特高压混合直流输电系统线路故障清除策略研究

Research on Line Fault Clearing Strategy of UHV Hybrid HVDC Transmission System

在特高压直流工程中,对于特高压混合直流输电系统,直流架空线路故障的清除对于系统的稳定运行起着至关重要的作用,而柔直站对线路故障的处理是其中的关键。首先阐述了特高压混合直流系统线路故障清除所采用的方式及需解决的关键问题;然后结合特高压混合直流系统的线路故障等效回路及特性分析,提出了基于主动限流的直流线路故障自适应清除策略及实现方案,该方案可实现不同类型线路故障有效清除、高低压换流器直流电压均衡以及子模块电容电压稳定等关键目标;最后通过实时数字仿真平台试验验证了所提策略的有效性。

In UHVDC engineering,for UHVDC hybrid transmission system,the fault removal of overhead DC line plays an important role in the stable operation of the system,and the handling of the line faults of the flexible HVDC station is the key.This paper first elaborates the methods and key problems to be solved for fault clearance of UHV hybrid DC system.Then,combined with the line fault equivalent circuit and characteristics analysis of hybrid UHVDC system,the paper proposes an adaptive fault clearing strategy and implementation scheme of DC line based on active current limiting control.This scheme can realize the key goals of effective removal of different types of line faults,DC voltage equalization of high and low voltage converters and capacitor voltage stability of sub-modules.Finally,the paper verifies the effectiveness of the proposed strategy by a real-time digital simulation platform.