SUMMARY
This paper presents the method to visualize a set of feasible loading points, called “feasible regionâ€, in the two-dimensional power flow solution space. The visualization can be done by tracing the boundary of feasible region. The boundary points are determined by optimizing the reduced cost function with operational constraints. The method can also determine several kinds of feasible regions by assigning the appropriate free variables and its criteria. These feasible regions show the robustness of operating points and the limit of control actions. The six-bus test system illustrates the boundary tracing and impacts of system parameters on the shape of feasible region, i.e. the capacitor bank operation, load shedding, generator voltage controls, and load level.