Study of Useful Life of Dry-Type WTSU Transformers

Abstract

Dry-type transformers are rapidly becoming popular as  wind  turbine  step-up  (WTSU)  transformers,  especially  in  offshore  wind  farms.  Cast  resin  transformers  are  not  flammable  and   are   also   resistant   to   moisture.   However,   their   thermal-electrical degradation must be carefully analysed given the special conditions of wind farm installations. The present paper studies the remaining   useful   life   (RUL)   calculation of   dry-type   WTSU   transformers based on the most thermally stressed location i.e. the winding  hot-spot.  The  estimation  of  the  loss  of  life  of  the  transformer can be used for diagnostic and prognostic monitoring purposes  in  the  framework  of  digital  twins.  The  methodology  is  then  applied  to  a  typical  WTSU  load  profile  and the  impact  of  several transformer  characteristics  and  operating  conditions  are  compared to the reference case.