A Second Order Sliding Power Control & Resonant Filtering Approach to Mitigate Grid Unbalance Effects on a DOIG Wind Energy Based System Grid Unbalance Effects on a DOIG Wind Energy Based System

Abstract

This paper presents a multivariable power control design applied to a DFIG Wind Energy Conversion based System (WECS).  The  multiple  control  objectives  pursued  in  this  work include not only tracking temporal profiles of active and reactive power  grid  injection  but  also  regulate  some  important  internal variables  like  the  DC  bus  voltage.  To  fulfil  these  targets  a multivariable  control  scheme  is  developed  following  second order sliding mode techniques. This theoretical framework allows synthesizing  controllers  with  attractive  features  like  finite  time convergence,  robustness  against  external  perturbations  and unmodeled dynamics, simple implementation, etc. To endorse the control  system  with  grid  support  features  under  voltage unbalances the multivariable SOSM controller is combined with a  set  of  resonant  filters.  This  mixed  scheme  allows  to substantially  reduce  the  oscillations  of  simple  and  double  grid frequency on the electric torque and the power injected into the grid.  The  overall  performance  of  this  control  proposal  is evaluated using representative simulations.