code: def storage_at_hvmv_substation(mv_grid, parameters, mode=None):
      
      storage = set_up_storage(node=mv_grid.station, parameters=parameters,
                               operational_mode=mode)
      line = connect_storage(storage, mv_grid.station)
      return storage, line
docs: Place storage at HV/MV substation bus bar.
  
      Parameters
      ----------
      mv_grid : :class:`~.grid.grids.MVGrid`
          MV grid instance
      parameters : :obj:`dict`
          Dictionary with storage parameters. Must at least contain
          'nominal_power'. See :class:`~.grid.network.StorageControl` for more
          information.
      mode : :obj:`str`, optional
          Operational mode. See :class:`~.grid.network.StorageControl` for
          possible options and more information. Default: None.
  
      Returns
      -------
      :class:`~.grid.components.Storage`, :class:`~.grid.components.Line`
          Created storage instance and newly added line to connect storage.