Research on the substation Environmental Monitoring System based on LoRa

 The modern society is inseparable from the power grid. With the rise of the Internet of Things technology, sensors, communication, computer and automation technologies are widely used in the power grid. These technologies are combined with the traditional power grid theory and technology, which promote the overall intelligent progress of the power grid to a greater extent. More and more new technologies are applied to the power grid and the good integration of the traditional power grid, promoting the development of smart grid, so the development of smart grid is the inevitable result of the development of power grid technology.

 Substation is an extremely important part of the smart grid, its safe operation will directly affect the stability of the reliability of the power grid, so intelligent substation upgrade is very necessary, and now the domestic substation intelligent level is not high enough, the problems are more, such as substation environmental monitoring system is not perfect or even missing, the data transmission mode leads to limited data transmission distance, etc. With the continuous maturity of the Internet of Things technology, many problems in the substation have been solved. The perfect monitoring system can reflect the conditions of important locations and important equipment inside the substation in real time, greatly improving the safety and reliability of the substation. Therefore, in order to ensure the stable power supply to power users in all social industries, the safety and stability of the substation must be maintained.

 In order to ensure the stable operation, in many places people monitoring of substation station mainly depends on manual inspection way, this way is laborious, and feedback is slow, low efficiency, now, some substation has been unattended, to achieve this level, must be the Internet of things technology and traditional power technology, using the Internet of things sensor technology acquisition advantage, LoRa technology data transmission advantage, in view of the existing problems of domestic substation, design with suitable monitoring system, improve the overall level of intelligent substation.

 The current domestic substation monitoring system is still mostly ZigBee communication technology as the main means of transmission, even still on the basis of wired transmission monitoring system, and LoRa technology in data transmission distance is more advantages than ZigBee technology, using ZigBee technology monitoring system because the data transmission distance problem by a lot of restrictions, by contrast, LoRa technology is more suitable for application in the substation monitoring system. Therefore, a set of intelligent monitoring system was designed and developed for the problem of insufficient monitoring level of the existing substation, so as to solve the problems of internal environmental monitoring, data collection and transmission of the substation.

 In the mid-20th century, Westinghouse Electric took the lead in invented and manufacturing an electrical monitoring device that can monitor the condition of the motor during operation and whether the motor has damaged the motor during operation. Subsequently, Japan, Canada and other countries have also started to study the problem of substation monitoring, due to many reasons, data monitoring is difficult, can not be carried out. Therefore, the overall development progress of electrical monitoring equipment is slow.

 In 1975, Japan, Canada and other countries successively developed the gas analysis equipment in substation oil, which promoted the development of monitoring equipment. In the early 1980s, the new concept of daily equipment maintenance of substations was introduced into the condition monitoring and maintenance, and the United States, Japan and other countries also studied and developed the oil-immersed gas monitoring system for transformers. At the beginning of the 21st century, due to the increasing improvement of sensor technology and communication technology, the development of monitoring system gradually showed the trend of information and intelligence.

 In the process of China's power grid construction, a large number of substations appear, which greatly increases the possibility of various accidents within the power system. In order to ensure the normal operation of the power grid, it is necessary to carry out a comprehensive and meticulous maintenance of the electrical equipment in the substation. Domestic research in the field of substation monitoring system compared with foreign late, in the early 1980s, the state grid and other related power departments absorbed the foreign technology, and related research and development of substation monitoring, in 1986, Tianjin university of Long Jiaong developed and made the substation local discharge equipment monitor, further study the local discharge of the substation and the sensitivity of various discharge model. Huang Yizhuang, Huang Shanyi, Liu Jianzheng and others from Tsinghua University have established the monitoring system of the first computer substation in China. The running state of the system is also relatively stable in the operation test.

 For this reason, many well-known universities in China have cooperated with State Grid Corporation and started a large number of research experiments. It has studied the substation computer monitoring system, substation electromagnetic radiation intensity monitoring system, substation insulation monitoring system and the first domestic smart substation monitoring system based on IEC61850 international standard.

 Nowadays, the common substation monitoring system for the definition of monitoring data without strict unified standard, it is difficult to realize more equipment operation status monitoring integration, so it is difficult to meet the basic principles of smart grid standardization, informatization, intelligent, and the existing environmental monitoring system to monitor the data type than the actual demand serious shortage, cannot meet the basic needs of the existing substation monitoring. There are still many problems in the substation monitoring system today. Most of the monitoring systems in the domestic market are in the stage of laboratory tests, and have not reached the state of stable operation, which cannot guarantee the safety in the substation, so it cannot be installed in the substation.

 With the gradual improvement and maturity of the Internet of Things technology, the wireless communication technology with the advantages of wireless transmission, saving space, low cost and strong applicability has gradually replaced the traditional wired communication, and the wireless communication technology continues to develop rapidly. The advantages of wireless communication technology are also reflected in the diversification of wireless access modes, which can make it better adapt to a variety of different application scenarios.

 LoRa wireless communication technology is a very representative technology in low power WAN. Compared with other communication modes, LoRa technology has the advantages of high freedom of setting communication protocol, flexible network mode, free unauthorized frequency band, strong anti-interference, low hardware cost, no base station, and long transmission distance.

 LoRa is developing rapidly in foreign countries, and in China, the development process of LoRa wireless communication technology is also very rapid. Many well-known Internet companies have joined the LoRa Alliance, actively promoting the promotion and development of LoRa network in China.

 Power station is an extremely important part of the whole power grid system, and its stability is an important guarantee for the normal operation of the whole power grid system. Today's power grid system has developed more and more to smart grid. As the main body of smart grid, smart substation will be widely used in the future.Based on the Internet of Things technology, a monitoring system for the internal environment of a substation area is designed, which provides a guarantee for the safety and reliability of the substation operation.

 There are still many problems in the application of Internet of Things technology in substations, such as the accuracy of sensor data collection and the stability of data transmission. Therefore, the design monitoring system takes STM32F103C8T6 SCM as the core, and designs the substation environmental monitoring system based on LoRa.

 First, the monitoring node module is designed. The node module is mainly responsible for monitoring the environmental parameters in the substation area, including the indoor temperature and humidity, the water level of the cable trench and the concentration of sulfur hexafluoride gas. Then the node module packages the collected data and sends it to the terminal module through LoRa communication. The hardware part of the node module includes the main control chip, sensor module and LoRa module. In which the sensor module is composed of temperature and humidity sensor, water level sensor and sulfur hexafluoride sensor. The software design is a program to communicate between the sensor module and LoRa module in C and Python in the Keil 5 and Pycharm software environments.

 Secondly, the hardware and software design of the terminal module is made. The terminal module is mainly responsible for receiving the data transmitted from the node module through LoRa, processing the data and transmitting it to the Ali Cloud platform through 4G communication mode. The hardware part of the terminal module mainly includes the LoRa communication module, the 4G communication module, and the circuit schematic diagram design and the PCB design of some peripheral circuits. After completing the hardware design, the software programmed its LoRa and 4G module through Python language.

 Finally, the substation environment monitoring cloud platform was built, and the basic functions of the cloud platform and human-computer interaction were debugged, and the visual display of the data collected by all monitoring nodes on the computer and mobile APP was completed, and the alarm function was set and tested to realize real-time feedback and early warning.

After testing, the system has the advantages of strong stability, high accuracy, no manual assistance, flexible, simple operation, multi-point monitoring, remote monitoring and other advantages, reasonably applies the Internet of Things technology in the environmental monitoring of the substation, significantly improves the safety and reliability of the substation. 

Article is reprinted in the Internet of Things 123