CN104568016A - Cable joint health diagnosis and heat fault pre-warning system - Google Patents

Abstract

The invention proposes a cable joint health diagnosis and thermal fault early warning system, including a measurement control module, a communication module, a display module, an alarm module, a temperature sensor, a humidity sensor, a gas sensor, a stress sensor, a hoop metal belt, an ambient temperature sensor, Environmental humidity sensor, control center network server. The combination of different sensors is used for on-line monitoring of cable joints, which is different from the current way of alarming after a fault. It measures and analyzes the unhealthy state of cable joints and the operating environment, including temperature, humidity, gas and smoke, expansion, respiration, Ambient temperature, ambient humidity, etc., make the guarantee cost lower, and greatly improve the sensitivity and accuracy of the early warning system. In this way, the health diagnosis and thermal fault warning of cable joints can be realized, which can effectively prevent problems before they happen, improve the reliability of cable joints and even the operation of power systems, speed up the fault handling time of cable joints, and greatly reduce the economic losses caused by cable joint failures. loss.

Description

Cable joint health diagnosis and thermal fault early warning system

technical field

The invention relates to a cable joint protection device, in particular to a cable joint health diagnosis and thermal fault early warning system.

Background technique

Cable joints heat up and even explode, which is a common fault in power production and operation. It will not only cause a large amount of power loss, but also seriously affect the normal operation of electrical equipment. It will cause insulation breakdown, form a short circuit, cause an explosion, cause a fire, cause equipment damage, interrupt ongoing production, scientific research, medical operations and other activities, causing incalculable losses.

The main reasons for the heating or explosion of cable joints include the following aspects. (1) Mechanical damage: due to poor urban construction management and poor construction, accounting for about 50% of cable accidents; (2) lead package fatigue, cracks, and swelling: this is due to poor cable installation conditions Poor manufacturing quality, long-term cable overload and other reasons, most of which occur on a section of cable near the terminal of the intermediate joint box, and some occur in places where the cables are densely packed and have poor heat dissipation. (3) Water immersion explosion at the outdoor terminal head: most of them occur on lines of 10KV and below. Due to improper construction and operation and maintenance, the condensed water at the terminal head accumulates in the cable head, which eventually leads to moisture breakdown of the insulation and causes an explosion. (4) Explosion of the middle joint of the cable: This is mostly due to the expansion of the insulating glue in the joint box due to overload and the expansion of the shell, or the poor connection of the conductors to overheat the joint and explode. (5) Respiration: When the cable load or the external temperature changes, the insulating glue in the terminal head expands with heat and contracts with cold, and "respiration" occurs to form internal and external air exchanges, so that moisture invades and condenses on the inner wall and gap of the terminal head. The insulation is broken down and broken down.

From the analysis of the above reasons, it can be seen that when there is a problem with the cable joint, it is manifested by temperature changes, humidity changes, and volume changes. When the temperature is too high for a long time, smoke and gas will be produced during the gradual damage of the insulation. Therefore, from the on-line monitoring and comprehensive analysis of these factors, it is possible to make an accurate judgment on the health status of the cable, and to make an early warning of possible faults such as short circuit and explosion of the cable joint.

At present, the protection monitoring of cable joints is mainly to monitor temperature changes, some of which are combined with humidity monitoring, and there is no literature on the health diagnosis and thermal fault warning of cable joints. For example, the Chinese patent "A monitoring device for the state of high-voltage cable joints in mine roadways" (application number: 200910074978.1) proposes a device for continuously collecting temperature, humidity, and current. Fault judgment and processing time, etc.; in addition, in fact, the current is not accurate as a judgment parameter for the status of the cable joint, because after the contact resistance of the cable joint increases, overheating or even explosion may occur when the current is normal.

It is of great practical significance to predict the operating health status of cable joints in advance and give early warning before failures, which can effectively reduce equipment damage, ensure power supply reliability, and reduce economic losses and casualties.

