Voltage stability index based on standard deviation-mean ratio for identification of weak nodes

In electric power systems, it is important to Identify weak buses for operational and planning purposes. The conventional methods for assessing voltage stability are time consuming because they are based on schemes that vary the reactive power at a load bus one at time, while keeping reactive power at all other buses constant. In this paper, a framework that uses the ratio of standard deviation to mean of the magnitude of voltage at load buses to identify weak buses is proposed. In the framework, reactive powers atl load buses are generated simultaneously based on probability distribution functions. The 39-Bus New England test system is used to test the framework in DigSilent Power-Factory in conjunction with Python programming language. The result shows that weak buses can be identified with the proposed framework.