Power System Voltage Stability Research

Power system voltage instability or voltage collapse is an important factor in power system instability. Because voltage collapse accident can cause great economic loss and bad influence to the society, it becomes an emergent problem to be solved for the security of power system. The scale of power systems is increasing, more and more loads sensitive to voltage, the load in load center is increasing very fast, load of the entire power system is increasing each day, means to control reactive power and voltage is insufficient, voltage instability and voltage collapse will become more dangerous to the security of power system.This paper discusses several topics related to voltage stability: voltage stability mechanism, load modeling, static voltage stability analysis of power systems, voltage stability dynamical analysis method. Refers to classical voltage collapse case and considers people's thinking habit, analyzes voltage stability mechanism, improves people's cognition about voltage stability. Refers to August 14th blackout in the United States and Canada, discusses new characteristic of modern voltage collapse accident, points out that modern power system collapse accident not only relates to voltage instability and power angle instability, but also relates to other factors, such as thermal stability limitation, action of relay devices. Combines with load modeling research job of actual power system, demonstrates the entire process of load modeling, points out and discusses some problems in actual load modeling job. Especially discusses simulation step control method in continuation power flow, analyzes how to use variable dV of continuation power flow calculation to adjust the step size. Refers to this step size adjust method, writes P-U curve simulation program, and applies this program in simulation of 2 generator-5 bus system, 3 generator-9bus system and 99 generator-495 bus system, the result is good. Writes U-Q curve simulation program, and applies it in simulation of simple system and actual system. Finally, this paper gives some discussion to the methods of power system voltage stability dynamical analysis.