Research On Operation Monitoring And Management Of Seafloor Junction Box

Seafloor junction box is the node of power conversion and communication and is the center of seafloor observation network. It is very important to monitor and manage seafloor junction box for the long-term reliable and stable operation of seafloor observation network. A operation monitoring and management system applied in seafloor observatory network junction box was designed and implemented in this paper, which involved the function of scene monitoring, network communication and system management. The system is mainly used for power distribution and monitoring of junction box. Voltage and current of each channel, temperature and leakage of control chamber and high voltage power chamber are all monitored, and the exception will be handled in real time. Monitoring data will be uploaded to base-station host computer by ethernet communication, and the system can be remotely controlled and managed by host computer of base-station. The system, which is flexible, reliable and fast response, is an important guarantee for the long term stable operation of seafloor observatory network.In hardware design, the structure of "MCU+CPLD" was used for the main control circuit.C8051F020 was selected as the MCU and EPM570 was selected as the CPLD. Voltage and current transform was implemented by power isolated sensor. The transformed signals were converted to digital data by MAX 1304, which is high speed A/D conversion chip, to improve the rapid response. NTC resistance and DS18B20 were both used for temperature measurement in chambers of seafloor of junction box. Leak sensor cable was used for leakage detection, electromagnetic relay in series with power MOSFET combined the power switch module.PCA9555,remote 16 bit I2C and SMBus I/O expander, was used to design the enable/unenable control circuit of the DC-DC power array. The slave system in seafloor junction box communicate with the host computer by RS232/Ethernet convertor.In software design,the main function in the program of the MCU which was developed by Keil C51 included serial communication with host computer, A/D conversion control of voltage, current, temperature and leakage transformed signals, read/write control to CPLD, I2C bus control and 1-Wire bus control. The control logic of CPLD, developed by Verilog HDL, included the synchronization state machine for the control of A/D conversion of MAX1304,the abnormalities comparison module and the read/write interface with MCU. The host computer program in base station was developed by VC++. CAsyncSocket was used to communicate with the slave system in seafloor junction box and the database server program. Friendly man-machine control interface was designed for remote control and management of seafloor junction box.In the end, the real time of abnormal response was tested. The laboratory and submarine operation experiments both successed.