Modified tangent vector‐based voltage stability constrained optimal power flow considering limit‐induced bifurcation

Abstract

A modified tangent vector (TV)-based voltage stability constrained optimal power flow method is proposed. The proposed method determines an optimal stable equilibrium point (SEP) satisfying the required voltage stability margin (VSM) considering limit-induced bifurcation (LIB). LIB, which occurs when a generator reaches a reactive power limit during load increasing, may cause an optimistic overestimation of voltage stability and inadequate operation. The key of the proposed method is to use approximated TV for considering LIB as a voltage stability constraint to ensure that the solution becomes an SEP and to avoid inappropriate operation caused by LIB. The validity of the approximation is evaluated analytically and numerically in this study. The threshold for the approximated TV is updated based on the continuation power flow calculation result to satisfy the required VSM. The proposed method was implemented on MATPOWER, and evaluated with a 2-machine 4bus system and an IEEJ standard WEST10-O/V system. The results show that the proposed method can determine the optimal SEP satisfying the required VSM even if LIB occurs.