| Thunder and lightning are one of the main reasons for the damage of electronic equipment.Installing Surge Protection Device(SPD)at the front end of the protection equipment can greatly reduce the instantaneous overvoltage of the protected line in the lightning environment.At present,in many lightning protections projects,SPD is used in a large number and its installation position is complex,which leads to the difficulty of manual detection and maintenance of SPD,low efficiency and long cycle.At the same time,there are also risks of missing detection and false detection,so that people can’t find any abnormal conditions of SPD in time,which is risky.In order to deal with the relevant anomalies in time,it is necessary to grasp the real-time running condition of SPD accurately,timely,stably and comprehensively,and carry out the corresponding repair work.It is disputable that the detection of SPD working condition is of great significance.According to the shortcomings of the current thunder and lightning protection technology,we have designed an SPD real-time monitoring system based on the Internet of Things technology in this article.The self-designed Lo Ra wireless networking technology is used to wirelessly collect the information of SPD monitoring equipment for real-time detection.The device is connected to the Internet,and the SPD working condition information is uploaded to the cloud platform to realize the storage of historical data by the means of the Open Wrt router operating system.At the same time,the cloud platform,background and web client are designed to realize the remote control and management of the system.The information of SPD monitoring equipment is displayed on the front page in real time.When the equipment is abnormal,it will send the alarm automatically.The monitoring system has the characteristics of real-time and memorable.In order to achieve a wider range of SPD equipment monitoring,we propose a design of Lo Ra wireless network based on time slot CSMA / CA algorithm,referring to IEEE802.15.4 protocol and combining the characteristics of Lo Ra wireless sensor in this paper.First of all,the process of back-off algorithm is analyzed and optimized,and then the MAC protocol is designed based on the characteristics of Lo Ra.Finally,the network layer and application layer of wireless network are designed.The test results show that the network communication delay of the design is less than0.2S,the horizontal communication range in the building is 80 meters,the vertical distance is the height of 2-story building,the distance in the open outdoor test is 1300 meters,and the outdoor test distance can reach 250 meters when there are obstacles.When the report period of multi node is 4S,the packet loss rate is less than 0.5%,which meets the requirements of the design indicator.In order to improve the collection efficiency and stability of the system,we have analyzed the data link of the SPD monitoring system by adopting multi-layer cooperation mode.The data acquisition layer uses the characteristics of modbus to improve the query efficiency of the SPD monitoring equipment.The frequency of transmission is reduced by grouping the devices and formulating the corresponding frame format.The Openwrt operating system is adopted in the data transmission layer.When the network condition is unstable,the function of continuous transmission after network interruption is designed.At the same time,timing differential reporting and aggregation reporting are implemented to reduce the cost of redundant data in the communication process.In the data service layer,the mechanism of device replacement and remote update is designed.The test shows that when the SPD data changes,the changed data will be pushed to the WEB client within 2.5s.Compared with the transparent transmission mode,the data flow is saved by 70%.Under the condition of full load,the system can save 10 minutes of offline data.The gateway http is six times more efficient than mqtt and meets the design criteria. |
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