根据日本特高压输电项目的背景及概况做了1 100 kV交流输电的系统方面的介绍。东京电力公司(TEPCO)已经设计并建造了430 km特高压双回输电线路，目前以550 kV电压等级运行，这些线路是东京电力公司超高压电网的重要组成部分。由于北部和东部地区大规模核电的发展，要求提高向西部地区的输电能力，目前已建成的超高压设计线路的运行电压将升级到1 100 kV。提出了线路升级到1 100 kV运行过程中存在的一些技术问题，介绍了这些有待探讨的问题及其相应的解决办法。特高压变电站的设备正在进行现场试验。设备的技术规格将在现场试验和对系统进一步研究的基础上最终确定。

This paper describes the system aspects of 1 100 kV AC transmission with the background and overview of UHV transmission project in Japan. Tokyo electric power company (TEPCO) has already constructed 430 km ultra high voltage designed double-circuit transmission lines, which are operated at 550kV and compose an important part of the EHV grid in TEPCO. Operating voltage of the constructed UHV- designed lines will be upgraded to 1 100 kV in response to the increase in westward power flow in the control area due to the large-scale nuclear power generation development in North and East area. There exist some technical issues to be addressed for upgrading these lines to 1 100 kV operation. This paper describes the issues and solutions under consideration. Substation equipment for UHV has been under the field tests. Technical specifications of equipment will be formulated based on the results of the field tests and further system studies.