The analysis on the L-index based optimal power flow considering voltage stability constraints

In the environment of electricity markets, power systems are operated nearer against the voltage stability limit than before. For this reason, this paper presents a novel optimal power flow (OPF) formulation containing voltage stability constraints. By adopting the L index function that can reflect stability margin from the collapse point as voltage stability constraints, this model can obtain the demanded voltage security level by adjusting the upper limits of these constraints. So its optimal solution can satisfy the security and economical demand of power systems simultaneously. At the same time, the primal-dual interior point method (IPM) based on the perturbed Karush-Kuhn- Tucker (KKT) conditions is proposed to solve this problem. Simulation results on five test systems demonstrate the effectiveness of the presented OPF model with voltage stability constraints, and the proposed computation approach has good convergence.