CN112834871B - A system and method for on-line monitoring of insulation faults of high-voltage large-length cables - Google Patents

Abstract

The invention relates to an on-line monitoring system for insulation fault of a high-voltage long-section cable, which comprises: a central processing system and a plurality of distributed information integration systems; the distributed information integration system includes: the system comprises an information sensing module, a data distributed acquisition module, a data distributed storage module, a distributed processing module and an information communication module which are connected in sequence; the central processing system comprises a long-length cable central processing module and a display module. The on-line monitoring system for the insulation fault of the high-voltage long-section cable provided by the invention integrates various physical information such as ultrasonic, ultrahigh frequency, pulse current, infrared thermal image and the like, and realizes the positioning of the insulation defect. The method realizes the positioning of the fault on each insulating layer of the high-voltage large-section cable, namely radial positioning, and also realizes the positioning of the fault on the position of the large-length cable, namely axial positioning. The diagnosis system of the invention is safe and reliable, has high fault diagnosis precision and sensitivity, and is easy to implement.

Description

A system and method for on-line monitoring of insulation faults of high-voltage large-length cables

technical field

The invention relates to an on-line monitoring system and method for insulation faults of high-voltage long-section cables, belonging to the technical field of high-voltage cable insulation state monitoring.

Background technique

At present, my country's economy is developing rapidly, and the society is developing towards modernization and intelligence. The power consumption of society is increasing day by day, and the demand for electric energy is constantly increasing. In such an environment, the requirements for the safety, quality and intelligence of the power grid are getting higher and higher. The power cables used to connect various electrical equipment, transmit and distribute electric energy in the power grid have been used more and more in the power grid due to the advantages of high safety, high reliability, less maintenance workload, and conducive to improving the safe operation level of the power grid. Wide range of applications. With the increasing use of power cables, the faults caused by power cables also account for a certain share of power grid faults.

Cable insulation failure is accompanied by a variety of physical signals, including sound, heat, gas, etc. Traditional cable insulation fault diagnosis is mostly based on a single signal for partial discharge diagnosis. Even if multiple signals are used for diagnosis, the shielding effect of the armored layer in the cable structure on high-frequency signals is ignored. The current research focus on cable fault location focuses on axial location, but there is a lack of research on the location of faults in the radial direction of cables. In addition, with the increase of long-distance transmission cable lines, the insulation fault signal attenuation of long-distance cables is also one of the factors affecting cable monitoring.

After searching, it was found that the application number is CN 2019103710679, an acousto-optic joint detection method and system for high-voltage cable partial discharge, which integrates two non-electrical detection technologies, ultrasonic and ultraviolet sensing, but the fusion information of this method is small, and the fault degree cannot be judged , fault location cannot be performed. The application number is CN 2018113669657, a multi-cable section cable network partial discharge detection and positioning system and its detection and positioning method. It detects each joint of the cable network, and uses wavelet decomposition to obtain the energy characteristic value according to the current and temperature information, and then judges the Partial discharge location, but its fault location accuracy is difficult to quantify, and the ranging accuracy cannot be guaranteed.

Contents of the invention

The technical problem to be solved by the present invention is: to overcome the shortcomings of the above-mentioned technologies, and provide an on-line monitoring system and method for insulation faults of high-voltage long-segment cables.

In order to solve the above-mentioned technical problems, the first technical solution proposed by the present invention is: an online monitoring system for insulation faults of high-voltage large and long cables, including: a central processing system and several distributed information integration systems; the distributed information integration system installed on cables at intervals; the distributed information integration system includes: sequentially connected information sensing modules, distributed data acquisition modules, distributed data storage modules, distributed processing modules, and information communication modules; the central processing system includes A central processing module and a display module of a long cable; the information communication module is connected to the central processing module of a long cable, and the display module is connected to the central processing module of a long cable;

The information sensing module includes an ultrasonic sensor, a UHF sensor, an infrared thermal image sensor and a high frequency current sensor;

The distributed data collection module is used to collect the high-voltage cable insulation status information included in the information sensing module;

The data distributed storage module is used to store the high-voltage cable insulation state information collected by the data distributed collection module;

The distributed processing module is used to calculate and analyze the high-voltage cable insulation state information stored in the data distributed storage module, determine whether there is a fault and calibrate the fault degree;

The information communication module transmits the calculation and analysis results of the distributed processing module to the central processing module of the long-distance cable;

The central processing module of the long-distance cable judges the fault degree and fault location according to the processing results of each distributed processing module transmitted by the information communication module, and sends the result to the display module.

