An online monitoring device capable of capturing waveforms and a monitoring method thereof

Abstract

The application belongs to the field of lightning arrester monitoring, and particularly relates to an online monitoring device capable of capturing waveforms and a monitoring method thereof. The online monitoring device comprises a total current sensor, a lightning current sensor, a signal processing and calculation module and a counting module. The total current sensor and the lightning current sensor are respectively used for monitoring the current of the grounding wire of the lightning arrester. The signal processing and calculation module comprises an ADC, an FPGA and a storage unit connected in sequence. The total current sensor and the lightning current sensor are respectively connected with the ADC. The FPGA is connected with the counting module and is used for sending a counting pulse to the counting module. The online monitoring device can record complete waveforms before and after the fault, provide data support for fault analysis, reduce blind power outage and equipment replacement, and help improve the operation and maintenance accuracy.

Description

Technical Field

[0001] This invention belongs to the field of surge arrester monitoring, specifically relating to an online monitoring device and method capable of capturing waveforms. Background Technology

[0002] Traditional monitors can only count the number of surge arrester actions and collect steady-state leakage current values. They lack a pre-trigger buffering mechanism and cannot fully capture and record the original waveforms generated by overvoltages. This leads to problems such as a lack of original waveform data for fault diagnosis, ineffective recording of transient and intermittent anomalies, and insufficient depth of equipment status assessment. Furthermore, traditional monitors have limited functionality and cannot effectively assess the aging and moisture conditions of surge arresters. They cannot provide accurate and reliable data support for fault early warning and condition-based maintenance of surge arresters, posing significant safety hazards. In addition, the lack of clear fault causes leads to blind power outages and equipment replacements, resulting in high maintenance costs. Summary of the Invention

[0003] To address the problems existing in the prior art, this invention provides an online monitoring device and method capable of capturing waveforms. This device can record complete waveforms before and after a fault, providing data support for fault analysis, reducing blind power outages and equipment replacements due to unclear fault causes, and contributing to improved operational accuracy, economic efficiency, and safety benefits.

[0004] The specific technical solution adopted in this invention is as follows:

[0005] An online monitoring device capable of capturing waveforms is installed at the low-voltage end of a surge arrester for monitoring the surge arrester. The online monitoring device is connected to a power supply via a power line. The online monitoring device includes a full current sensor, a lightning current sensor, a signal processing and calculation module, and a counting module. The full current sensor and the lightning current sensor are used to monitor the current of the grounding wire of the surge arrester. The signal processing and calculation module includes an ADC, an FPGA, and a storage unit connected in sequence. The full current sensor and the lightning current sensor are connected to the ADC. The FPGA is connected to the counting module and is used to send counting pulses to the counting module.

[0006] The online monitoring device also includes a housing, in which the full current sensor, lightning current sensor, signal processing and calculation module and counting module are all housed. The full current sensor and lightning current sensor are both through-hole type sensors. A grounding wire is provided through a hole on the side wall of the housing. The grounding wire passes through the housing and is grounded. The grounding wire passes through the inner ring of the full current sensor and lightning current sensor respectively inside the housing.

[0007] An insulating tube is installed between the vias. The insulating tube passes through the inner ring of the full current sensor and the lightning current sensor. The grounding wire passes through the insulating tube and is then grounded.

[0008] The insulating tube is fitted with the through hole at both ends. A sealing ring is provided between the insulating tube and the wall of the through hole. The sealing ring has a raised edge at both ends, which abuts against the inner and outer sides of the side wall of the housing.

[0009] The inner wall of the sealing ring is provided with a set of annular protrusions along its axial direction, and the outer wall of the insulating tube is abutted against the annular protrusions.

[0010] An air switch is installed on the power supply line, and a waterproof cable connector is installed on the housing. The power supply line cable is connected to the online monitoring device through the waterproof cable connector.

[0011] The power supply is located on the control cabinet, which is equipped with an online monitoring terminal connected to the background control system. The signal processing and calculation module and the counting module are respectively connected to the online monitoring terminal.

[0012] The signal input terminal of the signal processing and calculation module is also connected to a voltage sampling unit. The input terminal of the voltage sampling unit is connected to the PT cabinet, and the voltage sampling unit is installed on the control cabinet.

[0013] A monitoring method for an online monitoring device capable of capturing waveforms includes the following steps:

[0014] S1. The full current sensor and lightning current sensor acquire the simulated current signal of the grounding wire in real time, and output the acquired simulated current signal to the signal processing and calculation module.

[0015] S2. The high-speed ADC receives the analog current signal and converts it into a digital waveform. The FPGA receives the digital waveform and writes it cyclically into the ring pre-trigger buffer of the storage unit.

