A bushing flange position external insulation discharge measuring device

Abstract

The utility model relates to voltage measurement technical field, concretely, relate to a bushing flange position external insulation discharge measuring device, including bushing, metal induction board, shielded box, detection circuit, metal induction board is embedded on shielded box, on metal induction board wiring to detection circuit board, whole detection circuit is in shielded box, the cable hole of rear U type board of shielded box is used for through cable output electric signal, adopts non -contact measurement mode, does not change grounding structure, measures and obtains bushing voltage, has improved bushing end screen potential, easy partial discharge and voltage phase error problem.

Description

Technical Field

[0001] This utility model relates to the field of voltage measurement technology, and more specifically, to a bushing flange position external insulation discharge measuring device. Background Technology

[0002] To analyze the characteristics and causes of corona discharge at the bushing's end screen, it is necessary to obtain the synchronously measured bushing voltage waveform. Existing voltage measurement methods include the voltage transformer method, the external voltage division method, and the fiber optic voltage sensor method.

[0003] The voltage transformer method takes a capacitive voltage transformer (CVT) as an example, such as... Figure 3 The diagram shows the electrical structure of a CVT. The capacitor divider consists of a high-voltage arm capacitor CH and a low-voltage arm capacitor CL connected in series. The electromagnetic unit comprises an intermediate transformer T, a compensating reactor L, a damper D, etc., with Z being the secondary load. The line voltage Us is stepped down by the capacitor divider and then input to the electromagnetic unit. After the compensating reactor's "compensation effect," it is input to the intermediate transformer, where it undergoes a "secondary voltage step-down" before being output. CVTs measuring line voltage suffer from poor transient characteristics. Furthermore, near the transformer, there may be situations where CVTs are far apart, the electromagnetic environment is complex, and voltage acquisition may be difficult.

[0004] The external voltage divider method involves constructing a voltage divider circuit based on the existing equipment structure of the power system, and then measuring the voltage. An example is a capacitive voltage divider based on a current transformer. (See...) Figure 5 This method utilizes existing current transformers (CTs) in the power system, using the stray capacitance C1 of the high-voltage conductor to the CT as the high-voltage arm and an external capacitor as the low-voltage arm to form a capacitive voltage divider. Using existing CTs as voltage dividers avoids a series of problems associated with traditional high-voltage voltage dividers connected in parallel with the high-voltage grid for extended periods. However, the main drawbacks are the instability of capacitor C1 and significant measurement errors. Another example is external voltage division using capacitive equipment (bushings), such as... Figure 6 As shown, the method of adding a capacitive sensor outside an existing capacitive device (bushing) works on the same principle as a high-voltage divider. The geometric capacitance of the capacitive device serves as the equivalent high-voltage capacitor, and the added capacitor is equivalent to a low-voltage capacitor. The two are connected in series, forming a capacitive voltage divider. The external impedance voltage of the capacitive device is measured, and the line voltage is calculated inversely. Because a capacitor is added to the grounding loop, the bushing's end screen potential is increased, making partial discharge more likely. Simultaneously, the capacitive device itself has a certain resistance, which introduces a certain voltage phase difference.

[0005] The fiber optic voltage sensor method utilizes fiber optic sensors to change the refractive index of a crystal based on the voltage of a specific laser crystal. This change in refractive index causes a shift in the phase or polarization direction of the light. An interferometer or polarization detector then converts this change in light into a voltage value. Its disadvantages include: the need to install current transformers or voltage dividers to obtain signals from a high-voltage power grid; poor electrical safety when obtaining signals from high-voltage lines or conductors; high precision requirements for optical components, susceptibility to interference leading to errors; high cost; and susceptibility to electromagnetic interference during signal transmission.

