Design Of Self-adaptive Differential Protection For Busbar

Traditional busbar protection devices take up a considerable proportion in real operation nowadays. However, these devices are mostly hard to meet the actual requirements for their old principles and poor adaptabilities, many problems are also found in real operation, for example, they have a low capability of anti-saturation to TA and they can't cut off faults of turnover type quickly. Combined with the requirements of real operation, a new type busbar protection device which has a high capability of anti-saturation to TA and cuting off faults of all kinds quickly is researched and designed in this paper.After researching the power companies in the tender on technical requirements of busbar protection devices at present and analyzing the advantages and disadvantages of the domestic and alien current differential protection criterions, an integrative judgement criterion of busbar protection based on the fault current characteristic is presented. This criterion is composed of differential starting component, differential protection component and trouble bus selection component, each component is in detail, which breaks the limitation that criterion of each traditional busbar protection device has a singul component. Moreover, a unique scheme to sovle the problem of anti-saturation to Ta is presented by analyzing its saturation characteristic. the divided-period integrative judgement criterion and the practical scheme to sovle the problem of anti-saturation to Ta are two notable features of this paper.The hardware is designed of parallel processing with double DSP, furthermore, the analog singal input part, the import and exit part are introduced simplely. The sorftware is designed modularly by the Self-adaptive judgement criterion, the modules of the digital processing and the protection function are detached, and every module shares the data each other, accordingly, the software is more optimized.Finally, the test result indicated that the adaptive busbar differential protection in this paper is one kind of quite ideal protection. It can real-time change protection criterion according to the change of busbar movement and fault station to enables its protection performance to achieve superiorly. besides, the protection has a high capability of anti-saturation to TA, it can operated correctly after the fault out of the area with the TA saturating converts to the fault in the area.