基于导纳参数识别的分布式母线保护新原理

摘要

针对现有分布式母线电流差动保护受间隔数据采样不同步及传输延时影响的问题,提出了一种基于导纳参数识别的分布式母线保护新原理.通过引入电压量来计算导纳,定义各间隔导纳和的绝对值为差动导纳,各间隔导纳绝对值的和为制动导纳.当母线发生区内故障时,差动导纳等于制动导纳;当母线发生区外故障时,差动导纳反映母线对地的杂散电容,远小于制动导纳.利用差动导纳和制动导纳的大小关系能够可靠区分母线区内、外故障.EMTP仿真和实际录波数据分析表明:所提新原理无需各间隔数据采样同步,受传输延时影响小,耐过渡电阻能力强,在各种工况下均能可靠地区分母线区内外故障.%As the existing distributed bus current differential protection is affected by the asynchronous sampling and transmission delay of bay data,a protection principle based on the admittance parameter identification is proposed.The voltage variable is introduced to calculate the admittance,the differential admittance is defined as the absolute summation of all bay admittances,and the braking admittance is defined as the summation of all absolute bay admittances.When an in-zone bus fault occurs,the braking admittance equals to the differential admittance;when an out-zone bus fault occurs,the differential admittance,reflecting the bus-ground stray capacitance,is much less than the braking admittance.The relationship between differential and braking admittances can be used to reliably distinguish an in-zone bus fault from an out-zone bus fault.EMTP simulation and actual fault-wave records show:being less affected by the transmission delay and better tolerant of the transition resistance,the proposed principle does not need the synchronous sampling of bay data and can identify the in-zone and out-zone bus faults in different operating conditions.