Development of the emergency voltage control scheme using VMPI

Recently, as power system loads are located further away from power plants and as they are distributed more unevenly, reactive power losses have increased due to the heavier power flows with the growth in high load demand and long distance transmission. Therefore, concerns over voltage instability phenomena have grown as significant voltage drops and voltage collapse have been experienced. Thus, preventive voltage control schemes using voltage stability indices have become of importance in a considerable number of studies. However, there are some cases in which the bus voltage exceeds the upper voltage limit when preventive voltage controls are conducted in a system with long distance transmission lines. Therefore, it is the goal of this paper to develop an emergency voltage stability control with the index VMPI (Voltage Margin Proximity Index) and the ellipse fitting P-V curves. Simulations are run using the IEEJ WEST 30 machine 115 bus system to verify the effectiveness of the proposed method.