This project is concerned create DC transmission . Which aims to study the structure and operation of the transmission system with DC sources. To convert the power from the AC system. The model consists of full bright 12-pulse converters using thyristors as switching deivces, and power circuit approach is bipolar. A converter acting as a sender is controlled in rectifying mode in order to convert power from AC system to DC system. The another converter is controlled in inverting mode controlled in inverting mode based on line commutation in order to convert DC power to AC power for supplying loads on another AC source