Line voltage stability calculations in power systems

Voltage instability and voltage collapses are increasingly attracting worldwide interest. Operating power system closer to its stability limits, transferring large amounts of powers from long distance and an inadequate supply of reactive power contribute to system voltage instability and eventually to voltage collapse. Accurate calculations of voltage stability, precise prediction of voltage collapse points and low time consumption of procedures computation are essential needs for operators to take the necessary actions to prevent such system incidents. Although several methods have been used in voltage stability analysis, successful avoidance of power system collapse is based on accuracy, rapid indication and very low calculation time. This paper presents a competent method for conducting line voltage stability analysis in power systems. This newly developed method is accurate, fast, simple, and theoretically proven for calculating voltage stability at each individual line and finding accurate voltage collapse points. Voltage stability margins based on line analysis can be easily calculated, providing an indication of how far the line(s) is from its severe load condition and permitting separate analysis if one line is highly stressed. The proposed method was demonstrated on the IEEE 57-bus system and compared with existing methods to show its efficiency.