The Research And Realization For Digital Bus-bar Protection Device

With the continuous enlargement of the scale of power network, the damage of bus-bar fault to electric devices and system stabilization become increasingly serious, so that the deeper reasearch for bus-bar protection device becomes necessary than ever before. The digital bus-bar protection has gained great achievement at present, meanwhile, some defects still existed. and therefore, further developments is required. To design a sort of digital bus-bar protector with rapidity, sensitivity, reliability can get enormous economic benefits and accelerate its development, so developing the research on digital bus-bar protection device is a valuable workIn the first part of this paper, introduce the importance of busbar protection for power grid, the development history and progress of busbar protection and some hot issues which would affect the performance of busbar protection. Based on above discussed, the main content of the paper is determined. By analyzing and comparing the fundamental principles as well as studying on the main algorithm of the busbar protection, we established a combined solution scheme for the differential current protection, i.e. That is divided phase percentage differential protection by using sampled value and fault component sampled value.In the second part of the paper, the main research work is focused on two key problems: anti-TA saturation and self-adaptive to operation mode. Based on the understanding of current transformer saturation mechanism, comparing the merit and demerit of present anti-TA saturation schemes, we proposes a new scheme of anti-TA saturation, which is employed the character of differential current waveform,this method can discriminate the TA saturation reliability in the case of external fault and opening busbar protection under evolved fault condition. Based on analyzing about existed self-adaptation schemes, select the optimal scheme for this protector, it is ideal for bus-bar protection to get the isolator auxiliary contact as dominant factor, the current criterion is used to verify the state of isolator auxiliary contact and rectify the errors automatically. This scheme would increase the reliability for bus-bar protection.In the third part of the paper, introduct the overall designs of software and hardware about the experimental facility. Dissertate the hardware design considerations ,compositive segments and characteristics.Software realizes program development using modular design method.The program frame of every function module, the main program, interrupt serve subprogram and differential protection subprogram flowcharting of the busbar protection were designed detailedly.In the last part, not only all of the research work accomplished in this thesis is summarized, future improvement is pointed out as well.