Due to raise in demand, the transmission system becomes more exhausted, which in turn, forces the system to be more susceptible to voltage instability. The aim of this research is to study the enhancement in voltage stability margin by installation the SVC which is represented as Static of VAR Compensator or STATCOM that is represented as Static of Synchronous Compensator. Voltage stabilization dilemma considers an essential issue in the electric networks which may lead to a voltage collapse in electric power networks.
L-index has been used to predict and identify points of breakdown voltages in the power system with sufficient accuracy. L -index has been employed due to its accuracy and effectiveness in the computing voltage collapse points for different load buses with sufficient precision at a short circuit and also at various loads situations. Voltage stability index has been tested on the 9-wscc test system and 14-IEEE test system .Then it has been applied to the Iraqi national grid 400 kV.
A shunt facts(SVC or STATCOM) devices are installed individually at the weak bus bar based on Voltage Stability Index(L indicator) detection, The simulation results are first obtained for an uncompensated system, and the voltage profiles are studied. The results so obtained are compared with the results obtained after compensating the system with SVC and STATCOM to show the voltage stability margin enhancement. The outcomes acquired after simulation demonstrate the performances of shunt fact devices (SVC and STATCOM) when connected to a system Subjected to 3-phase short circuit fault at different locations. All the simulation results have been carried out using MATLAB version 7.10 and Power System Analysis Toolbox (PSAT) package.