HVDC controls for power system stability

This paper discusses the impact of HVDC on Power System Stability and proposes a control mechanism to augment the system angle stability. At first, the authors discuss the HVDC model used in transient studies. Basically, it is the same as used in power flow studies, details of which have been given in Section II of the paper. The model considers the limits of HVDC lines, which consists of many control modes. A case has been studied where the HVDC tends to make the system unstable if the setting of the line is not changed during and after a fault. They then propose a control mechanism to strengthen the system stability. Two types of controllers, namely proportional control and proportional-integral control have been studied and compared. Also they have shown their effects on the system stability.