Research Of Current Sensing Technology Based On Optical Fiber Thermometry

With the rapid development of electric power industry in recent years, and thegrowing demands of power resources in economic constructions and daily lives of people,the technology of high voltage DC transmission (HVDC), with its huge ascendancy inlong-distance&high-capacity transmission and power grid interconnection, etc, hasbecame a new trend in development of transmission technology. To implement DCtransmission, good quality of DC current transformer is the basic condition. At present,there are mainly two categories of sensing technology widely used in the DC transmissionsystem: electromagnetic and optical technologies. The electromagnetic transformer, withthe inherent defects such as magnetic saturation, great bulk, secondary overvoltage andelectromagnetic interference, has no longer met the requirements of the large-capacity DCtransmission system. While the DC current transformer based on optical technology has agood application prospect, there are many problems in technical implementation about it.On basis of he thin film sensing technology, the project of current sensing technologybased on optical fiber thermometry is proposed in this paper. Using passive sensingtechnology, this system solved the problem about power supply on high voltage side inoptical sensor. And it has low cost, good insulation, strong anti-jamming ability etc.At the beginning of this paper, the principles are expounded about the three maincomponents of the system. And the thin film resistor is thermally simulated and analyzedwith the purpose of determining its design parameters. And then, the preliminaryexperiment on low-voltage side measurement display system is done by using laboratoryDC current source instead of shunt and heavy current source in order to further perfect thesystem. After that, the suitable shunt and heavy current source are chosen to make up theentire system. In the last part of this paper, the relationship between the current and thetime constant of fluorescent lifetime is calibrated, the heavy current can be Real-TimeDetected and displayed.