Signal acquisition and processing circuit for partial discharge of switch cabinet based on current method and gain method

Abstract

The utility model discloses a switch cabinet partial discharge signal acquisition processing circuit based on a current method and a gain method, comprising a chip U10 and an operational amplifier U11, a pin 2 of the operational amplifier U11 is provided with a high-low pass filter circuit, a pin 5 of the operational amplifier U11 is provided with a signal filter circuit, the high-low pass filter circuit and the signal filter circuit are jointly connected with a current sensor, and the current sensor is connected with the operational amplifier U11. The current sensor is installed on a main cable of the switch cabinet and used for detecting a current signal PD A, a pin 4 and a pin 8 of the operational amplifier U11 are provided with power supply filter circuits, and a pin 1 of the operational amplifier U11 is connected with a pin 3, a pin 4 and a pin 5 of the chip U10. According to the utility model, the current sensor is directly installed on the main cable, a current signal PD A of the main cable can be filtered and amplified and then sent to the programmable gain device U10, the current signal PD A can be restored and amplified to the greatest extent so as to be conveniently processed by a single-chip microcomputer, the partial discharge position of the high-voltage cable can be accurately reflected, and the device can be applied to GIS equipment, and has the advantages of small size, low cost and high reliability. The cost is low.

Description

Technical Field

[0001] This utility model relates to insulation detection of power cables, specifically a signal acquisition and processing circuit for partial discharge in switchgear based on current method and gain method. Background Technology

[0002] As an important piece of electrical equipment, the insulation performance of power cables is crucial to the safety of the line. Partial discharge detection, as a detection method, plays an important supporting role in evaluating whether the insulation condition of the cable is good.

[0003] Partial discharge detection and location of any form; arc, tracking, and corona detection; partial discharge detection of electrical equipment such as transformers, switchgear, ring main units, cable heads, insulators, circuit breakers, bus bushings, CT / PT, reactors, GIS / GCB, power supply cabinets, and communication cabinets; SF6 leakage detection; pneumatic system leakage detection; and mechanical fault detection.

[0004] Currently, the mainstream detection methods include ultrasonic monitoring and TEV monitoring. Ultrasonic monitoring is convenient to use but cannot accurately locate the partial discharge. Transient ground voltage (TEV) monitoring can automatically determine the location, but its application range is relatively narrow and it cannot be applied to GIS equipment. Utility Model Content

[0005] To address the shortcomings of the existing technology, this invention provides a signal acquisition and processing circuit for partial discharge in switchgear based on the current method and gain method. This invention directly mounts the current sensor on the main cable, and after filtering and amplifying the main cable current signal PDA, it sends it to the programmable gain unit U10, which maximizes the restoration and amplification of the current signal PDA for microcontroller processing. This allows for accurate detection of the partial discharge location of high-voltage cables, and it can be applied to GIS equipment. It is small in size and low in cost.

[0006] To achieve the above technical objectives, this utility model adopts the following technical solution: a signal acquisition and processing circuit for partial discharge in switchgear based on current method and gain method, including chip U10 and operational amplifier U11. A high-pass and low-pass filter circuit is set at pin 2 of operational amplifier U11, and a signal filter circuit is set at pin 5 of operational amplifier U11. The high-pass and low-pass filter circuits and the signal filter circuit are connected to a current sensor. The current sensor is installed on the main cable of the switchgear for detecting the current signal PDA. A power supply filter circuit is set at pins 4 and 8 of operational amplifier U11. Pin 1 of operational amplifier U11 is connected to pins 3, 4, and 5 of chip U10.

[0007] The high-pass and low-pass filter circuit includes capacitor CL1, resistor R63, resistor R124, and capacitor C45. CL1 and R63 form a high-pass filter, while R124 and C45 form a low-pass filter. Pin 2 of the operational amplifier U11 is divided into three paths: the first path connects to resistor RW3; the second path connects to capacitor C46; RW3 and C46 are connected in parallel and then to pin 1 of the operational amplifier U11; the third path connects to resistor RW2, which is connected to resistor R124 and capacitor C45. Diode D13 is also connected in parallel with capacitor C45 and then grounded. Resistor R124 is connected to capacitor CL1 and resistor R6, which is grounded. Capacitor CL1 is connected to capacitor CB1, which is connected to resistor RV1, which is grounded. Capacitor CB1 also receives the cable current signal PDA from the switchgear.

