重覆冰过山段线路耐雷水平计算与防雷措施分析

Calculation of Lightning Withstand Level and Anti-lightning Method Analysis for Transmissions Lines Across Heavily Icing Region

云南电网220kV福贡—兰坪输电线跨越碧罗雪山的线路段受高海拔重覆冰的地理气象条件限制,每年一到覆冰季节,线路不均匀脱冰时经常出现导线对避雷线放电引起跳闸中断供电,致使线路被强迫停运数月。塔顶架设双避雷线的防雷措施对线路的供电可靠性造成了极大的影响,为此根据雷电定位系统的监测该线路过雪山段不处于雷电活动频繁区的情况提出两种线路改造方案:在拆除双避雷线后,架设耦合地线或旁路屏蔽地线,旨在保证线路防雷性能的前提下减小不均匀脱冰带来的影响。构建在不同防雷措施下的本段线路仿真模型并进行雷击电磁暂态仿真计算,比较耐雷水平以验证所提方案的防雷效果。仿真结果表明,线路避雷线拆除后仅架设耦合地线或仅架设旁路屏蔽地线,雷击杆塔时线路耐雷水平都能满足电力行业标准的要求。该线路经防雷改造后已经过一雷电季节和覆冰季节的运行,实际运行结果表明以上防雷措施改造方案能在保证线路防雷性能的前提下有效减少线路的不均匀脱冰跳闸事故。

Due to the heavy ice loading conditions and high altitude geographical environment,discharge between lightning shielding wires and phase conductors frequently happens as a result of uneven ice shedding in part of 220 kV Fugong-Lanping transmission line across Biluo snow-capped mountain in Yunnan province.This condition is often accompanied by tripping accidents.According to the monitoring of lightning location system,this line segment through icing mountain doesn’t belong to frequent lightning activity area.Based on the situation above,two line reconstruction schemes are put forward.One is to install single coupling ground wire after removing lightning shielding wires;the other is to install double side shielding ground wires after removing lightning shielding wires.Simulation models of this line under different anti-lightning methods were constructed,and lightning stroke simulations were conducted on EMTDC.The proposed methods are verified effectively by comparisons of lightning withstand levels.Simulation results indicate that lightning withstand levels can meet the demands of power enterprise standard under both anti-lightning methods.And lightning withstand levels are higher if double side shielding ground wires are installed and electrical connections are made between side shielding ground wire system and transmission line system.The practical running results through one lightning and one icing seasons after the line reconstruction of anti-lightning method indicate that,the reform program can reduce tripping accidents caused by uneven ice shedding and ensure the anti-lightning performance at the same time.