Contingency Analysis for Improved Power System Stability of the Nigerian 330 Kv, 48-Bus System Using Series Facts Controllers

Stressed electric network, either due to increased loading because of system expansion, or due to extreme contingencies, often result in voltage limit violations and overload of lines leading to extreme degradation in the system's damping torque, metamorphosing into fluctuations and dynamic instability. This paper employs two series, Flexible Alternating Current Transmission System (FACTS) controllers; Static Synchronous Series Compensator (SSSC) and Thyristor Controlled Series Compensator (TCSC) to investigate the system responses during line outages for dynamic stability improvement. The commercial version of Power System Analysis Toolbox (PSAT) was used to model the Nigerian 48-bus power system network with simulation of line outages using breakers on lines 6-8 (Oshogbo to Ikeja West transmission stations) and 35-39 (Ugwuaji to Ikot Ekpene transmission stations). SSSC and TCSC were optimally positioned on line 21-28 close to bus 21 (Jos transmission station) after continuation power flow simulation and computation of voltage sensitivity factor of all the load buses. Results show that the two FACTS controllers effectively improved the system stability by reducing the rotor angle and speed and by damping the post outage oscillations of the bus voltage and real power.