[0008] The signal filtering circuit includes resistor R58 and capacitor C39. Resistor R58 and capacitor C39 are connected in parallel, with one end grounded and the other end connected to resistor RB1 and resistor R50. Resistor RB1 is connected to the output terminal of capacitor CB1. Resistor R50 is connected to resistor R44 and pin 5 of operational amplifier U11. Resistor R44 is connected to +5V OP. Pin 6 of operational amplifier U11 is connected to pin 7 of operational amplifier U11.

[0009] The power supply filtering circuit includes capacitors C35 and C36, resistor R43, capacitor CC1, capacitor C40, capacitor C41, resistor R54, and capacitor C38. Capacitors C35 and C36 are connected in parallel, with one end grounded and the other end connected to pin 8 of operational amplifier U11. One end of resistor R43 is connected to pin 8 of operational amplifier U11, and the other end is connected to capacitor CC1 and a +5V OP (operational amplifier). Capacitor CC1 is grounded. Capacitors C40 and C41 are connected in parallel, with one end grounded and the other end connected to pin 4 of operational amplifier U11. One end of resistor R54 is connected to pin 4 of operational amplifier U11, and the other end is connected to capacitor C38 and a -5V OP (operational amplifier). Capacitor C38 is grounded.

[0010] Pins 3 and 4 of chip U10 are connected to resistor R52. Resistor R52 and pin 5 of chip U10 are connected to resistor RB2. Resistor RB2 is connected to pin 1 of operational amplifier U11.

[0011] Pin 1 of chip U10 is grounded, pin 2 is connected to resistor R51, pin 6 is connected to resistor R55, and resistors R51 and R55 are grounded. Pin 7 is connected to pin 14, pin 8 is connected to pin 13, and pin 12 is connected to resistor R59. Resistor R59 is connected to capacitor C44, resistor R62, and resistor R60. Capacitor C44 and resistor R62 are connected in parallel and then grounded. Resistor R60 is divided into three paths: the first path is connected to pin 13, the second path is connected to fuse FB2, and the third path is grounded through capacitor C43. Pin 14 is connected to capacitor C42. Grounding; Pin 15 is connected to resistor R56, which is connected to resistor R49, capacitor C37, and resistor R57. Resistor R49 and capacitor C37 are connected in parallel and then grounded. Resistor R57 is connected to fuse FB1 and capacitor C42. Pin 16 outputs the amplified Signal_OUT signal. Pin 17 is grounded through resistor R53, pin 18 is grounded through resistors R47 and R48, pin 19 is grounded through resistors R45 and R46, and pin 20 is grounded through resistors R41 and R42.

[0012] In summary, this utility model achieves the following technical effects:

[0013] This invention can filter and amplify the main cable current signal PDA and then send it to the programmable gain unit U10, so that the current signal PDA can be restored and amplified to the maximum extent for microcontroller processing.

[0014] Low cost: The market price of current sensors is around a few yuan, while the prices of ultrasonic detection sensors, TEV detection sensors, and UHF sensors range from several hundred to several thousand yuan. Therefore, the cost of this application is low.

[0015] Accurate positioning: Since the current sensor is directly installed on the main cable, it can accurately identify changes in the main circuit current and accurately reflect the partial discharge location of the high-voltage cable;

[0016] Product miniaturization: This device features small sensors, fewer main components, and software that replaces some hardware functions, significantly reducing the overall size of the device. Attached Figure Description

[0017] Figure 1 It is a signal acquisition and processing circuit for partial discharge in switchgear based on the current method and the gain method;

[0018] Figure 2 This is a circuit connection diagram for op-amp U11;

[0019] Figure 3 This is a circuit connection diagram of the programmable chip U10. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to the accompanying drawings.

[0021] This specific embodiment is merely an explanation of the present utility model and is not intended to limit the present utility model. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but as long as they are within the scope of the claims of the present utility model, they are protected by patent law.

