Research On Non-contact Temperature Monitoring System Of Catenary Line Clamps

Catenary line is an important component of electrified railway, which is related to the security and reliability of railway transportation. Catenary line works in bad environment with large load current, which leads to the traffic interruptions and phenomenon of frequent burning happened to electrical cable clamps and switch gears. Therefore, it is necessary to measure the clamp temperature and summary the data for overall monitoring in real time. This paper designed a non-contact on-line measurement system for catenary line.Firstly, the paper conducted a large number of literature research and compared the characteristics and application scopes of infrared temperature measurement methods. The paper also introduced infrared detectors and the principle of thermopile detectors. Aiming at the anti-interference and high precision design requirements, the system is constituted by differential zero position structure.The controller output PWM wave and make differential with measured signals through two-stage RC filter in closed loop feedback.This structure devoted differential output to zero through adjusting the duty cycle of PWM by fuzzy PID. Due to the high requirement of real-time performance of the system, FPGA was adopted in charge of PWM closed loop adjustment meanwhile DSP was responsible for data processing. In this mode, the system played an advantageous role not only in stabilization and reliability of FPGA, but also showed its feature of computing processing ability and simple programming of DSP.Secondly, based on the basic theory of fuzzy control, the paper discussed the basic structure of controller and the course of its design. A fuzzy PID controller was designed and applied to the simulation model of closed-loop feedback part in the system by MATLAB. The simulation proved the fuzzy controller in excellent performance compared with traditional PID.Thirdly, the paper described the hardware design and software programming of the system. In hardware part, differential zero position structure circuit, A/Dconversion circuit, Zig Bee communication circuit and power supply circuit were designed and achieved. The software mainly included the programming of fuzzy PID controller and IIR digital filter in FPGA, serial communication and data processing in DSP, software development by Lab VIEW.Finally, a non-contact on-line measurement system was set up and performance tests for the whole system was finished. The paper also made a summary and analysis of the experiment which proved the performance of the system good. The paper put forward some suggestions for system improvement and made another simple discussion about error processing.