Capacitive bushing tap grounding state detection device

Abstract

The invention relates to the technical field of capacitance type bushing tap grounding state detection, and provides a capacitance type bushing tap grounding state detection device, which utilizes a high-frequency signal to directly detect a capacitance type bushing, remarkably improves the sensitivity and response speed of grounding state detection, and ensures that the grounding condition is quickly and accurately identified. The high-frequency signal generation module supports 0-300kHz signal output, adapts to detection requirements of capacitive bushings with different capacitances, and has relatively high applicability; the LCD man-machine interaction module is arranged, so that a user can visually display the detected capacitance, the operation convenience is improved, and the user experience is enhanced; the auxiliary circuit can provide corresponding stable voltage for each module.

Description

Technical Field

[0001] The invention relates to the technical field of capacitive bushing end screen grounding state detection, in particular to a capacitive bushing end screen grounding state detection device. Background Art

[0002] Bushing is a device used to pass through partitions such as walls and boxes. Its main function is to allow one or more conductors to pass through partitions such as walls or boxes, and to act as an insulator and support device. Capacitor bushing is a special type of bushing. It has all the properties and functions of bushings. The difference between it and conventional bushings is that the main insulation of capacitor bushings is composed of a coaxial cylindrical series capacitor group formed by alternately winding layered insulating materials and foil-like metal electrodes on conductive rods.

[0003] For capacitor bushings above 60kV, there are generally measurement terminals, which are led out from the end screen (i.e. the outermost electrode of the core) through a small porcelain sleeve and grounded during operation. During the operation of the transformer, real-time monitoring can be carried out without removing the bushing, and the insulation status of the bushing can be obtained in time, thereby ensuring the safe and stable operation of the equipment.

[0004] At present, the main insulating capacitor screen structure of the capacitor bushing in operation is not much different, but the external wiring terminals of the bushing, especially the end screen structure, are quite different. According to the existing technical solutions, there are generally three grounding methods used for the end screen of the capacitor bushing in the system: external, internal and normally grounded. With the advancement of technology and the improvement of manufacturing technology, its structure has also changed greatly. Since the past few years, the internal grounding structure has gradually become the mainstream in the new capacitor bushing end screen grounding method (grounding through the grounding cover and grounding cap).

[0005] However, this built-in grounding design brings a lot of difficulties in the process of checking the grounding restoration of the end screen after the on-site bushing test. The consequences of transformer failure caused by the unreliable grounding of the end screen are serious and cannot be ignored.

[0006] Under the action of high-frequency signals, capacitors can effectively charge and discharge, forming a rapid movement of charge. High-frequency signals usually refer to AC signals with frequencies between several thousand hertz and several hundred megahertz. When high-frequency signals pass through capacitors, the potential difference across the capacitors will change rapidly, thus affecting signal transmission and device stability.

[0007] The impedance method is a method suitable for measuring capacitor characteristics under AC conditions, especially in measuring high-frequency characteristics. By applying an AC voltage of a certain frequency to the capacitor, the impedance method can measure the impedance and phase angle of the capacitor, thereby obtaining the capacitance value and its equivalent series resistance. This provides an effective means for detecting the grounding status of capacitive bushings.

[0008] Based on this, the present invention proposes a capacitive bushing end screen grounding status detection device to efficiently and reliably check the end screen grounding recovery after on-site bushing testing. Summary of the invention

[0009] The purpose of the present invention is to solve the deficiencies of the prior art and to provide a capacitive bushing end screen grounding state detection device to efficiently and reliably check the end screen grounding recovery after field bushing testing.

[0010] In order to achieve the above object, the present invention adopts the following technical solutions:

[0011] A capacitive bushing end screen grounding state detection device comprises: a housing, an LCD human-machine interaction module arranged inside the housing, a high-frequency signal generation module, a detection circuit, an MCU main control and data processing module, a power supply module, and an auxiliary circuit; the MCU main control and data processing module are electrically connected to the LCD human-machine interaction module, the high-frequency signal generation module, the detection circuit, the power supply module, and the auxiliary circuit respectively; the output of the high-frequency signal generation module is electrically connected to the upper end of the capacitive bushing;

[0012] The LCD human-computer interaction module is used to present the data processed by the MCU main control and data processing modules, and transmit control commands to the MCU main control and data processing modules;

