基于EMTP的三芯海底电缆线路序参数的计算与分析

Calculation and Analysis on Sequence Parameters of Three-core Submarine Cable Lines Based on EMTP

三芯海底电缆线路常用于海上风电的送出。在相关的规划设计和仿真分析中,三芯海底电缆线路的序参数是基础之一。基于电磁暂态仿真程序EMTP,以1条截面为3×500 mm^(2)的220 kV海底电缆线路为例,对三芯海底电缆线路的序参数进行了计算与分析。文章计算了半导电聚乙烯护套的径向电阻,讨论了金属护套的处理方式。推导了三芯海底电缆线路单位长度的正序和零序阻抗、金属护套和铠装电流的计算式。研究了钢丝铠装的磁导率对三芯海底电缆线路电流分布及序参数的影响。此外,还分析了不同接地情况下光纤单元的铠装对三芯海底电缆线路序参数的影响。研究表明,三芯海底电缆线路的零序电阻远大于正序电阻,甚至可能大于零序电抗;当等值的相对磁导率μr在一定的范围内,可能出现零序电抗小于正序电抗的情况。文章将仿真与实测结果进行了对比。结果表明:选择适当的钢丝铠装磁导率,可以得到合理的计算结果。

Three-core submarine cable lines are commonly used for offshore wind power transmission.In the relevant planning design and simulation analysis,the design of sequence parameters of three-core submarine cable lines is one of the foundations.Based on electromagnetic transients program(EMTP),a 220 kV submarine cable line with a section of 3×500 mm^(2) are taken as an example,the sequence parameters of three-core submarine cable lines are calculated and analyzed.The radial resistance of semi-conductive polyethylene sheath is calculated,and the treatment method of metal sheath is discussed.The formulas for calculating the positive and zero sequence impedances per unit length,metal sheath and armor currents of three-core submarine cable lines are derived.The influences of magnetic permeability of steel wire armor on the current distribution and sequence parameters of three-core submarine cable lines are studied.In addition,the influences of optical fiber unit armor on sequence parameters of three-core submarine cable lines under different grounding conditions are also analyzed.The research shows that zero sequence resistance of three-core submarine cable lines is much greater than positive sequence resistance,and may even be greater than zero sequence reactance;when the equivalent relative magnetic permeabilityμr is within a certain range,the zero sequence reactance may be less than the positive sequence reactance.The simulation results are compared with measured results.The results show that reasonable calculation results can be obtained by selecting appropriate magnetic permeability of steel wire armor.