| Power cables are important equipment for urban power grids and bear the heavy responsibility of power transmission.Cross-linked polyethylene(XLPE)cables have been widely used in power systems in recent years due to their oil-free,small bending radius,and easy maintenance.In order to ensure the normal operation of XLPE insulated cables,it is necessary to perform condition monitoring and fault prediction on them.XLPE insulated cables are divided into land cables and submarine cables.This paper uses ANSYS finite element analysis method to simulate and analyze the electric and thermal characteristics of the two cables under different laying methods and laying environments,and provides a theoretical basis for cable condition monitoring.Based on the electrothermal finite element theory,this paper simplified the cable model according to the thermodynamic characteristics of each layer of the cable,and used the finite element analysis software ANSYS to establish finite element model s for land cable serpentine laying,bending laying and pipe laying.The ampacity of the free section of the cable and the influence of different laying methods on the temperature distribution of the cable insulation under cyclic loading are obtained.The effects of different material fixtures on the current carrying capacity of the cable and the effect of different clamping distances of the same fixture on the temperature distribution of the cable were investigated.The thermal time constants of the cables under different material fixtures were compared.The relationship between the fixture distance and the conductor temperature was obtained through data processing.According to the working conditions and status of the submarine cable in actual operation,corresponding finite element models were established,and the steady-state and transient electrothermal characteristics of the landing cable and the underwater cable are analyzed.According to the creep,anchoring and other problems that the submarine cable may encounter,an insulation electric field model is established,and the temperature distribution cloud diagram of the cable insulation layer and the temperature time-varying curve of the cable layer under cyclic load are obtained.Using the least square method,the function relationship of the insulation electric fi eld strength and the creep rate,compression rate were obtained.The functions of the insulation electric field strength and creep rate,and the insulation electric field and compressibility were respectively fitted by the least square method.According to the research results of this article,the real-time temperature and insulation electric field strength of the cable can be monitored using distributed optical fiber sensing technology to obtain the actual operating status of the cable,providing theoretical basis and data reference for the operation and maintenance of XLPE insulated cables. |
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