[0006] Existing voltage measurement methods for induced charge measurement are based on flat plate induction and are applied to circuits. However, partial discharge at the bushing end screen and surface discharge at the flange position are not applicable if the induction metal plate is located at different positions on the front and back of the bushing and is blocked by the bushing body, so the induction metal plate cannot generate induction. The method of analyzing the induced charge on the surface of the induction plate by electrostatic field mirror analysis is no longer applicable. Utility Model Content

[0007] This invention addresses the problem that existing voltage measurement methods, which rely on flat-plate induction and electrostatic field mirror analysis of the induced charge on the induction plate surface, are no longer applicable. It proposes a bushing flange external insulation discharge measurement device, comprising a bushing, a metal induction plate, a shielding box, and a detection circuit. The metal induction plate is embedded in the shielding box, and wires are connected to the detection circuit board. The entire detection circuit is located within the shielding box. The cable hole in the rear U-shaped plate of the shielding box is used to output an electrical signal via a cable. A non-contact measurement method is used, without altering the grounding structure, to measure the bushing voltage. This invention solves the problems of bushing end-screen potential, susceptibility to partial discharge, and voltage phase error.

[0008] The specific implementation details of this utility model are as follows: A bushing flange position external insulation discharge measuring device includes a bushing, a metal induction plate, a shielding box, and a detection circuit; The metal sensing plate is arranged around the lower end of the sleeve, and the metal sensing plate is provided with an opening that surrounds the lower end portion of the sleeve. One end of the opening of the metal sensing plate is embedded in the shielding box and connected to the detection circuit set inside the shielding box.

[0009] To better realize this utility model, the shielding box further includes a front U-shaped shell, a rear U-shaped shell, an upper cover plate, and a lower cover plate; The front U-shaped shell and the rear U-shaped shell are provided with a first bolt hole at one end near the upper cover plate, and the metal sensing plate is connected to the first bolt hole; A cable hole is provided at one end of the rear U-shaped shell near the lower cover plate, and the detection circuit is connected to the cable hole.

[0010] To better realize this utility model, a sixth bolt hole is further provided on the rear U-shaped shell; The detection circuit is connected to the rear U-shaped shell through the sixth bolt hole.

[0011] To better realize this utility model, the sleeve flange position external insulation discharge measuring device further includes a signal processing and acquisition device and a micro current coil; The signal processing and acquisition device is located on the outside of the surrounding metal induction plate; One end of the signal processing and acquisition device passes through a cable hole and is connected to the detection circuit, while the other end is connected to a micro-current coil to measure the micro-current on the connection line between the end screen and the flange.

[0012] To better realize this utility model, the sleeve flange position external insulation discharge measuring device further includes an insulation support structure; The insulating support structure includes multiple insulating rods evenly arranged inside the surrounding metal induction plate.

[0013] To better realize this utility model, the upper cover plate further includes a first upper cover plate and a second upper cover plate; The first upper cover plate is connected to the front U-shaped shell through the second screw hole at the top of the front U-shaped shell, and the second upper cover plate is connected to the rear U-shaped shell through the third screw hole at the top of the rear U-shaped shell. A metal sensing plate embedding slot is provided between the first upper cover plate and the second upper cover plate. The lower cover plate is connected to the front U-shaped shell and the rear U-shaped shell through the fourth screw hole at the bottom of the front U-shaped shell and the fifth screw hole at the bottom of the rear U-shaped shell.

[0014] To better realize this utility model, the detection circuit further includes capacitor C1, resistor R1, resistor R2, and resistor R3; One end of the capacitor C1 is connected to the metal induction plate, and the other end is connected to the grounded resistor R1; One end of the resistor R2 is connected between the metal induction plate and the capacitor C1, and the other end is connected to the signal processing and acquisition device through a shielded cable.

[0015] To better realize this utility model, the metal sensing plate is further described as an aluminum alloy sensing plate.

[0016] This utility model has the following beneficial effects: This invention does not change the grounding structure and uses a non-contact measurement method to measure the bushing voltage. It improves the problem of bushing end screen potential, easy partial discharge and voltage phase error, and solves the safety risks of directly connecting or taking equipment voltage at close range in CVT methods.

[0017] The induction plate, detection circuit, and shielding structure of this utility model adopt a lightweight design while ensuring the effectiveness of the function; the integrated structure of the induction plate embedded in the shielding box, and the detection circuit is fully shielded in the shielding box and is not affected by external electromagnetic signals.

[0018] This utility model device has a simple structure, low cost, short detection time, requires no complex signal processing, and is easy to operate and use. Attached Figure Description

[0019] Figure 1 The electrical structure diagram of the CVT provided for this utility model.

