Novel Techniques for Continuation Method to Calculate the Limit-induced Bifurcation of the Power Flow Equation

This article proposes an improved continuation method to calculate the limit-induced bifurcation associated with the power flow equation due to the encounter with reactive power limits by generators. One of the distinguishing features is that the maximum loadability characteristics of limit-induced bifurcation are used for identification so that the computation efforts can be minimized. Another distinctive characteristic of the method is that, to ensure accuracy, the tangent vector of the continuation power flow equation at the reactive power limit encountering point is used to differentiate between limit-induced bifurcation and saddle-node bifurcation, as the latter also represents maximum loadability. The proposed method also adopts the conventional schemes of secant prediction, arc-length correction, and a new step-size control, i.e., the convergence-dependent step-size control. Numerical results of the IEEE 118-bus system are used to illustrate the improvements of the proposed continuation method in comparison with the existing one.