Improving Power Flow Control in AC Transmission System Using Phase Shifting Transformer (PST)

Abstract

Obtaining optimal power flow has been a challenge over the years for power system engineers. Several ways and technologies ranging from conventional to the use of modern Flexible Alternating Current Transmission Systems (FACTS) devices have been incorporated into the power system to ensure optimal flow of power. FACTS devices used are capable of mitigating several power system problems ranging from line overloading, voltage instability, transient instability, and Power system congestion and so on. Phase shifting transformer (PST) is a FACTS device that is capable of controlling power flow problems in a network by varying its phase angle. PST, when installed at appropriate locations on the power system is capable of redirecting and redistributing power flow from overloaded lines to the less loaded ones, hence ensuring an optimal performance and improved performance of the power system.This paper evaluates the effect of incorporating the PST on the IEEE 5 bus system. Newton-Raphson load flow technique is employed in modeling the IEEE 5 bus system and the PST. Simulation was carried out using MATLAB software package for both the steady state condition and with the incorporation of PST. Results showed that overloading on some transmission lines was checked and mitigated by redistribution of active power across the system. There was also reduction of losses on the lines. Keywords: Phase Shifting Transformer, Power System, Power flow, MATLAB, Newton-Raphson. DOI: 10.7176/CEIS/11-4-03 Publication date: June 30 th 2020