Fast Approach for Voltage Stability Constrained Optimal Power Flow Based on Load Impedance Modulus Margin

A fast approach for voltage stability constrained optimal power flow (VSC-OPF) is proposed in this paper to minimize the fuel cost of generation and improve voltage stability simultaneously when power system is operating at stressed conditions. In the proposed method, a fast voltage stability evaluation index called load impedance modulus margin (LIMM) is incorporated into the proposed optimal model as a complementary voltage stability constraint for the first time. Moreover, to improve the accuracy of voltage stability assessment (VSA), the influence on LIMM of voltage characteristics of static ZIP load is considered while calculating LIMM. Based on the above, an improved optimization model of VSC-OPF is established, which greatly reduces the time for updating VSC-OPF results to improve its ability to adapt to mode changes of the power system. The proposed approach is tested in the IEEE 30-bus standard system and the real-world 220kV network in Hunan province in China. The simulation results verify the effectiveness and practicality of the proposed VSC-OPF approach.