说明：  ：高压直流三极输电技术采用电流调制控制模式，同时 利用三相导线，只需要对线路进行有限改造，就可有效提升 原线路输送容量。因此高压直流三极输电技术是潜在的解决 输电线路输送容量瓶颈效应的有效方案。为进一步推动高压 直流三极输电技术的研究和应用，介绍了该技术的发展历 程、系统结构、电流调制原理以及运行方式，详细分析了高 压直流三极输电与常规高压直流输电相比的技术优势和经 济特点，最后针对该技术的工程应用提出了需要重点研究的 几个关键领域。
(In view of adopting current modulation control mode and utilizing existing three-phase conductors, to which limited renovation is needed, the application of tripole high voltage direct current (tripole HVDC) transmission technology can substantially uprate the transmission capacity of original AC transmission line, therefore tripole HVDC transmission technology is a potential and effective scheme to solve the bottleneck in uprating transmission capability. To push on the research and application of tripole HVDC transmission technology further, the development course, system structure, principle of current modulation and operational modes of tripole HVDC transmission technology are presented, and comparing with conventional HVDC transmission technology the technological superiority and economic traits of tripole HVDC transmission technology are analyzed in detail. Finally, for the engineering application of tripole HVDC transmission technology, several key issues in this)