دانلود Distance protection for microgrids in distribution system

Abstract

Owing  to  the  increasing  penetration  of  distributed generation, there are some challenges for the conventional protection  in  distribution  system.  Bidirectional  power  flow  and  variable  fault  current  because  of  the  various  operation  modes  may  lead  to  the  selectivity  and  sensitivity  of  the  overcurrent  protection  decreased.  This  paper  adopts  distance  protection  for one mid-voltage level microgrid in Aalborg, Denmark. Different operation  modes  of  the  network  are  analyzed  and  tested  in  the paper.  The  simulation  results  show  that  the  variations  of  the  fault  currents  seen  by  the  forward  relays  are  much  larger  than  the backward relays. Meanwhile, the fault currents change little with the randomness of renewable energy except the intermittence. Finally, it shows that the designed distance protection  has  satisfactory  performance  to  clear  the  various faults.