Optimal design and application of permanent-temporary combination for 750 kV single-circuit transmission lines—A case study of Ta’e–Karamay transmission line project
750kV单回线路永临结合优化设计与应用研究——以塔额～克拉玛依线路工程为例

摘要

针对塔额～克拉玛依750kV线路工程接入塔城托里煤电送出工程时，原开断接入设计方案存在成本高、施工风险大、停电时间长等问题，本文提出了单回线路永临结合优化设计方案。以工程20mm重冰区段开断点为核心研究对象，结合重覆冰线路设计规范要求，从路径选择、绝缘配合、铁塔结构设计三个维度开展优化设计：优化接入路径并加大档距以降低转角角度，按行业标准确定间隙取值并加长横担满足本期绝缘要求，采用JC4120J干字型铁塔并通过抗扭验算、有限元模拟、强化结构设计、选用高等级钢材等措施，解决杆塔近远期受力协调及受扭问题。对比分析结果表明，优化方案相较原方案节省投资约88万元，施工风险等级从二级降至三级及以下，电网停电时间从13天缩短至1天以内，同时简化了施工流程、降低了协调难度。该永临结合设计方案实现了工程本期建设与远期接入的统筹规划，有效规避了资源浪费，提升了工程建设的经济性、安全性与电网供电可靠性，其设计思路和技术措施可为复杂气象地理条件下超高压输电线路开断接入工程提供重要的工程参考。

Abstract

When the Ta’e–Karamay 750 kV transmission line project is connected to the Tacheng Tuoli coal-fired power delivery project, the original breaking-in connection scheme is faced with problems such as high cost, high construction risks, and long power outage duration. This paper proposes an optimized design scheme using the permanent-temporary combination for single-circuit transmission lines. Taking the breaking point in the 20 mm heavy icing section of the project as the core research object, and in accordance with the design specifications for heavy icing transmission lines, the optimization is carried out in three dimensions: route selection, insulation coordination, and tower structure design. The connection route is optimized and the span is increased to reduce the corner angle. The clearance values are determined per industrial standards, and the cross-arms are lengthened to meet the current insulation requirements. The JC4120J guyed-type tower is adopted, and measures including torsional resistance checking, finite element simulation, structural reinforcement, and high-grade steel selection are implemented to resolve the issues of coordinated stress and torsion of the tower under short-term and long-term conditions. Comparative analysis shows that compared with the original scheme, the optimized scheme reduces the investment by about 880,000 yuan, lowers the construction risk level from Level II to Level III and below, and shortens the power grid outage duration from 13 days to less than 1 day. Meanwhile, it simplifies the construction process and reduces coordination difficulty. This permanent-temporary design realizes the overall planning of current construction and future connection, effectively avoids resource waste, and improves the economic efficiency, safety of project construction, and power supply reliability of the power grid. Its design concept and technical measures can provide important engineering references for breaking-in connection projects of EHV transmission lines under complex meteorological and geographical conditions.