Weighting function integrated in grid-interfacing converters for unbalanced voltage correction

Abstract

In  this  paper  a  weighting  function  for  voltage  unbalance  correction  is  proposed  to  be  integrated  into  the  control  of  distributed  grid-interfacing  systems.  The  correction  action  can  help  decrease  the  negative-sequence  voltage  at  the  point   of   connection   with   the   grid.   Based   on   the   voltage   unbalance  factor  and  system  power  capacity,  the  interfacing  converter delivers a small amount of negative-sequence current to  the  grid  and  helps  correcting  the  negative-sequence  voltage.  Although the reduced amplitudes contributed by each individual DG  system  are  very  small  compared  to  the  total  negative-sequence    component,    many    DG    system    modules    can    collectively achieve substantial results in the grid. As a practical example,   a   three-phase   grid-interfacing   converter   servicing   sensitive loads with distributed sources is employed to integrate this   additional   function.   Design   principles,   simulation   and   experimental results are presented to verify the proposal.