The further improvement of the above scheme is: the distributed information integration system is installed at equal intervals, the ultrasonic sensor, UHF sensor and infrared thermal imaging sensor are set at intervals of 20 meters, and the high frequency current sensor is installed on the cable ground wire.

In order to solve the above-mentioned technical problems, the second technical solution proposed by the present invention is: a monitoring method using the above-mentioned high-voltage large-length cable insulation fault on-line monitoring system, including the following steps:

Step 1: Start the information sensing module to collect ultrasonic signal S1, UHF signal S2 and infrared signal S3;

Step 2: For the ultrasonic signal, UHF signal and infrared signal collected in step 1, set the first thresholds A1, A2 and A3 respectively; if only the ultrasonic signal S1 is greater than the threshold A1, it is determined that the fault occurred near the core Insulation layer or shielding layer; if the ultrasonic signal S1 is greater than the threshold A1, and the infrared signal S3 is greater than the threshold A3, it is determined that the fault occurs in the insulating layer or shielding layer close to the armored layer; if the ultrasonic signal S1 is greater than the threshold A1, the UHF signal S2 is greater than the threshold A2, and the infrared signal S3 is greater than the threshold A3, it is determined that the fault has developed to the armor layer and the armor layer has been destroyed.

The further improvement of the above solution is: if it is determined in the step 2 that the cable has an insulation fault, the following steps are also performed;

Step a: Compare the collected high-frequency current signals S4, and filter out the sensor L1 with the largest grounding current and the sensor L2 with the second largest grounding current, then the fault occurs in the interval between L1 and L2, and the position with the largest grounding high-frequency current is close to the fault point, to realize the preliminary determination of the fault location;

Step b: If it is determined that the fault only occurs in the insulating layer or shielding layer, compare the ultrasonic signal S1 between L1 and L2, and screen out the sensor Q1 that received the ultrasonic signal first and the sensor Q2 that received the ultrasonic signal second, then the fault occurs In the interval between Q1 and Q2, according to the time difference t between the two signals received, the length of the fault distance from the Q1 sensor is 1/2 (L-t*v), where L is the distance between the sensors Q1 and Q2, and v is the ultrasonic signal speed of propagation;

Step c: If it is judged that the fault only occurs in the armor layer, then compare the ultrasonic signal S1 and the UHF signal S2 between L1 and L2, and screen out the sensor Q1 that received the ultrasonic signal first and the sensor Q2 that received the ultrasonic signal second , and at the same time screen out the sensor R1 that received the UHF signal first and the sensor R2 that received the UHF signal second, then the fault occurs in the interval between Q1 and Q2 and R1 and R2, and the two ultrasonic sensors Q1 and Q2 receive The time difference t1 between the two UHF sensors R1 and R2, the time difference t2 received by the two UHF sensors R1 and R2, the length of the fault distance from the Q1 sensor is 1/2 (L1-t1*v1), where L1 is the distance between the sensors Q1 and Q2 , v1 is the propagation velocity of the ultrasonic signal; the length of the fault distance R1 sensor is 1/2 (L2-t2*v2), where L2 is the distance between the sensors R1 and R2, and v2 is the propagation velocity of the UHF signal.

Step a: start the information sensing module, collect the ultrasonic signal S1, the UHF signal S2 and the high frequency current signal S4;

Step b: If it is determined in step 2 that the cable has an insulation fault, go to the next step;

Step c: Compare the collected high-frequency current signals S4, and filter out the sensor L1 with the largest grounding current and the sensor L2 with the second largest grounding current, then the fault occurs in the interval between L1 and L2, and the position with the largest grounding high-frequency current is close to the fault point, to realize the preliminary determination of the fault location;

