Distributed distribution network cable joint state monitoring and fault early warning positioning system

Abstract

The invention belongs to the technical field of cable fault detection, and relates to a distributed distribution network cable joint state monitoring and fault early warning positioning system. The system comprises a partial discharge / temperature measurement sensor module, a receiving host module and a cloud platform module, the partial discharge / temperature measurement sensor module is fixedly arranged at a cable joint and is used for acquiring partial discharge information and temperature at the cable joint and uploading the partial discharge information and temperature to the receiving host module; the receiving host module is connected with the partial discharge / temperature measurement sensor module and uploads the received partial discharge information and temperature to the cloud platform module; and the cloud platform module compares and analyzes the received partial discharge information and temperature with a set threshold value and then pushes the information to operation and maintenance personnel, thereby realizing monitoring of the operation state of the cable intermediate joint and fault early warning and positioning. The system can monitor the temperature, partial discharge and other states of the distributed distribution network cable joint in real time, early warns overheating and insulation aging in time, guides a user to carry out preventive maintenance, and prolongs the service life of equipment.

Description

Technical Field

[0001] The present invention belongs to the technical field of cable fault detection, and relates to a distributed distribution network cable joint status monitoring and fault early warning positioning system. Background Art

[0002] With economic development, urban power grids are increasingly relying on underground cables for power transmission and distribution. However, due to impure raw materials, cable insulation structures can contain air gaps and harmful impurities, or process-related protrusions and spikes. These gaps and impurity tips are prone to local discharge (PD). The long-term effects of PD lead to gradual degradation of the insulation material, ultimately leading to insulation breakdown and serious accidents. According to relevant data, power cable accidents in power systems primarily occur at joints. Failures in cable joints are primarily caused by: construction techniques, insulation degradation caused by the underground environment, inappropriate cable well design (e.g., water immersion, corrosive gases and liquids), cable accessory material, and inadequate maintenance and management of electrical facilities by operators. The number of cable joint failures increases with the length of underground cable, severely impacting the normal operation of distribution networks. However, due to the harsh and complex environment in cable wells, such as high humidity, weak signals, inability to access power, and numerous cable paths, conventional monitoring equipment struggles to operate reliably and over the long term in the high-humidity and high-corrosive environments of cable wells. Furthermore, inspections of distribution network cable joints still rely primarily on regular manual inspections, which is inefficient and difficult to pinpoint in the event of a fault. Therefore, distribution network cable joints currently face a data-free blind spot. Furthermore, distribution network cable monitoring faces numerous challenges in communication transmission and adaptability to on-site environments. Currently, there are relatively few successful inspection / monitoring cases for intermediate joints in distribution network cables. There is an urgent need for extensive on-line inspection and verification to establish signal-defect correlations, sensor equipment selection, on-site inspection and verification, and the development of new equipment, along with the development of relevant operating instructions and technical standards. Distribution network cables have historically been prone to faults, and live-line inspections, aside from power outage methods like oscillating waves and ultra-low frequency testing, have been ineffective. Specific inspections of distribution network cables themselves are rare, primarily performed through the integration of equipment for terminal testing. Monitoring / testing intermediate joints is even rarer, with few products directly suitable for online monitoring of distribution network cables. Summary of the Invention

[0003] In order to solve the problems existing in the prior art, the present invention provides a distributed distribution network cable joint status monitoring and fault warning and positioning system, including a partial discharge / temperature measurement sensor module, a receiving host module, and a cloud platform module; the partial discharge / temperature measurement sensor module is fixedly installed at the cable joint, and is used to collect partial discharge information and temperature at the cable joint, and upload them to the receiving host module; the receiving host module is connected to the partial discharge / temperature measurement sensor module, and uploads the received partial discharge information and temperature to the cloud platform module; the cloud platform module compares and analyzes the received partial discharge information and temperature with the set threshold value, and then pushes the information to the operation and maintenance personnel, thereby realizing the monitoring of the operating status of the cable intermediate joint and the fault warning and positioning.

[0004] Preferably, the partial discharge / temperature measurement sensor module includes several partial discharge / temperature measurement sensors; the technical parameters of the partial discharge / temperature measurement sensor are: working voltage of DC 7.2V, acquisition frequency of 1h / time, transmission frequency of 1h / time, monitoring principle of transient ground voltage, sampling period of 1 hour, measurement content of local signal, transmission mode of LoRa, detection range of 0-60dB, alarm threshold of 30dB, power less than 150mw, temperature range of -40℃-120℃, and temperature accuracy of ±0.5℃.

