Stability improvement of power system by simultaneous AC–DC power transmission

This paper presents a concept of improving the transient stability of power system by simultaneous AC–DC power transmission through a transmission line. A double circuit long transmission line is converted to simultaneous AC–DC line for feasibility study. Loss of synchronism is prevented by quickly producing sufficient decelerating energy to counteract accelerating energy gained during fault and subsequently due to loss of line after clearing the fault. Fast controllability and modulation of DC component is utilized to achieve this feature. The system under consideration is found to remain stable under transient condition up to transmission angle of 80°. Simulation study on PSCAD/EMTDC is carried out to validate the concept.