| In the high-speed development of urban power grids,power cables have been widely used,and the safe operation of powers cable is closely related to social production and life.Therefore,how to ensure the safe operation of powers cable has become the primary concern of the power grid.Cable temperature as an important parameter reflecting the operating state of the cable,real-time monitoring of its temperature has become an effective way to detect the safe operation of the cable.With the continuous development of optical fiber sensing technology,the use of optical fiber to monitor cable temperature online has become a research hotspot.Therefore,this paper has carried out research on power cable distributed optical fiber online temperature measurement system.Based on the sensing characteristics of distributed optical fiber temperature measurement,the principles of fiber Raman scattering and Optical Time Domain Reflection are analyzed.For the distributed optical fiber temperature measurement,only the online monitoring of the cable skin temperature can be realized.By using the characteristics of the cable temperature field and the thermoelectric coupling relationship,a first-order differential mathematical model of the cable conductor temperature is established to calculate the cable conductor temperature.These provide theoretical support for the design of cable distributed optical fiber temperature measurement system.A cable distributed optical fiber temperature measurement system is designed.The parameter structure and selection criteria of each device of the system are introduced,as well as various performance indicators of the system.The corresponding distributed optical fiber temperature measurement system experimental platform is built,and the Distributed Temperature online monitoring function,Cable Conductor steady state and transient Temperature online calculation function,and cable fault online alarm and positioning function are analyzed and verified.In order to improve the temperature measurement accuracy of the cable distributed optical fiber temperature measurement system,the Monte-Carlo method is used to simulate the distributed fiber Raman scattering effect,and the demodulation sensing model of the corresponding cable distributed optical fiber temperature measurement system is established.The nonlinear genetic algorithm performs parameter identification and optimization on the temperature demodulation sensing model.The simulation and experimental verification of the established temperature demodulation model are carried out.The experimental and simulation results show that the model has good predictability.In order to verify the reliability of the established cable conductor temperature model,the YJLW03-64/110KV-1×300mm2 single-core cable is taken as the research object,and the finite element model of the temperature field under the cable load operation is established,and the model is simulated and analyzed by using COMSOL finite element software.The simulation results show that the calculation model has achieved the expected goal. |
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