Study Of Microcomputer-Based Bus Protection Suit For MV Or LV Power System

Nowadays ,busbarprotection is commonly uninstalled on MV or LV power system in our country. But when fault was occurred ,sometimes there would be great loss. For the reason, the paper put forward a microcomputer bus protection scheme suit for MV or LV power system with low current grounding based on the great researching about the working theory of current bus protections and the characteristic of MV OR LV system with low current grounding . Based on it, the paper has designed the platform of the hardware and the software programs.Firstly , the paper introduced the commonly hardware configure of microcomputer relaying and the function of every module of industry controlling computer STD90386 . Secondly ,the paper introduced several types busbarprotection which was commonly installed on electric power system and the characteristic of MV OR LV system with low current grounding .Based on it, the paper put forwards the theory of percentage-restraint differential relay .After that ,in the discussing every problems of the relaying working the paper put the emphasis on the negative effect of the CT saturation and countermeasure. As the kernel of software ,the algorithm is another emphasis of the paper's works. Based on the principle of relaying working, after comparing the effect between the algorithm of instantaneous sampling and the algorithm of vector ,the virtue ofshort data windows and precision action was stood out. And the choice of algorithm with three sampling data was for the reason of short data windows. In the end of the paper is the discussing of how to improving the performance of device. As the important part of theory applying, every researcher of microcomputer relaying must think of it carefully.