Improved Computations of the Voltage Collapse Point

This work develops and applies an improved approach for estimating the point of voltage collapse based on the P-index method. The P-index is a voltage stability monitoring and prediction tool that was proposed in a recent research effort. Prediction of distance to voltage collapse in the original P-index method assumes a linear approximation of voltage-load relationship. The prediction has provided enhanced precision over most recognized indices. However, it also resulted in inaccuracies because the actual voltage-load behavior in general is not linear but rather more complex. The new model proposed here is based on a more accurate relationship between bus voltage and load. It was applied to a number of IEEE benchmark systems for several operating conditions and a comparison made with the original method. In all the tests, the new model provided higher overall accuracy in prediction of voltage collapse point compared to the linear method.