[0022] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0023] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0024] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; 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; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0025] In this utility model, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0026] Example:

[0027] Figure 1 This is a signal acquisition and processing circuit for partial discharge in switchgear based on current method and gain method. It belongs to the signal acquisition device for partial discharge in switchgear based on current method and real-time variable gain method. It includes chip U10 and operational amplifier U11. High-pass and low-pass filter circuit is set on pin 2 of operational amplifier U11, and signal filter circuit is set on pin 5 of operational amplifier U11. The high-pass and low-pass filter circuit and the signal filter circuit are connected to a current sensor. The current sensor is installed on the main cable of the switchgear for detecting current signal PDA. Power supply filter circuit is set on pins 4 and 8 of operational amplifier U11. Pin 1 of operational amplifier U11 is connected to pins 3, 4 and 5 of chip U10.

[0028] The current sensor (not shown) is directly mounted on the main cable and can accurately detect the partial discharge location of the high-voltage cable. The current sensor model is HCS-ES5-10A, with pin 2 outputting a current signal PDA. The electrical connection between the current sensor and the main cable is existing technology and will not be described further here.

[0029] This application uses a current sensor to collect the current signal of the main cable and uses a convenient current method to collect and process the signal, which is suitable for partial discharge detection in different switch cabinets. The cost of the current sensor is much lower than that of ultrasonic sensors, TEV sensors, UHF sensors, etc., thus the cost of this application is low.

[0030] Figure 2 This is a circuit connection diagram for operational amplifier U11, and a schematic diagram of the circuit to the left of U10. Figure 1 The diagram shows a partially enlarged view. Operational amplifier U11 is model 082C. In this embodiment, operational amplifier U11 is divided into operational amplifier U11A, operational amplifier U11B, and operational amplifier U11C according to different pins. Operational amplifier U11A represents pins 1, 2, and 3 of operational amplifier U11, operational amplifier U11B represents pins 5, 6, and 7 of operational amplifier U11, and operational amplifier U11C represents pins 4 and 8 of operational amplifier U11. The connection circuit of operational amplifier U11 will be described below according to operational amplifier U11A, operational amplifier U11B, and operational amplifier U11C.

[0031] like Figure 2As shown, the high-pass and low-pass filter circuit includes capacitor CL1, resistor R63, resistor R124, and capacitor C45. Capacitor CL1 and resistor R63 form a high-pass filter, and resistor R124 and capacitor C45 form a low-pass filter. Pin 2 of the operational amplifier U11 is divided into three paths: the first path connects to resistor RW3; the second path connects to capacitor C46; resistor RW3 and capacitor C46 are connected in parallel and then connected to pin 1 of the operational amplifier U11; the third path connects to resistor RW2, which is connected to resistor R124 and capacitor C45. Capacitor C45 is also connected in parallel with diode D13, and the parallel connection of capacitor C45 and diode D13 is grounded. Resistor R124 is connected to capacitor CL1 and resistor R6, which is grounded. Capacitor CL1 is connected to capacitor CB1, which is connected to resistor RV1, which is grounded. Capacitor CB1 also receives the cable current signal PDA from the switchgear.

[0032] Capacitor CL1 and resistor R63 form a high-pass filter, and resistor R124 and capacitor C45 form a low-pass filter to filter high and low signals respectively and prevent noise interference.

[0033] like Figure 2 As shown, the signal filtering circuit is used to filter interference signals. The signal filtering circuit includes resistor R58 and capacitor C39. Resistor R58 and capacitor C39 are connected in parallel, with one end grounded and the other end connected to resistor RB1 and resistor R50. Resistor RB1 is connected to the output terminal of capacitor CB1. Resistor R50 is connected to resistor R44 and pin 5 of operational amplifier U11. Resistor R44 is connected to +5V OP. Pin 6 of operational amplifier U11 is connected to pin 7 of operational amplifier U11.