[0013] The high-frequency signal generating module is used to output a high-frequency sinusoidal AC signal through a signal output port under the control of the MCU main control and data processing module, and inject the high-frequency AC signal into the capacitive bushing; a resistor R is connected in series between the output of the high-frequency signal generating module and the capacitive bushing;

[0014] The detection circuit is used to detect the feedback signal loaded between the terminal at the top of the bushing and the transformer housing, and output the detected signal to the MCU main control and data processing module;

[0015] The MCU main control and data processing module is used to output the detection circuit to the MCU main control after analog-to-digital conversion. The MCU main control uses the signal output by the detection circuit to calculate the voltage signal loaded on the capacitive bushing, and outputs the total capacitance of other capacitors and the bushing main capacitor in parallel, and transmits the total capacitance signal to the LCD human-computer interaction module;

[0016] The power supply module is used to supply power to the LCD human-computer interaction module, the high-frequency signal generation module, the detection circuit, the MCU main control and the data processing module;

[0017] The auxiliary circuit is used to convert the voltage output by the power module to provide an adaptive voltage for the LCD human-computer interaction module, the high-frequency signal generation module, the detection circuit, the MCU main control and the data processing module.

[0018] Preferably, the shell is a rectangular box, the LCD human-computer interaction module is fixed to the front side of the shell, the top of the shell is provided with signal output, input and device shell grounding sockets, the high-frequency signal generating module, the detection circuit, the MCU main control and data processing module, the auxiliary circuit and the power supply module are arranged inside the shell, and a power plug is provided on the side of the shell; the signal output socket is connected to the end of the resistor R away from the high-frequency signal generating module, the signal input socket is connected to the detection circuit, and the power plug is connected to the power module.

[0019] Preferably, the high-frequency signal generating module outputs a high-frequency sinusoidal AC signal with a frequency range of 0 to 300 kHz.

[0020] Preferably, the high-frequency signal generating module includes: capacitors C1, C2, C4, inductor L1, and a common-phase gate driver U1; pin 1 of the common-phase gate driver U1 is connected to a 5V power supply, pins 2 and 4 of the common-phase gate driver U1 are grounded, pin 3 of the common-phase gate driver U1 is connected to SPWM1 output by the MCU, pin 5 of the common-phase gate driver U1 is connected in series with the inductor L1, and the idle end of the inductor L1 is the output signal port SIN1; capacitors C2 and C4 are connected in parallel between pin 1 and pin 2 of the common-phase gate driver U1.

[0021] Preferably, the detection circuit detects the voltage across the resistor R, and the detection circuit is two high-frequency voltage signal acquisition and amplification circuits, which are respectively connected between the two ends of R and the grounding point.

[0022] Preferably, the detection circuit is a high-frequency voltage signal acquisition and amplification circuit; the high-frequency voltage signal acquisition and amplification circuit includes: inductors L2, L3, inductors C38-C45, diodes ZD2, resistors R6-R10, operational amplifier U2, and potentiometer U6; one end of the inductor L2 is connected to the resistor R, and the other end is grounded; one side of the inductor L2 is the inductor L3, one end of the inductor L3 is connected to pin 1 of the operational amplifier U2, and the other end is grounded, a capacitor C42 is provided between one end of the inductor L3 and pin 1 of the operational amplifier U2, pin 2 of the operational amplifier U2 is grounded, pin 3 of the operational amplifier U2 is connected to pin 1 of the potentiometer U6, a resistor R10 is connected in series at the end of pin 4 of the operational amplifier U2, and the vacant end of the resistor R10 is the signal output port U_ADC 1. Pin 5 of the operational amplifier U2 is connected to a 3.3V power supply. C38, C39, and series resistors R6 and R7 are connected in parallel between pin 5 of the operational amplifier U2 and the ground respectively. A capacitor C40 is connected in parallel at both ends of the resistor R7, and capacitor C42 is connected to capacitor C40 via resistor R8. Pin 2 of the potentiometer U6 is connected to a 3.3V power supply. A capacitor C43 is provided between pin 2 and the ground. Pin 3 of the potentiometer U6 is grounded. Pins 4-6 of the potentiometer U6 are connected to corresponding outputs of the MCU. Pin 7 of the potentiometer U6 is connected to pin 4 of the operational amplifier U2, and the connection point is grounded via resistor R9. Pin 7 of the potentiometer U6 is grounded via capacitor C41. The front end of the output port U_ADC1 is grounded via capacitor C44. A diode ZD2 is connected in parallel at both ends of the inductor L3.