[0020] Figure 2 A schematic diagram of the capacitive voltage divider of the current transformer provided by this utility model.

[0021] Figure 3 A schematic diagram of the bushing end-frequency voltage sensor provided by this utility model.

[0022] Figure 4 A schematic diagram of the overall structure of the bushing flange position external insulation discharge measuring device provided by this utility model.

[0023] Figure 5 A schematic diagram of the cross-sectional structure of the external insulation discharge measuring device at the sleeve flange position provided by this utility model.

[0024] Figure 6 A schematic diagram of the shielding box structure provided by this utility model.

[0025] Figure 7 This is a front view of the through-hole current sensor structure provided by this utility model.

[0026] Figure 8 This is a top view of the through-hole current sensor structure provided by this utility model.

[0027] Figure 9 A schematic diagram of the circuit structure of the through-hole current sensor structure provided by this utility model.

[0028] Figure 10 The schematic diagram of the detection circuit provided by this utility model.

[0029] Among them, 1. Sleeve, 2. Metal induction plate, 3. Shielding box, 4. Detection circuit, 5. Front U-shaped shell, 6. Rear U-shaped shell, 7. Top cover plate, 71. First top cover plate, 72. Second top cover plate, 8. Bottom cover plate, 9. First bolt hole, 10. Cable hole, 11. Signal processing and acquisition device, 12. Micro-current coil, 13. Insulating support structure, 14. Insulating rod, 15. Second screw hole, 16. Third screw hole, 17. Metal induction plate embedding slot, 18. Fourth screw hole, 19. Fifth screw hole, 20. End screen, 21. Flange, 22. Sixth bolt hole. Detailed Implementation

[0030] To more clearly illustrate the technical solutions of the embodiments of this utility model, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. It should be understood that the described embodiments are only some embodiments of this utility model, not all embodiments, and therefore should not be regarded as a limitation on the scope of protection. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0031] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "set up," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0032] Example 1:

[0033] This embodiment proposes a device for measuring external insulation discharge at the location of a bushing flange, such as... Figure 4 As shown, it includes a sleeve 1, a metal sensing plate 2, a shielding box 3, and a detection circuit 4; The metal sensing plate 2 is arranged around the lower end of the sleeve 1, and the metal sensing plate 2 is provided with an opening that surrounds the lower end portion of the sleeve 1. One end of the opening of the metal sensing plate 2 is embedded in the shielding box 3 and connected to the detection circuit 4 set in the shielding box 3.

[0034] Working principle: This embodiment does not change the grounding structure and uses a non-contact measurement method to measure the bushing voltage. It improves the problem of bushing end screen potential, easy partial discharge and voltage phase error, and solves the safety risks of directly connecting or taking equipment voltage at close range in CVT method.

[0035] like Figure 4 As shown, the metal induction plate 2 is embedded in the shielding box 3. The metal induction plate 2 is connected to the detection circuit 4, and the entire detection circuit 4 is inside the shielding box 3. The lower plate of the shielding box 3 has an opening for outputting electrical signals via cables. The metal induction plate 2 can be replaced according to different sleeve models, adapting to sleeves 1 of different sizes to measure partial discharge of the end screen 20 and surface discharge of the flange 21. The metal induction plate 2 is made of aluminum alloy, approximately 75cm wide, about 1m away from the flange 21, and 0.5cm thick. It forms an arc shape with a certain degree of elasticity, and the opening can open to a certain extent, surrounding the flange 21, the end screen 20, and the ceramic sleeve connected to the flange 21. The metal induction plate 2 is fixed to the insulating support structure 13, which can support the flange 21.

[0036] Example 2:

[0037] This embodiment is based on the above embodiment 1, such as... Figure 6 As shown, the structure of the shielding box 3 is described using a specific embodiment.

[0038] The shielding box 3 includes a front U-shaped shell 5, a rear U-shaped shell 6, an upper cover plate 7, and a lower cover plate 8; The front U-shaped shell 5 and the rear U-shaped shell 6 are provided with a first bolt hole 9 at one end near the upper cover plate 7, and the metal sensing plate 2 is connected to the first bolt hole 9; The rear U-shaped shell 6 has a cable hole 10 at one end near the lower cover plate 8, and the detection circuit 4 is connected to the cable hole 10.

