Utilization of Supercapacitor to Extend the Critical Clearing Time in a Power System

Future power systems with a high penetration level of inverter-based renewable sources (IBRSs) will be vulnerable to severe grid faults because of the noticeable reduction in the total system inertia. Particularly, challenges will arise in securing the transient stability limits of synchronous generators in the systems. Fortunately, the stability limits can be extended by utilizing the existing inverter-based units as virtual damping devices. This paper proposes the utilization of an inverter-based supercapacitor (IBSC) to extend the critical clearing time (CCT) of a power system with a high penetration level of IBRSs; thus, it makes it possible to secure the transient stability limits of SGs. In order to utilize an IBSC, the controllability of the IBSC is explored by considering two factors: control scheme and location of the IBSC. First, to determine an effective control scheme for the IBSC, three control schemes, which are power-damping control, speed-damping control, and power and speed-damping control, are tested under severe fault conditions. Then, using each control scheme, the location of the IBSC is chosen in a certain power system by the most extended CCT. The proposed utilization strategy was validated under various scenarios in a modified IEEE 14-bus system using the PSCAD simulator.