A cable fault detection device and method based on optical fiber synchronization

Abstract

The application discloses a kind of cable fault detection device and method based on optical fiber synchronization, belong to cable fault detection technical field, for cable fault detection and positioning, by setting two cable fault positioning detection mechanisms and through optical fiber connection, wherein the fault cable is equal to the length of optical fiber, the two ends of the fault cable are connected with the fault positioning sensor on the two cable fault positioning detection mechanisms respectively, and the waveform oscillation characteristics of fault signal in cable are acquired, threshold setting is carried out by Schmidt trigger to carry out anti-interference processing, and the inversion of NAND gate, by the transmission of optical transceiver TTL, pre-trigger acquisition of acquisition card, the positioning calculation of the data collected by two monitoring equipment is realized, and the fault position of the fault cable is judged.

Description

Technical Field

[0001] This invention belongs to the field of cable fault detection technology and is used for cable fault detection and location. In particular, it relates to a cable fault detection device and method based on optical fiber synchronization. Background Technology

[0002] With the rapid development of the national economy and the implementation of urban power grid transformation, power cables are widely used in power distribution lines. Due to the complexity of laying conditions and the influence of the daily use environment, power cable faults occur frequently, especially single-phase grounding and two-phase short circuits, which seriously affect the safe operation of the power system and people's daily lives, and even cause safety accidents, endangering people's lives and property. An existing cable fault location visualization simulation test method, cable fault location method, device and system, patent numbers (CN102798802B, CN115267420A), is used to improve the accuracy and efficiency of simulation test operation, meet the increasing demand for power system visualization, and can accurately obtain the actual fault location of the cable. In actual use, this technology relies heavily on a time synchronization module, which requires two devices to collect data synchronously through time synchronization. The time synchronization period is critical, and it can only locate a single type of fault. Summary of the Invention

[0003] The purpose of this invention is to provide a cable fault detection device and method based on optical fiber synchronization. According to the waveform oscillation characteristics of the fault signal in the cable, the device performs anti-interference processing by setting the threshold through a Schmitt trigger and inverting the NOT gate. Through the TTL transmission of the optical transceiver and the pre-triggered acquisition by the acquisition card, the device realizes the positioning calculation of the data collected by two monitoring devices.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a cable fault detection device based on optical fiber synchronization, comprising two cable fault location detection mechanisms connected by optical fiber. Each of the two cable fault location detection mechanisms includes a fault location sensor, a signal conditioning board, an optical fiber synchronous transmission module, an optical fiber synchronous receiving module, and a pre-trigger acquisition card. The fault location sensor is electrically connected to the pre-trigger acquisition card. The pre-trigger acquisition card, the optical fiber synchronous transmission module, and the optical fiber synchronous receiving module are respectively connected to the signal conditioning board. The two ends of the optical fiber are respectively connected to the optical fiber synchronous transmission module and the optical fiber synchronous receiving module.

[0005] The fault location sensor consists of two semi-circular manganese-zinc materials. A coil is wound on one side of each semi-circular manganese-zinc material. The coil outputs through an integrating circuit and is electrically connected to the pre-trigger acquisition card.

[0006] The signal conditioning board includes a detector circuit, whose input is connected to a first-stage operational amplifier, and whose output is connected to an SMA connector and a Schmitt trigger. The output pin of the Schmitt trigger is connected to an NOT gate.

[0007] A cable fault detection method based on optical fiber synchronization includes a cable fault point, wherein the cable and the optical fiber have equal lengths, and the cable fault detection method comprises:

[0008] The two ends of the faulty cable are respectively connected to the fault location sensors on the two cable fault location detection mechanisms to obtain the waveform oscillation characteristics of the fault signal in the cable.

[0009] Interference suppression is achieved by setting thresholds using Schmitt triggers, and by inverting NOT gates;

[0010] Through TTL transmission via optical transceiver, the acquisition card pre-triggers acquisition, enabling the location calculation of data collected by the two monitoring devices, and determining the fault location of the faulty cable.

[0011] The anti-interference processing includes extracting the envelope signal from the waveform oscillation characteristics, adjusting it to a TTL signal through a Schmitt trigger to generate a negative pulse signal, and then inverting it into a square wave signal through a 74LSO4 circuit.

