You Do Need power plug adapter while traveling from Bulgaria to British Virgin Islands.

Here is Why You Need An Adapter

The outlet and plug type used in British Virgin Islands are A and B and in Bulgaria are C and F. This is how they look like.

Bulgaria

In Bulgaria, outlets of type C and F are in use.

Type C

Type F

British Virgin Islands

In British Virgin Islands, outlets of type A and B are in use.

Type A

Type B