A New Method for Identifying Bifurcation Points in Steady-State Voltage Stability Analysis

Based on analysis of the case of the saddle-node bifurcation and the limit-induced bifurcation, a new method for identifying and calculation bifurcation points in steady-state voltage stability analysis is presented. By using continuation power flow based on piecewise linear load prediction curve, in which the load increasing directions are determined by load prediction curve, it go through the collapse point by a large step. Firstly, if there is no one or more generators reaching their reactive power limits (Q limit generators) when the collapse point is went through, the collapse point is saddle-node bifurcation; or else the proposed criteria can be used to quickly identify the type of the collapse point. We can get the accurate saddle-node bifurcation point by point of collapse method and limit-induced bifurcation point by including the set voltage of Q-limit generator into the power flow equations as continuation variable. The practicability and effectiveness of the proposed method is validated on IEEE 118-bus system.