Voltage instability criterion based on variation relationship of power and current

After analysis of voltage instability mechanism and the course of voltage collapse, a criterion of transient and long-term voltage instability was presented. The criterion is based on variation relationship of power and current, and criterion judgment only needs to monitor several electrical variables to evaluate the voltage stability of the receiving system connecting with the sending system by several transmission lines. Moreover, the criterion has characteristics of strong adaptability, convenience and low computational complexity. Several simulation examples show that the criterion is effective. © 2010 Chin. Soc. for Elec. Eng.