[0034] like Figure 2 As shown, the power supply filter circuit includes capacitor C35, capacitor C36, resistor R43, capacitor CC1, capacitor C40, capacitor C41, resistor R54, and capacitor C38. Capacitors C35 and C36 are connected in parallel, with one end grounded and the other end connected to pin 8 of operational amplifier U11. One end of resistor R43 is connected to pin 8 of operational amplifier U11, and the other end is connected to capacitor CC1 and a +5V OP. Capacitor CC1 is grounded. Capacitors C40 and C41 are connected in parallel, with one end grounded and the other end connected to pin 4 of operational amplifier U11. One end of resistor R54 is connected to pin 4 of operational amplifier U11, and the other end is connected to capacitor C38 and a -5V OP. Capacitor C38 is grounded.

[0035] Figure 3 This is a schematic diagram of the connection circuit for chip U10, and a schematic diagram of U10 and the circuit on the right. Figure 1 The enlarged schematic diagram shows that pins 3 and 4 of chip U10 are connected to resistor R52, and resistor R52 and pin 5 of chip U10 are connected to resistor RB2. Resistor RB2 is connected to pin 1 of operational amplifier U11.

[0036] The U10 chip uses a programmable amplifier, model THS7001CPWP, which is programmable and can automatically adjust the gain, replacing the use of hardware components, resulting in a small size and low cost.

[0037] Pin 1 of chip U10 is grounded, pin 2 is connected to resistor R51, pin 6 is connected to resistor R55, and resistors R51 and R55 are grounded. Pin 7 is connected to pin 14, pin 8 is connected to pin 13, and pin 12 is connected to resistor R59. Resistor R59 is connected to capacitor C44, resistor R62, and resistor R60. Capacitor C44 and resistor R62 are connected in parallel and then grounded. Resistor R60 is divided into three paths: the first path is connected to pin 13, the second path is connected to fuse FB2, and the third path is grounded through capacitor C43. Pin 14 is connected to capacitor C42. Pin 15 is grounded; pin 15 is connected to resistor R56, which in turn is connected to resistor R49, capacitor C37, and resistor R57. Resistor R49 and capacitor C37 are connected in parallel and then grounded. Resistor R57 is connected to fuse FB1 and capacitor C42. Pin 16 outputs the amplified Signal_OUT signal. Pin 17 is grounded through resistor R53, pin 18 through resistors R47 and R48, pin 19 through resistors R45 and R46, and pin 20 through resistors R41 and R42. The Signal_OUT signal is sent to subsequent processing circuitry.

[0038] First, the current sensor is attached to the three-phase power supply main cable. It collects the real-time current change value based on the real-time current change and sends it to the operational amplifier U11. After filtering and amplification, it is sent to the programmable amplifier U10. Furthermore, U10 uses the variable gain programmable amplifier chip THS7001CPWP, which can be calculated and processed by software, replacing the use of hardware devices, making it smaller and cheaper.

[0039] Because the sensor is installed on the main cable, it can accurately detect the partial discharge location of the high-voltage cable.

[0040] The input signal is the main cable current signal PDA collected by the current sensor. After passing through the high-frequency capacitor CB1, the signal is filtered by the RC high-pass filter CL1 and R63, and the low-pass filter R124 and C45. After being amplified by the operational amplifier TL082C, it is sent to the programmable gain unit U10 to automatically adjust the gain. This invention enables the signal to be restored and amplified to the maximum extent so that it can be processed by the microcontroller.

[0041] It adopts the traditional current transformer detection method and the automatic gain adjustment method after identifying the strength of the signal. It can be compatible with the advantages of UHF partial discharge detection bandwidth, TEV discharge type identification and the non-invasive installation of ultrasound. It can also accurately identify which main circuit is generating partial discharge and automatically adjust the acquired signal.

[0042] 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, equivalent changes and alterations made to the above embodiments based on the technical essence of the present utility model shall fall within the scope of the technical solution of the present utility model.

Claims

1. A signal acquisition and processing circuit for partial discharge in switchgear based on current method and gain method, characterized in that: The device includes a chip U10 and an operational amplifier U11. A high-pass and low-pass filter circuit is set at pin 2 of the operational amplifier U11, and a signal filter circuit is set at pin 5 of the operational amplifier U11. The high-pass and low-pass filter circuits and the signal filter circuit are connected to a current sensor. The current sensor is installed on the main cable of the switch cabinet to detect the current signal PDA. A power supply filter circuit is set at pins 4 and 8 of the operational amplifier U11. Pin 1 of the operational amplifier U11 is connected to pins 3, 4, and 5 of the chip U10.

