A kind of ring main unit partial discharge on-line monitoring device based on capacitive coupling

Abstract

The utility model relates to a kind of ring main unit partial discharge on-line monitoring device based on capacitive coupling, it includes base and monitoring acquisition probe, base whole is U-shaped structure, base one side lower portion is provided with on-line monitor, on-line monitor upper portion is provided with power supply, base opening side is equipped with monitoring acquisition probe, monitoring acquisition probe is electrically connected with on-line monitor, monitoring acquisition probe, on-line monitor is electrically connected with power supply respectively;Monitoring acquisition probe and the nuclear phase hole of electrified display are in parallel, obtain ring main unit partial discharge information, and upload to on-line monitor;The utility model has the advantages of reasonable structure, accurate detection, easy to install, convenient to use.

Description

Technical Field

[0001] This utility model belongs to the technical field of ring main unit partial discharge monitoring equipment, specifically relating to an online monitoring device for partial discharge of ring main units based on capacitive coupling. Background Technology

[0002] Ring main units (RNBs) are affected by humid and high-temperature environments, resulting in insulation aging failures accounting for over 70% of all failures. Currently, power companies mostly rely on manual periodic inspections for fault diagnosis, but the main problem is the untimely detection of faults. To detect partial discharge in electrical equipment at its early stages and reduce its impact on insulation, various detection methods have been proposed, including differential methods, directional coupling methods, electromagnetic coupling methods, transient voltage-to-ground methods, inductive coupling methods, ultra-high frequency methods, and ultrasonic methods. However, these methods still have the following problems: ① The partial discharge signal in the RNB is very weak and can easily be detected during operation. The following are some of the reasons why partial discharge monitoring devices for ring main units (RNBs) are not widely adopted: ① They are subject to noise interference; ② The working environment of RNBs is harsh and easily affected by electromagnetic interference, which cannot be completely filtered out by hardware filtering alone; ③ Some detection methods can only measure partial discharge signals from the outside of the RNB, making it difficult to detect partial discharge phenomena occurring inside the RNB, such as at cable joints; ④ Some detection methods use expensive sensors, making them difficult to widely adopt; ⑤ The signals collected by the sensors are distorted after filtering, making it difficult to accurately identify the signals. Therefore, it is very necessary to provide a reasonably structured, accurate, easy-to-install, and convenient online partial discharge monitoring device for RNBs based on capacitive coupling. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a partial discharge online monitoring device for ring main units based on capacitive coupling that is structurally reasonable, accurate in detection, easy to install, and convenient to use.

[0004] The purpose of this utility model is achieved as follows: A partial discharge online monitoring device for ring main units based on capacitive coupling includes a base and a monitoring and acquisition probe. The base has an overall U-shaped structure. An online monitoring instrument is installed on the lower side of one side of the base, and a power supply is installed above the online monitoring instrument. The monitoring and acquisition probe is installed on the side of the opening of the base. The monitoring and acquisition probe is electrically connected to the online monitoring instrument, and the monitoring and acquisition probe and the online monitoring instrument are respectively electrically connected to the power supply. The monitoring and acquisition probe is connected in parallel with the phase detection hole of the live display to acquire partial discharge information of the ring main unit and upload it to the online monitoring instrument.

[0005] The base has positioning plates on both the top and bottom sides, which can be detachably attached to different monitoring positions for online monitoring.

[0006] Each of the four corners of the positioning plate is provided with a mounting sleeve, each mounting sleeve is provided with a positioning nut, each mounting sleeve is provided with a screw rod, the screw rod is threadedly connected to the positioning nut, and each end of the screw rod that passes through the positioning plate is provided with a suction cup, and each suction cup is provided with a valve.

[0007] The monitoring and acquisition probe is moved along the base by a driving device to adjust the position of the monitoring and acquisition data.

[0008] The driving device includes a driver disposed on the upper side of the base. The output end of the driver is poweredly connected to a drive bevel gear. The drive bevel gear meshes with a driven bevel gear. The shaft of the driven bevel gear is connected to a lead screw. The lead screw is connected to the monitoring and acquisition probe through a lead screw seat.

