Research Into Longitudinal Differential Protection Of Optical Fiber Based On DSP

Longitudinal differential protection of optical fiber,which is of many merits, has beenused more and more widely in EHV transmission line protection. DSP has excellent capabilityin data processing, so it can be applied in microprocessor-based protection to handlecomplicated algorithm of protection rapidly. A relaying protection device of longitudinaldifferential protection of optical fiber based on DSP is introduced detailedly in this paper.Firstly, several criterions of current differential protection are represented, meanwhileemulation are made with ATP, then the results of emulation are analyzed. The method ofcapacitive current compensation is also introduced. Based on above work, a scheme of currentdifferential protection is put forward. Secondly, the methods of communication andsynchronous sampling are discussed. Thirdly, the hardware design of this protection device isshown in detail. Finally, the software of this device is brought forward according to the designof the hardware and the protective theory. In this wise, a sheme of longitudinal differentialprotection of optical fiber is formed.