Influence of mode of operation of the SSSC on the small disturbance and transient stability of a radial power system

The static synchronous series compensator (SSSC), as a series compensator, has two ways of controlling the magnitude of the compensation, which are called 1) the constant reactance mode and 2) the constant quadrature voltage mode. In the constant reactance mode, the voltage, injected by SSSC, is proportional to the line current. In the constant quadrature voltage mode, the injected voltage of the SSSC is a constant that is in quadrature to the line current. This paper investigates the influence of the two modes on the damping power, synchronizing power, and transient stability limit of a radial power system. Eigenvalue analysis and digital simulation using HYPERSIM show that when the SSSC is in the constant reactance mode it provides higher damping power, synchronizing power, and transient stability limit than the case when the SSSC is in the constant quadrature voltage mode.