Power System Stability Enhancement by Simultaneous AC-DC Power Transmission

This paper presents the concept of simultaneous ac-dc power transmission. Long extra high voltage (EHV) ac lines cannot be loaded to their thermal limits due to this instability occurs in the power system. It is difficult to load long extra high voltage (EHV) ac lines to their thermal limits as a sufficient margin is kept against transient instability. With the model proposed in this thesis, it will be possible to load these lines close to their thermal limits. The transmission lines are allowed to carry usual ac along with dc superimposed on it. The conductors are allowed to carry usual ac along dc superimposed on it. This thesis gives us the feasibility of converting a double circuit ac line into composite ac–dc power transmission line to get the advantages of parallel ac–dc transmission in order to transient stability and dynamic stability and dampen out oscillations. Simulation has been carried out in MATLAB software package (Simulink Model). The results show the stability of power system both for natural response when compared with only ac transmission.