摘要
在基于模块化多电平换流器(MMC)的柔性直流输电系统中,高效可靠地识别线路故障是系统安全经济运行的重要保证之一。为快速可靠识别线路故障,提出一种基于交叉重叠差分(SOD)变换的区内外故障识别方法。首先分析MMC等效阻抗模型形成的物理边界对高频分量的衰减作用,当线路发生内部故障时,其故障电压起始变化陡峭、幅值大、长时窗时域波形有振荡;当线路发生外部故障时,其故障电压起始变化平缓、幅值小。其次利用交叉重叠差分对故障电压和故障电流进行变换,变换后的电压和电流信号相乘得到SP,定义K为SP绝对值的最大值,根据K值判断区内外故障。在PSCAD/EMTDC上搭建MMC-HVDC系统仿真模型,仿真结果表明,该方法能可靠准确地识别区内外故障,速动性好,具有较强的耐过渡电阻能力和适用性。
In the high voltage direct current transmission based on modular multilevel converter(MMC)system,identifying line faults efficiently and reliably was one of the important guarantees for the safe and economic operation of the system.In order to identify line faults quickly and reliably,an internal and external fault identification method based on sequential overlapping derivative(SOD)transform was proposed.This paper first analyzes the physical boundary formed by the MMC equivalent impedance model,which has a strong attenuation effect on high frequency components,the start voltage caused by the line fault changes steeply when amplitude is large and the time-domin waveform isshowen shaking violently;the the start voltage caused by the external fault changes gently and amplitude is small.Secondly,the SOD transformation is used to transform the fault voltage and current.The converted voltage and current signal are multiplied to obtain SP,and K is defined as the maximum value of the absolute value of SP,and the internal and external faults are determined according to the K value.The MMC-HVDC system simulation model is built on PSCAD/EMTDC.The simulation results show that the method,which has good quick action,certain resistance to transition resistance and strong applicability,can reliably and accurately identify internal faults and external faults.
作者
束洪春
代月
安娜
田鑫萃
王广雪
Shu Hongchun;Dai Yue;An Na;Tian Xincui;Wang Guangxue(Faculty of Electric Power Engineering Kunming University of Science and Technology,Kunming,650500,China)
出处
《电工技术学报》
EI
CSCD
北大核心
2021年第1期203-214,226,共13页
Transactions of China Electrotechnical Society
基金
国家自然科学基金(51807084、52037003)
云南省重大专项(202002AF080001)资助项目。
关键词
高压直流输电
模块化多电平换流器
物理边界
交叉重叠差分变换
故障特性分
析
故障识别
HVDC
modular multilevel converter
physical boundary
sequential overlapping derivative transform
fault characteristic analysis
fault identification