Contents of the invention

The purpose of the present invention is to provide a protection and early warning system with simple structure, low cost and sensitive and accurate action for the current problems of thermal faults such as heating or explosion of cable joints, which can automatically monitor the health status of cable joints online and arrange maintenance reasonably. And provide early warning before thermal failure occurs or there is a possibility of explosion.

The technical scheme that the present invention adopts in order to solve the above problems is:

The cable joint health diagnosis and thermal fault early warning system includes a measurement control module (1), a communication module (2), a display module (3), an alarm module (4), a temperature sensor (5), and a humidity sensor (6).

Among them, the temperature sensor (5) measures the temperature inside the cable joint, and sends the data to the measurement control module (1), and calculates and analyzes the time length, times, and the ratio of the temperature exceeding the set limit value to the unit operating time. When the ratio After the set safety value is exceeded, it is judged that the cable joint is in an unhealthy operating state. The greater the proportion of time that the temperature exceeds the set limit, the higher the aging degree of the cable joint; the more times the temperature exceeds the set limit per unit time, the lower the insulation coefficient of the cable joint, and the less safe it is. When encountering this kind of situation, it is necessary to remind the operating personnel to strengthen the patrol inspection. The temperature inside the traditional cable joint only judges whether the temperature exceeds the set limit value, so it can only alarm, but cannot give early warning.

The humidity sensor (6) measures the humidity inside the cable joint and sends the data to the measurement control module (1) to calculate and analyze whether the humidity exceeds the set limit value. When it exceeds, it is judged that the cable joint is in an unhealthy operating state. When there is water vapor in the cable joint, it will deteriorate the operating environment of the cable joint. It is necessary to remind the operating personnel to perform maintenance and treatment, so as to avoid breakdown due to damp insulation and explosion due to overheating.

Furthermore, when the measurement control module (1) judges that the humidity exceeds the set limit value, if the temperature exceeds the set critical value, that is, if there is enough water vapor inside the cable joint, if the temperature is high enough, the water vapor will vaporize, resulting in volume Expansion, the possibility of explosion is very large, then carry out the early warning of explosion.

The measurement control module (1) sends the status of cable joint operation, early warning and alarm information to the display module (3) for display in real time, drives the alarm module (4) to alarm, and transfers to storage through the communication module (2) or uploads via the network. Operators can also read data for a period of time on site with handheld devices, U disks, etc.; when the cable joint is in an abnormal operating state, an early warning signal is issued; when the cable joint is in a faulty operating state, an alarm signal is issued, which can Sound and light alarm can also be alarmed via wired or wireless network.

In order to further strengthen the function, the system further includes a gas sensor (7), a stress sensor (8), a hoop metal belt (9), an ambient temperature sensor (10), and an ambient humidity sensor (11).

Among them, the gas sensor (7) measures the gas and smoke around the cable joint and its concentration, and the measured data is sent to the measurement control module (1) to judge whether the cable joint has insulation overheating and causes aging and damage. When the insulation of the cable joint is overheated, the insulating material decomposes, producing gases such as methane, carbon monoxide, carbon dioxide, and water vapor, and even forms smoke due to the volatilization of a large amount of liquids such as phenylethyl alcohol and cumyl alcohol. When the concentration of methane, carbon monoxide, carbon dioxide and other gases around the cable joint or the concentration of smoke generated by decomposition exceeds the limit value, an early warning signal will be issued. It is used to improve the accuracy of health diagnosis and early warning.

The stress sensor (8) measures the external stress change of the cable joint, and the measured data is sent to the measurement control module (1) to calculate and analyze the expansion of the cable joint and the frequency of respiration. The expansion of the cable joint means that when the insulation of the cable joint is overheated, the insulation material decomposes to produce a large amount of gas and liquid decomposition products, which increases the internal pressure of the cable joint, which in turn leads to the expansion of the cable joint; respiration means that when the internal and external temperature of the cable joint changes, The insulating glue in the joint expands with heat and contracts with cold, forming an exchange of internal and external air, so that moisture invades and condenses on the inner wall and gap of the joint, causing the insulation to drop and be broken down.

