Performance Analysis of FACTS Devices for Stability and Control of 1100 kV Power System

Abstract Ultra-high-voltage (UHV) ac corridors rated at 1100 kV carry several gigawatts over hundreds of kilometres, so their usable capacity is limited by angle, voltage and oscillatory stability long before conductor thermal limits are reached. This paper presents a consistent, quantitative performance analysis of five flexible ac transmission system (FACTS) controllers—the static var compensator (SVC), static synchronous compensator (STATCOM), thyristor-controlled series capacitor (TCSC), static synchronous series compensator (SSSC) and unified power flow controller (UPFC)—applied to a 600 km double-circuit 1100 kV corridor that connects a 12 GW generation hub to a receiving grid. The system architecture, colour circuit topologies and mathematical models (distributed-parameter line, flux-decay generator with high-gain static exciter, current- and voltage-injection device models and a wide-area power-oscillation damper with communication latency) are developed and implemented in a phasor-domain simulator. Power–angle and P–V analysis, eigenvalue analysis, time-domain fault simulation with critical clearing time (CCT) search and a latency sensitivity study are performed under identical operating conditions. At a 7 GW transfer the corridor’s 0.83 Hz electromechanical mode has only 1.5% damping; wide-area damping control raises it to about 10% with ± 3 Gvar shunt controllers and to about 20% with series-connected controllers. The TCSC extends the CCT from 146 ms to 268 ms and the N-1 voltage-stability limit from 4.46 GW to 7.06 GW, whereas the UPFC gives the largest loadability gain (+ 65% under N-1) and the best voltage support. The results provide practical guidance for selecting, rating and coordinating FACTS controllers on 1100 kV systems.