Study On Passive Fiber Optic DC Current Sensor

HVDC has more advantages than HVAC, so it has become the focus of the development. DC current sensor is the key of HVDC, so the high performance is demanded. With the increasing of voltage network level and the expansion of power system capacity, the traditional transformer shows more and more shortcomings. It can not meet the development demand of automation and digitization, so it is the inevitable trend that the new DC current transformer replaces the traditional one. Active optical current transformer is a new type of current transformer, and its technology is relatively mature, so the feasibility of the program is larger. However, the sensing head must use the electronic or optical components. Therefore, in high voltage side, there will be the isolation problems, and it is difficult to supply the electric power.Based on the above, this paper presents a new design of the DC current sensor-the DC current sensor based on optical fiber thermometry. It is a new project based on the thin film sensing technology. It combines the thin film sensing technology and the temperature measurement technology. It can avoid providing power supply in high voltage side. The new project does not need electronic components, so solve the long-term problems in high voltage side. Optical fiber temperature measurement technology is already mature, and the thin film sensing technology has the advantage of small type and low cost, and it has become a research hotspot in recent years, so the project has the technical advantage.This paper proposes two new designs for the thin film resistor that is the main part of the system. The mathematical model of the thin film resistor is established and the parameter is designed by ANSYS. Achieve the final technical specifications and solve the problems of slow dynamic response speed and low temperature rise. Propose the design that can verify the reasonableness of the experiment. Set up the test circuit and debug it. The experimental data is processed by MATLAB using the integral area ratio method. Verify the theoretical correctness of the design from the experiment. Finally, debug the whole system. The experimental results verify the validity of the theoretical analysis.