[0012] The location calculation of the data collected by the two monitoring devices is as follows: the data is transmitted from the fiber optic port to the fiber optic module of the cable fault location detection mechanism through a 232 to fiber optic circuit, and the TTL signal is extracted from the RX level port of the fiber optic port. The RX and TX electrical ports are shorted to form a loop. This TTL signal is connected to the pre-trigger port of an FPGA acquisition card of the cable fault location detection mechanism. When the other pre-trigger port receives the rising edge signal of the TTL signal, the FPGA acquisition card pre-acquires several hundred microseconds of data to prevent the fault signal from being lost.

[0013] The fault location calculation process is as follows: The fault signal acquired by cable fault location detection mechanism A corresponds to the number of acquisition card points N1; the fault signal acquisition card number of cable fault location detection mechanism B is N2; the cable length is L; the sampling rate of the acquisition card corresponds to the time of each point as 1 / N; and the fiber optic module delay time is... The time difference between cable fault location detection mechanism A and cable fault location detection mechanism B is T0 = (N1 / N - N2 / N - ... The fault signal transmission rate is V, and the distance from the fault point to the cable fault location and detection mechanism A is L1. The fault distance L1 = (V 0.01 T0 -L) / 2.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] The present invention provides a cable fault detection device and method based on optical fiber synchronization. Two cable fault location and detection mechanisms are set up and connected by optical fiber, wherein the faulty cable and the optical fiber are of equal length. Both ends of the faulty cable are connected to fault location sensors on the two cable fault location and detection mechanisms, respectively. The waveform oscillation characteristics of the fault signal in the cable are acquired. Interference suppression is performed by setting a threshold using a Schmitt trigger and by inverting a NOT gate. Transmission is achieved via a TTL optical transceiver, and data acquisition is pre-triggered by a data acquisition card. This enables the location calculation of the data collected by the two monitoring devices and determines the fault location of the faulty cable. Attached Figure Description

[0016] Figure 1 This is a schematic diagram showing the connection between the two cable fault location and detection mechanisms of the present invention;

[0017] Figure 2 This is a schematic diagram of the fault location and monitoring device of the present invention;

[0018] Figure 3 This is a schematic diagram of the fault location synchronous location detection circuit of the present invention;

[0019] Figure 4 This is a schematic diagram of the optical fiber synchronous transmission module of the present invention;

[0020] Figure 5 This is a schematic diagram of the optical fiber synchronization receiving module of the present invention;

[0021] Figure 6 This is a schematic diagram of the fault location sensor of the present invention. Detailed Implementation

[0022] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0023] like Figure 1As shown, a cable fault detection device based on fiber optic synchronization includes two cable fault location and detection mechanisms connected by optical fiber. Each mechanism includes a fault location sensor, a signal conditioning board, a fiber optic synchronous transmission module, a fiber optic synchronous reception module, and a pre-triggered acquisition card. The fault location sensor is electrically connected to the pre-triggered acquisition card. The pre-triggered acquisition card, the fiber optic synchronous transmission module, and the fiber optic synchronous reception module are respectively connected to the signal conditioning board. Both ends of the optical fiber are connected to the fiber optic synchronous transmission module and the fiber optic synchronous reception module, respectively. The device connects both ends of the faulty cable to the fault location sensor on each of the two cable fault location and detection mechanisms, acquires the waveform oscillation characteristics of the fault signal in the cable, performs anti-interference processing by setting a threshold using a Schmitt trigger, and inverts the signal using a NOT gate. Through TTL transmission via an optical transceiver and pre-triggered acquisition by the acquisition card, the device realizes the location calculation of the data collected by the two monitoring devices and determines the fault location of the faulty cable.