2. The signal acquisition and processing circuit for partial discharge in switchgear based on current method and gain method according to claim 1, characterized in that: The high-pass and low-pass filter circuit includes capacitor CL1, resistor R63, resistor R124, and capacitor C45. CL1 and R63 form a high-pass filter, and R124 and C45 form a low-pass filter. Pin 2 of operational amplifier U11 is divided into three paths: the first path connects to resistor RW3; the second path connects to capacitor C46; RW3 and C46 are connected in parallel and then to pin 1 of operational amplifier U11; the third path connects to resistor RW2, which is connected to resistor R124 and capacitor C45. Diode D13 is also connected in parallel with capacitor C45 and then grounded. Resistor R124 is connected to capacitor CL1 and resistor R6, which is grounded. Capacitor CL1 is connected to capacitor CB1, which is connected to resistor RV1, which is grounded. Capacitor CB1 also receives the cable current signal PDA from the switchgear.

3. The signal acquisition and processing circuit for partial discharge in switchgear based on current method and gain method according to claim 2, characterized in that: The signal filtering circuit includes resistor R58 and capacitor C39. Resistor R58 and capacitor C39 are connected in parallel, with one end grounded and the other end connected to resistor RB1 and resistor R50. Resistor RB1 is connected to the output terminal of capacitor CB1. Resistor R50 is connected to resistor R44 and pin 5 of operational amplifier U11. Resistor R44 is connected to +5VOP. Pin 6 of operational amplifier U11 is connected to pin 7 of operational amplifier U11.

4. The signal acquisition and processing circuit for partial discharge in switchgear based on current method and gain method according to claim 3, characterized in that: The power supply filtering circuit includes capacitors C35 and C36, resistor R43, capacitor CC1, capacitor C40, capacitor C41, resistor R54, and capacitor C38. Capacitors C35 and C36 are connected in parallel, with one end grounded and the other end connected to pin 8 of operational amplifier U11. One end of resistor R43 is connected to pin 8 of operational amplifier U11, and the other end is connected to capacitor CC1 and a +5V OP. Capacitor CC1 is grounded. Capacitors C40 and C41 are connected in parallel, with one end grounded and the other end connected to pin 4 of operational amplifier U11. One end of resistor R54 is connected to pin 4 of operational amplifier U11, and the other end is connected to capacitor C38 and a -5V OP. Capacitor C38 is grounded.

5. The signal acquisition and processing circuit for partial discharge in switchgear based on current method and gain method according to claim 1, characterized in that: Pins 3 and 4 of the chip U10 are connected to resistor R52. Resistor R52 and pin 5 of the chip U10 are connected to resistor RB2. Resistor RB2 is connected to pin 1 of the operational amplifier U11.

6. The signal acquisition and processing circuit for partial discharge in switchgear based on current method and gain method according to claim 1, characterized in that: The chip U10 has the following pin configurations: pin 1 is grounded; pin 2 is connected to resistor R51; pin 6 is connected to resistor R55; resistors R51 and R55 are grounded; pin 7 is connected to pin 14; pin 8 is connected to pin 13; pin 12 is connected to resistor R59; resistor R59 is connected to capacitor C44, resistor R62, and resistor R60; capacitor C44 and resistor R62 are connected in parallel and then grounded; resistor R60 is divided into three paths: the first path is connected to pin 13; the second path is connected to fuse FB2; and the third path is grounded through capacitor C43. Pin 14 is grounded through capacitor C42; pin 15 is connected to resistor R56; resistor R56 is connected to resistor R49, capacitor C37, and resistor R57; resistors R49 and capacitor C37 are connected in parallel and then grounded; resistor R57 is connected to fuse FB1 and capacitor C42; pin 16 outputs the amplified Signal_OUT signal. Pin 17 is grounded through resistor R53, pin 18 is grounded through resistors R47 and R48, pin 19 is grounded through resistors R45 and R46, and pin 20 is grounded through resistors R41 and R42.

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