CALCULATION OF CRITICAL LOADING CONDITION WITH NOSE CURVE USING HOMOTOPY CONTINUATION METHOD

Voltage instability has received much attention in the electric utility industry. This paper presents a new method for calculating power systems' nose curves and critical loading condition. In this paper, the nose curve (PV curve), which denotes the relationship between total load and system voltages, is calculated by a new approach based on the Homotopy Continuation Method. The critical loading condition, which might be called the bifurcation point, is also calculated precisely as the final point of the nose curve. This method does not require an exhausting cut-and-try process or a rough-approximation process. This method is based on the conventional Newton-Raphson load flow calculation, but overcomes the notorious numerical difficulties associated with the singularity of the Jacobian matrix. The results of applying the proposed method to the IEEE 118-bus system and to other large practical systems (e.g., a 496-bus system) verify its robustness and feasibility.