摘要
将保护装置安装在T区两侧,基于T区中低频衰减特性构成方向元件,提出一种特高压三端混合直流输电线路单端方向保护方法。分析特高压三端混合直流输电系统整流侧、T区以及线路末端逆变侧三端边界频率特性,发现T区边界对故障电流暂态信号中低频分量有一定的衰减作用、整流侧边界和线路末端逆变侧边界对故障电流暂态信号高频分量有明显衰减作用。利用小波分解,根据T区两侧线路暂态电流中低频能量差判断故障方向,并提出故障方向判据。当T区左侧发生故障时,利用线路L1末端所检测到的高频暂态电流能量与低频暂态电流能量的比值来判别整流侧区内、外故障;当T区右侧发生故障时,利用线路L2首端所检测到的高频暂态电流能量与低频暂态电流能量的比值来判别线路末端逆变侧区内、外故障;T区发生故障时,判定为线路区外故障。给出基于T区中低频衰减特性构成方向元件的特高压三端混合直流输电线路单端方向保护方案,最后在PSCAD/EMTDC仿真平台搭建昆柳龙特高压三端混合直流输电系统模型并对所提保护方法进行验证,仿真表明该文所提保护方法能实现特高压三端混合直流输电线路全线速动保护。
Protection devices are installed on both sides of the T-zone line,Propose a transient current direction protection method for UHV three-terminal hybrid DC transmission lines.The frequency characteristics of the rectifier side,the T-zone,and the inverter side boundary of the line end of the UHV three-terminal hybrid DC transmission system are analyzed,and it is found the T-zone boundary has a certain attenuation effect on the low-frequency component of the fault current transient signal.Rectifier side boundary and end of line inverter side boundary had a significant attenuation effect on the high-frequency components of the fault current transient signal.Using wavelet decom-position,according to the T zone on both sides of the line transient current in the low-frequency band energy difference to determine the direction of the fault,put forward the fault direction criterion.When the fault occurs on the left side of the T-zone,the high-frequency transient current energy detected at the end of the line and the ratio of the low-frequency transient current energy to discriminate the rectifier side within and outside the fault;when the fault occurs on the right side of the T-zone,the high-frequency transient current energy detected at the first end of the line and the ratio of the low-frequency transient current energy to discriminate the inverter side of the end of the line within and outside the fault;When a fault occurs within the T zone,it is directly determined as an outside zone fault.To give a single-end direction-preserving expansion scheme for UHV three-terminal hybrid DC transmission lines based on the T-zine low and medium frequency attenuation characteristics constituting the directional element,Finally,the PSCAD/EMTDC simulation platform was used to build a model of the Kunliulong UHV three-terminated hybrid DC transmission system and to validate the proposed protection method.The simulation shows that the method proposed in this paper can realize the complete line speed protection of UHV three-terminated hybrid DC transmission lines.
作者
邢超
黄泽
毕贵红
陈仕龙
王龙
牛元有
XING Chao;HUANG Ze;BI Guihong;CHEN Shilong;WANG Long;NIU Yuanyou(Electric Power Research Institute of Yunnan Power Grid Co.,Ltd.,Kunming 650217,Yunnan Province,China;School of Electric Power Engineering,Kunming University of Science and Technology,Kunming 650500,Yunnan Province,China)
出处
《电网技术》
EI
CSCD
北大核心
2024年第6期2622-2631,I0110-I0114,共15页
Power System Technology
基金
国家自然科学基金项目(52067009)。
关键词
特高压三端混合直流
输电线路
T区
暂态电流高低频能量差
方向保护
UHV three-terminal hybrid DC
transmission lines
T zone
high and low-frequency energy differences in transient currents
direction protection
