Overheating faults caused by abnormal temperature rise of high-voltage switching equipment or insulating materials mostly occur at large-current connection parts (such as switch contacts, copper busbar connection points, high-voltage cable terminals and other special parts). Therefore, real-time monitoring and control of the temperature rise of large-current overheating parts in high-voltage switching equipment becomes very necessary. Real-time monitoring of the temperature rise of these abnormal parts through the online monitoring system can not only improve the automation level of high-voltage switching equipment detection and control, but also provide detailed and effective data for dynamic maintenance of switchgear. In actual projects, it has been found that upgrading the online status detection technology of high-voltage switching equipment can reduce the average annual equipment maintenance cost of the power supply system by 25%-45%, and the system diagnosis can identify possible problem points of the switch equipment, reducing power-off maintenance time by more than 60%, greatly improving the safety and reliability of switchgear power distribution.
Compared with infrared temperature measurement systems, the switchgear temperature measurement system avoids direct contact with large-current temperature measurement points and is a non-contact temperature measurement method. However, this method can only measure the temperature rise of the electrical equipment surface and cannot directly measure the inside of the high-voltage switchgear, and is easily affected by the working temperature and electromagnetic induction around the electrical equipment. Since the infrared sensor installation part must keep a certain distance from the measurement target, and the whole temperature measurement process must be manually operated, it is not conducive to the requirements of online monitoring of high-voltage switch temperature rise.
The fiber optic sensor uses light instead of electricity as the main signal medium, and the optical cable replaces the traditional cable transmission line as the main medium of sensitive information. The switchgear distributed fiber optic temperature measurement system based on optical cable temperature sensors is a distributed online temperature rise monitoring system for high-voltage switchgear: taking n 110KV switchgears distributed in different positions of the power plant as monitoring targets, the temperature-sensing optical cable collects in real time the points prone to abnormal temperature rise in the enclosed high-voltage switchgear (here, the switchgear isolation switch contacts, busbar lap joints and 110KV high-voltage cable terminals are selected). In order to reflect the comprehensive temperature rise condition of each phase inside the high-voltage switch, the system sets corresponding temperature monitoring points on the three phases in the switchgear. Since the distributed fiber optic temperature measurement system has the characteristics of full-scale space temperature measurement, there is no need to set special monitoring points in the switchgear — just laying the fiber effectively along the switchgear arrangement can meet the temperature measurement requirements of the system.