[0039] Working principle: The metal induction plate 2 is embedded in the shielding box 3 and connected to the detection circuit 4. The shielding box 3 is a split aluminum shell with a shell thickness of 2mm. The front and rear U-shaped shells 5 have the first bolt hole 9 (the two larger holes in the diagram) for connecting the induction plate, and the rear U-shaped plate 6 has the sixth bolt hole 22. Figure 6 The four smaller holes in the middle are used to fix the detection circuit board, the bottom center hole is used to pass the cable, the front U-shaped shell 5 and the rear U-shaped shell 6 can be fitted and sealed; the middle gap of the top cover plate 7 is used to embed and fix the metal sensing plate 2.

[0040] The other parts of this embodiment are the same as those in Embodiment 1 above, so they will not be described again.

[0041] Example 3:

[0042] This embodiment is based on any one of Embodiments 1-2 above, such as Figure 10 As shown, the entire detection circuit 4 is installed in the shielding box 3 in the form of a circuit board.

[0043] The detection circuit 4 includes a capacitor C1, a resistor R1, a resistor R2, and a resistor R3; One end of the capacitor C1 is connected to the metal induction plate, and the other end is connected to the grounded resistor R1; One end of the resistor R2 is connected between the metal induction plate and the capacitor C1, and the other end is connected to the signal processing and acquisition device through a shielded cable.

[0044] Working principle: The detection circuit 4 mainly consists of a protection capacitor and a matching resistor. The circuit principle is as follows: Figure 10 As shown, the entire detection circuit is installed in the shielded box 3 in the form of a circuit board.

[0045] The measured voltage signals U1 and U2 are led out by shielded cables. The cables lead out signals from the circuit board of the detection circuit 4, pass through the lower cover plate 8 of the shielded box, and then transmit U1 / U2 to the signal processing and acquisition device 11 for acquisition. The current signal I collected by the micro-current coil 12 is also acquired by the acquisition device 11.

[0046] The signal processing and acquisition device 11 acquires signals U1 and U2. The induced voltage signal U1 is a low-frequency signal, acquired at a sampling rate of 100Msa / s or higher; the discharge signal U2 contains discharge pulses and is a high-frequency signal, acquired at a sampling rate of 1Gsa / s or higher. Using an oscilloscope as an example, the induced voltage waveform and discharge pulse signal waveform are obtained from the signal processing and acquisition device 11.

[0047] Under actual working conditions, measurements can be taken at a horizontal distance of 1m from the bushing 1. The sensitivity of charge-induced voltage and discharge pulse measurement is high, and the anti-interference performance is good. The sensor is mainly composed of a metal induction plate 2, a shielding box 3, and a relatively simple passive detection circuit 4, which is low in cost. The detection time is short, and the signal can be used to analyze the corona discharge characteristics after simple processing.

[0048] This method solves the problems of low safety in direct measurement of corona current, the need for power outage measurement in pulse current method, the limitation of detection distance in ultraviolet detection method, and the significant influence of electromagnetic interference on ultrasonic detection method, as well as the limitations in measuring corona discharge of sleeve flanges. It also solves the problems of reliance on specialized instruments and high cost in the existing more accurate measurement technology, ultraviolet imaging method. Furthermore, it addresses the complex signal processing and application issues of detection technologies such as ultraviolet detection and ultrasonic detection.

[0049] By combining bushing voltage and charge-induced voltage, the characteristics of partial discharge, discharge intensity, and discharge phase of the end screen were analyzed, solving the problem that existing technologies cannot analyze and judge the degree and phase of corona discharge.

[0050] The other parts of this embodiment are the same as any one of the above embodiments 1-2, so they will not be described again.

[0051] Example 4:

[0052] This embodiment is based on any one of embodiments 1-3 above, such as Figure 7 , Figure 8 , Figure 9 As shown, the structure of the microcurrent coil 12 is illustrated with a specific embodiment.

[0053] The external insulation discharge measuring device at the bushing flange position also includes a signal processing and acquisition device 11 and a micro-current coil 12. The signal processing and acquisition device 11 is disposed on the outside of the surrounding metal induction plate 2; One end of the signal processing and acquisition device 11 passes through the cable hole 10 and is connected to the detection circuit 4, while the other end is connected to the micro-current coil 12 to measure the micro-current on the connection line between the end screen 20 and the flange 21.