[0016] S3. The FPGA acquires the sampled lightning current output by the high-speed ADC in real time and compares the sampled lightning current with the preset action threshold. When the sampled lightning current is greater than or equal to the preset action threshold, it is determined that the surge arrester has overvoltage action.

[0017] S4. The FPGA latches the pre-fault waveform in the pre-trigger buffer and writes the complete waveform before and after the fault into the fault waveform hardened storage area of ​​the storage unit; at the same time, the FPGA controls the action counting module to accumulate the count, the FPGA records the number of actions, action time, action current and binds the counting metadata with the fault waveform and stores it in the storage unit;

[0018] S5. The external online monitoring terminal sends query messages periodically. The FPGA retrieves real-time electrical parameters, stores fault waveforms and action count data, and sends them back to the online monitoring terminal. The online monitoring terminal converts the data and uploads it to the background control system for maintenance personnel to analyze fault factors.

[0019] The beneficial effects of this invention are:

[0020] In this invention, the signal processing and calculation module integrates a dedicated waveform capture module composed of an ADC, FPGA multi-condition triggering logic, and dual-mode storage unit. This module records the complete waveform of the fault event, not just the number of actions and leakage current. The full current sensor and lightning current sensor realize the multi-point monitoring function of high-precision, high-frequency sensors, monitoring multiple current points at the moment of arrester action to obtain waveform diagrams. This solves the problem of no data for reference when substation maintenance personnel deal with arrester faults.

[0021] The FPGA receives digital waveforms and continuously writes them cyclically into a circular pre-trigger buffer in the storage unit, overwriting historical waveforms to form a pre-trigger cyclic buffer mechanism. This solves the problem of transient fault waveforms being difficult to capture and easily lost. This design allows online monitoring devices to still retain key waveforms from hundreds of microseconds before the event occurs, enabling accurate fault backtracking and providing data support for analyzing the cause of the fault. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of the present invention;

[0023] Figure 2 This is a schematic diagram illustrating the application state of the present invention;

[0024] Figure 3 This is a schematic diagram of the sealing ring structure;

[0025] Figure 4 This is an application block diagram of the invention;

[0026] In the attached diagram, 1 is a surge arrester, 2 is a power supply, 3 is a full current sensor, 4 is a lightning current sensor, 5 is a signal processing and calculation module, 6 is a counting module, 7 is a grounding wire, 8 is a housing, 9 is an insulating tube, 10 is a sealing ring, 101 is a raised edge, 102 is an annular raised ridge, 11 is an air switch, 12 is a waterproof cable connector, 13 is a control cabinet, 14 is an online monitoring terminal, 15 is a voltage sampling unit, 16 is a PT cabinet, and 17 is a circuit board. Detailed Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0028] Specific implementation examples Figure 1 , Figure 2 , Figure 4 As shown, this invention relates to an online monitoring device capable of capturing waveforms, installed at the low-voltage end of a surge arrester 1 for monitoring the surge arrester 1. The online monitoring device is connected to a power supply 2 via a power supply line. The online monitoring device includes a full current sensor 3, a lightning current sensor 4, a signal processing and calculation module 5, and a counting module 6. Preferably, the signal processing and calculation module 5 and the counting module 6 are integrated on the same circuit board 16. The full current sensor 3 and the lightning current sensor 4 are used to monitor the current of the grounding wire 7 of the surge arrester 1. The signal processing and calculation module 5 includes an ADC, an FPGA, and a storage unit connected in sequence. The ADC is a high-speed ADC with a sampling rate ≥10MSPS, and the storage unit is a dual-mode storage unit. The full current sensor 3 and the lightning current sensor 4 are connected to the ADC. The FPGA is connected to the counting module 6 and is used to send counting pulses to the counting module 6. The full current sensor 3 and the lightning current sensor 4 transmit the monitored current to the ADC. The ADC receives and simulates the current signal and receives the ADC output from the FPGA.

[0029] The high-speed ADC receives analog current signals from the full-current sensor 3 and the lightning current sensor 4 and converts them into digital waveforms. The FPGA receives the digital waveforms and continuously writes them cyclically into a circular pre-trigger buffer in the storage unit, overwriting historical waveforms to form a pre-trigger cyclic buffer mechanism. This solves the problem of transient fault waveforms being difficult to capture and easily lost. This design allows the online monitoring device to still retain key waveforms from hundreds of microseconds before the event occurred, enabling accurate fault backtracking and providing data support for analyzing the cause of the fault.

