Is there away to create active record model in Yii for portioned tables in PostgreSQL?

Yes you can since it's Yii :)

Easily create normal model for main table, and make table name change before running your operation; query(), save(), delete(), and so on.

To change table name, you need to use before and after capability that Yii support, and specially CActiveRecord, like overriding beforeSave and afterSave functions for save function.

Changing table name is tricky, since CActiveRecord functions takes table name from table meta data, so you need to flush this data after changing table name, and don't forget to revert table name to original table name after your operation, to make the object works normally.