| With the increasing demand for electricity on the islands and offshore platforms in China,the three-core optical fiber composite submarine cable with the function of transmission and communication has been widely used.For the three-core optical fiber composite submarine cable is expensive and the laying environment is complex,the physical electrical test not only takes a lot of manpower and material resources,but also is difficult to get the data of the inner structure of the cable.To ensure the normal operation of the three-core optical fiber composite submarine cable and obtain the electric thermal characteristics of the submarine cable,it is necessary to simulate the electrical fault of the three-core submarine cable by finite element method.A simulation study on electrical faults is carried out on the basis of the three-core optical fiber composite submarine cable of an online monitoring project of the submarine cable of a power company.Firstly,the paper introduces the causes and classification of submarine cable electrical faults,gives the basic idea,characteristics and solving steps of finite element analysis,and clarifies the basic finite element theory of thermoelectric coupling analysis of submarine cables.Secondly,combining the structure of the three-core submarine cable and the finite element analysis characteristic,this paper establishes a three-core submarine cable finite element model under the premise of guaranteeing the calculation precision,and verifies the correctness of the built model by the steady state analysis.Based on the above research,a transient simulation analysis of the cycle load and overload operation of the three-core submarine cable land section and the submarine section model is carried out to obtain the periodic variation of the temperature of the copper conductor and the fiber unit of the three-core submarine cable according to the current load,and the emergency time of the three-core submarine cable under different overload operation conditions.Finally,according to the need of online fault monitoring of submarine optical fiber sensor,the three-core cable single-phase grounding fault is simulated by finite element method.In this paper,a single-phase grounding short-circuit fault model of three-core submarine cable is established to obtain the distribution of current vector and the temperature change of submarine cable core during fault occurrence,analyzing the temperature of the optical unit before and after the fault and obtain a graph of the temperature of the optical unit of the optical cable at different times with the space and time and also the influence of different breakdown resistance on the temperature of optical unit is analyzed,which provide a theoretical basis for on-line monitoring of submarine cable electrical faults using distributed optical fiber sensing technology.Research on the electrical fault of three-core optical fiber composite submarine cable provides a new economic and reliable way for data acquisition in the occurrence of electrical fault of submarine cable and a theoretical basis for the online fault monitoring of the three-core submarine cable,which can provide theoretical reference for the normal operation of the submarine cable in the engineering. |