[0054] Working principle: The grounding wire between the end screen 20 and the flange 21 passes through the circular hole on the microcurrent sensor, i.e., the microcurrent coil 12 (i.e., In+→In-), enabling non-contact microcurrent detection; the positive output (pin 3) and common ground (pin 4) are connected to the signal processing and acquisition device, and the signal is acquired through the signal processing and acquisition device 11. Figure 8 Signal I.

[0055] The other parts of this embodiment are the same as any one of the embodiments 1-3 above, so they will not be described again.

[0056] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present utility model shall fall within the protection scope of the present utility model.

Claims

1. A bushing flange position external insulation discharge measuring device, characterized in that, Includes a sleeve (1), a metal induction plate (2), a shielding box (3), and a detection circuit (4); The metal sensing plate (2) is arranged around the lower end of the sleeve (1), and the metal sensing plate (2) is provided with an opening that surrounds the lower end portion of the sleeve (1). One end of the opening of the metal sensing plate (2) is embedded in the shielding box (3) and connected to the detection circuit (4) set in the shielding box (3).

2. The bushing flange position external insulation discharge measuring device according to claim 1, characterized in that, The shielding box (3) includes a front U-shaped shell (5), a rear U-shaped shell (6), an upper cover plate (7), and a lower cover plate (8). The front U-shaped shell (5) and the rear U-shaped shell (6) are provided with a first bolt hole (9) at one end near the upper cover plate, and the metal sensing plate (2) is connected to the first bolt hole (9); The rear U-shaped shell (6) has a cable hole (10) at one end near the lower cover plate (8), and the detection circuit (4) is connected to the cable hole (10).

3. The bushing flange position external insulation discharge measuring device according to claim 2, characterized in that, The rear U-shaped shell (6) is also provided with a sixth bolt hole (22); The detection circuit (4) is connected to the rear U-shaped shell (6) through the sixth bolt hole (22).

4. The bushing flange position external insulation discharge measuring device according to claim 2, characterized in that, The bushing flange position external insulation discharge measuring device also includes a signal processing and acquisition device (11) and a micro current coil (12). The signal processing and acquisition device (11) is located outside the surrounding metal induction plate (2); One end of the signal processing acquisition device (11) passes through the cable hole (10) and is connected to the detection circuit (4), while the other end is connected to the micro-current coil (12) to measure the micro-current on the connection line between the end screen (20) and the flange (21).

5. The bushing flange position external insulation discharge measuring device according to claim 1, characterized in that, The external insulation discharge measuring device at the bushing flange position also includes an insulation support structure (13). The insulating support structure (13) includes multiple insulating rods (14) evenly arranged inside the surrounding metal induction plate (2).

6. The bushing flange position external insulation discharge measuring device according to claim 2, characterized in that, The upper cover plate (7) includes a first upper cover plate (71) and a second upper cover plate (72); The first upper cover plate (71) is connected to the front U-shaped shell (5) through the second screw hole (15) at the top of the front U-shaped shell (5), and the second upper cover plate (72) is connected to the rear U-shaped shell (6) through the third screw hole (16) at the top of the rear U-shaped shell (6). A metal sensor plate embedding slot (17) is provided between the first upper cover plate (71) and the second upper cover plate (72). The lower cover plate (8) is connected to the front U-shaped shell (5) and the rear U-shaped shell (6) through the fourth screw hole (18) at the bottom of the front U-shaped shell (5) and the fifth screw hole (19) at the bottom of the rear U-shaped shell (6).

7. The bushing flange position external insulation discharge measuring device according to claim 1, characterized in that, The detection circuit includes capacitor C1, resistor R1, resistor R2, and resistor R3; One end of the capacitor C1 is connected to the metal induction plate, and the other end is connected to the grounded resistor R1; One end of the resistor R2 is connected between the metal induction plate and the capacitor C1, and the other end is connected to the signal processing and acquisition device (11) through a shielded cable.

8. A bushing flange position external insulation discharge measuring device according to any one of claims 1-7, characterized in that, The metal induction plate is an aluminum alloy induction plate.

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