The Transient Stability of Alternators: a Graphical Solution of the Two-Machine Case

The transient stability of two isolated synchronous machines working in parallel is generally treated in terms of the power/angle curves, to which the equal-area criterion is applied. In such a treatment the angle of separation between the machines is obtained, as a function of time, from a double integration of the power curves, generally by the step-by-step method or by integraph. The paper describes a method in which the transient stability is treated in terms of energy/angle curves and in which the time taken to reach a given angle of separation is calculated from a single step-by-step differentiation.