220kV高压单芯电力电缆金属护套环流分析

Analysis of Circulating Current in Sheaths of 220 kV XLPE Single-core Cables

根据单芯XLPE电力电缆金属护套环流计算模型,编写C++程序,计算了交叉互联单元内三段电缆布置方式和段长不一致时的金属护套环流,并将计算结果与现场测试结果进行比较分析。根据计算和现场测试结果,一个交叉互联单元内三段电缆的段长和布置方式不一致对金属护套环流有影响,当电缆采用直角三角形和水平布置方式时影响尤为严重。为减小金属护套环流,高压单芯电缆应尽可能采用正三角形布置方式且保证三段电缆布置方式一致,段长尽量相等。

By using the calculation model of circulating current in the sheaths of single-core XLPE cables, a C＋＋ program is coded, and the circulating current in a grounding unit, in which sheaths of cables are connected via cross-bonding, is calculated for three-cable connection with different arrangements and lengths. And the calculated results are compared with the data measured in site. According to the calculated results and measured data, different cable arrangement and length of the three-cable connection lead to different circulating current in the sheaths of single-core XLPE cables. To reduce the circulating current in the sheaths, the connected three cables in a grounding unit should take equilateral triangle arrangement with same cable length.