[0023] Preferably, the detection circuit also includes a high-frequency current signal acquisition and amplification circuit. The current sensor of the high-frequency current signal acquisition and amplification circuit is an open type and is installed on the external capacitive bushing end screen grounding wire to perform current detection in the end screen grounding wire.

[0024] Preferably, the MCU main control adopts an STM32F301K8T6 single-chip microcomputer, and the MCU main control is equipped with a crystal oscillator circuit, a connector, and a decoupling circuit.

[0025] Preferably, the auxiliary circuit includes a 12V to 5V circuit and a 5V to 3.3V circuit, the 2V to 5V circuit uses an LM2596 chip; the 5V to 3.3V circuit uses an LM2596 chip.

[0026] The present invention discloses a capacitive bushing end screen grounding state detection device having the following beneficial effects.

[0027] The present invention utilizes high-frequency signals to directly detect capacitive bushings, significantly improving the sensitivity and response speed of grounding state detection, ensuring rapid and accurate identification of grounding conditions; the high-frequency signal generation module supports 0-300kHz signal output, adapts to the detection requirements of capacitive bushings with different capacitances, and has strong applicability; equipped with an LCD human-computer interaction module, users can intuitively display the grounding state, improve operational convenience, and enhance user experience; the auxiliary circuit can provide corresponding stable voltages for each module, reducing maintenance costs and improving work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The present invention is a system block diagram of the capacitive bushing end screen grounding state detection device.

[0029] Figure 2 This is a circuit schematic diagram of the high-frequency signal generating module of the present invention.

[0030] Figure 3 This is a schematic diagram of the high-frequency voltage signal acquisition and amplification circuit of the present invention.

[0031] Figure 4 The schematic diagram of the high-frequency current signal acquisition and amplification circuit of the present invention is

[0032] Figure 5 This is a schematic diagram of the MCU main control and some functional circuits of the present invention.

[0033] Figure 6 It is a partial circuit schematic diagram of the auxiliary circuit of the present invention.

[0034] Figure 7 It is a partial circuit schematic diagram of the auxiliary circuit of the present invention.

[0035] Figure 8 This is a schematic diagram of the external structure of a capacitive bushing end screen grounding status detection device.

[0036] In the attached figure: 1. Shell; 2. Signal output socket; 3. Signal input socket; 4. Device shell grounding socket; 5. LCD human-computer interaction module; 6. High-frequency signal generation module; 7. Detection circuit; 8. MCU main control and data processing module; 9. Auxiliary circuit; 10. Power module; 11. Input power plug; 12. Button; 13. Capacitive sleeve; 14. Current sensor. DETAILED DESCRIPTION

[0037] In order to explain in detail the possible application scenarios, technical principles, specific schemes that can be implemented, and the purposes and effects that can be achieved, the following is a detailed description of the specific embodiments listed in conjunction with the accompanying drawings. The embodiments described herein are only used to more clearly illustrate the technical solutions of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0038] Reference to "embodiment" herein means that the specific features, structures or characteristics described in conjunction with the embodiment may be included in at least one embodiment of the present application. The term "embodiment" appearing in various places in the specification does not necessarily refer to the same embodiment, nor does it particularly limit its independence or association with other embodiments. In principle, in the present application, as long as there is no technical contradiction or conflict, the various technical features mentioned in the embodiments can be combined in any way to form a corresponding implementable technical solution.

[0039] Unless otherwise defined, the technical terms used in this document have the same meanings as those commonly understood by technicians in the technical field to which this application belongs; the use of relevant terms in this document is only for describing specific embodiments and is not intended to limit this application.

[0040] In the description of this application, the term "and / or" is an expression used to describe the logical relationship between objects, indicating that three relationships may exist, for example, A and / or B, which means: A exists, B exists, and A and B exist at the same time. In addition, the character " / " in this article generally indicates that the objects before and after are in an "or" logical relationship.

[0041] Without further limitations, in this application, the words "include", "comprises", "has" or other similar expressions used in the sentences are intended to cover non-exclusive inclusion. These expressions do not exclude the presence of additional elements in the process, method or product including the elements, so that the process, method or product including a series of elements may include not only those limited elements, but also other elements not explicitly listed, or also include elements inherent to such process, method or product.