[0009] The online monitoring instrument includes an FPGA, a core microprocessor, a memory, a human-machine interface display, a communication chip, at least one network transformer, a signal conditioning circuit, and a high-speed analog-to-digital converter circuit; the memory includes a FLASH memory, a TF card memory, and an off-chip SRAM; the communication chip is a 4G communication chip, which establishes a communication connection with the core microprocessor via RS485; the high-speed analog-to-digital converter circuit has a built-in high-speed partial discharge signal acquisition circuit.

[0010] The three independent network transformers respectively perform high-pass filtering on the three-phase voltage signal of the energized display, and obtain partial discharge information in combination with the high-speed partial discharge signal acquisition circuit. The FPGA stores the acquired partial discharge signal in external SRAM.

[0011] The live display device consists of a capacitive sensor and a display. The capacitive sensor is installed as a coupling capacitor in the cable compartment or busbar compartment and connected to the busbar.

[0012] The capacitive sensor is equivalent to two capacitors in series, namely the voltage withstand capacitor C3 and the storage capacitor C4.

[0013] The beneficial effects of this utility model are as follows: This utility model is an online monitoring device for partial discharge in a ring main unit based on capacitive coupling. In use, the device can be detachably and adsorbed at different monitoring positions via a positioning plate for online monitoring, making installation convenient and quick. Furthermore, the device can drive the monitoring and acquisition probe along the base via a drive device, changing its position to allow for adaptive adjustments based on the actual connection position of the live indicator, greatly improving convenience and flexibility, and enhancing practicality. This utility model, through the capacitive sensor configured in the live indicator installed in the ring main unit, combined with a high-speed partial discharge signal acquisition circuit, directly obtains partial discharge information from inside the ring main unit. Partial discharge monitoring is less affected by external signal interference and can also monitor discharge information inside the cable joints within the unit, providing accurate detection, high cost-effectiveness, and easy installation. Monitoring partial discharge can save significant manpower and resources, which is of great importance for ensuring power supply safety. This utility model has the advantages of reasonable structure, accurate detection, easy installation, and convenient use. Attached Figure Description

[0014] Figure 1 This is a three-dimensional view of the overall structure of this utility model.

[0015] Figure 2 This is a front view of the overall structure of this utility model.

[0016] Figure 3 This is a schematic diagram of the positioning plate of this utility model.

[0017] Figure 4 This is a block diagram of the online monitoring instrument of this utility model.

[0018] Figure 5 This is a schematic diagram illustrating the working principle of the charged display of this utility model.

[0019] Figure 6 This is a schematic diagram of the coupling capacitor method of this utility model.

[0020] Figure 7 This is the wiring method and equivalent circuit diagram of the capacitive coupling method of this utility model.

[0021] Figure 8 This is the internal discharge model and equivalent circuit diagram of the insulating medium of this utility model.

[0022] Figure 9 This is the Thevenin equivalent circuit diagram of partial discharge according to this utility model.

[0023] In the diagram: 1. Base; 2. Online monitoring instrument; 3. Power supply; 4. Positioning plate; 41. Mounting sleeve; 42. Screw; 43. Suction cup; 44. Valve; 5. Positioning nut; 6. Monitoring and acquisition probe; 7. Drive device; 71. Driver; 72. Drive bevel gear; 73. Driven bevel gear; 74. Lead screw; 75. Lead screw seat. Detailed Implementation

[0024] This invention proposes a partial discharge detection device based on capacitive coupling. This device obtains partial discharge signals from the phase sequence aperture of the live indicator in a ring main unit. Compared with ultra-high frequency and ultrasonic methods, it does not require expensive sensors, does not affect the normal operation of the live indicator, and does not affect the insulation performance of the cable itself or its auxiliary equipment. Furthermore, this method obtains signals from inside the ring main unit, exhibiting strong anti-interference capabilities and possessing significant potential for widespread application. The essence of using capacitive coupling to monitor partial discharge is to monitor the pulse current generated during partial discharge. By detecting the pulse impedance, a pulse voltage signal proportional to the pulse current can be obtained, thereby acquiring the corresponding partial discharge parameters. The apparent discharge quantity during partial discharge is a crucial indicator for determining whether the device has experienced insulation aging. As the apparent discharge quantity increases, the degree of aging of the electrical equipment also deepens. The capacitive coupling method can accurately measure the apparent discharge quantity, and the insulation damage and aging status of the equipment can be determined based on the apparent discharge quantity. This method is simple in principle and low in cost, making it suitable for field application and possessing significant potential for widespread application.

