CN-121995272-A - Intelligent on-line monitoring equipment applied to cable joint

CN121995272ACN 121995272 ACN121995272 ACN 121995272ACN-121995272-A

Abstract

The invention discloses intelligent on-line monitoring equipment applied to a cable joint, which belongs to the technical field of cable detection and comprises a transmission optical fiber, an optical fiber Bragg grating sensor, an optical fiber demodulator, a data processing unit and an intelligent early warning unit. The optical fiber sensor is arranged at a key temperature measuring part of a cable joint and is connected in series through optical fiber fusion to form a sensing network, the optical fiber demodulator is used for realizing multi-joint positioning monitoring and wavelength offset acquisition through a wavelength division multiplexing or time division multiplexing technology, the data processing unit is used for converting the wavelength offset into a temperature variation, and the intelligent early warning unit is used for realizing fault grading early warning and advanced early judgment of a temperature rising trend by adopting a convolutional neural network, a bidirectional long-short-term memory network and a self-attention mechanism mixed model. The invention does not need on-site power supply, has strong electromagnetic interference resistance, can realize all-weather on-line monitoring and accurate positioning, and effectively improves the accuracy and timeliness of cable joint fault early warning.

Inventors

BAI XUENING
XU TAO
CHEN LE
LIU JINGYUN
YIN SHANYAO
JIANG SHENGWU
YE JIAYI
LUO YILING
ZOU LONGFEI

Assignees

广东电网有限责任公司惠州供电局

Dates

Publication Date: 20260508
Application Date: 20260331

Claims (7)

1. The intelligent on-line monitoring equipment applied to the cable joint is characterized by comprising a transmission optical fiber, an optical fiber Bragg grating sensor, an optical fiber demodulator, a data processing unit and an intelligent early warning unit, wherein the transmission optical fiber is used for transmitting optical signals, the transmission optical fiber is embedded in a cable outer sheath, under an armor layer or fixed on the outer wall of a laid cable in the cable production process, the optical fiber Bragg grating sensor is used as a sensing unit and is arranged at a key temperature measuring part of the cable joint and used for sensing the surface temperature change of the joint in real time, each optical fiber Bragg grating sensor is welded with the transmission optical fiber in a low-loss manner through an optical fiber welding machine, a plurality of optical fiber Bragg grating sensors are connected in series to form a quasi-distributed sensing network, the optical fiber demodulator comprises a laser source, a modulation unit and a signal receiving unit, the modulation unit is used for outputting laser wavelength range modulation and power amplification, the signal receiving unit is used for receiving reflection peak signals of the optical fiber Bragg grating sensors, the data processing unit is used for processing the reflection peak signals to obtain reflection peak signals, and the arrival wavelength offset of each reflection peak and the arrival wavelength is calculated in real time The intelligent early warning unit is internally provided with a fault discrimination model, inputs fusion temperature time sequence data, and outputs a fault grading early warning result and a future 10-30 minutes temperature predicted value.
2. The intelligent on-line monitoring device for cable joints according to claim 1, wherein when the fiber bragg grating sensor positioning adopts a wavelength division multiplexing method, the fiber bragg grating sensor at each cable joint writes in different bragg wavelengths The optical fiber demodulator scans the whole wavelength range, and different optical fiber Bragg grating sensors are distinguished by identifying the wavelength of the reflection peak, so that the joint positioning is realized.
3. The intelligent on-line monitoring device for cable joints according to claim 1, wherein when the fiber bragg grating sensor is positioned by a time division multiplexing method, a pulse laser source is adopted or continuous laser is modulated into light pulses through a modulation unit, the time difference of the return of the reflected pulses is measured, and the distance between the fiber bragg grating sensor and a demodulator is calculated by combining the light speed, so that the cable joint is positioned.
4. The intelligent on-line monitoring device for cable joint according to claim 1, wherein the fiber bragg grating sensor is sleeved with a polymer sleeve, the fiber is in a loose bending state in the tube, two ends of the fiber are fixed by glue to realize decoupling of temperature and strain, and the wavelength offset in the data processing unit is as follows The conversion relation with the temperature change amount Δt is: Wherein Is a temperature coefficient.
5. The intelligent on-line monitoring device for the cable joint according to claim 1, wherein the fault discrimination model of the intelligent early warning unit comprises a convolutional neural network layer, a two-way long-short-term memory network layer, a self-attention mechanism layer and a double output head, the double output head comprises a classification head and a regression head, the classification head outputs three levels of fault probability of normal, fault early warning and emergency warning, and the regression head predicts a temperature value of 10-30 minutes in the future.
6. The intelligent on-line monitoring device for the cable joint according to claim 5, wherein the fault discrimination model is obtained by training a historical temperature time sequence data set containing multiple working conditions of normal operation, overload temperature rise, poor contact temperature rise, sealing failure damp temperature rise and structure loosening deformation temperature rise in a training stage through data enhancement and time sequence standardization pretreatment.
7. An intelligent on-line monitoring device for cable joints according to claim 1, characterized in that the modulating unit of the fiber optic demodulator modulates the wavelength range of the laser light covering the initial bragg wavelengths of all fiber bragg grating sensors, and the spectral detection range of the signal receiving unit has to cover the initial bragg wavelengths of all FBG sensors and their maximum expected offset in the measurement range.

