摘要
电流互感器(CT)饱和是影响差动保护可靠性的关键因素之一。单一的CT饱和识别方法难以兼顾各种复杂情况,需研究多样化的辅助识别方法。通过理论分析和录波数据仿真发现,差动电流的滑动数据窗半周积分结果,在区内故障时呈现单调递增特性;而在区外故障CT饱和时则呈现明显的拐点,变化趋势为先增大后减小。据此,提出一种基于差电流半周积分特征的CT饱和识别方法。并以该方法为基础设计了实用化判据和差动保护的闭锁方案,适用于变压器、母线及传输采样值的输电线路差动保护。对采用该方案的智能母线保护进行RTDS实验,结果表明所提出的识别方法和整体方案,能明确区分内部故障和CT饱和,在转换性故障时也可以快速开放。该方法可以作为时差法的有益补充,有利于完善差动保护抵御CT饱和的能力。
Currenttransformer （CT） saturationisakey factor affectingreliability of differential protection.Anysole method for identifying CT saturationisdifficult to balance various complex conditions,so it isinurgentneedtodevelop diversifiedauxiliaryrecognitionmethods.Theoretical analysis and simulation of recorded data show thathalf-cycle integral of differential currentwithasliding data-windowwill monotonically increaseatinternal faultoccurrence. However there is a significantknee pointwhenanexternal faultoccurs withCT saturation,namely,the half-cycle integral increases firstly and then decreases.Accordingly,a novel recognition methodforCT saturationisproposed. Furthermore,practical criterionand blockingschemeofdifferential protectionare designed, suitable for transformer, busbar and transmission line relayswith exchangedsampled values.RTDS experiment is carried out on busbarprotection ofsmartsubstationusingthe proposed scheme.Testresultsshow that the proposed approach and scheme can clearly distinguish internalandexternal faults and CT saturationfrom each other; differential relay can also trip rapidly whenanexternal fault transfers to internal.This method can be used as a supplement todelta-time method, conduciveto improve differential protection abilitytoresist CT saturation.
出处
《电网技术》
EI
CSCD
北大核心
2016年第9期2889-2895,共7页
Power System Technology
基金
山东省自然科学基金项目(ZR2014EEM039)~~
关键词
差动保护
电流互感器
饱和
半周积分算法
differential protection
current transformer
saturation
half-cycle integral algorithm