[0025] The present invention will be further described below with reference to the accompanying drawings.

[0026] Example 1

[0027] like Figures 1-9 As shown, an online monitoring device for partial discharge of a ring main unit based on capacitive coupling includes a base 1 and a monitoring and acquisition probe 6. The base 1 has an overall U-shaped structure. An online monitoring instrument 2 is installed on the lower side of one side of the base 1, and a power supply 3 is installed above the online monitoring instrument 2. The monitoring and acquisition probe 6 is installed on the side of the opening of the base 1 and is electrically connected to the online monitoring instrument 2. The monitoring and acquisition probe 6 and the online monitoring instrument 2 are respectively electrically connected to the power supply 3. The monitoring and acquisition probe 6 is connected in parallel with the phase detection hole of the live display to acquire partial discharge information of the ring main unit and upload it to the online monitoring instrument 2.

[0028] The base 1 has positioning plates 4 on both the top and bottom sides. The positioning plates 4 can be detachably attached to different monitoring positions for online monitoring.

[0029] Each of the four corners of the positioning plate 4 is provided with a mounting sleeve 41, and each mounting sleeve 41 is provided with a positioning nut 5. Each mounting sleeve 41 is provided with a screw 42 inside, and the screw 42 is threadedly connected to the positioning nut 5. Each end of the screw 42 that passes through the positioning plate 4 is provided with a suction cup 43, and each suction cup 43 is provided with a valve 44 inside.

[0030] In this embodiment, the positioning plate controls the adsorption and release of the suction cup through the rotational engagement of the positioning nut and the screw. When the positioning nut drives the screw to rotate, it drives the suction cup to perform corresponding actions, thereby achieving the function of adsorbing or releasing the workpiece. Specifically: Adsorption: When the positioning nut drives the screw to rotate, the connecting component drives the piston or valve inside the suction cup to act, drawing out the air inside the suction cup to form a vacuum, thereby adsorbing the workpiece; Release: The positioning nut rotates the screw in the opposite direction, restoring the air pressure inside the suction cup, and the workpiece can be released. This utility model has a compact overall structure, is easy to install and operate, has a firm adsorption, and a good overall connection and fastening. It can effectively prevent the equipment from falling off, which is beneficial to improving the accuracy of monitoring. At the same time, during the monitoring process, it can monitor and pre-control different positions, effectively avoiding the influence of the external environment on the monitoring equipment.

[0031] The monitoring and acquisition probe 6 is moved along the base 1 by the driving device 7, so as to realize the change and adjustment of the position of the monitoring and acquisition data.

[0032] The driving device 7 includes a driver 71 disposed on the upper side of the base 1. The output end of the driver 71 is poweredly connected to a driving bevel gear 72. The driving bevel gear 72 is meshed with a driven bevel gear 73. The driven bevel gear 73 is shaft-connected to a lead screw 74. The lead screw 74 is connected to the monitoring and acquisition probe 6 through a lead screw seat 75.

[0033] In this embodiment, the driver is activated, and the driver transmits power through a bevel gear set consisting of a driven bevel gear and a driven bevel gear, which drives the lead screw to rotate. The lead screw, in cooperation with the lead screw seat, moves the monitoring and acquisition probe along the lead screw, thereby changing the relative position of the monitoring and acquisition probe on the base, meeting different monitoring connection requirements, and is highly practical.

[0034] Direct benefits: This utility model can be used for online monitoring of partial discharge in switchgear such as medium-voltage switchgear and ring main units. If calculated at a sales price of 0.5 million yuan per set and an annual sales volume of 1,000 sets, it can generate nearly 5 million yuan in direct economic benefits annually, which is considerable. Indirect benefits: This utility model uses a live indicator installed in the ring main unit and a capacitive sensor configured in the live indicator to directly acquire discharge information inside the ring main unit. It can also directly acquire discharge information inside cable joints. Since the discharge information is acquired from the inside, it has strong anti-interference ability, does not require special expensive sensors, and is easy to install and promote. It has important practical significance for ensuring power supply safety.

