Design of an Online Monitoring System for Urban Power Optical Cables Based on Distributed Fiber Optic Sensing

In recent years, the occurrence of fiber optic cable damage due to external breakage and other factors has become increasingly common. However, traditional fiber optic line monitoring equipment often utilizes a monitoring mode that only monitors backup fiber optic lines. This mode fails to meet the online detection requirements of fiber optic cables when backup lines are switched to working lines. This article presents the design of an online monitoring system for urban power fiber optic transmission lines, utilizing distributed fiber optic sensing technology. The system is divided into four main components: a power supply unit, an optical monitoring unit, an embedded control unit, and a data transmission unit. The monitoring equipment is controlled remotely by the main computer. It has the capability to monitor four power optical fibers simultaneously and offers two monitoring modes that can be easily switched for each monitoring line. The online monitoring system has been applied to a 2563-kilometer 10kV optical cable power communication line of a certain company in the State Grid. The system has chosen to conduct online monitoring of 2563 kilometers of power communication optical cables and 10kV optical cables operated and maintained by a specific company in the State Grid. This monitoring system achieves mode switching of power optical fiber lines and monitoring line switching. The mechanical optical switch has a switching capacity of over 3 × 107 times and an insertion loss of less than 0.8dB. This enables quick fault detection and improves the timeliness of fault monitoring.