Research on the protection algorithm of laboratory-microgrid system

There are several distributed power sources exist in the microgrid system, they have reversible trend power-flow characters; Influenced by the fault current restrictions of inverter, the amplitude of fault current is small, so the traditional over current protection of radioactive electric distribution network is no longer suitable. This paper make use of multipoint information, meanwhile combine the variations of voltage parameters and the direction of the power before and after fault, to realize fault area judgment, fault point resection and some other functions. This paper takes laboratory-microgrid for the research object, do simulation analysis to the detect of voltage under dq rotating coordinate system and establish the switch-branch associated matrix, and obtain the fault area and tripping operation information by matrix operation. Theoretical analysis shows that this method can complete the relay protection task whether microgrid is running under parallel operation status or islanding operation status.