[0030] The signal processing and calculation module 5 integrates a dedicated waveform capture module composed of an ADC (analog-to-digital converter), an FPGA (field-programmable gate array) multi-condition triggering logic, and a dual-mode storage unit. This enables the recording of complete waveforms of fault events, not just the number of actions and leakage current. Through high-precision, high-frequency full-current sensor 3 and lightning current sensor 4, multi-point monitoring is achieved, monitoring multiple current points at the moment of arrester operation to obtain waveform diagrams. This solves the problem of no data for reference when substation maintenance personnel deal with arrester faults.

[0031] Among them, the full current sensor 3 is a zero-flux full current sensor used to collect the μA or mA level full current of the surge arrester 1 under normal operating conditions. The manufacturer of the full current sensor 3 is Nanjing Bonawei, and the model is BNWXL-1T. Since the grounding wire 7 passes through the full current sensor 3, the full current sensor 3 can obtain an induced electromotive force proportional to the leakage current based on the principle of electromagnetic induction, and transmit this data to the signal processing and calculation module 5. The signal processing and calculation module 5 uses the known proportional relationship to calculate the magnitude of the leakage current of the surge arrester 1, thereby determining whether the surge arrester 1 is normally energized. The lightning current sensor 4 is used to collect the kA level current when the surge arrester operates under overvoltage. The manufacturer of the lightning current sensor 4 is the same as that of the full current sensor 3, and the model of the lightning current sensor 4 is BNWXL-2T. The signal processing and calculation module 5 is used to extract the resistive current component from the full current and calculate the power consumption. The counting module 6 is used to record the overvoltage operation event.

[0032] Because the total current of surge arrester 1 is mostly in the μA or mA range during normal operation, but its operating current often reaches the kA range when it trips due to overvoltage, the range is quite large. To ensure the accuracy of current measurement, a total current sensor 3 and a lightning current sensor 4 are used to collect total current and operating current data, respectively, and the collected data are transmitted to the signal processing and calculation module 5 for analysis. When the total current of surge arrester 1 is extremely small during normal operation, the impedance of surge arrester 1 decreases sharply when affected by overvoltage. The lightning current sensor 4 detects an increase in current through the grounding wire 7. When the current value received by the signal processing and calculation module 5 reaches the set lower limit operating current (usually 50A), it is considered that surge arrester 1 has tripped. The value of the counting module 6 is incremented by 1, and the operating time and the total current value at the time of operation are recorded.

[0033] The online monitoring device also includes a housing 8. The full current sensor 3, lightning current sensor 4, signal processing and calculation module 5, and counting module 6 are all disposed inside the housing 8. The full current sensor 3 and lightning current sensor 4 are both through-hole sensors. A through hole for grounding wire 7 is provided through the side wall of the housing 8. The grounding wire 7 passes through the through hole and is grounded after passing through the housing 8. The grounding wire 7 passes through the inner ring of the full current sensor 3 and lightning current sensor 4 inside the housing 8.

[0034] The signal processing and calculation module 5, the counting module 6, and the through-hole sensor are integrated into the same housing 8, eliminating the traditional method of sampling the leakage current of the surge arrester through external wiring. This eliminates complex wiring, makes the structure compact and easier to install, and avoids sampling failures caused by loose external wiring, damaged lines, or external forces in the external environment, which helps to improve the stability and reliability of the entire monitoring system.

[0035] The housing 8 has a door panel, forming a closed chamber inside, which improves the protection of the signal processing and calculation module 5, the counting module 6, and the through-core sensor, avoiding measurement failures caused by corrosion and water ingress, and adapting to harsh outdoor operating environments.

[0036] An insulating tube 9 is provided between the vias. The insulating tube 9 passes through the inner ring of the full current sensor 3 and the lightning current sensor 4. The grounding wire 7 passes through the insulating tube 9 and is grounded. The insulating tube 9 can prevent the grounding wire 7 from directly contacting the full current sensor 3 and the lightning current sensor 4 and causing wear, which helps to improve the accuracy of the monitoring data.

[0037] Both ends of the insulating tube 9 are respectively fitted into the through hole, and a sealing ring 10 is provided between the insulating tube 9 and the wall of the through hole, such as... Figure 3 As shown, the sealing ring 10 has protruding edges 101 at both ends. The protruding edges 101 abut against the inner and outer sides of the sidewall of the housing 8. Preferably, the end of the sealing ring 10 is tapered, which makes it easy to insert the end of the sealing ring 10 with the protruding edges 101 into the mounting hole. The protruding edges 101 at both ends of the sealing ring 10 press against the sidewall of the housing 8, which can significantly improve the connection stability between the sealing ring 10 and the housing 8 and ensure the sealing effect.