Description

Intelligent on-line monitoring equipment applied to cable joint Technical Field The invention relates to the technical field of cable detection, in particular to intelligent on-line monitoring equipment applied to a cable joint. Background The cable line is used as a core carrier for power transmission and energy distribution, is limited by the actual requirements of cable manufacturing process and engineering laying, the cable cannot be laid in a continuous long distance without splicing, and the cable joint becomes an indispensable key component in the cable line. However, the cable joint needs to realize conductor connection of two sections of cables, tiny physical gaps, oxide films, greasy dirt or dust inevitably remain on contact surfaces, the contact resistance of the joint can be directly increased by the impurities, local high-temperature points are formed at the joint, when the temperature of the joint exceeds the temperature-resistant threshold value of an insulating layer, the insulating layer is melted or even burnt, and finally short-circuit fire and large-area power failure accidents are caused. In the face of the serious safety risk, the existing monitoring and protecting means still have the defects that 24-hour all-weather online monitoring cannot be realized by relying on a regular manual inspection or handheld temperature measurement mode, huge time and space dead zones exist, the method is difficult to capture the early slight heating phenomenon and abnormal temperature rise rate of the joint, the early warning is seriously delayed and the optimal treatment window is lost when faults are developed to the middle and later stages and the temperature is obviously exceeded; the prior art focuses on regional temperature monitoring or open fire identification after fire, is difficult to accurately locate to a specific joint in a densely paved cable network, once an alarm occurs, operation and maintenance personnel still need to spend a large amount of time to check one by one, the position cannot be quickly determined after the fault occurs, the rush repair time is greatly delayed, the operation and maintenance efficiency is reduced, most monitoring systems only can provide basic temperature data, lack deep intelligent analysis on temperature change trend, speed and related characteristics, cannot effectively identify early hidden troubles caused by slight increase of contact resistance, slow sealing failure and the like, further cannot realize advanced early warning based on a prediction model, so that operation and maintenance work is in a passive mode of 'post response' for a long time, for the cable joint which is located at a scattered, remote and inaccessible position such as high altitude, high voltage, underwater or narrow gaps, the prior art generally installs monitoring devices independently for each joint, the devices are often large in size, additional on-site power supply (such as a battery or electricity taking) is required, therefore, manual battery replacement or charging is required regularly, the maintenance difficulty is high in a severe environment, the life cycle is high, its large volume also limits the application in compact spaces. Disclosure of Invention The invention aims to provide intelligent on-line monitoring equipment applied to a cable joint, and solves the technical problems. In order to achieve the above purpose, the present invention provides the following technical solutions: The intelligent on-line monitoring equipment applied to the cable joint comprises a transmission optical fiber, an optical fiber Bragg grating sensor (FBG), an optical fiber demodulator, a data processing unit and an intelligent early warning unit. The transmission optical fiber can be directly embedded into the outer sheath of the cable and under the armor layer in the cable production process, so that the structural integration of the sensing unit and the cable is realized; in the field construction of a laid cable, a transmission optical fiber can be tightly fixed on the outer wall of the cable through a high-temperature-resistant binding belt, a clamp or a special adhesive to realize physical contact coupling with the cable, the FBG sensors are used as sensing units and are directly arranged at key temperature measuring parts of a cable joint to sense the temperature change of the surface of the joint in real time, each FBG sensor is in low-loss and high-reliability fusion connection with the transmission optical cable through an optical fiber fusion splicer, so that a plurality of sensors are connected in series to the same optical fiber link to form a quasi-distributed sensing network, and then the sensing signals are remotely transmitted to an optical fiber demodulator of a monitoring center through the transmission optical cable, the FBG is sheathed with a polymer sleeve, the optical fiber is in a loose bending state, two ends of the optical fiber are fixed through the adhesive,