Abstract
The power system planning, design and operation study require load flow analysis to know the now day loads and generation also plan for future load demand in the network. Moreover, to know the voltages at every bus to connect suitable devices that can support the voltage stability. In this paper the study has been done on real network of 220/66 kV substation ( Houn substation, Libyan network). Electrical Transient Analyzer Program (ETAP), is used to model and analysis the network. The switchgears, transformers and lines in the substation had modeled to do the power flow analysis. The power flow analysis determine the buses that suffer from under voltage and that need reactive power injected to maintain system voltages within specified limits. The results showed that the optimum location of capacitors connection to the network could improve the system voltage. Keywords: under voltage, Load Flow Analysis, ETAP software.