Linearized voltage stability incorporation with line-wise optimal power flow

Abstract

Ensuring the voltage stability of power systems is one of the main goals of operators and researchers. The incorporation of voltage stability with optimal power flow (OPF) has received a great deal of attention in the past few years. The line-wise power flow method is shown to provide a faster solution, up to twice the speed of bus-wise power balance equations, and has a better solution space due to the use of square of voltage magnitudes. Further, the line voltage collapse index (VCI) developed using the set of line-wise power balance equations is shown to be an accurate voltage stability assessment indicator in the literature. In this paper, two novel linear models of voltage stability incorporation with line-wise optimal power flow are proposed based on the set of line-wise power balance equations and its line voltage collapse index. The difference between the two models is based on the way the VCI is utilized. In the first model, VCIs are employed as a set of voltage stability constraints while in the second model VCIs form the objective function. The two models are solved using successive linear programming (SLP) technique. The study test results on several IEEE benchmark systems demonstrate the effectiveness of the proposed two models in attaining a higher voltage stable system at lower cost.