Operation and Protection of Grid Connected Wind Farm

Abstract

In  modern  power  systems,  wind  energy  shares  significant amount   in   electricity   generation.      Accordingly,   the   grid performance could be affected due to the natural behavior of the  connected  wind  farms.      The  main  challenge  is  to  fulfill the  voltage  ride  through  (FRT)  requirements  and  fast  fault detection   as   well   as   reactive   power   coordination   using FACTs    devices    such    as    STATCOM.    Fulfilling    these requirements    will    minimize    the    loss    of    wind    energy generation   due   to   emerged   disconnection   of   the   wind turbines from the grid.  This paper presents fast and efficient over current and under voltage  protections  against  faults  on  both  grid  high  voltage line  and  on  medium  voltage  feeders  connecting  the  wind turbines   to   the   point   of   common   coupling   (PCC).   The proposed  protection  scheme  based  on  measuring  the  voltage and  current  signals  at  PCC  bus,  evaluating  and  analyzing these signals for fault detection. Thereby, the main objective is to keep wind turbines connected to the grid and to regulate the    reactive    power    and    voltage    level    during    grid-transmission  line  faults  using  STATCOM.  Under  voltage, relay time delay settings is proposed to fulfill the Fault Ride-Through  (FRT)  requirement.  Moreover,  over  current  relay settings  is  presented  to  isolate  the  wind  farm  from  the  grid during the internal wind farm feeder faults.