[0042] Unless otherwise expressly specified or limited, in the description of the embodiments of the present application, the terms such as "install", "connect", "connect", "fix", "set", etc. used should be understood in a broad sense. For example, the "connection" can be a fixed connection, a detachable connection, or an integrated setting; it can be a mechanical connection, an electrical connection, or a communication connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. For technicians in the technical field to which the present application belongs, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0043] Example 1

[0044] Please refer to Figure 1 , the present embodiment provides a capacitive bushing end screen grounding state detection device, comprising: a housing 1, an LCD human-machine interaction module 5, a high-frequency signal generating module 6, a detection circuit 7, an MCU main control and data processing module 8, a power module 10, and an auxiliary circuit 9 arranged inside the housing 1; the MCU main control and data processing module 8 are electrically connected to the LCD human-machine interaction module 5, the high-frequency signal generating module 6, the detection circuit 7, the power module 10, and the auxiliary circuit 9 respectively; the output of the high-frequency signal generating module 6 is electrically connected to the upper end of the capacitive bushing 13; specifically, the output of the MCU main control and data processing module 8 is connected to the LCD human-machine interaction module 5, the high-frequency signal generating module 6, and the input of the detection circuit 7 respectively; the input of the MCU main control and data processing module 8 is connected to the output of the LCD human-machine interaction module 5, the high-frequency signal generating module 6, and the detection circuit 7 respectively;

[0045] LCD human-computer interaction module 5, used to present the data processed by MCU main control and data processing module 8, and transmit control commands to MCU main control and data processing module 8;

[0046] The high-frequency signal generating module 6 is used to output a high-frequency sinusoidal AC signal through a signal output port under the control of the MCU main control and data processing module 8, and inject the high-frequency AC signal into the capacitive bushing 13; a resistor R is connected in series between the output of the high-frequency signal generating module 6 and the capacitive bushing 13;

[0047] The detection circuit 7 is used to detect the feedback signal loaded between the top terminal of the bushing and the transformer housing 1, and output the detected signal to the MCU main control and data processing module 8; the detection circuit 7 detects the voltage across the resistor R, and the detection circuit 7 is two high-frequency voltage signal acquisition and amplification circuits, which are respectively connected between the two ends of R and the grounding point. Figure 1 The high-frequency voltage measurement circuit connected at V1 and V2 detects the voltage between the two ends of R1 and the ground;

[0048] The MCU main control and data processing module 8 is used to output the detection circuit 7 to the MCU main control after analog-to-digital conversion. The MCU main control uses the signal output by the detection circuit 7 to calculate the voltage signal loaded on the capacitive bushing 13, and outputs the total capacitance after other capacitors and the bushing main capacitor are connected in parallel, and transmits the total capacitance signal to the LCD human-computer interaction module 5; the MCU main control and data processing module 8 calculates the current and voltage signals loaded on the bushing, thereby further calculating C its (other capacitances). It should be noted that C its is a fixed value that is only related to the transformer parameters, and the total capacitance after C main (capacitive bushing 13 capacitance) is connected in parallel. The MCU main control saves the total capacitance calculation result; Figure 5 As shown, the MCU main control adopts the STM32F301K8T6 single-chip microcomputer, and the MCU main control is equipped with functional circuits such as crystal oscillator circuit, connector, and decoupling circuit.

[0049] The power module 10 is used to supply power to the LCD human-computer interaction module 5, the high-frequency signal generation module 6, the detection circuit 7, the MCU main control and data processing module 8;

[0050] The auxiliary circuit 9 is used to convert the voltage output by the power module 10 to provide an adaptive voltage for the LCD human-computer interaction module 5, the high-frequency signal generating module 6, the detection circuit 7, the MCU main control and the data processing module 8. The auxiliary circuit 9 is electrically connected to the LCD human-computer interaction module 5, the high-frequency signal generating module 6, the detection circuit 7, the MCU main control and the data processing module 8 respectively.

[0051] As a preferred embodiment, please refer to Figure 6 and Figure 7 The auxiliary circuit 9 includes a 12V to 5V circuit and a 5V to 3.3V circuit. The 2V to 5V circuit uses the TPS56320x chip; the 5V to 3.3V circuit uses the TPS56320x chip.

