The analysis of a large interconnection power system, under the severe disturbances such as those that can lead to a voltage collapse (VC), is necessary to develop the performance of the available protection schemes and to avoid critical conditions that can lead to instability or system blackout. In this paper, a Strategy to improve voltage instability in the 30-Bus IEEE power system model as an example to large interconnected power systems. One case study of a large unit tripping is tested and voltage instability was studied. Also, the required remedial actions are considered.