Research And Development Of Intelligent Direct Reading Equipment For SF₆ Meters In Substations

Sulfur hexafluoride（SF₆）is widely used as insulation gas for high-voltage equipment in substations.Its operating pressure,temperature,and density are related to the normal operation of substations and the safety of personnel and equipment.The state stipulates that SF₆ circuit breakers must be equipped with SF₆ gas.Density table.With the gradual promotion of smart grid construction in recent years,remote monitoring of various meters has become an indispensable part of smart substations.At present,most of the traditional mechanical SF₆ density meters used in substations cannot remotely monitor the measured gas pressure data,which can no longer meet the needs of substation automation management.To solve the problem that traditional mechanical SF₆ density meters are difficult to apply in smart substations,this paper proposes a machine vision-based direct reading device for SF₆density meters in substations,which can automatically read SF₆ density indications without any participation.Upload.This paper conducts research and elaboration from five aspects of the subject’s technical background,hardware design,algorithm design,software design,and functional testing.The main contents of this paper are as follows:（1）Based on the research on the direct reading equipment of SF₆ density meter in power station,this paper designs a set of a remote acquisition system for substation SF₆ density meter readings based on this equipment as the core,combined with LoRa wireless communication technology.（2）The hardware of this system is mainly divided into two parts:direct reading terminal and concentrator.The direct-reading terminal is the SF₆ density meter direct-reading device proposed in this article.The hardware circuit is based on the MCU,and the peripheral expansion of the image acquisition circuit,LoRa wireless communication circuit and RTC timing circuit,and other functional modules;while using lithium batteries for power supply,the circuit Low-power processing is done to achieve a standby time of more than one year;besides,solar energy is used to manage power to further improve the endurance.The concentrator is the transfer station of the entire system data.In addition to the MCU control unit,the LoRa circuit is also designed to interact with the direct reading terminal;the communication with the host computer is carried out through the Ethernet PHY circuit;besides,the power failure detection circuit is also designed,To detect its power supply status and timely feedback to improve the stability of its work.（3）The direct reading equipment of the SF₆ density meter in this paper adopts machine vision technology to realize the reading of SF₆ density indication.First,combined with traditional image algorithms such as template matching,using the characteristics of the spatial distribution of pixels,the virtual pointer method is used to determine the angle of the pointer;then according to the law of the gradient of the pixel point,the angle of the starting tick mark is found,and finally,Then calculate the reading of the SF₆ density meter.The reading algorithm of the SF₆ density meter designed in this paper can automatically determine the position of the starting scale,which solves the problem that most of the current SF₆ density meter readings require manual calibration of the starting scale,and also solves the problem that the traditional mechanical SF₆ density meter data cannot be read.Transmission problem.（4）The direct-reading terminal of this system and the concentrator adopt LoRa wireless spread spectrum communication technology for data interaction,which solves the hidden safety hazards caused by the difficulty of wired transmission and wiring,and the data security problems caused by NB-Io T data through the operator.The system software uses the function as the framework,designing the communication logic of LoRa and the communication protocol frame of the data link layer.Besides,the interactive interface of the upper computer is designed to remotely monitor the gas density of SF₆ and the status information of each device.（5）After completing all the software and hardware design of the direct reading device and the concentrator,the power performance of the direct reading terminal,the power consumption of the device,the communication quality of LoRa,the feasibility of the power failure detection circuit of the concentrator,and the display of the host computer interface The effect was tested,and each part was evaluated based on the test results.The test results show that the functions and performance of each part have reached the expected requirements,so the system can be applied to the remote monitoring of SF₆ density meters in substations,which has an important reference value for the application of substation automation management.