电力系统保护与控制2023，Vol.51Issue(24)：1-12,12.DOI:10.19783/j.cnki.pspc.230664
基于换流站不同出线低频暂态能量比值的多端柔直电网线路保护方案
Protection scheme for a multi-terminal flexible DC grid line based on low frequency transient energy ratios of different outgoing lines at the converter station
摘要
Abstract
The multi-terminal flexible DC grid line protection based on the characteristics of line boundary elements is hard to apply to the power grid when a current limiting reactor is installed at the outlet of the converter station.Thus a multi-terminal flexible DC grid line protection scheme based on low frequency transient energy ratios of the different outgoing lines of the converter station is proposed.First,through analyzing the impedance frequency characteristics of an MMC on the DC side after a fault,it is concluded that the MMC exhibits an inductive characteristic when the actual frequency is greater than the resonant frequency.Then through analyzing the variation rule of the voltage traveling wave refractive index at the bus with frequency is analyzed,we conclude that the low-frequency components with frequencies greater than the resonant frequency have obvious attenuation characteristics after being refracted by the bus.Then the difference in the low-frequency transient energy ratio of different outgoing lines of the converter station during forward and reverse faults is analyzed based on this conclusion.The fault direction can be determined via this difference.Finally,simulation results of PSCAD/EMTDC show that the proposed protection scheme can reliably identify fault directions without relying on line boundary elements,and it has a certain ability to withstand transition resistance.关键词
多端柔性直流电网/限流电抗器/阻抗频率特性/低频暂态能量Key words
multi-terminal flexible DC grid/current-limiting reactor/impedance frequency characteristics/low-frequency transient energy引用本文复制引用
郑涛,李紫肖,陈颖..基于换流站不同出线低频暂态能量比值的多端柔直电网线路保护方案[J].电力系统保护与控制,2023,51(24):1-12,12.基金项目
This work is supported by the Joint Fund of National Natural Science Foundation of China(No.U2166205). 国家自然科学基金联合基金项目资助(U2166205) （No.U2166205）
