消解多直流馈入问题的两种新技术

描述了可消解多直流馈入问题的电网动态分区技术和柔性直流输电技术.基于对物理机理的分析,将多直流馈入问题分为两个方面,即由交流系统故障引起的多回直流线路同时换相失败问题和由直流线路双极故障导致的潮流大范围转移问题.针对电网动态分区技术的实现途径,提出了采用大阻抗故障限流器实现电网动态分区的技术方法,并演示了电网动态分区技术解决多回直流线路同时换相失败问题的有效性.阐述了采用柔性直流输电技术消解多直流馈入两方面问题的有效性,并对柔性直流输电技术向大容量和架空线路方向发展所遇到的接地方式、串并联组合式换流器技术和直流侧故障自清除问题进行了探讨.

Two New Technologies for Eliminating the Problems with LMultiple HVDC Infeeds

Two new technologies for eliminating the problems involved with multi-infeed HVDC systems, i.e. the grid dynamic segmentation technology and the VSC-HVDC technology are presented in this paper. Based on the analysis of the mechanisms of the HVDC multi-infeed problems, two aspects of the problems is identified, i.e. the simultaneous commutation failures caused by AC network faults and the large area great power flow shift caused by bipole faults of some HVDC systems. In connection with the approaches to fulfill the grid dynamic segmentation, the paper proposes an approach with large-impedance fault current limiter, and illustrates the effectiveness of the grid dynamic segmentation to solve the simultaneous commutation failure problem. The effectiveness of the VSC-HVDC to eliminate the two aspect problems of multi-infeed HVDC systems is also discussed, while the associated problems with bulk power overhead transmission for VSC-HVDC, such as the grounding mode selection, the bulk power converter assembly composed of multiple series and parallel connected converter units, and the DC side fault self-clearing capability, are analyzed.