[0035] This invention relates to an online partial discharge monitoring device for ring main units based on capacitive coupling. In use, the device is detachably and magnetically mounted at different monitoring positions via a positioning plate 4 for online monitoring, making installation convenient and quick. Furthermore, the device can be driven by a drive device 7 to move the monitoring and acquisition probe 6 along the base 1, changing its position to allow for adaptive adjustments based on the actual connection location of the live indicator, greatly improving convenience and flexibility, and enhancing practicality. This invention utilizes the capacitive sensor configured in the live indicator installed in the ring main unit, combined with a high-speed partial discharge signal acquisition circuit, to directly obtain partial discharge information from inside the ring main unit. Partial discharge monitoring is less affected by external signal interference and can also monitor discharge information inside cable joints within the unit, offering accurate detection, high cost-effectiveness, and easy installation. Monitoring partial discharge can save significant manpower and resources, playing a crucial role in ensuring power supply safety. This invention boasts advantages such as reasonable structure, accurate detection, ease of installation, and convenient use.

[0036] Example 2

[0037] like Figures 1-9 As shown, an online monitoring device for partial discharge of a ring main unit based on capacitive coupling includes a base 1 and a monitoring and acquisition probe 6. The base 1 has an overall U-shaped structure. An online monitoring instrument 2 is installed on the lower side of one side of the base 1, and a power supply 3 is installed above the online monitoring instrument 2. The monitoring and acquisition probe 6 is installed on the side of the opening of the base 1 and is electrically connected to the online monitoring instrument 2. The monitoring and acquisition probe 6 and the online monitoring instrument 2 are respectively electrically connected to the power supply 3. The monitoring and acquisition probe 6 is connected in parallel with the phase detection hole of the live display to acquire partial discharge information of the ring main unit and upload it to the online monitoring instrument 2.

[0038] The online monitoring instrument 2 includes an FPGA, a core microprocessor, a memory, a human-machine interface display, a communication chip, at least one network transformer, a signal conditioning circuit, and a high-speed analog-to-digital conversion circuit; the memory includes a FLASH memory, a TF card memory, and an off-chip SRAM; the communication chip is a 4G communication chip, which establishes a communication connection with the core microprocessor via RS485; the high-speed analog-to-digital conversion circuit has a built-in high-speed partial discharge signal acquisition circuit.

[0039] In this embodiment, the three-phase voltage signal coupled to the capacitive sensor configured in the charged display is high-pass filtered by three independent network transformers. The bandpass of the network transformers is 100kHz-100MHz. The -5V to +5V is converted to 1 to 3V by a differential amplifier circuit composed of AD8065 for signal processing. Then, it is sampled by a 12-bit A / D chip AD9226 with a sampling rate of 50MSPS. Thus, 500k data points can be collected within 10ms.

[0040] The three independent network transformers respectively perform high-pass filtering on the three-phase voltage signal of the energized display, and combine it with the high-speed sampling circuit to obtain partial discharge information. The FPGA stores the acquired partial discharge signal in the external SRAM.

[0041] In this embodiment, the principle of the capacitive coupling method is as follows: The principle of monitoring partial discharge of the ring main unit using the capacitive coupling method is to obtain the partial discharge signal from the phase hole of the live display of the ring main unit using the principle of capacitive voltage division. The capacitive sensor can be equivalent to two capacitors in series. When partial discharge occurs in the ring main unit, the partial discharge electrical signal obtained from the lower voltage dividing capacitor according to the principle of voltage division is sent to the live display and also to the input signal conditioning terminal of the partial discharge online monitoring device. The conditioned voltage signal is collected by a high-speed A / D converter. The occurrence of partial discharge in the ring main unit is determined based on the collected partial discharge waveform and spectrum.

[0042] The capacitive coupling method uses a coupling capacitor to detect partial discharge. The principle diagram of the coupling capacitor method is shown in Figure 6. Because capacitors have the characteristic of blocking DC and passing AC, when both DC and AC signals are present in the circuit, only the AC signal can pass to the subsequent circuit. The main function of the coupling capacitor is to transmit the preceding signal to the following signal with as little loss as possible, while also removing unwanted signals. This invention is connected in parallel with the phase detection port of the live display. A capacitive sensor is located on the phase detection port of the live display, which acts as the coupling capacitor. When partial discharge occurs in a phase of the ring main unit, the capacitive sensor couples the discharge pulse generated by that phase to the partial discharge monitoring device, thereby detecting the partial discharge information. After analyzing the waveform and spectrum of the partial discharge, the severity of the partial discharge phenomenon can be inferred. Using the capacitive coupling method does not affect the insulation characteristics of the cable itself and its accessories, making it suitable for monitoring partial discharge in cable accessories.

