"Cable safety fire prevention remote online monitoring system" was successfully developed

The staff used the monitoring management software system to realize the remote real-time monitoring of the temperature of the cable connector. Xu Bingshe



Cable joint temperature on-site monitoring. Ji Guang photo "to stay at home" can "be clear"

"The temperature of the 66-kilovolt long Jiajia and A-wire rod connector rose by 4 degrees Celsius in one hour, and the temperature increased rapidly. You have looked at it."

In the remote monitoring room of the cable work area of ​​the Changchun Power Supply Company, Pang Dan, the deputy director of the work area, found a “transaction” on the monitoring screen and immediately called the outside inspector to check and check the scene.

Ten minutes later, the on-site message was returned: After the on-site infrared temperature check, the temperature of the cable joints of Changjiajiao and Bianyi No. 1 rods actually increased, and the field temperature value was consistent with the data obtained by the monitoring center. Judgment of the increase in line load caused normal temperature rise of the cable connector.

After notifying the dispatch center to timely adjust the grid operation mode to reduce the load on Changjia Jia and B lines, Pang Dan looked at the numerical curve on the display screen and showed a satisfied smile.

It enables him to know the temperature change of 4 degrees Celsius of a cable joint more than ten kilometers away without leaving home, and discovers the overheating phenomenon in time, relying on the “Cable Safety Fire-fighting Remote Online Monitoring System that has just passed acceptance and put into use last year. ". The R&D and application of this system also allowed the Changchun Power Supply Company's cable work area to enter the “third change” in terms of temperature monitoring methods for cable joints.

"Failed to make up" to "prevention"

Cables that are widely used in power grids, regardless of whether the cable insulation layer or the outer sheath gives the cable cores much protection, are the most sensitive and fragile parts of cables that are exposed and are connected to other equipment. Line load is too high, or the difference in process quality of cable joints, and even extreme weather conditions, may cause insulation damage at the cable joints, high temperature, overheating, serious fire may occur, leading to power grid accidents. Mastering the temperature changes of cable joints is a long-term important task for grid employees engaged in professional cable work.

The longest history and longest-term use of joint temperature measurement monitoring methods is the method used by older generation of electric power workers as “wax touch”. Whether the wax piece melts or not, determine if the cable connector is “overheated”. Obviously, even in the early days when the power industry was not well-developed and the number of cable contacts was relatively small, the temperature of each cable connector could not be checked in a timely and effective manner using this "wax touch" method.

In the 21st century, infrared temperature measurement technology has been widely used in China's power grids, and cable joint temperature monitoring has entered the "infrared" era. Compared with the “wax touch”, infrared temperature measurement efficiency has been greatly improved, but infrared temperature measurement still requires manual inspection, and the atmospheric environment, background radiation, the device's own sensitivity and operating methods, may interfere with the judgment of technical personnel.

With the acceleration of urbanization, the "cable" trend of transmission lines is also accelerating. In the city of Changchun alone, at the end of 2011, the length of the 220-kilovolt cable has reached 16.08 kilometers, the length of the 66-kilovolt cable is 132.04 kilometers, and the length of the 10-kilovolt cable is more than 1,000 kilometers. There are thousands of cable contacts throughout the city.

“Manual patrols have a long infrared temperature measurement period, and it is impossible to grasp the operational status of the cable and its changing trend in real time.” Jiguang Chang, a staff member of the cable work area of ​​Changchun Power Supply Company, deeply felt that “it is often until the overheating causes a fault to occur before we can find the fault point. where".

"Failed sheep" is always inferior to "prevention." To build a strong smart grid, there is an urgent need to place cables under effective "real-time monitoring." In this context, the "Cable Safety Fire Prevention Remote Online Monitoring System" came into being.

Technology breakthroughs

In 2009, Changchun Power Supply Company and Northeast Dianli University began the road to tackle the problem of the “Cable Safety Fire Prevention Remote Online Monitoring System”. After extensive research and research and development over the past two years, we have formed a combination of “acquisition of real-time data on site and theoretical calculation of monitoring load currents, uploading of monitoring data via wireless communication (GPRS), and analysis and analysis of the central computer to achieve cable operation status. The design of early warning and over-limit warnings has gradually become a practical monitoring system. One technical difficulty was overcome during the period.

The cable connectors in operation are exposed high-potential conductors, and ordinary temperature sensors cannot solve safety problems. In this regard, the project team chose the wireless communication method and used a wireless temperature sensor with only the size of a lighter to solve the high voltage insulation problem of the sensor.

High-voltage cable distribution boxes are distributed in every corner of the city. The distribution radius is often several tens of kilometers, and thousands of monitoring points make cable transmission costs unattainable. The research group adopted a data communication method that combines GSM short message and GPRS. Utilizing an off-the-shelf wireless mobile communication network, the investment in the power communication business is turned to the public mobile communication network, which greatly saves costs and realizes the best cost-effectiveness ratio.

Unlike other monitoring systems, monitoring the temperature of the cable connector requires the sensor to be attached to the high voltage cable connector. Once installed, it is difficult to maintain. How to ensure the stable power supply of sensors, signal relays, and transmission devices has also become a difficult problem to be solved. After comprehensively comparing common power supply methods such as solar energy, capacitor storage, and bus sensing, the group creatively “coupled” several types of power supply—using the energy pick-up coil to power the detector and adding power to the power line. The super capacitor meets the instantaneous high-power supply demand during data transmission and reception. If installed outdoors, a tablet-sized solar panel can be used to provide reliable and stable power for the data acquisition repeater.

A set of "superordinate computer monitoring management analysis software system" with auxiliary analysis has become the "nerve center" of the whole system. Through the software design, the "nerve center" has remote monitoring of the cable connector temperature, alarm and cable connector operating status. evaluation of. In the past, the professional cable workers who came to the rain and went to the rain, stood at the monitoring center and knew the status of the various cable connectors in the city.

“With this monitoring system, the work intensity of our employees has been reduced.” Wang Jianlong, the specialist of Jilin Power Co., Ltd.'s Science and Technology Information Department, said that, more importantly, let our cable temperature detection achieve a “third change”. In the future, grid operation will make users feel more at ease.