When the cable joint expands and breathes, the hoop metal band (9) is located outside the cable joint, and the auxiliary stress sensor (8) measures the stress change outside the cable joint, and sends an alarm signal when the pressure of the cable joint exceeds the limit value; Or when the frequency of respiration is too high, it means that the working environment of the cable joint is bad, and sending out an early warning signal can improve the accuracy of health diagnosis and early warning.

Among them, the ambient temperature sensor (10) and the ambient humidity sensor (11) detect the temperature and humidity of the working environment of the cable joint, and the measured data are sent to the measurement control module (1), and if the ambient temperature or the ambient humidity is too high, an early warning will be issued Signal. When the ambient temperature and ambient humidity are too high, it means that the working environment of the cable joint becomes worse, and the possibility of problems increases. It is necessary to send an early warning signal to remind the operator to improve the working environment of the cable joint in time, and pay attention to maintenance and observation.

The display module (3) in the system is used to display the operation status, parameters, early warning and alarm information of the cable joint, and the alarm module (4) is used to send out early warning and alarm signals. The running state of the cable joint includes three states: normal, abnormal and fault. When the cable joint is in the normal operating state, various normal operating parameters measured are displayed; when the cable joint is in the abnormal or unhealthy operating state, Display various currently measured operating parameters and abnormal causes, etc., and send an early warning signal by the alarm module (4); when the cable joint is in a faulty operating state, display various currently measured operating parameters and fault parameters, and An alarm signal is sent by the alarm module (4).

In order to improve work efficiency and intelligence, the system also includes a control center network server (12), which exchanges data with the measurement and analysis module (1) via the communication module (2), including operating parameters and abnormal parameters in various operating states , lower computer parameter configuration, remote alarm and early warning, remote control, etc.

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

Using a humidity sensor combined with a temperature sensor, in addition to an overheating alarm, it can also realize an early warning of an explosion; using a gas sensor, it is possible to obtain information on the aging and damage of the cable joint insulation; using a stress sensor, it is possible to obtain the expansion of the cable joint and the frequency information of respiration; the combination of the ambient temperature sensor and the ambient humidity sensor can obtain the quality of the external environment when the cable joint is working, so as to indicate the possibility of a problem with the cable joint, and determine whether to remind the operation Personnel pay attention to maintenance and observation.

The on-line monitoring method combined with a variety of low-cost general-purpose sensors is used to comprehensively measure the parameters of the cable joint operation, which makes the cost lower and greatly improves the sensitivity and accuracy of the early warning system.

Different from the current way of alarming after a fault, it measures and analyzes the unhealthy state of the cable joint and the operating environment to realize the health diagnosis and fault warning of the cable joint, which can effectively prevent problems before they happen, and improve the safety of the cable joint and even the power system. Reliability speeds up the troubleshooting time of cable joints and greatly reduces the economic losses caused by cable joint failures.

Description of drawings

Figure 1: Schematic diagram of cable joint health diagnosis and thermal fault early warning system.

Figure 2: Schematic diagram of sensor installation.

In the figure: 1—measurement control module, 2—communication module, 3—display module, 4—alarm module, 5—temperature sensor, 6—humidity sensor, 7—gas sensor, 8—stress sensor, 9—hoop metal belt , 10—environmental temperature sensor, 11—environmental humidity sensor, 12—control center network server.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings.

In Figure 1, the system consists of a measurement control module (1), a communication module (2), a display module (3), an alarm module (4), a temperature sensor (5), a humidity sensor (6), and a gas sensor (7) , a stress sensor (8), an ambient temperature sensor (10), an ambient humidity sensor (11), and a control center network server (12).

The temperature sensor (5) measures the temperature inside the cable joint, and sends the data to the measurement control module (1), and calculates and analyzes the time length, times, and ratio of the temperature exceeding the set limit value to the unit operating time. When the ratio exceeds After setting the safe value, judge whether the cable joint is in an unhealthy operating state.

