Abstract: In this study, various aspects of voltage instability in electrical power network using the Nigeria 330 kV transmission network as a case study were analysed. The study considered various causes of voltage instability such as loss of generators or lines, 3 phase faults, load increases which were simulated on the network using the Power World Simulator. The study revealed that the present 330 kV trasmission grid is highly unstable and require remedial measures to improve the voltage stability. Thus, shunt compensation, load shedding and strengthening of the network by incoporating additional lines into the grid showed greater improvment on the network. The study therefore, proposed a modified network that will improve the voltage stability in the network.