Power system is exposed to quite adiverse mixture of disturbances such as,small as well as large disturbances.Small load changes that occur continually leads to small disturbance in the system.While during a large disturbances,the system must also be able to survive large disturbance.Therefore,the system should have the capability to work satisfactorily by controlling the voltage.This thesis has introduced advanced methods using sensitivity analysis to preserve the voltage within the secure limits when power system faces disturbances.The influence of distributed generation(DG)and its control method on sensitivity has also been taken into consideration.Finally,load shedding considering user’s priority is implemented based on sensitivity and priorityto ensure consumers’comfort to alleviate the voltage.Those objectives are elaborated below in more detail.　　The first objectiveis to compute firstly the static sensitivity index during small disturbance,without considering the difference between static and dynamic load shedding.Then,obtain the dynamic sensitivity index when a large disturbance occurred in the system and finally describe the difference between static and dynamic load shedding during large disturbance and its impact on voltage recovery during transient state.　　Secondly,DG was introduced to the network by placing it on various location in the network in order to illustrate the effect ofitin both static and dynamic sensitivity.PQ control and V/F control methods were implemented to show the difference of those two control manners in the system and their impact in sensitivity and voltage recovery.　　Finally,in order to decide which device to switch on or off when voltage goes below its standard value,it particularly depends on the users’priorities and load sensitivities.Some users do not want their loads to be cut during under voltage circumstance.Therefore,load shedding scheme based on priority and sensitivity are designed to satisfy the users’preference and alleviate voltage particularly,during small and large disturbance.　　Simulation was implemented on IEEE-33test bus system,the results showed that these methods are reasonable and efficient.