (7) is kept horizontally attached to the long side of the cam (20); when the cam (20) rotates to its highest position, the height of the support (7) is just The lower gear (22) is meshed with the upper gear (23), and the upper gear (23) is driven to rotate by turning over the rotating shaft (21), and the lower gear (22) will also rotate accordingly, thereby driving the coaxial cylindrical structure test device to turn over together. 4. a kind of DC GIL basin type insulator surface charge density measurement and observation platform according to claim 1, is characterized in that, described electric charge measurement device comprises electrostatic capacitance probe (4) and is fixed on three-dimensional motion control mechanism ( 5), the Z-axis of the three-dimensional motion control mechanism (5) is fixedly installed on the inner wall of the metal cavity (12). 5. A kind of DC GIL pot insulator surface charge density measurement and observation platform according to claim 1, is characterized in that, described metal casing (2) adopts aluminum alloy to make; Described test pot insulator (1) adopts Made of epoxy resin, the shape is truncated circular, the slope angle is 10°, the center thickness is 5mm, and the bottom surface diameter is 90mm; the outer diameter of the internal thread copper insert is 20mm. 6. A platform for measuring and observing the surface charge density of a DC GIL basin-type insulator according to claim 1, wherein the metal cavity (12) is made of stainless steel and can withstand an air pressure of up to 0.5Mpa. 7. according to the said a kind of DC GIL basin type insulator surface charge density measurement and observation platform of claim 1, it is characterized in that, described flashover observation window along the surface is 20mm by a thickness, and diameter is the circular quartz window of 120mm ( 8) composition, the quartz window (8) is sealed and installed on the top of the chamber on the right side of the metal cavity (12) through the flange cover (16) and the O-ring, and the center of the circle of the quartz window (8) is in line with the test The center of circle of pot type insulator (1) is on a vertical line. 8. The platform for measuring and observing the charge density on the surface of a DC GIL basin-type insulator according to claim 1, wherein the high-speed camera (17) is used to photograph and record the surface flashover process of the test insulator. 9. according to claim 1, a kind of direct current GIL basin type insulator surface charge density measurement and observation platform, is characterized in that, described direct current voltage generator (15) is a digital direct current voltage generator, maximum output voltage 200kV , Long-term stable supply of high-voltage direct current with a ripple factor <0.3%.