The humidity sensor (6) measures the humidity inside the cable joint, and sends the data to the measurement control module (1), and calculates and analyzes whether the humidity exceeds the set limit value. When it exceeds, it is judged that the cable joint is in an unhealthy operating state. The measurement control module (1) judges that the humidity exceeds the set limit value and at the same time, if the temperature exceeds the set critical value, an early warning of explosion is performed.

The gas sensor (7) measures the gas and smoke around the cable joint and its concentration, and the measured data is sent to the measurement control module (1) for judging whether the cable joint is aging and damaged due to insulation overheating.

The stress sensor (8) measures the stress change of the cable joint, and the measured data is sent to the measurement control module (1) to calculate and analyze the expansion of the cable joint and the frequency of respiration.

The ambient temperature sensor (10) and the ambient humidity sensor (11) detect the temperature and humidity of the working environment of the cable joint, and the measured data are sent to the measurement control module (1) to issue an early warning when it is judged that the ambient temperature is too high or the ambient humidity is too high Signal.

The measurement control module (1) sends the status, parameters, early warning and alarm information of the cable joint to the display module (3) for display in real time, drives the alarm module (4) to alarm, transfers to the control through the communication module (2) or uploads it via the network Central network server (12), and exchange data with it.

The layout of the sensors can be seen in Figure 2, the temperature sensor (5) and the humidity sensor (6) are installed inside the cable joint; the gas sensor (7) is installed outside the cable joint; On the cable joint, the stress sensor (8) is placed between the hoop metal band (9) and the cable joint; the ambient temperature sensor (10) and the environmental humidity sensor (11) are installed outside the cable joint, and can also be installed inside the cable joint. inside the electrical cabinet.

The above descriptions are only preferred implementation examples of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection of the present invention. within range.

Claims (5)

1. Cable joint health diagnosis and thermal fault early warning system, characterized in that the system includes measurement control module (1), communication module (2), display module (3), alarm module (4), temperature sensor (5), humidity sensor (6); The temperature sensor (5) measures the temperature inside the cable joint, and sends the data to the measurement control module (1), and calculates and analyzes the time length, times, and ratio of the temperature exceeding the set limit value to the unit operating time. When the ratio exceeds After setting the safety value, judge whether the cable joint is in an unhealthy operating state; The humidity sensor (6) measures the humidity inside the cable joint, and sends the data to the measurement control module (1), and calculates and analyzes whether the humidity exceeds the set limit value. When it exceeds, it is judged that the cable joint is in an unhealthy operating state; The measurement control module (1) judges that the humidity exceeds the set limit value and at the same time, if the temperature exceeds the set critical value, it will give an early warning of explosion; The measurement control module (1) sends the status, parameters, early warning and alarm information of the cable joint to the display module (3) for display in real time, drives the alarm module (4) to alarm, and transfers the information through the communication module (2) or uploads via the network. 2. The cable joint health diagnosis and thermal fault early warning system according to claim 1, characterized in that the system includes a gas sensor (7) to measure the gas and smoke around the cable joint and their concentration, and the measured data are sent to the measurement The control module (1) judges whether the cable connector is aged and damaged due to insulation overheating. 3. The cable joint health diagnosis and thermal fault early warning system according to claim 1, characterized in that: the system includes a stress sensor (8), a metal band (9) is hooped outside the cable joint, and the stress sensor (8) measures The stress changes, and the measured data are sent to the measurement control module (1) to calculate and analyze the expansion of the cable joint and the frequency of respiration. 4. The cable joint health diagnosis and thermal fault early warning system according to claim 1, characterized in that: the system includes an ambient temperature sensor (10) and an environmental humidity sensor (11) to detect the working environment temperature and humidity of the cable joint, and measure The data is sent to the measurement control module (1), and when it is judged that the ambient temperature is too high or the ambient humidity is too high, an early warning signal is issued. 5. The cable joint health diagnosis and thermal fault early warning system according to claim 1, characterized in that the system includes a control center network server (12), and the measurement control module (1) communicates with the control center network server via the communication module (2) (12) Exchange data.