新松—东方±800kV特高压直流工程运行初期输电能力受限问题及对策

Transmission Capability Problem and Countermeasures During Early Operation Period of Xinsong—Dongfang UHVDC Project

针对新松—东方±800 kV特高压直流工程投产初期,存在直流送端配套电源投产进度严重滞后于原定投产计划、送端开机不足的情况,结合新松换流站有效短路比水平,分析了直流被动进入孤岛后孤岛系统的稳定性、过电压水平、谐波谐振风险等多方面因素对直流输电能力的影响。研究结果表明新东直流的输电能力受各方面因素限制,无法满足调试阶段对直流输送容量的要求。为提升直流输送能力,提出了进入孤岛后采取主动闭锁直流双极的临时措施,分析了应用临时措施后直流能达到的最大输电能力。最后还研究了在保证新东直流具有额定容量送电能力的前提下,退出临时措施所需的条件。研究成果保障了新东直流投产初期送电的安全性与充裕性,为系统调试阶段各项试验工作的顺利开展提供了重要指导。

During early operation period of±800 kV Xinsong-Dongfang UHVDC project,the construction progress of the accessory power plants at the sending-end falls far behind the original schedule,causing a lack of generation problem in sending-end power grid.In such a situation,the stability of the islanding system after Xinsong station switching into islanding mode,the overvoltage of the islanding system and the harmonic resonance risks of the islanding system are key elements which affect the transmission capability of Xinsong-Dongfang UHVDC project.All of these elements are analyzed in this paper.The analysis results show that the transmission capability of Xinsong-Dongfang HVDC project is constrained and unable to meet the demand of system commission tests.For enhancing the transmission capability of Xinsong-Dongfang UHVDC project,a stopgap according to which the UHVDC system will block itself following a preset strategy if the converter station switches into islanding mode is presented.And the transmission capability of Xinsong-Dongfang UHVDC project after adopting the stopgap is also analyzed.Finally,the quitting conditions of the stopgap,is researched under which Xinsong-Dongfang UHVDC project can reach its rated transmission capacity safely without any stopgap.The study results of this paper guarantee the security and adequacy of Xinsong-Dongfang UHVDC project s power transmission in early operation period,and also provide valuable guidance on experiments conducting in system commissioning test periods.