Prediction of Voltage Collapse in Presence of Voltage Dependent Loads by PV Curve Approximation

In this paper a method for prediction of voltage collapse point in presence of voltage dependent loads is proposed. When a part of load is voltage dependent type, the voltage collapse point does not coincide with maximum loading point and lower portion of PV curve can be stable. In the proposed method, at first this portion of PV curve is approximated with a quadratic function by some successive local measurements of voltage magnitude and active power. Then, the voltage collapse point is predicted by comparison of this function with the load characteristic. The presented method is reliable, simple and computationally very fast. The simulation results on the IEEE 30 Bus test system are presented with promising results.