[0024] like Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6As shown, in this embodiment, the internal modules of the two cable fault location and detection mechanisms are identical. The signal conditioning board uses a three-channel bandwidth 30M signal conditioning, and any channel outputs a 3.3V 10ns rising edge pulse through an OR gate. The pre-trigger acquisition card uses a dual-channel FPGA data acquisition card. The fiber optic synchronous transmission module uses a 15km 25G DWDM optical module, and the fiber optic synchronous receiving module uses a TORX173 fiber optic receiving module and a 232 to fiber optic module. The fault location sensor consists of two semi-circular manganese-zinc materials. A coil is wound on one side of the semi-circular manganese-zinc material, and the coil outputs through an integrating circuit. The coil is electrically connected to the pre-trigger acquisition card. During use, the alternating magnetic field generated by the current induces a voltage in the coil. This voltage is proportional to the rate of change of the current. The direct output of the coil is Vout=M dI / dt is given, where M is the mutual inductance of the coil and dI / dt is the rate of change of current. To complete the operation of the transducer, the voltage is electronically integrated so that the output of the integrator is a voltage that can accurately reproduce the current waveform. Specifically, the cable fault location detection mechanism includes a fault location sensor, a TTL signal conditioning board, an optical fiber synchronous transmission module, an optical fiber synchronous receiving module, and an FPGA acquisition card. The fault location sensor is composed of two semi-circular manganese-zinc materials with a frequency between 100KHz and 10MHz. The manganese-zinc single-sided wound coil is output through an integrating circuit. The TTL signal conditioning board is connected to the location sensor. The fault location sensor uses a first-stage operational amplifier for signal-to-noise boosting. The TTL signal conditioning board includes a detector circuit whose input is connected to the first-stage operational amplifier, and whose output is connected to an SMA. The head is connected to a Schmitt trigger, and the output pin of the Schmitt trigger is connected to a NOT gate for signal inversion. The TX terminal of the fiber optic synchronization module input 232 is connected to the TTL signal conditioning board. The TTL terminal of the TX port of the optical module is connected to the FPGA pre-trigger port. The ST port of the optical fiber is normally connected to another set of optical fiber ports. The input terminal of the PGA pre-trigger acquisition card is connected to the fault location sensor. The specific processing procedure is as follows: When a fault signal occurs, one end of the fault signal is input to the acquisition card, and the other end is input to the fault location fiber optic synchronization detection circuit. The detection circuit extracts the envelope signal according to the oscillation signal characteristics and adjusts it into a TTL signal through a Schmitt trigger. Since the Schmitt trigger generates a negative pulse signal, it is then inverted into a square wave signal by a 74LSO4 circuit. The square wave signal level is higher than 3.3V is connected to the 232TX end, and transmitted from the fiber optic port to the 232 to fiber optic module at one end of the cable fault location detection device 2 through the 232 to fiber optic circuit. A TTL signal can be extracted from the RX level port of the fiber optic port of the fault location detection device 2, and the RX and TX electrical ports are shorted to form a loop. This TTL signal is connected to the pre-trigger port of an FPGA acquisition card in the fault location monitoring device 2. When the other pre-trigger port receives the rising edge signal of the TTL signal, the FPGA acquisition card pre-acquires several hundred microseconds of data to prevent the fault signal from being lost. The calculation process is as follows: the fault signal acquired by the fault location monitoring device 1 corresponds to the number of acquisition card points N1, the fault signal acquisition card number of the monitoring device 2 is N2, the cable length is L, the time for each point corresponding to the sampling rate of the acquisition card is 1 / N, the fiber optic length is equal to the cable length, and the fiber optic module delay time. The time difference between fault location monitoring device 1 and fault location monitoring device 2 is T0 = (N1 / N - N2 / N - ... If the fault signal transmission rate is V, and the distance from the fault point to the fault location monitoring device 1 is L1, then the fault distance L1 = (V 0.01 T0 -L) / 2 is used to calculate the location of the data collected by the two monitoring devices and determine the fault location of the faulty cable.

[0025] A cable fault detection method based on fiber optic synchronization includes a cable fault point, wherein the cable and optical fiber are of equal length. The method comprises: connecting both ends of the faulty cable to fault location sensors on two cable fault location and detection mechanisms to acquire the waveform oscillation characteristics of the fault signal in the cable; performing anti-interference processing by setting a threshold using a Schmitt trigger and inverting a NOT gate; transmitting data via an optical transceiver in TTL mode and pre-triggered data acquisition using a data acquisition card to realize the location calculation of the data collected by the two monitoring devices and determine the fault location of the faulty cable; the anti-interference processing includes extracting the envelope signal from the waveform oscillation characteristics, adjusting it to a TTL signal using a Schmitt trigger to generate a negative pulse signal, and then inverting it into a square wave signal using a 74LSO4 circuit. The location calculation for the data collected by the two monitoring devices is as follows: The signal is transmitted from the fiber optic port to the fiber optic module of the cable fault location detection mechanism via a 232-to-fiber optic circuit. A TTL signal is extracted from the RX level of the fiber optic port, and the RX and TX electrical ports are shorted to form a loop. This TTL signal is then connected to the pre-trigger port of an FPGA acquisition card in the cable fault location detection mechanism. When the rising edge of the TTL signal is received at the other pre-trigger port, the FPGA acquisition card pre-collects several hundred microseconds of data to prevent fault signal loss. The fault signal acquired by cable fault location detection mechanism A corresponds to the number of acquisition card points N1, and the fault signal acquisition card for cable fault location detection mechanism B corresponds to the number of acquisition card points N2. The cable length is L, the sampling rate of the acquisition card corresponds to a time of 1 / N for each point, and the fiber optic module delay time is... The time difference between cable fault location detection mechanism A and cable fault location detection mechanism B is T0 = (N1 / N - N2 / N - ... The fault signal transmission rate is V, and the distance from the fault point to the cable fault location and detection mechanism A is L1. The fault distance L1 = (V 0.01 T0-L) / 2; Connect both ends of the faulty cable to the fault location sensors on two cable fault location detection mechanisms respectively, and obtain the waveform oscillation characteristics of the fault signal in the cable. Use Schmitt trigger to set the threshold for anti-interference processing, and invert the NOT gate. Transmit the data through the optical transceiver TTL and pre-trigger the acquisition card to realize the location calculation of the data collected by the two monitoring devices and determine the fault location of the faulty cable.

