交流750 kV单回线路杆塔空气间隙的研究

由于修订电力行业标准DL/T620-1997《交流电气装置的过电压保护和绝缘配合》需要增补750 kV电压等级的相关内容，文章基于超、特高压输电线路的绝缘配合原则和杆塔外绝缘放电特性的研究结果，对750 kV单回线路杆塔的空气间隙进行了分析研究，认为操作过电压不会成为杆塔边相横担长度的控制条件，并给出了建议值：塔窗中相V型串间隙为4.8 m，边相I型串间隙为3.5 m。最后建议充分利用特高压试验基地资源，尽快开展波头长度为1 000 ms及以上的超、特高压输电线路和变电站仿真电极尺寸的操作冲击电压的试验研究，以适应目前超、特高压输电工程发展的需要。

Research on Air Clearance of Tower for AC 750kV Single Circuit Transmission Line

The contents related to the 750kV voltage grade must be added in the revised power industry standard DL/T620-1997, i.e., Overvoltage Protection and Insulation Coordination for AC Electrical Installations. For this reason, based on the research results in the field of insulation coordination principle for extra- and ultra-high voltage transmission lines and discharge characteristics of external insulation for towers, the author researches and analyzes the air clearance of the towers for AC 750kV single circuit transmission line, and points out that the switching overvoltage should not be regarded as the controlled condition for the length of tower cross-arm for side phases. In this paper the recommended values of air clearance are given, that is, the air clearance should be 4.8m for the middle phase with V-type of insulator strings within the tower window; the air clearance should be 3.5m for side phase with I-type of insulator strings within the tower window. Finally, it is suggested to fully utilize the resources in test base for ultra-voltage transmission to carry out the experimental studies on the extra-and ultra-voltage transmission lines with wave-head lengths of 1000ms and above as well as the studies on the switching impulse of substation simulation electrodes to meet the demand of the development of extra- and ultra-voltage transmission projects.