High Voltage Direct Current systems have been used for transporting electrical energy for very long distances, at high voltages (100- 1000 kv). On utilize thyristorized or transistorized power converters, one converter is working as rectifier at sending side, and the other is working as inverter at receiving side. Back to Back Converters are used also where the rectifier and inverter are at the same station, transmission line has hundreds of meters as long. In our model we used non controlled three phase rectifier as sending station and controlled three phase bridge as receiving station (Graitze).