云广±800kV线路对地及交叉跨越距离研究

Research About Ground Clearance and Cross and Span of YUN-GUANG ±800kV UHVDC Transmission Lines

为确定云广±800kV线路对地及交叉跨越距离,首先根据国内外资料确定有影响的环境标准,包括静电场、合成场强、离子流密度、无线电干扰及可听噪声等,在公众能到达的地方,按美国电科院EPRI Report EL2257推荐的方法进行静电场、合成场强、离子流密度计算,根据计算结果确定其导线最小对地距离;再根据系统确定的操作过电压倍数及电气绝缘强度(空气间隙)来确定在人不宜到达地方的交叉跨越距离;部分区域综合考虑地面合成场强及电气绝缘强度的影响确定相关距离。根据以上结论提出了±800kV线路导线对地最小距离及交叉跨越间隙的建议值。

Research about ground clearance and cross and span of UHV DC transmission lines is an important topic of UHV DC transmission technique. It affects the width of line, range of move houses and the technical economical target of transmission lines. So, this topic is decides conductor to ground and cross and span distance in ±800 kV transmission lines. This topic certain the influence standard of the environment according to domestic and international data, including nominal electric field strength, total electric field strength, ion currnet density, radio interference and audible noise. On this base, through considering places that the public easy to arrive, and according to EPRI Report EL 2257 expressions calculate nominal electric field strength, total electric field strength, ion current density to ascertains the safe distance of conductor to ground in the place that the public easy to arrive. We decide the cross and span clearance by over-voltage times and electrical insulation strength （air spacing） from the system major in places that the public not easy to arrive. Also, in Parts of districts, we consider the ground composite electrical field strength and electrical insulation strength effects together. Finally we suggest the values of minimum ground clearance of conductor to ground and cross and span distance in ±800 kV transmission lines.