[0038] The inner wall of the sealing ring 10 is provided with a set of annular protrusions 102 along its axial direction. The outer wall of the insulating tube 9 abuts against the annular protrusions 102 to form multiple independent annular seals. Under the same assembly pressure, the contact pressure is greater and the sealing effect is more reliable. At the same time, it can increase the clamping force and friction between the sealing ring 10 and the insulating tube 9, prevent the insulating tube 9 from rotating or moving axially under vibration, and improve the overall structural stability and sealing reliability.

[0039] An air switch 11 is installed on the power supply line, and a waterproof cable connector 12 is installed on the housing 8. The cable of the power supply line is connected to the online monitoring device through the waterproof cable connector 12. The air switch 11 protects the circuit board 16 during the power supply process of the power supply 2, and the waterproof cable connector 12 ensures the sealing and waterproof performance of the external cable connection point, which helps to improve the reliability of power supply and the overall protection performance of the online monitoring device.

[0040] The power supply 2 is mounted on the control cabinet 13, which is equipped with an online monitoring terminal 14 connected to the backend control system. The signal processing and calculation module 5 and the counting module 6 are respectively connected to the online monitoring terminal 14. The polling mechanism of the online monitoring terminal 14 sends a message to the online monitoring device via an RS485 communication cable at regular intervals. After receiving the corresponding message, the online monitoring device responds by transmitting the monitored total current, resistive current, and number of actions to the online monitoring terminal 14 in the form of a message. The online monitoring terminal 14 then converts the data into 61850 protocol data and transmits it to the backend control system via optical fiber, completing the remote transmission and management of the collected data without the need for on-site inspection and confirmation of the surge arrester's operating data.

[0041] The signal input terminal of the signal processing and calculation module 5 is also connected to a voltage sampling unit 15, the input terminal of which is connected to the PT cabinet 16. The voltage sampling unit is located on the control cabinet 13. The online monitoring device can use the phase method, employing the principle that the resistive current is in phase with the operating voltage of the surge arrester, to measure the value of the total current of the surge arrester corresponding to the maximum value of the operating voltage, thus obtaining the resistive current. To achieve this function, it is necessary to obtain the voltage phase angle that is in the same phase as the leakage current. The voltage sampling unit 15 installed in the control cabinet 13 can collect the voltage signal in the PT cabinet 16 and transmit the voltage signal to the online monitoring device via an RS485 communication cable. The signal processing and calculation module 5 in the online monitoring device calculates the voltage phase angle and separates the resistive current to obtain the resistive current reflecting the insulation degradation of the surge arrester 1. This allows for accurate judgment of whether the surge arrester has early hidden faults such as aging, moisture, or internal defects, enabling condition assessment and fault early warning, providing reliable data support for condition-based maintenance of the surge arrester, and eliminating potential safety hazards.

[0042] A monitoring method for an online monitoring device capable of capturing waveforms includes the following steps:

[0043] S1, the full current sensor 3, and the lightning current sensor 4 acquire the current simulation signal of the grounding wire 7 in real time, and output the acquired current simulation signal to the signal processing and calculation module 5; at the same time, the FPGA receives the voltage phase signal of the voltage sampling unit 15, separates the resistive current in real time, and calculates the power consumption.

[0044] S2. The high-speed ADC receives the analog current signal and converts it into a digital waveform. The FPGA receives the digital waveform and continuously writes it into the ring pre-trigger buffer of the storage unit, cyclically overwriting the historical waveform. The operating current and voltage amplitude of the surge arrester at multiple operating moments are collected by a high-precision, high-sampling-rate sensor, thereby obtaining the waveform of the overall operation.

[0045] S3. The FPGA acquires the sampled lightning current output by the high-speed ADC in real time and compares the sampled lightning current with the preset action threshold. When the sampled lightning current is greater than or equal to the preset action threshold, it is determined that the surge arrester has taken overvoltage action.

[0046] S4. The FPGA latches the waveform hundreds of microseconds before the fault in the pre-trigger buffer and writes the complete waveform before and after the fault into the fault waveform solidification storage area of ​​the storage unit; at the same time, the FPGA controls the action counting module to accumulate the count, and the FPGA records the number of actions, the action time, and the total current value at the time of the action.

[0047] S5. The polling mechanism of the external online monitoring terminal 14 periodically sends query messages, which are transmitted to the online monitoring device via an RS485 communication cable. The FPGA retrieves real-time electrical parameters, stores fault waveforms, action counts, and other data, and sends them back to the online monitoring terminal 14. The online monitoring terminal 14 converts the data into 61850 protocol data and transmits it to the back-end control system via optical fiber for maintenance personnel to analyze fault factors. This invention adopts a standardized data interface, supporting deep integration with upper-layer systems.

