Application of Operation Temperature Detection Technique for On-line Power Cable Lines

TLDR: In this paper, the authors proposed a temperature detection technique of distribution optic fiber applied to power cable line on-line based on optic frequency domain reflection (OFDR) theory and TCP/IP communication criterion.

Abstract: The loading current quantity and overload ability of power cable line is able to be adjusted accurately if the temperature of cable conductor was detected in real time. Specially, the bottleneck effect of loading current quantity of long power cable line may be formed because the partial over-hot spot caused by the differences of soil thermal resistance, heating resources and laying conditions, etc. along this cable line. On the other hand, partial defect in dielectric of cable accessories and breakdown foreboding as well as fire accidents are relation with the temperature of power cable to a certain extent. Therefore, it is a basic method to ascertain the bottleneck location, dielectric operating state and calculating the loading current quantity in real time by continuously detecting operation temperature of power cable line on-line. But it is well known that conductor temperature of power cable being detected is more difficult than detection of outer sheath temperature . That is, it is very easy to realize outer sheath temperature detection on-line with the help of distribution optic fiber or thermoelectric couple. According to detecting results of outer sheath temperature of power cable in real time, the temperature of power cable conductor may be calculated by mathematic principles, i.e. Node Voltage Method at the same time. In this paper, we prefer to choose distribution optic fiber for temperature detection on-line due to its reliability, accuracy and temperature detected continuously in real time. The temperature detection technique of distribution optic fiber applied to power cable line on-line based on optic frequency domain reflection (OFDR) theory and TCP/IP communication criterion were researched in this paper. Comparing with optic time domain reflection (OTDF), OFDR solves many problems such as prolonging the life of laser generator and optic switch, decreasing the power of laser generator, and increasing space distinguish ratio as well as data network transmission and background processing easily, etc. The research results proved that the temperature detection technique based on OFDR may meet the requirements of outer sheath temperature detection of power cable line rated voltage from 110kV up to 500kV in real time on-line and its temperature detection accuracy and space distinguish ratio are 1.5 °C and ±1.0 m.