[0052] Please refer to Figure 8Preferably, the shell 1 is a rectangular box, the LCD human-machine interaction module 5 is fixed to the front side of the shell 1, the top of the shell 1 is provided with signal output, input and device shell grounding sockets 4, the high-frequency signal generating module 6, the detection circuit 7, the MCU main control and data processing module 8, the auxiliary circuit 9 and the power supply module 10 are arranged inside the shell 1, and the side of the shell 1 is provided with a power plug; there is a button 12 on the LCD human-machine interaction module 5, and the button 12 is used to operate the LCD display screen; the signal output socket 2 is connected to the end of the resistor R away from the high-frequency signal generating module 6, the signal input socket 3 is connected to the detection circuit 7, the power plug is connected to the power supply module 10, the signal output socket 2 is used to output the high-frequency signal output by the high-frequency signal generating module 6, and the signal input socket 3 is used to input the current sensor 14 detection signal. The input power plug 11 is electrically connected to the power module 10 through a wire, the power module 10 is electrically connected to the LCD human-computer interaction module 5 through the auxiliary circuit 9 through a wire, the power module 10 is electrically connected to the high-frequency signal generating module 6 through the auxiliary circuit 9 through a wire, the power module 10 is electrically connected to the detection circuit 7 through the auxiliary circuit 9 through a wire, the power module 10 is electrically connected to the MCU main control and data processing module 8 through the auxiliary circuit 9 through a wire, the high-frequency signal generating module 6 is electrically connected to the MCU main control and data processing module 8 through a wire, the high-frequency signal generating module 6 is electrically connected to the detection circuit 7 through a wire, the detection circuit 7 is electrically connected to the MCU main control and data processing module 8 through a wire, the MCU main control and data processing module 8 is electrically connected to the LCD human-computer interaction module 5 through a wire, and the LCD human-computer interaction module 5 adopts the Taojingchi serial port screen TJC8048X543_011C_l, and its main control chip model is AIHMI T8.

[0053] Please refer to Figure 2 As a preferred embodiment, the high-frequency signal generating module 6 includes: capacitors C1, C2, C4, inductor L1, and in-phase gate driver U1; pin 1 of the in-phase gate driver U1 is connected to a 5V power supply, pins 2 and 4 of the in-phase gate driver U1 are grounded, pin 3 of the in-phase gate driver U1 is connected to SPWM1 output by the MCU, pin 5 of the in-phase gate driver U1 is connected in series with the inductor L1, and the idle end of the inductor L1 is the output signal port SIN1; capacitors C2 and C4 are connected in parallel between pins 1 and 2 of the in-phase gate driver U1. The in-phase gate driver U1 adopts UCC27517DBVR, a 4A single-channel low-side in-phase gate driver chip;

[0054] Please refer to Figure 3As a preferred embodiment, the high-frequency voltage signal acquisition and amplification circuit includes: inductors L2, L3, inductors C38-C45, diodes ZD2, resistors R6-R10, operational amplifier U2, and potentiometer U6; one end of the inductor L2 is connected to the resistor R, and the other end is grounded; one side of the inductor L2 is the inductor L3, one end of the inductor L3 is connected to pin 1 of the operational amplifier U2, and the other end is grounded, a capacitor C42 is arranged between one end of the inductor L3 and pin 1 of the operational amplifier U2, pin 2 of the operational amplifier U2 is grounded, pin 3 of the operational amplifier U2 is connected to pin 1 of the potentiometer U6, a resistor R10 is connected in series at the end of pin 4 of the operational amplifier U2, the vacant end of the resistor R10 is the signal output port U_ADC1, and the operational amplifier U2 pin 5 is connected to the 3.3V power supply, and C38, C39, and series resistors R6 and R7 are connected in parallel between the operational amplifier U2 pin 5 and the ground; capacitor C40 is connected in parallel at both ends of the resistor R7, and capacitor C42 is connected to capacitor C40 through resistor R8; potentiometer U6 pin 2 is connected to the 3.3V power supply, and capacitor C43 is provided between pin 2 and the ground, potentiometer U6 pin 3 is grounded, and potentiometer U6 pins 4-6 are connected to the corresponding output of the MCU; potentiometer U6 pin 7 is connected to operational amplifier U2 pin 4, and the connection point is grounded through resistor R9, and potentiometer U6 pin 7 is grounded through capacitor C41; the front end of the output port U_ADC1 is grounded through capacitor C44; diode ZD2 is connected in parallel at both ends of the inductor L3. Another group of voltage signal acquisition and amplification circuits has the same structure as this group of voltage signal acquisition and amplification circuits, except that the sampling point is another section of the resistor R sampled by this group, and the output port is U_ADC2. The high-frequency voltage signal acquisition and amplification circuit is provided with a potentiometer U6 which can adjust the amplification factor of the operational amplifier U2 to obtain the most suitable signal. The potentiometer U6 adopts the TPL0501 256-tap single-channel digital potentiometer.

