Electromagnetic Test System Design For Power Transmission Line Based On STM32F407

Nowadays the construction of high-voltage power grid is highly developed, but the techniques for inspecting the defects in transmission line are still lacking. Therefore in this paper we develop a new electromagnetic nondestructive testing method for detecting damages in transmission line. This method combines eddy current testing technique and magnetic flux leakage technique, and it gives full play to the advantages of the two technologies. It can not only detect broken strands and cracks in aluminum wires and steel core, but also position the steel cores in steel hydraulic tube of butt joint. This new method has the advantages such as simple equipment, intuitive testing result and easiness to realize automation. In this thesis, a detection system with ARM controller has been designed based on this method, which is used to conduct laboratory demonstration experiments.On the basis of the above ideas, this paper focuses on the design and implementation of the proposed non-destructive testing system. Firstly, the overall system solution is put forward for the special structure of the transmission line. The eddy current testing device is designed by using DDS IC and orthogonal lock-in amplifier. The magnetic flux leakage testing device is designed by adopting radial excitation and differential measurement techniques. USB interface technology is used to realize the data communication between upper and lower computers. Secondly, the designs of hardware circuitry and software program which is needed to achieve the above solutions are introduced. This part of works include the related peripheral interface circuits of STM32F407 microcontroller, the excitation signal module using DDS chip AD9954, lock-in amplifier circuit with AD630, the microcontroller program written in C and application programs of PC written in Lab VIEW. Finally, we introduce debugging and integrated methods of this system, and show the detection process according to the user-interface. The test results show that this detecting system is stable and has reached design requirement, and it can effectively obtain the damage signal in transmission line.