A new method for detecting loss of synchronism using power and current measured on a line

When a fault occurs, coherently swinging generators form one group and the remaining ones form another. If the fault is severe, loss of synchronism may take place between groups after single or multiple swings. This paper proposes a new method for detecting loss of synchronism. With this method, power and current are measured at regular intervals on a tie-line linking sub-networks to which groups of generators belong. Changes in power and current are calculated during the interval, the location and direction of the operating point of the power system moving on the curve of power versus phase angle is estimated and the loss of synchronism is detected. The validity of the method is shown by simulations using model networks