Investigation of Combined SVC and TCSC versus IPFC in Enhancing Power System Static Security

Abstract

Electrical power systems are often required to operate at full loading capacity due to ever increasing demand and transmission line contingencies with limited grid expansion. This results in line overload and operating near system limit, thereby threatening system security. Utilization of existing system can be achieved using Flexible Alternating Current Transmission System (FACTS) devices without violating system limits. This research investigation involves static security assessment of a modelled IEEE 30-bus test system in MATLAB/SIMULINK/PSAT environment. The security status with the incorporation of combined Static Var Compensator (SVC), Thyristor Controlled Series Compensator (TCSC) and Interline Power Flow Controller (IPFC) were determined. Prior to this, Contingency Severity Index (CSI) based on Performance Index (PI) of Voltage and Active Power was employed to determine the optimal location of the FACTS devices. Sequential Quadratic Programming (SQP) was applied to determine the optimal sizing/percentage compensation of FACTS. Subsequently, power system with and without the incorporation of FACTS devices were modelled. The ability of the compensated system to withstand credible transmission line contingencies without violating the normal operating limits (bus voltage and line thermal) was examined and presented. The paper presents how combined SVC/TCSC and an IPFC aided the power system to boost its steady state security in the face of possible line contingencies.