Design and performance evaluation of SSSC supplementary modulation controller in power systems using SPEF method

Controllable series line compensation is a cornerstone to increase the transmittable power, improve the transient stability and power oscillation damping. The initiative of FACTS allows for fast and vernier control of series compensation using static synchronous series compensator (SSSC). This paper presents the control laws and location index proposed for a SSSC based on a circuit analogy of the electro-mechanical system. The signals which are used can be synthesized using locally available measurements. A detailed study of small signal analysis is carried out to study the effectiveness of the control law and strategic location of the damping controller. With the objective of damping oscillations, a nonlinear constrained optimization technique has been presented for tuning the controller parameters. Transient stability analysis has then been performed with SSSC for a multimachine power system. A path independent structure preserving energy function method (SPEF) is derived for the SSSC. Direct evaluation of the effect of SSSC on transient stability is investigated. Case studies considered illustrate the effect of SSSC on transient stability and its accurate prediction. Comparison of results of the proposed approach with that of the method proposed by M.H. Haque, clearly indicate that there is a good enhancement in the system stability.

► Control strategies and location factors have been used for design and location of SSSC in a multi-machine power system.
► Optimum design values of SSSC are obtained by applying nonlinear constrained optimization technique.
► Small and large signal stability studies, energy analysis are used to assess the SSSC.