Effects of Phase Shifting Transformers on Weak and Ill-Conditioned Network: Nigerian 330kV Grid System

Abstract

The present Nigerian 330kV grid system is predominantly known to be unstable, fragile, and ill-conditioned. This is due to rapid increase in the consumers demand for electricity and other technical factors. A network is said to be weak and ill-conditioned when it is deficit of reactive power, with low voltages below the nominal limit and has high R/X line ratios. To maintain a secure, efficient and economical operation of electrical power system and to meet the enormous demand by consumers, it becomes imperative to carry out real power flow control and its redirection. Presented in this paper is the application of phase shifting transformers to the Nigerian 330kV grid system for active power flow control. Newton Raphson Iterative algorithm was adopted for solving the power flow problems. Modified power flow algorithm was implemented by the application of phase shifter approach using Phase Shifting Transformers (PST). The phase shifting transformer was inserted one at a time on each of the four suitable transmission lines directly connected to the generator bus. These lines are between Benin to Osogbo (8-10), Alaoji to Onitsha (12-14), Benin to Onitsha (8-14), and Osogbo to Ikeja West (10-5). Results obtained show that, with the incorporation of PST, active power flow can be redirected between the two points in power system and hence, enhancing its operation in terms of efficiency and reduced system losses.