The Design Of Distributed Optical Fiber Temperature Measurement System For Power Cables And Analysis Of Current Carrying Capacity

With the rapid development of the power grid,power cables have been widely used due to their unique advantages.Cable temperature is an important parameter of power cables.It not only reflects the operating conditions of the cable,but also determines the transmission capacity of the cable current.Therefore,it is very important to monitor the temperature of power cables.Distributed optical fiber temperature measurement technology has strong anti-electromagnetic interference ability,good performance in dangerous high-power electromagnetic environment,and is not afraid of acid and alkali corrosion.It is very suitable for power cable temperature monitoring system.Using optical fiber to monitor cable temperature has become a research hotspot.Therefore,this paper designs a distributed optical fiber temperature measurement system for power cables.Based on the sensing characteristics of distributed optical fiber temperature measurement,the principle of optical fiber Raman scattering temperature measurement and the principle of optical time domain reflection are analyzed and introduced,and the traditional temperature demodulation method of distributed optical fiber temperature measurement is described in detail.According to the cable sheath temperature measured by distributed optical fiber temperature measurement,using the characteristics of the temperature field of the power cable and the thermal path model of the cable,a cable conductor temperature calculation model is established to realize the calculation of the cable conductor temperature and current carrying capacity.Combining the characteristics of optical fiber temperature measurement and sensing and the established cable conductor temperature calculation model,a distributed optical fiber temperature measurement system for power cable is designed,and the selection of main components and key performance indicators are analyzed and explained.In order to obtain more accurate temperature measurement results and make up for the shortcomings of the traditional temperature demodulation method,such as large measurement error and low temperature measurement accuracy,the Monte-Carlo method is used to establish the DTS sensing model,and the adaptive inertia weight PSO algorithmis used to establish The DTS sensor model performs parameter identification.The corresponding distributed optical fiber temperature measurement system experimental platform is built,and the established DTS sensing model is simulated and predicted and verified by experiments.The experimental and simulation results show that the model has good predictability.In order to verify the reliability of the established cable conductor temperature calculation model,taking three single-core cables as the research object,a finite element model of the power cable temperature field is established,and simulation analysis is performed using ANSYS finite element software.The simulation results show that the calculation model has reached the expected goal.The effects of soil temperature,soil thermal resistance coefficient,air temperature,cable laying depth and cable laying distance on current carrying capacity are analyzed through simulation,and several suggestions for increasing the current carrying capacity of underground directly buried cables are proposed.