[0026] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any simple modifications, alterations, or equivalent structural changes made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A cable fault detection device based on fiber optic synchronization, characterized in that, The system includes two cable fault location and detection mechanisms connected by optical fiber. Each mechanism includes a fault location sensor, a signal conditioning board, an optical fiber synchronous transmission module, an optical fiber synchronous reception module, and a pre-trigger acquisition card. The fault location sensor is electrically connected to the pre-trigger acquisition card. The pre-trigger acquisition card, the optical fiber synchronous transmission module, and the optical fiber synchronous reception module are respectively connected to the signal conditioning board. The two ends of the optical fiber are respectively connected to the optical fiber synchronous transmission module and the optical fiber synchronous reception module. The fault location sensor comprises two semi-circular manganese-zinc materials, each with a coil wound on one side. The coil outputs through an integrating circuit and is electrically connected to the pre-trigger acquisition card. The signal conditioning board includes a detector circuit, whose input is connected to a first-stage operational amplifier, and whose output is connected to an SMA connector and a Schmitt trigger. The output pin of the Schmitt trigger is connected to an NOT gate.

2. A cable fault detection method based on fiber optic synchronization, employing the cable fault detection device based on fiber optic synchronization as described in claim 1, characterized in that: Including cable fault points, wherein the cable and the optical fiber are of equal length, the cable fault detection method includes: The two ends of the faulty cable are respectively connected to the fault location sensors on the two cable fault location detection mechanisms to obtain the waveform oscillation characteristics of the fault signal in the cable. Interference suppression is achieved by setting thresholds using Schmitt triggers, and by inverting NOT gates; Through TTL transmission via optical transceiver, the acquisition card pre-triggers acquisition, enabling the location calculation of data collected by the two monitoring devices, and determining the fault location of the faulty cable.

3. The cable fault detection method based on optical fiber synchronization according to claim 2, characterized in that: The anti-interference processing includes extracting the envelope signal from the waveform oscillation characteristics, adjusting it to a TTL signal through a Schmitt trigger to generate a negative pulse signal, and then inverting it into a square wave signal through a 74LSO4 circuit.

4. The cable fault detection method based on optical fiber synchronization according to claim 2, characterized in that: The location calculation of the data collected by the two monitoring devices is as follows: the data is transmitted from the fiber optic port to the fiber optic module of the cable fault location detection mechanism through a 232 to fiber optic circuit, and the TTL signal is extracted from the RX level port of the fiber optic port. The RX and TX electrical ports are shorted to form a loop. This TTL signal is connected to the pre-trigger port of an FPGA acquisition card of the cable fault location detection mechanism. When the other pre-trigger port receives the rising edge signal of the TTL signal, the FPGA acquisition card pre-acquires several hundred microseconds of data to prevent the fault signal from being lost.

5. The cable fault detection method based on optical fiber synchronization according to claim 2, characterized in that: The fault location calculation process is as follows: The fault signal acquired by cable fault location detection mechanism A corresponds to the number of acquisition card points N1; the fault signal acquisition card number of cable fault location detection mechanism B is N2; the cable length is L; the sampling rate of the acquisition card corresponds to the time of each point as 1 / N; and the fiber optic module delay time is... The time difference between cable fault location detection mechanism A and cable fault location detection mechanism B is T0 = (N1 / N - N2 / N - ... The fault signal transmission rate is V, and the distance from the fault point to the cable fault location and detection mechanism A is L1. The fault distance L1 = (V 0.01 T0 -L) / 2.

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