| The abnormal temperature during the operation of the power cable is a precursor to the cable failure.Due to the special environment of the high-voltage cable used in the underground coal mine,it is very difficult to realize real-time online monitoring of the temperature of the cable during operation.At present,fiber-optic composite cable technology has been used in many fields.In this paper,the mining fiber-optic composite high-voltage cable is taken as the research object,and the temperature field of the mine fiber-optic composite cable is systematically studied by simulation.The distributed optical fiber temperature measurement technology is applied to the theoretical reference of mine cable condition monitoring.Firstly,the optical fiber temperature measurement technology based on Rayleigh scattering,Raman scattering and Brillouin scattering is elaborated in detail,and three methods are compared and analyzed.The results show that the distributed optical fiber temperature measurement technology based on Raman scattering is superior to the other two technologies in engineering realizability.In addition,the hardware composition and technical specifications of Raman scattering temperature measurement system and the principle of optical time domain reflection technology for temperature location are studied.The temperature demodulation method of Raman scattering is analyzed in detail.The results show that the two-way demodulation method has more advantages in stability.Secondly,the laying scheme of optical fibers in mine optical fiber composite high voltage cable is designed.The temperature measuring optical fibers are placed between the inner sheath of the cable and the metal shielding layer.This laying method can not only make the optical fibers more accurately sense the temperature change of the cable core,but also reduce the influence of material thermal expansion on the loss of optical fibers.The steady-state equivalent thermal circuit model of mine cable is deeply studied,and the losses of conductor,insulating cover and metal shield are quantitatively analyzed.The influence of temperature rise caused by dielectric loss increase on cable temperature field is analyzed by means of thermal circuit model and loss calculation formula.Thirdly,the Electromagnetic-Thermal coupling simulation of the composite high-voltage cables with optical fibers for mining is carried out by using the multi-physical field coupling simulation software.The simulation results of temperature field show that the temperature field of the cables is little affected by the addition of temperature measuring optical fibers.By changing the current carrying capacity and the ambient temperature to analyze the variation of the cable temperature field,the temperature measurement fiber temperature and copper core conductor temperature data are obtained,and the data is fitted.The empirical relationship between temperature measurement fiber temperature,copper core conductor temperature and ambient temperature was obtained and verified.Finally,the multi-physics simulation software is used to build the temperature field model of the mining cable under abnormal working conditions;the temperature field of the mining cable is simulated during the whole aging,and the variation of the cable temperature field is analyzed by setting different aging coefficients;In this paper,the influence of partial discharge fault on cable temperature field is analyzed in detail.From the level of partial discharge energy loss,the bubble thermal field in cable insulation is simulated.The simulation results show that the cable temperature rise and the distribution of local temperature field will be significantly affected when the partial discharge is serious.This paper studies the distribution of temperature field and the variation trend of cable temperature when one cable overloads,two cables overloads and three cables overload when laying multiple cables on the same cable frame in underground roadway.It provides a reference basis for the practical application of underground cable installation and laying and optical fiber temperature measurement technology in mine cables. |
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