The Design Of Vacuum Degree On-line Detection Systerm Base On DSP

Along with the switch un-oilble was promoted in power grid, the vacuum switch have been widely used in electric power grid, and it appeared more and more important in term of ensuring power grid security. Vacuum arcing chamber is the core of the vacuum switch components, and its internal vacuum degree is closely related to the dielectric strength and structure performance about vacuum switch. There are two major detection methods of vacuum degree at present, off-line and on-line methods. In comparison with on-line detection, the off-line detection method is relatively mature and it has higher sensitivity. And there have been mature off-line detection products put on the market. The on-line detection method is still stay in the laboratory research stage by its lower sensitivity. As the power system demanded safely factor more and more high, the off-line detection already can’t satisfy the need of people to monitor the switchgear to estimate its reliability. So realize the vacuum degree on-line monitoring and improving the detection’s sensitivity becomes increasingly urgent and important.Firstly, the paper has carried on the simple introduction about vacuum switch and compared several major on-line detection methods at home and aboard. And then, the paper analyzed the advantages and disadvantages of the theory of various detection methods. On this basis, this paper emphatically introduced the theory of shielding potential method, and analyzed the feasibility of this method. A new on-line detection system has been proposed relied on the theory of shield potential. The detection target of this system is the variation of shielding electric field. The detection system obtained the changing information of vacuum degree within VCB by utilizing rotary electric field probe to detect the change of direct potential. The system adopted DSP technology to design data acquisition and digital filter so that reduced the peripheral circuit to improve system stability. The sensitivity of detection device has been improved through modifying the front-end signal collection circuit and handling digital filter processing. Using MATLAB-DSP integrated development environment makes the designed system more convenient and flexible and shortens the development cycle. Using Lab VIEW, a graphical programming language, designed the operation interface and the communication program between DSP and PC. The processed data by DSP transmitted to the PC through serial port, thus realized the detection of vacuum degree.