Step d: If it is judged in step 2 that the fault only occurs in the insulating layer or shielding layer, compare the ultrasonic signal S1 between L1 and L2, and screen out the sensor Q1 that received the ultrasonic signal first and the sensor Q2 that received the ultrasonic signal second, Then the fault occurs in the interval between Q1 and Q2. According to the time difference t between the two signals received, the length of the fault from the Q1 sensor is 1/2(L-t*v), where L is the distance between the sensors Q1 and Q2, v is the propagation velocity of the ultrasonic signal;

Step e: If it is determined in step 2 that the fault only occurs in the armor layer, compare the ultrasonic signal S1 and the UHF signal S2 between L1 and L2, and screen out the sensor Q1 that received the ultrasonic signal first and the sensor that received the ultrasonic signal second At the same time, the sensor R1 that received the UHF signal and the second sensor R2 that received the UHF signal were screened out at the same time, then the fault occurred in the interval between Q1 and Q2 and R1 and R2, and the two ultrasonic sensors Q1 and The time difference t1 received by Q2, and the time difference t2 received by the two UHF sensors R1 and R2, the length of the fault distance from the Q1 sensor is 1/2 (L1-t1*v1), where L1 is the distance between the sensors Q1 and Q2 V1 is the propagation speed of the ultrasonic signal; the length of the fault distance R1 sensor is 1/2 (L2-t2*v2), where L2 is the distance between the sensors R1 and R2, v2 is the UHF signal transmission speed.

The on-line monitoring system and method for insulation faults of high-voltage long-segment cables provided by the present invention integrate multiple physical information such as ultrasound, UHF, pulse current, and infrared thermal images to realize the location of insulation defects. It realizes the location of the fault on each insulating layer of the high-voltage large-section cable, that is, radial location, and also realizes the location of the fault on the position of the long section of the cable, that is, axial location. The diagnosis system of the invention is safe and reliable, has high fault diagnosis accuracy and sensitivity, and is easy to implement.

Description of drawings

Fig. 1 is a schematic structural diagram of a preferred embodiment of the present invention.

Figure 2 is a flow chart of radial location of high voltage cable insulation faults.

Figure 3 is a flow chart of axial positioning of high voltage cable insulation faults.

Detailed ways

Example

When a high-voltage cable has an insulation fault, it will emit signals such as ultrasound, heat, UHF, and high-frequency current, and the fault often develops from the insulation layer or the shielding layer. In severe cases, a discharge channel is formed on the insulation layer and the shielding layer. If the insulation fault continues to develop, the armor layer will be burned. Since the UHF signal cannot penetrate the armor layer, only after the armor layer is damaged can the high frequency signal be collected outside. In addition, when the insulation fault develops close to the armor layer or the armor layer is damaged, the temperature of infrared thermal imaging has better sensitivity. Based on the above theories, the present invention proposes an on-line monitoring system and method for insulation faults of high-voltage long-section cables.

The high-voltage long section cable insulation fault on-line monitoring system of this embodiment, as shown in Figure 1, includes: a number of distributed information integration systems M and central processing system N, distributed information integration systems M are installed according to equal intervals; Information integration system A includes information sensing module 1, distributed data acquisition module 2, distributed data storage module 3, distributed processing module 4, and information communication module 5; central processing system B includes central processing module 6 for long-distance cables , display module 7; information sensing module 1 is connected with data distributed acquisition module 2, data distributed acquisition module 2 is connected with data distributed storage module 3, data distributed storage module 3 is connected with distributed processing module 4, The distributed processing module 4 is connected with the information communication module 5, the information communication module 5 is connected with the central processing module 6 of the long-distance cable, and the display module 7 is connected with the central processing module 6 of the long-distance cable.

The information sensing module 1 includes an ultrasonic sensor 1A, an ultra-high frequency sensor 1B, an infrared thermal imaging sensor 1C and a high-frequency current sensor 1D, and realizes distributed sensing of insulation status information of large and long cables;

The distributed data collection module 2 is used to collect the high-voltage cable insulation status information contained in the information sensing module 1;

The data distributed storage module 3 stores the high-voltage cable insulation state information collected by the data distributed acquisition module 2;

The distributed processing module 4 calculates and analyzes the high-voltage cable insulation state information stored in the data distributed storage module 3, determines whether there is a fault and calibrates the fault degree;

The information communication module 5 transmits the result calculated and analyzed by the distributed processing module 4 to the central processing module 6 of the large and long cable;

The central processing module 6 of the long-distance cable judges the fault degree and fault location according to the processing results of each distributed processing module 4 delivered by the information communication module 5 , and sends the result to the display module 7 .