[0055] When the capacitive bushing end screen grounding state detection device is used, before the on-site bushing test is carried out, after the power is turned off, step 1 is to input the test command by the LCD human-computer interaction module 5; step 2 is to control the MCU main control and data processing module 8 to control the high-frequency signal generation module 6 to inject the high-frequency AC signal into the capacitive bushing 13, specifically to load it between the bushing top terminal and the transformer housing 1; step 3 is to detect the circuit 7 through Figure 1The high-frequency voltage measurement circuit connected at V1 and V2 detects the voltage between the two ends of R1 to the ground, and outputs it to the MCU main control and data processing module 8; Step 4 The MCU main control calculates the current and voltage signal loaded into the bushing according to the voltage between the two ends of R1 to the ground, thereby further calculating the total capacitance after C its (other capacitors) and C main (capacitive bushing 13 capacitors) are connected in parallel, and the MCU main control saves the total capacitance calculation result; After the on-site bushing test, repeat steps 1-4, and compare the two saved total capacitance results with each other. If the total capacitance before the on-site bushing test is greater than the total capacitance after the on-site bushing test, it is considered that the grounding state of the capacitor bushing end screen is unreliable; If the total capacitance before the on-site bushing test is less than or equal to the total capacitance after the on-site bushing test, it is considered that the grounding state of the capacitor bushing end screen is reliable.

[0056] Example 2

[0057] Based on Example 1, please refer to Figure 1 and Figure 4 The detection circuit 7 provided in this embodiment also includes a high-frequency current signal acquisition and amplification circuit. The current sensor 14 of the high-frequency current signal acquisition and amplification circuit is an open type and is installed on the external capacitive bushing end screen grounding wire to detect the current in the end screen grounding wire; the external grounding state of the end screen of the capacitive bushing 13 can be detected. If there is no current, it proves that it is not grounded.

[0058] The above are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. The substitution may be a substitution of a part of the structure, device, method step, or a complete technical solution. The equivalent replacement or change according to the technical solution and the inventive concept of the present invention shall be covered within the protection scope of the present invention.

Claims

1. A capacitive bushing end screen grounding state detection device, characterized in that: include: A housing, an LCD human-machine interaction module, a high-frequency signal generating module, a detection circuit, an MCU main control and data processing module, a power module, and an auxiliary circuit arranged inside the housing; the MCU main control and data processing module are electrically connected to the LCD human-machine interaction module, the high-frequency signal generating module, the detection circuit, the power module, and the auxiliary circuit respectively; the output of the high-frequency signal generating module is electrically connected to the upper end of the capacitive sleeve; The LCD human-computer interaction module is used to present the data processed by the MCU main control and data processing modules, and transmit control commands to the MCU main control and data processing modules; The high-frequency signal generating module is used to output a high-frequency sinusoidal AC signal through a signal output port under the control of the MCU main control and data processing module, and inject the high-frequency AC signal into the capacitive bushing; a resistor R is connected in series between the output of the high-frequency signal generating module and the capacitive bushing; The detection circuit is used to detect the feedback signal loaded between the terminal at the top of the bushing and the transformer housing, and output the detected signal to the MCU main control and data processing module; The MCU main control and data processing module is used to output the detection circuit to the MCU main control after analog-to-digital conversion. The MCU main control uses the signal output by the detection circuit to calculate the voltage signal loaded on the capacitive bushing, and outputs the total capacitance of other capacitors and the bushing main capacitor in parallel, and transmits the total capacitance signal to the LCD human-computer interaction module; The power supply module is used to supply power to the LCD human-computer interaction module, the high-frequency signal generation module, the detection circuit, the MCU main control and the data processing module; The auxiliary circuit is used to convert the voltage output by the power module to provide an adaptive voltage for the LCD human-computer interaction module, the high-frequency signal generation module, the detection circuit, the MCU main control and the data processing module.

