Abstract
When a fault occurs in a large interconnected power system, several generators may swing coherently and form a group. Loss of synchronism may occur among the groups of these generators. In order to develop a stabilizing control system, two new methods are proposed in this paper. The first method is to select generators which swing coherently.
The method uses a new index that is based on the physical relation : when two generators swing coherently, a phase angle of a generator terminal voltage increases when the angle of the other generator increases and decreases when the other decreases. To detect a loss of synchronism, power P and current I measured on a line with the interval of a certain time period are used. By using this method, the position of an operating point of power system after disturbance on the power angle curve can be estimated. This means that the degree of stability can be observed with a small number of data measured on a line.