Distributed information integration system M is installed at equal intervals, considering the attenuation characteristics of cable insulation status information in propagation, set up a set of ultrasonic sensor 1A, UHF sensor 1B and infrared thermal imaging sensor 1C at intervals of 20 meters, high frequency The current sensor 1D is installed on the ground wire of the cable.

Integrate multiple physical information such as ultrasound, UHF, pulse current and infrared thermal image to realize the location of insulation defects. The location contains two meanings: one is to realize the location of faults in each insulation layer of high-voltage large-section cables, that is, radial Location; the other is to realize the location of the fault on the position of the long cable, that is, the axial location.

Based on the three physical information of ultrasound, UHF and infrared thermal images, the positioning of the insulation layer of high-voltage large-section cables, that is, radial positioning, is realized. The specific scheme is as follows:

Step 1: Start the information sensing module 1 to collect ultrasonic signal S1, UHF signal S2 and infrared signal S3;

Step 2: For the 3 signals collected in step 1, set the first thresholds A1, A2 and A3 respectively; if only the ultrasonic signal S1 is greater than the threshold A1, it is determined that the fault occurs in the insulating layer or shielding layer close to the core; if the ultrasonic signal S1 is greater than the threshold A1, and the infrared signal S3 is greater than the threshold A3, it is determined that the fault occurs in the insulating layer or shielding layer close to the armored layer; if the ultrasonic signal S1 is greater than the threshold A1, the UHF signal S2 is greater than the threshold A2, and the infrared signal S3 If it is greater than the threshold A3, it is determined that the fault has developed to the armor layer and the armor layer has been destroyed.

Based on the three physical information of ultrasound, ultra-high frequency and high-frequency current, the location of the fault on the position of the long cable is realized, that is, the axial location. The specific scheme is as follows:

Step a: start the information sensing module 1, collect the ultrasonic signal S1, the UHF signal S2 and the high frequency current signal S4;

Step b: If it is determined in step 2 that the cable has an insulation fault, go to the next step;

Step c: Compare the collected high-frequency current signals S4, and filter out the sensor L1 with the largest grounding current and the sensor L2 with the second largest grounding current, then the fault occurs in the interval between L1 and L2, and is close to the position where the grounding high-frequency current is the largest Fault point, to realize the preliminary determination of the fault location;

Step d: If it is judged in step 2 that the fault only occurs in the insulating layer or shielding layer, compare the ultrasonic signal S1 between L1 and L2, and screen out the sensor Q1 that received the ultrasonic signal first and the sensor Q2 that received the ultrasonic signal second , then the fault occurs between Q1 and Q2. According to the time difference t between the two signals received, the length of the fault from the Q1 sensor is 1/2L-t*v, where L is the distance between the sensors Q1 and Q2, v is the propagation velocity of the ultrasonic signal.

Step e: If it is determined in step 2 that the fault only occurs in the armor layer, compare the ultrasonic signal S1 and the UHF signal S2 between L1 and L2, and screen out the sensor Q1 that received the ultrasonic signal first and the sensor that received the ultrasonic signal second At the same time, the sensor R1 that received the UHF signal and the second sensor R2 that received the UHF signal were screened out at the same time. The fault occurred in the interval between Q1 and Q2 and R1 and R2. The two ultrasonic sensors Q1 and Q2 The received time difference t1, the time difference t2 received by the two UHF sensors R1 and R2, the length of the fault distance from the Q1 sensor is 1/2L1-t1*v1, where L1 is the distance between the sensors Q1 and Q2, v1 is the propagation speed of the ultrasonic signal; the length of the fault distance R1 sensor is 1/2L2-t2*v2, where L2 is the distance between the sensors R1 and R2, and v2 is the propagation speed of the UHF signal.

The present invention is not limited to the above-described embodiments. All technical solutions formed by equivalent replacements fall within the scope of protection required by the present invention.