[0043] When internal discharge occurs inside the ring main unit, if the insulating medium contains air bubbles, such as... Figure 8 (a) In the figure, the solid black area refers to the electrode plate, the shaded area is the insulating medium, c is the bubble portion in the insulating medium, b is the insulating medium connected in series with c, and a represents the remaining insulating medium; assuming that bubble c is flat and perpendicular to the direction of the electric field, the following can be derived: Figure 8 (b) shows the equivalent circuit, where U is the voltage between the two plates, and C... c The capacitance value of bubble c, C b For the capacitance value within the range of b, C a Let be the capacitance value within the range 'a', where C0 represents the coupling capacitance, L0 is the equivalent inductance of the charging circuit, R0 is the equivalent resistance of the charging circuit, and L... c R is the equivalent inductance of the discharge circuit. c The equivalent resistance of the discharge circuit is given. Since the period of the partial discharge pulse is on the order of nanoseconds, there is no need to substitute the fluctuation of the power frequency voltage into the calculation. In summary, the circuit is converted into the following form: Figure 9 The Thevenin equivalent circuit for partial discharge.

[0044] Due to U a -U b =U c And C a =C c By Thevenin's theorem, the voltages to the right of points 1 and 2 can be obtained as follows: The equivalent impedance is: Before partial discharge occurs, because U0 = U a The current can be obtained: Among them U c C b q is a constant a =U c ×Cb It can be known that within the S domain: The current I(S) exists at 4 points in the S-domain: By performing a reverse transformation on the S-domain expression, the time-domain current can be calculated as follows: When all four roots of the time-domain current are real, the peak current is at zero, and the peak current is positively correlated with the apparent discharge. The time-domain current waveform can be divided into a superposition of four DC exponential waveforms. When the four roots are two real and two complex, the peak current is not at zero, and there is an oscillating decay after the peak. The time-domain current waveform can be divided into two DC exponential decay waveforms and one oscillating decay waveform. When all four roots are complex, the time-domain current waveform can be divided into two oscillating decay waveforms. When partial discharge exists, the equivalent resistance R... c Since R0 is relatively small, we can conclude that: When all four roots are complex, the current i(t) is: in,

[0045] As deduced above, partial discharge between the cable head sleeve and the fuse well insulation medium of the ring main unit will form a damped oscillating circuit with a certain frequency in the insulation medium. This will generate a fixed-frequency damped oscillating voltage signal between the cable head sleeve and the fuse well. By collecting and processing this high-frequency voltage signal, the occurrence of partial discharge within the ring main unit can be monitored. The ring main unit is equipped with a live indicator to help inspection personnel confirm the power supply's energization status. This invention, based on the capacitive coupling method for monitoring partial discharge in the ring main unit, utilizes the capacitive voltage division principle to obtain the partial discharge signal from the phase detection aperture of the live indicator. The occurrence of partial discharge in the ring main unit is determined based on the collected partial discharge waveform and spectrum. The connection diagram between the device and the phase detection aperture of the live indicator is shown below. Figure 7 As shown in (a), the equivalent circuit is as follows: Figure 7 As shown in (b).

[0046] exist Figure 7 In (b), Z m This is a high-voltage current-limiting resistor to prevent short circuits in high-voltage AC power; C x C is the capacitance of an insulating medium containing internal air bubbles. k This refers to the capacitance between the output terminal of the capacitive sensor and the high-voltage busbar; C d This refers to the capacitance between the output terminal of the capacitive sensor and the ground wire; therefore, C d The voltage across the terminals is: C in a capacitive sensor d =C kAfter converting the high-voltage signal into a low-voltage signal based on the principle of capacitor voltage division, the acquired signal includes not only the required high-frequency partial discharge signal but also a 50Hz power frequency signal. In order to acquire an accurate partial discharge voltage signal, it is necessary to filter out the low-frequency interference first. A network transformer can be used for high-pass filtering, but this transformer can only transmit frequency signals above 100kHz.

