Coordination of TCSC and SVC for stability improvement of power systems

The TCSC (thyristor controlled series compensator) and SVC (static VAr compensator) are both members of the FACTS (flexible AC transmission systems) family. With the ability of flexible adjustment, they can presumably each increase the stability of power systems. In this paper, a combination of the TCSC and the SVC installation is proposed to acquire superior performance for the power system. A nonlinear design technique, DFL (direct feedback linearization), is used to deduce the control scheme for the TCSC and SVC. The coordination between the two pieces of equipment is also designed in the paper with the SVC treated as the supplement of the TCSC. When operation of the TCSC is constrained by the inherent limitation of equipment, such as due to the voltage protection of the MOV (metal oxide varistor), or the firing-angle limitation of the thyristors, the adjustable SVC can supply the auxiliary support to improve the overall performance. Analysis and simulation have proved the effectiveness of the nonlinear control strategy. The transient stability and damping performance can be greatly improved with the compatible control schemes of the TCSC and the SVC.