code: def data_to_sys_base(self):
          
          if not self.n or self._flags['sysbase'] is True:
              return
  
          self.copy_data_ext(model='Synchronous', field='Sn', dest='Sn', idx=self.gen)
          super(GovernorBase, self).data_to_sys_base()
          self._store['R'] = self.R
  
          self.R = self.system.mva * div(self.R, self.Sn)
docs: Custom system base conversion function