Claims (2)

1. A monitoring method of a high-voltage long-section cable insulation fault on-line monitoring system is characterized in that the high-voltage long-section cable insulation fault on-line monitoring system comprises the following steps: a central processing system and a plurality of distributed information integration systems; the distributed information integration systems are installed on the cable at intervals; the distributed information integration system includes: the system comprises an information sensing module, a data distributed acquisition module, a data distributed storage module, a distributed processing module and an information communication module which are connected in sequence; the central processing system comprises a large-length cable central processing module and a display module; the information communication module is connected with the long-section cable central processing module, and the display module is connected with the long-section cable central processing module;

the information sensing module comprises an ultrasonic sensor, an ultrahigh frequency sensor, an infrared thermal image sensor and a high-frequency current sensor;

the data distributed acquisition module is used for acquiring the insulation state information of the high-voltage cable contained in the information sensing module;

the data distributed storage module is used for storing the high-voltage cable insulation state information acquired by the data distributed acquisition module;

the distributed processing module is used for calculating and analyzing the high-voltage cable insulation state information stored in the data distributed storage module, judging whether a fault exists or not and calibrating the fault degree;

the information communication module transmits the calculation and analysis results of the distributed processing module to the long-section cable central processing module;

the large-length cable central processing module judges the fault degree and the fault position according to the results processed by the distributed processing modules transmitted by the information communication module and transmits the results to the display module;

the monitoring method comprises the following steps:

step 1: starting an information sensing module, and acquiring an ultrasonic signal S1, an ultrahigh frequency signal S2 and an infrared signal S3;

step 2: setting first threshold values A1, A2 and A3 respectively for the ultrasonic signals, the ultrahigh frequency signals and the infrared signals collected in the step 1; if only the ultrasonic signal S1 is larger than the threshold value A1, judging that the fault occurs in an insulating layer or a shielding layer close to the wire core; if the ultrasonic signal S1 is greater than the threshold A1 and the infrared signal S3 is greater than the threshold A3, judging that the fault occurs in an insulating layer or a shielding layer close to the armor layer; if the ultrasonic signal S1 is greater than the threshold A1, the ultrahigh frequency signal S2 is greater than the threshold A2, and the infrared signal S3 is greater than the threshold A3, it is determined that a fault has developed to the armor and the armor has been damaged.

2. The monitoring method according to claim 1, wherein: if the cable is judged to have the insulation fault in the step 2, further performing the following steps;

step a: comparing the collected high-frequency current signals S4, screening out the sensor L1 with the largest grounding current and the sensor L2 with the second largest grounding current, and then enabling the fault to occur between the L1 and the L2, wherein the position with the largest grounding high-frequency current is close to a fault point, so that the primary judgment of the fault position is realized;

step b: if the fault is judged to be only generated on the insulating layer or the shielding layer, comparing the ultrasonic wave signals S1 between the L1 interval and the L2 interval, screening out the sensor Q1 which receives the ultrasonic signal at the earliest and the sensor Q2 which receives the ultrasonic signal at the second interval, wherein the fault is generated between the Q1 interval and the Q2 interval, and according to the time difference t of the two signals, the length of the fault from the Q1 sensor is 1/2 (L-t v), wherein L is the distance between the sensors Q1 and Q2, and v is the propagation speed of the ultrasonic signal;

step c: if the fault is judged to be only generated in the armor layer, comparing the ultrasonic signal S1 and the ultrahigh frequency signal S2 in the L1 and L2 sections, screening out a sensor Q1 which receives the ultrasonic signal earliest and a sensor Q2 which receives the ultrasonic signal second, and simultaneously screening out a sensor R1 which receives the ultrahigh frequency signal earliest and a sensor R2 which receives the ultrahigh frequency signal second, wherein the fault is generated in the Q1 and Q2 sections and the R1 and R2 sections, the time difference t1 received by the two ultrasonic sensors Q1 and Q2 and the time difference t2 received by the two ultrahigh frequency sensors R1 and R2 are respectively, the length of the fault distance Q1 from the sensor Q1 is 1/2 (L1-t 1 v 1), wherein L1 is the distance between the sensors Q1 and Q2, and v1 is the propagation speed of the ultrasonic signal; the length of the fault from the sensor R1 is 1/2 (L2-t 2 v 2), wherein L2 is the distance between the sensors R1 and R2, and v2 is the propagation speed of the ultrahigh frequency signal.

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