I have 15hp 3phase motor rated 460/230V how can I run my motor if my supply voltage is 380v 3phase...

There are Buck-Boost transformers, connected as auto-transformers, for this purpose. You can either buck the 380 down to 230, or boost the 380 up to the 460, preference on the latter. The transformers need to be rated to handle the starting Kva of the motor.

I don't have buck-boost transformer. How about connecting my motor in parallel wye from the motor terminal? Is it possible?