Claims

1. An online monitoring device capable of capturing waveforms, installed at the low-voltage end of a surge arrester (1) for monitoring the surge arrester (1), wherein the online monitoring device is connected to a power supply (2) via a power supply line, characterized in that: The online monitoring device includes a full current sensor (3), a lightning current sensor (4), a signal processing and calculation module (5), and a counting module (6). The full current sensor (3) and the lightning current sensor (4) are used to monitor the current of the grounding wire (7) of the surge arrester (1). The signal processing and calculation module (5) includes an ADC, an FPGA, and a storage unit connected in sequence. The full current sensor (3) and the lightning current sensor (4) are connected to the ADC. The FPGA is connected to the counting module (6) and is used to send counting pulses to the counting module (6).

2. The online monitoring device capable of capturing waveforms according to claim 1, characterized in that: The online monitoring device also includes a housing (8). The full current sensor (3), lightning current sensor (4), signal processing and calculation module (5) and counting module (6) are all located inside the housing (8). The full current sensor (3) and lightning current sensor (4) are both through-hole sensors. A through hole for grounding wire (7) is provided on the side wall of the housing (8). The grounding wire (7) passes through the housing (8) through the through hole and is grounded. The grounding wire (7) passes through the inner ring of the full current sensor (3) and lightning current sensor (4) inside the housing (8).

3. The online monitoring device capable of capturing waveforms according to claim 2, characterized in that: An insulating tube (9) is provided between the vias. The insulating tube (9) passes through the inner ring of the full current sensor (3) and the lightning current sensor (4). The grounding wire (7) passes through the insulating tube (9) and is grounded.

4. The online monitoring device capable of capturing waveforms according to claim 3, characterized in that: The insulating tube (9) is fitted with the through hole at both ends. A sealing ring (10) is provided between the insulating tube (9) and the wall of the through hole. The sealing ring (10) has a raised edge (101) at both ends. The raised edge (101) abuts against the inner and outer sides of the side wall of the housing (8).

5. The online monitoring device capable of capturing waveforms according to claim 4, characterized in that: The inner wall of the sealing ring (10) is provided with a set of annular protrusions (102) along its axial direction, and the outer wall of the insulating tube (9) is abutted against the annular protrusions (102).

6. The online monitoring device capable of capturing waveforms according to claim 2, characterized in that: An air switch (11) is provided on the power supply line, and a waterproof cable connector (12) is provided on the housing (8). The cable of the power supply line is connected to the online monitoring device through the waterproof cable connector (12).

7. The online monitoring device capable of capturing waveforms according to claim 1, characterized in that: The power supply (2) is installed on the control cabinet (13), and the control cabinet (13) is equipped with an online monitoring terminal (14) connected to the background control system. The signal processing and calculation module (5) and the counting module (6) are respectively connected to the online monitoring terminal (14).

8. The online monitoring device capable of capturing waveforms according to claim 1, characterized in that: The signal input terminal of the signal processing and calculation module (5) is also connected to a voltage sampling unit (15), the input terminal of the voltage sampling unit (15) is connected to the PT cabinet (16), and the voltage sampling unit is set on the control cabinet (13).

9. A monitoring method for an online monitoring device capable of capturing waveforms, applied to the online monitoring device capable of capturing waveforms as described in claim 1, characterized in that, Includes the following steps: S1, the full current sensor (3) and the lightning current sensor (4) collect the current simulation signal of the grounding wire (7) in real time, and output the collected current simulation signal to the signal processing and calculation module (5). S2. The high-speed ADC receives the analog current signal and converts it into a digital waveform. The FPGA receives the digital waveform and writes it cyclically into the ring pre-trigger buffer of the storage unit. S3. The FPGA acquires the sampled lightning current output by the high-speed ADC in real time and compares the sampled lightning current with the preset action threshold. When the sampled lightning current is greater than or equal to the preset action threshold, it is determined that the surge arrester has overvoltage action. S4. The FPGA latches the pre-fault waveform in the pre-trigger buffer and writes the complete waveform before and after the fault into the fault waveform hardened storage area of ​​the storage unit; at the same time, the FPGA controls the action counting module to accumulate the count, the FPGA records the number of actions, action time, action current and binds the counting metadata with the fault waveform and stores it in the storage unit; S5. The external online monitoring terminal (14) sends query messages periodically. The FPGA retrieves real-time electrical parameters, stores fault waveforms and action count data, and sends them back to the online monitoring terminal (14). The online monitoring terminal (14) converts the data and uploads it to the background control system for maintenance personnel to analyze fault factors.

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