Abstract
In this thesis, first an ideal index is proposed for estimating the relative voltage stability of power system. This index has the merits of having quasilinear characteristic before system collapse, being easy to calculate, and being able to point out the weak places of the system. Next, based on the proposed index, a very practical and simple solution method is proposed for improving the system stability to live up to the desired criterion. This method is very understandable and hence is much easier to be accepted by power engineers than other methods such as linear programming or optimal power flow techniques. Finally, some numerical examples are given for illustrations.