[0047] The live display device consists of a capacitive sensor and a display. The capacitive sensor is installed as a coupling capacitor in the cable compartment or busbar compartment and connected to the busbar.

[0048] The capacitive sensor is equivalent to two capacitors in series, namely the voltage withstand capacitor C3 and the storage capacitor C4.

[0049] In this embodiment, the live indicator is a warning safety device installed on the ring main unit. It can directly display whether the ring main unit has working voltage. The live indicator will only flash on the display screen when the device has working voltage to remind the high-voltage equipment to be energized. The high-voltage live indicator device consists of a capacitive sensor and a display. The capacitive sensor is installed in the cable compartment or busbar compartment and connected to the busbar. The capacitive sensor matched with the live indicator constitutes a voltage divider sensor, which can convert the high voltage of the live body into a low voltage signal.

[0050] The working principle of a live display is as follows Figure 5 As shown, the parallel high-voltage capacitor C3 and the discharge tube protect the charged display. Capacitor C3 limits the current in the circuit, forming a voltage divider circuit, which can improve the transmission capability of high-frequency signals while reducing the transmission capability of low-frequency signals. C4 is used as a storage capacitor. The voltage flows through the rectifier bridge. The rectifier bridge converts the AC current fluctuating around zero point into unidirectional DC current through the unidirectional conduction principle of the diode. Using a rectifier bridge in an AC circuit can make the current in the circuit flow in one direction, and the amount of electricity will be stored in C4.

[0051] DB3 is a bidirectional trigger diode with the function of overvoltage protection. Its working principle is that when the applied voltage is greater than the breakdown voltage of the bidirectional trigger diode, the switch will be broken down. That is to say, if a trigger pulse is applied to its control electrode, the entire circuit will conduct. Let the voltage applied across DB3 be U, the forward breakdown voltage be V(BO), and the reverse breakdown voltage be V(BR). When U < V(BO), it is in a high-resistance state; when U > V(BO) or U > V(BR), the tube conducts and enters the negative-resistance region. Let the symmetry of the breakdown voltage be V(B), and usually V(B) < 2: V(B) = V(BO) - V(BR). Therefore, when power is detected and the applied voltage is greater than the trigger voltage of DB3, DB3 conducts, and the light-emitting diode will light up. This process will consume the electrical energy stored in the energy storage capacitor C4, and the voltage will decrease accordingly. When the voltage is less than the trigger voltage of DB3, DB3 turns off, and at this time the light-emitting diode goes out. When the energy storage capacitor C4 stores energy again and raises the voltage, the light-emitting diode will light up again. The above process will repeat continuously. Therefore, during the charging and discharging process, the light-emitting diode keeps flashing to determine whether this phase is powered.

[0052] In summary, the utility model has the following advantages: ① Monitoring partial discharge based on the capacitive coupling method, obtaining partial discharge signals from the phase-sequence verification hole of the live-line indicator of the ring main unit by using the capacitive voltage division principle, and judging the occurrence of partial discharge in the ring main unit according to the collected partial discharge waveforms and spectra; ② Obtaining and processing partial discharge signals based on the capacitive coupling method. The voltage signal coupled from the sensor of the live-line indicator of the ring main unit contains a low-frequency voltage signal with a relatively high amplitude and a high-frequency voltage signal with a relatively small amplitude. After high-pass filtering the three-phase voltage signals with three independent network transformers with frequencies above 100 kHz, a high-speed acquisition circuit is formed by using a high-speed analog-to-digital conversion chip with a sampling frequency of 50 MHz and an FPGA. 500k partial discharge data are obtained in 10 ms. 4096 sampling points around the partial discharge voltage peak are extracted. The Hanning window is used to prevent spectral leakage and reduce the fence effect. The partial discharge voltage spectrum diagram is generated through discrete fast Fourier transform. The occurrence of partial discharge in the ring main unit can be inferred through the partial discharge waveforms and spectra; ③ Combining a microprocessor and an FPGA chip to reduce power consumption and improve the anti-interference ability of the device.