[0005] Preferably, the partial discharge / temperature sensor consists of a transient voltage partial discharge sensor and a bonded thermistor temperature sensor.

[0006] Preferably, the operating voltage of the receiving host in the receiving host module is DC 7.2V, the temperature range is -40 to +70°C, the altitude is ≤1000 meters, and the maximum absolute humidity is g / m 3 :35, relative humidity %10~100, salt spray concentration %:5; temperature accuracy is ±0.5℃; transmission method is wireless communication.

[0007] The present invention provides a distributed distribution network cable joint status monitoring and fault warning and positioning system. When power cannot be obtained from the well trench, there is humidity, poor signal, many cable paths, and faults are difficult to locate, and underground distribution network cable joint accidents occur frequently, and there is currently no effective monitoring means, the system can monitor the temperature and partial discharge status of the distributed distribution network cable joints in real time, timely warn of overheating and insulation aging, guide users to perform preventive maintenance, extend equipment life, and avoid arc-induced fires and larger safety accidents; through background remote monitoring, the number of manual on-site inspections can be reduced, and the risk of operation and maintenance personnel being exposed to high-voltage environments and the inspection costs can be reduced; fault warning and rapid positioning can significantly shorten the power outage time, avoiding greater economic losses and inconvenience in user life caused by power outages; it can help users establish a cable joint ledger, realize asset management, and lay the foundation for the construction of new power systems such as smart distribution networks and digital twins; real-time monitoring of joint operation status, early warning of faults and precise positioning, improve operation and maintenance efficiency, reduce unplanned power outages, and improve user satisfaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 Schematic diagram of a distributed distribution network cable connector status monitoring and fault early warning and location system provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0009] To facilitate understanding of the present invention, the present invention will be described in more detail below with reference to the accompanying drawings and specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described in this specification. On the contrary, the purpose of providing these embodiments is to make the understanding of the present invention more thorough and comprehensive.

[0010] The present invention provides a distributed distribution network cable connector status monitoring and fault early warning positioning system, such as Figure 1 As shown, it mainly includes a partial discharge / temperature sensor module 101, a receiving host module 102, and a cloud platform module 103. The partial discharge / temperature sensor module 101 is fixed to the cable joint by a cable tie, collects partial discharge and temperature information, and transmits it to the receiving host module 102 via LoRa.

[0011] As a preferred embodiment of the present invention, the partial discharge / temperature sensor module 101 may be provided with several partial discharge / temperature sensors, and the technical parameters of the partial discharge / temperature sensor are as follows: working voltage is DC 7.2V, acquisition frequency is 1h / time, transmission frequency is 1h / time, monitoring principle is transient ground voltage, sampling period is 1 hour, measurement content is local signal, transmission mode is LoRa, detection range is 0-60dB, alarm threshold is 30dB, power is less than 150mw, temperature range is -40℃-120℃, temperature accuracy is ±0.5℃, temperature measurement quantity is two-way temperature measurement, service life is 6 years, IP grade IP 68, external dimensions can be 85mm*60mm*33mm, installation method can be bundled with cable ties, monitoring items: partial discharge, temperature, communication function: communication with external network platform, and can also be connected to the State Grid automation system, alarm mechanism: temperature and partial discharge abnormality alarm. The partial discharge / temperature sensor module has an IP68 waterproof grade, built-in power module, communication module and sensor module; When partial discharge occurs between the inner and outer shields of a cable joint, charged particles rapidly migrate from the charged conductor to the grounded, uncharged conductor, generating nanosecond-level high-frequency current pulses and molecular vibrations in the uncharged conductor. When this current wave encounters a discontinuous break or connection, it transfers from the inner cable surface to the outer surface, propagating into free space as an electromagnetic wave. This transient ground voltage is generated on the outer cable surface, which can be monitored using a specially designed transient ground voltage partial discharge sensor. The continued discharge causes the cable joint to heat up, which can be monitored using a bonded thermistor temperature sensor. The partial discharge / temperature sensor detects the signal and transmits it to the receiving host module via LoRa.

