dc transmission transmission system and combined ac and dc transmission system for power enhancement

Actually my main purpose is to design a dc transmission system and attatch load at the end in matlab(simulink) model and see how much voltage drop occured at the end after transmission line distance of 1000km when load is attatched to it. similarly when i talked about combined ac and dc transmission system i also wanted to see that how much voltage drop occured at the end after transmission of 1000km and see that combined ac and dc transmission system loadabilty( means more load is attatched at the end and transmission line is able to achieve its thermal limits) is increased means more load is attatched and less voltage drop occured .the whole design is on simulink based model. i have the designs of these ( dc system and combined ac and dc system but they are not according to my expected result in simulink). if you can help me i ll pay it for this.