[0053] This invention relates to an online partial discharge monitoring device for ring main units based on capacitive coupling. In use, the device is detachably and magnetically mounted at different monitoring positions via a positioning plate 4 for online monitoring, making installation convenient and quick. Furthermore, the device can be driven by a drive device 7 to move the monitoring and acquisition probe 6 along the base 1, changing its position to allow for adaptive adjustments based on the actual connection location of the live indicator, greatly improving convenience and flexibility, and enhancing practicality. This invention utilizes the capacitive sensor configured in the live indicator installed in the ring main unit, combined with a high-speed partial discharge signal acquisition circuit, to directly obtain partial discharge information from inside the ring main unit. Partial discharge monitoring is less affected by external signal interference and can also monitor discharge information inside cable joints within the unit, offering accurate detection, high cost-effectiveness, and easy installation. Monitoring partial discharge can save significant manpower and resources, playing a crucial role in ensuring power supply safety. This invention boasts advantages such as reasonable structure, accurate detection, ease of installation, and convenient use.

Claims

1. An online monitoring device for partial discharge of a ring main unit based on capacitive coupling, comprising a base and a monitoring and acquisition probe, characterized in that: The base has a U-shaped structure. An online monitoring instrument is installed on the lower side of one side of the base, and a power supply is installed above the online monitoring instrument. A monitoring and acquisition probe is installed on the side of the opening of the base. The monitoring and acquisition probe is electrically connected to the online monitoring instrument, and the monitoring and acquisition probe and the online monitoring instrument are respectively electrically connected to the power supply. The monitoring and acquisition probe is connected in parallel with the phase detection hole of the live display to acquire partial discharge information of the ring main unit and upload it to the online monitoring instrument.

2. The online monitoring device for partial discharge of a ring main unit based on capacitive coupling according to claim 1, characterized in that: The base has positioning plates on both the top and bottom sides, which can be detachably attached to different monitoring positions for online monitoring.

3. The online monitoring device for partial discharge of a ring main unit based on capacitive coupling according to claim 2, characterized in that: Each of the four corners of the positioning plate is provided with a mounting sleeve, each mounting sleeve is provided with a positioning nut, each mounting sleeve is provided with a screw rod, the screw rod is threadedly connected to the positioning nut, and each end of the screw rod that passes through the positioning plate is provided with a suction cup, and each suction cup is provided with a valve.

4. The online monitoring device for partial discharge of a ring main unit based on capacitive coupling according to claim 1, characterized in that: The monitoring and acquisition probe is moved along the base by a driving device to adjust the position of the monitoring and acquisition data.

5. The online monitoring device for partial discharge of a ring main unit based on capacitive coupling according to claim 4, characterized in that: The driving device includes a driver disposed on the upper side of the base. The output end of the driver is poweredly connected to a drive bevel gear. The drive bevel gear meshes with a driven bevel gear. The shaft of the driven bevel gear is connected to a lead screw. The lead screw is connected to the monitoring and acquisition probe through a lead screw seat.

6. The online monitoring device for partial discharge of a ring main unit based on capacitive coupling according to claim 1, characterized in that: The online monitoring instrument includes an FPGA, a core microprocessor, a memory, a human-machine interface display, a communication chip, at least one network transformer, a signal conditioning circuit, and a high-speed analog-to-digital converter circuit; the memory includes a FLASH memory, a TF card memory, and an off-chip SRAM; the communication chip is a 4G communication chip, which establishes a communication connection with the core microprocessor via RS485; the high-speed analog-to-digital converter circuit has a built-in high-speed partial discharge signal acquisition circuit.

7. The online monitoring device for partial discharge of a ring main unit based on capacitive coupling according to claim 6, characterized in that: The three independent network transformers respectively perform high-pass filtering on the three-phase voltage signal of the energized display, and obtain partial discharge information in combination with the high-speed partial discharge signal acquisition circuit. The FPGA stores the acquired partial discharge signal in external SRAM.

8. The online monitoring device for partial discharge of a ring main unit based on capacitive coupling according to claim 7, characterized in that: The live display consists of a capacitive sensor and a display. The capacitive sensor is installed as a coupling capacitor in the cable compartment or busbar compartment and connected to the busbar.

9. The online monitoring device for partial discharge of a ring main unit based on capacitive coupling according to claim 8, characterized in that: The capacitive sensor is equivalent to two capacitors in series, namely the voltage withstand capacitor C3 and the storage capacitor C4.

Images