Investigating the effects of selecting different slack bus on power systems

The load-flow study is a numerical analysis of the flow of electric power in an interconnected system in power engineering. Simplified notation such as the one-line diagram and per-unit system is used for power-flow study and focuses on various features of AC power parameters, such as voltages, voltage angles, real power and reactive power. It analyses the power systems in normal steady-state operation. So, the load flow studies play a major role in analyzing of the power systems. Generally, power system buses are categorized into three classes named load bus, power grid bus and slack bus or swing bus. In fact, slack buses in the power system are chosen among PV buses and also voltage value and phase angle of slack buses must be set 1 and 0, respectively. In this study, analysis of power flow was performed on six bus bar system using Gauss Seidel method. The study analyzed the change of effects that come from choosing different slack buses to determine the critical stress points, voltage stability, in the multi-bus systems. At the beginning of the each power flow analysis, different busses which have generator were determined as the slack bus and the analysis was performed without increasing the load. The effects of changes in critical points were examined at the end of the all possible analysis.