Development Of Online Monitoring System Of Power Cable Based On DTS

The power cable applies in the power system is getting more and more widespread. It's very significant to realize safe, reliable and economical operation of power cable to ensure the security and economy of power system. In actual power cable operation, it will be able to cause the local temperature of cable or cable accessories to rise before the cable has electrical failure, resulting in further damage until insulation breakdown. Based on distributed temperature sensing, the temperature of cable's surface can be measured. Then the potential safety risks can be discovered early through power cable temperature field analysis and dynamic current carrying capacity calculation. And it plays the role which prevents accidents before they occur.The whole frame structure of system is analyzed and designed in this paper by field works. The operating current of cable is required when analyzing the power cable thermal field and calculating the dynamic current-carrying capacity. When the system is applied in traditional transformer substation or power plant, it is difficult to obtain the cable electric current through corresponding with other detecting and controlling equipment in power system. Considering, the adaptability, scalability, independence and communication protocol influence of the system, an AC electricity conversion module is configured for the system. And the system can acquire the operating voltage and current of cable by high speed, multi-channel data acquisition card based on PCI bus.The main methods of power cable temperature field calculation are summarized in this paper. And the thermal circuit method and numerical heat transfer method are analyzed mainly. Because the thermal circuit's result is less conservative, and the numerical heat transfer method's computational speed is slow, field-circuit method based on temperature of cable surface is presented in this paper. According to the characteristics of single-core and three-core cable structure, One-Dimensional Thermal Model can be established for single-core cable temperature field, and two-Dimensional Thermal Model can be established for three-core cable temperature field. In the numerical solution procedure of three-core cable temperature field, the thermal circuit method's result can be applied as the initial value of iterative finite-difference method, effectively improving the convergence rate, saving the computing time.The system software has been designed according to demand analysis, software structure and software function in this paper. And the key technologies of software development have been analyzed. A dynamic link library which is used to calculate the single-core or three-core temperature field and dynamic current carrying capacity has been programmed separately in VC++ development environment. Further, the online monitoring software of power cable has been developed.