[0012] Receiving host module 102 is fixed with nails 5-10 cm below the edge of the cable well (trench) and transmits received information to cloud platform module 103 via 4G. As a preferred embodiment of the present invention, the receiving host in receiving host module 102 has an operating voltage of DC 7.2V, a temperature range of -40 to +70°C, an altitude (m): ≤1000 meters, a maximum absolute humidity of 35 g / m³, a relative humidity of 10% to 100%, a salt spray concentration of 5%, and a temperature accuracy of ±0.5°C. Host functions include one channel for ambient temperature and one channel for water immersion status. The transmission method is wireless communication: 4G / NB-IoT+LoRa. For 4G, the data reporting method is timed + triggered, with a default reporting period of 3 hours. The service life is 6 years. The IP rating is IP68, and the dimensions are optional: 167mm*95mm*70mm. Installation options include cable ties and screws. The ambient temperature probe has a 6-core core and is connected to the host interface and the partial discharge / temperature sensor interface.

[0013] Cloud platform module 103 comprehensively displays the number, location, and operational status of all cable connectors connected to the system. Temperature and partial discharge thresholds can be set. Received partial discharge and temperature data are compared and analyzed against these thresholds to generate alarms for data exceeding limits. These alarms are then pushed to specific operators via SMS, mini-programs, or apps, enabling timely monitoring and rapid location of cable connector status.

[0014] The steps for verifying the effectiveness of live detection and online monitoring of cable joints are as follows: 1. Non-pressurized test: a simulated partial discharge pulse signal is injected into the sample cable through a signal source, and at the same time, partial discharge detection and online monitoring of the transient ground voltage method are carried out on the cable joints; 2. Pressurized test: the discharge source is stimulated on the sample cable through series harmonic boosting, and the verification and comparison of the live detection and transient ground voltage monitoring effects are carried out simultaneously on the cable joints; 3. Factor influence test: the monitoring effect of the transient ground voltage method is verified by changing the signal frequency, discharge repetition rate, amplitude, and test location; after the construction of the test platform, sample cable defect processing and multiple test comparisons, it is concluded that the transient ground voltage detection has a more obvious effect on the partial discharge detection of the middle joint of the cable, and the monitoring effect can be guaranteed within 10 meters on both sides of the joint at a frequency of 6 to 100 MHz, and the discharge amount is positively correlated with the transient ground voltage.

[0015] Temperature validity verification: By changing the skin gradient temperature of the sample, the temperature data received by the cloud platform module is basically consistent, indicating that it is effective to monitor the skin temperature of the cable connector through the bonded thermistor temperature sensor.

Claims

1. A distributed distribution network cable connector status monitoring and fault early warning and positioning system, characterized by: It includes a partial discharge / temperature measurement sensor module, a receiving host module, and a cloud platform module; the partial discharge / temperature measurement sensor module is fixedly installed at the cable joint, and is used to collect partial discharge information and temperature at the cable joint, and upload them to the receiving host module; the receiving host module is connected to the partial discharge / temperature measurement sensor module, and uploads the received partial discharge information and temperature to the cloud platform module; the cloud platform module compares and analyzes the received partial discharge information and temperature with the set threshold value, and pushes the information to the operation and maintenance personnel, thereby realizing the monitoring of the operating status of the cable intermediate joint and fault warning and positioning.

2. The distributed distribution network cable connector status monitoring and fault early warning and positioning system according to claim 1 is characterized by: The partial discharge / temperature sensor module includes several partial discharge / temperature sensors; the technical parameters of the partial discharge / temperature sensor are as follows: an operating voltage of DC 7.2V, an acquisition frequency of 1h / time, a transmission frequency of 1h / time, a monitoring principle of transient ground voltage, a sampling period of 1 hour, a measurement content of a local signal, a transmission method of LoRa, a detection range of 0-60dB, an alarm threshold of 30dB, a power lower than 150mw, a temperature range of -40°C-120°C, and a temperature accuracy of ±0.5°C.

3. The distributed distribution network cable connector status monitoring and fault early warning and positioning system according to claim 2 is characterized by: The partial discharge / temperature measurement sensor consists of a transient voltage partial discharge sensor and a bonded thermistor temperature sensor.

4. The distributed distribution network cable connector status monitoring and fault early warning and positioning system according to claim 1 is characterized by: The operating voltage of the receiving host in the receiving host module is DC 7.2V, the temperature range is -40 ~ +70 ° C, the altitude is ≤ 1000 meters, and the maximum absolute humidity is g / m 3 :35, relative humidity %10~100, salt spray concentration %:5; temperature accuracy is ±0.5℃; transmission method is wireless communication.

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