±500kV同塔三回柔性多端直流输电线路防雷保护

Lightning Protection of±500 kV Three-circuit Multiterminal VSC-HVDC Overhead Transmission Lines on the Same Tower

同塔三回柔性直流输电线路在节约输电走廊等方面具有较大优势,但其防雷设计较单回或者双回输电线路有明显区别,特别在构成直流电网情况下,应从严控制线路雷击跳闸率。为此,以张北±500 kV柔性直流电网试验示范工程(单回)为背景,采用电气几何模型及行波法分析了±500 kV同塔三回柔性直流输电线路的耐雷性能,研究了极导线布置方式、避雷线保护角、地形地貌特征、接地电阻等典型因素对线路绕击及反击跳闸率的影响。计算结果表明,避雷线保护角采用–14°设计,极导线采用推荐的E布置方案时,可将三回直流输电线路的雷击跳闸率控制在0.1次/(100 km·a)以下。研究成果为后续±500 kV同塔三回柔性直流线路的防雷设计奠定了基础。

Three-circuit VSC-HVDC overhead transmission lines on the same tower are beneficial for saving transmission line corridors.However,the lightning protection design for three-circuit transmission lines is more complicated than that for single-circuit or double-circuit transmission lines.The striking flashover rate should be strictly controlled,particularly in DC gird structures.Based on the Zhangbei DC grid project,the lightning withstand performance of back striking and shielding failure are analyzed by adopting the wave-progress analysis model and electrical geometric model,respectively.In addition,the effect of polar line arrangement,grounding resistance,tower height,and other factors on the lightning withstand performance are analyzed.The calculation results show that the striking flashover rate of this project will satisfy the requirement of the reference value,no more than 0.1 times/(100 km·a),when the shielding angle used in the transmission line is not more than-14°and the pole transmission lines are arranged in the E style proposed by the authors.The results of this work can provide a basis for the lightning protection design for±500 kV three-circuit overhead transmission lines on the same tower.