Design Of Online Temperature Monitoring System For High Voltage Switchgear

With the rapid development of national economy in recent years, there is a increasing higher demand for industrial production and residential electricity consumption. As the important electric equipment in electric power system, the demand of the high voltage switchgear is also increasing. It’s difficult for high voltage switchgear to transfer heat from inside the full metal jacket to the outside environment. There is a situation that the contacts inside the cabinet have excessive temperature rise in some areas of heavy electic load. The excessive temperature rise can directly affect the life-span of equipment and even lead to the fires. So it is necessary to take some measures to monitor the contacts’temperature of the high voltage switchgear.Accoding to the temperature measurement methods and principles, existing measure equipments are most based on infrared temperature sensor or fiber Bragg grating sensor, besides, the hand-held infrared thermometer is used by inspectors on a very few occasions. It is difficult to be extensively used since the price of infrared sensor is high and complicated wires needed for fiber Bragg grating sensor, especially the new generation of high voltage switchgear become smaller and smaller.Based on the study of the temperature measuring methods both home and abroad, a new temperature monitoring system for high voltage switchgear is presented in combination with the current situation of china. Wireless signal transmission is adopted in cabinet and the signal transmission from the live spot to the upper computer is based on CAN bus. Six measuring uints and one coordinator are placed in one high voltage switchgear, which can form a star network topology. The temperature measuring unit with low power consumption can be powered by two higly efficient lithium batteries, it is comprised of TMP102temperature sensor and CC2530SCM. The main function of measuring unit is to achieve data picking and realize signal wireless transmission. The relay-monitoring node consists of CC2530RFchip, main processor STM32F107, CAN transceiver VP230, memory chip, display unit and power unit. The relay-monitoring node is hoped to recive data all times and be powered by continuous uninterrupted source of electricity. There is no direct electrical connection between temperature measuring node and relay-monitoring node, problems such as high-voltage insulation and complex wiring is solved. According to the scheme, the hardware circuit and software programme are completed, and the entire system has been analyzed and tested in this paper.On the hardware side, this paper describes the temperature sensor circuit design; Microcontroller CC2530and STM32F107hardware design and implementation; LCD unit hardware and alarm device circuit design; CAN bus remote communication hardware design. Hardware schematic and PCB are achieved in EDA Altium Designer6.9version development environment.The procedure of single-chip CC2530and STM32F107is programmed with IAR software and the program is written for each function module of the system. The program of the ZigBee ad-hoc network and wireless transmission is based on Z-stack protocol stack. PC monitor software adopts Visual Studio2008development environment, which is designed to realize displaying real-time data, historical curve recording, system alarming and configurating.At last, the whole system is tested. The test contains network testing, accuracy testing and anti-jamming testing. Experiments show that the system works normally and achieved the expected goal.