分极接入模式的多端直流特点与故障响应比较

Comparison of Characteristics and Fault Response of Multi-terminal HVDC with Two Poles Connected to Two Different AC Grids

大容量直流输电受端采用多端直流接入模式,有利于解决其大容量直流馈入电网特别是多回直流集中馈入电网带来的稳定性问题。介绍了分极接入、并联多端接入两种主要多端直流受端接入模式的设计特点,对交直流故障进行了电磁暂态仿真分析,对比了两种直流受端接入模式的故障响应特性、对控制保护的影响以及对受端电网影响的区别,指出分极接入模式下任何一极接入弱交流系统,均会影响整个直流系统的稳定运行能力,直流线路瞬时故障期间另一极接入的逆变站受影响小。研究结果可以为电力系统应对大容量直流接入优化设计提供参考。

Multi-terminal mode of the receiving ends of HVDC transmission technologies might be helpful for solving the stability problems caused by large HVDC infeed or especially multi-infeed HVDC. This paper introduces the design characteristics of two modes of multi-terminal HVDC ： two poles connected to two different AC grids （ TPTDG）, and parallel type multi-terminals HVDC （ MTH- VDC ）. Some results of AC and DC fault simulation analysis by EMTDC are presented. By comparing the two modes＇ properties under faults and influences on control protection system and AC grids, some different characteristics are obtained. It is pointed out that the capability of stable operation of HVDC might be affected with any pole of TPTDG connected to weak AC system, and the inverter sta- tion will be substatially less affected with transient faults occurred to the other DC line. The different characteristics between the two modes will provide reference for design optimization of large HVDC access.