"Whenever you arrive/are arrived/were arrived"
Solution 1:
The best is a variation of the first:
Let me know when you arrive.
The second two examples are incorrect, as to be isn't used followed by a past participle in this way.
An alternate formulation (which means pretty much the exact same thing) is to use the present perfect:
Let me know when you've arrived.
The difference in meaning between the simple present (in my first example) and the present perfect (in my second example) is very small in this case.