2. The capacitive bushing end screen grounding state detection device according to claim 1, characterized in that: The shell is a rectangular box, the LCD human-computer interaction module is fixed to the front side of the shell, the top of the shell is provided with signal output, input and device shell grounding sockets, the high-frequency signal generating module, the detection circuit, the MCU main control and data processing module, the auxiliary circuit and the power supply module are arranged inside the shell, and a power plug is provided on the side of the shell; the signal output socket is connected to the end of the resistor R away from the high-frequency signal generating module, the signal input socket is connected to the detection circuit, and the power plug is connected to the power module.

3. The capacitive bushing end screen grounding state detection device according to claim 1, characterized in that: The high-frequency signal generating module outputs a high-frequency sinusoidal AC signal with a frequency range of 0 to 300 kHz.

4. The capacitive bushing end screen grounding state detection device according to claim 3, characterized in that: The high-frequency signal generating module includes: capacitors C1, C2, C4, inductor L1, and a common-phase gate driver U1; pin 1 of the common-phase gate driver U1 is connected to a 5V power supply, pins 2 and 4 of the common-phase gate driver U1 are grounded, pin 3 of the common-phase gate driver U1 is connected to SPWM1 output by the MCU, pin 5 of the common-phase gate driver U1 is connected in series with the inductor L1, and the idle end of the inductor L1 is the output signal port SIN1; capacitors C2 and C4 are connected in parallel between pin 1 and pin 2 of the common-phase gate driver U1.

5. The capacitive bushing end screen grounding state detection device according to claim 1, characterized in that: The detection circuit detects the voltage across the resistor Rmeasure, and the detection circuit is two high-frequency voltage signal acquisition and amplification circuits, which are respectively connected between the two ends of Rmeasure and the grounding point.

6. The capacitive bushing end screen grounding state detection device according to claim 5, characterized in that: The detection circuit is a high-frequency voltage signal acquisition and amplification circuit; the high-frequency voltage signal acquisition and amplification circuit includes: inductors L2, L3, inductors C38-C45, diodes ZD2, resistors R6-R10, operational amplifier U2, and potentiometer U6; one end of the inductor L2 is connected to the resistor R, and the other end is grounded; one side of the inductor L2 is the inductor L3, one end of the inductor L3 is connected to the pin 1 of the operational amplifier U2, and the other end is grounded, a capacitor C42 is arranged between one end of the inductor L3 and the pin 1 of the operational amplifier U2, the pin 2 of the operational amplifier U2 is grounded, the pin 3 of the operational amplifier U2 is connected to the pin 1 of the potentiometer U6, the end of the pin 4 of the operational amplifier U2 is connected in series with a resistor R10, and the vacant end of the resistor R10 is the signal output port U_ADC1, Pin 5 of the operational amplifier U2 is connected to a 3.3V power supply, and C38, C39, and series resistors R6 and R7 are respectively connected in parallel between pin 5 of the operational amplifier U2 and ground; a capacitor C40 is connected in parallel at both ends of the resistor R7, and capacitor C42 is connected to capacitor C40 via a resistor R8; pin 2 of the potentiometer U6 is connected to a 3.3V power supply, and a capacitor C43 is provided between pin 2 and ground, pin 3 of the potentiometer U6 is grounded, and pins 4-6 of the potentiometer U6 are connected to corresponding outputs of the MCU; pin 7 of the potentiometer U6 is connected to pin 4 of the operational amplifier U2, and the connection point is grounded via a resistor R9, and pin 7 of the potentiometer U6 is grounded via a capacitor C41; the front end of the output port U_ADC1 is grounded via a capacitor C44; a diode ZD2 is connected in parallel at both ends of the inductor L3.

7. The capacitive bushing end screen grounding state detection device according to claim 5, characterized in that: The detection circuit also includes a high-frequency current signal acquisition and amplification circuit. The current sensor of the high-frequency current signal acquisition and amplification circuit is an open type and is installed on the external capacitive bushing end screen grounding wire to detect the current in the end screen grounding wire.

8. The capacitive bushing end screen grounding state detection device according to claim 1, characterized in that: The MCU main control adopts the STM32F301K8T6 single chip microcomputer, and the MCU main control is equipped with a crystal oscillator circuit, a connector, and a decoupling circuit.

9. The capacitive bushing end screen grounding state detection device according to claim 1, characterized in that: The auxiliary circuit includes a 12V to 5V circuit and a 5V to 3.3V circuit. The 2V to 5V circuit uses an LM2596 chip; the 5V to 3.3V circuit uses an LM2596 chip.

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