Use
You can use this method to get the current filter settings and pass them on to other components of the system. A row of the table describes the selection conditions for column entries that are not displayed. Columns for which no filter is set are not listed in the table.

You should never 'manually' set up the table with the filter criteria.
Features
CALL METHOD
<ref.var. to CL_GUI_ALV_GRID >-> get_filter_criteriaIMPORTING
Parameter |
Meaning |
ET_FILTER |
Table with filter settings for columns that have a filter set |
For an overview, see:
Methods of Class CL_GUI_ALV_GRID