Design And Implementation Of On-line Monitoring Terminal Of High Voltage Transmission Line Based On LoRa Wireless Technology And MQTT Communication Protocol

Transmission line as an important part of the smart grid,its operating status is related to the safety and stability of the entire grid.So,it is of great significance to realize on-line monitoring of high-voltage transmission lines.With the development of smart grid and dynamic capacity expansion technologies,the large-scale application of on-line monitoring for transmission lines has to be in conformity with the goal of smart grids for information,automation,and interactive construction.At present,on-line monitoring products for transmission lines are mainly limited by the technology and cost constraints.It only achieved single-point monitoring in disaster-prone areas and was unable to form a network monitoring system.Actually,existing products have exposed high failure rates,difficult to maintain and high communication costs.Based on the study of the above issues,this paper designs a set of monitoring terminals for transmission line on-line monitoring systems.The terminal adopts the inductive power-picking technology,which holds the characteristics of simple maintenance,high stability and low cost.The terminal deploys the LoRa wireless technology to form the local area network.The local area network converges the data and then uploads the data through the GPRS network.This effectively reduces the network communication cost.In terms of data transmission,the interaction between the terminal and the server adopts the MQTT protocol and provides the high-performance MQTT service by a third-party software,which effectively improves the data concurrency of the monitoring system.The stable operation of the test network shows that this solution is efficient in large-scale monitoring applications of transmission lines.The work of this article is as follows:1.According to the application requirements,the characteristics of the LoRa wireless technology and the MQTT protocol are investigated in detail,the feasibility of the application is discussed,and the overall design of the terminal is constructed.2.In terms of hardware design,based on the design scheme of terminal-inductive power-taking,the design and implementation of the induction power-accepting circuit and the voltage-conditioning circuit were completed.Then,aiming at the measurement of temperature and sag,the development of hardware circuits,such as infrared temperature module,tilt sensor module and processor module,was accomplished.Then,corresponding to the scheme of system communication framework,the LoRa wireless module and GPRS communication module are also designed and completed.3.In terms of software design,the order of development is underlying driver,middle tier service,and the upper application,following the top-down modular design philosophy.According to the terminal LAN,based on the protocol IEEE802.15.4,LoRa wireless star-networking was built.In the area of wide area network communication,the migration of MQTT client protocol,which is based on Eclipse Paho was performed.Then,the software maintenance of device was designed and implemented,which is also based on MQTT and includes upgrade and rollback functions.4.In order to validate the developed terminals,this article describes the experiment results about the equipment running in the transmission line of Zhengzhou Power Grid.In nearly one year of trial operation,the related terminal LAN equipment in field is stable and provides continuously status data of line-related parameters to the server,indicating that the designed monitoring network meets the requirements of associated application in smart grid.