Fiber Grating Temperature Monitoring System Based On ARM

Performance of the power transformer has a direct impact on the safety and stability of power system operation. The winding's temperature which has become an important parameter to monitor healthy risks and fault progression is a decisive factor of the safety, efficient operation and the life of transformer. In order to adjust the transformer's load and to maintain it previously avoiding transformer winding fault due to overheat, we should monitor the transformer winding's temperature and to determine their health status real timely. As a result, it can improve the safety and economy level of the transformer, and give an important guarantee to the safe operation of the power grids.Infrared temperature technology, thermal resistance technology and thermocouple temperature technology are commonly used to detect temperature of power transformer. But infrared temperature measurement technology is non-contact, so it can measure the surface temperature of the transformer only and it may be interfered by the ambient temperature and the surrounding magnetic field. Therefore, it needs manual operation and it can not be measured online. To thermal resistance and thermocouple measurement, the wire will pick up the noises and the eddy current will make the wire heat in the high-frequency alternating field. Thermal conductivity of electric wires can lead to disturbance of the detection, which makes measuring effect was not very satisfactory. Fiber grating sensing technology has so many advantages, such as small in size, electrical insulation, anti-electromagnetic interference, multiplexing, remote transmission, online measurement etc. So that it provides a good mean for power transformer temperature measurement.On the basis of analysis of the FBG sensor and demodulation technique both at home and abroad, hardware and software which fiber Bragg grating sensor demodulation requirements are designed. The main works are shown as follows:In this paper, the basic structure of the fiber, mechanism of Bragg grating and its production methods are described; FBG sensor's basic parameters of the spectral characteristics is analyzed; temperature sensing model of FBG is induced; FBG demodulation technique which is current commonly used is described in detail.Highlight analysis on the hardware design and principles of the monitoring system is given, which mainly consists of micro-controller circuit design, photoelectric conversion circuit, preamp and filter circuit, AD converter circuit, Ethernet communication circuits, liquid crystal display circuit and so on.Based on the hardware platform, the relevant drive of the modules is designed and tested to achieve sending and receiving real-time temperature data. Main achievement includes porting the uC/OS-II in the LPC2148, and realization of Ethernet communications using LwIP.System optical circuit is set up to test the monitoring system, and some useful data has been obtained for the further work.