How can I say "You should save your work 'at short regular interval'?"

I want to say that "You should save your file frequently at regular interval" because this area has electricity problem.

I want frequently at regular interval in a word.

Frequently will work by itself here, unless you mean that the intervals are to be of an exact duration. If this is the case you would say: "You need to save every 5 minutes", for example. The word frequently then becomes redundant.

You can use periodically to mean fairly often and regularly.

I think regularly works fine; the frequent part can be deduced by the context:

This area has frequent electricity problems; you should save your files regularly.