The study reviews and examines the definitions of reactive power, apparent power, and power factor. Among the different definitions of power factor in three-phase circuits under a non-sinusoidal condition, this study adopts the definition of the effective power factor, which is also advocated by IEEE Standard 1459-2010. The effective power factor is defined as the ratio of the real power consumed by the load over the effective apparent power. The effective apparent power is the maximum power transmitted to the load (or delivered by a source) while keeping the same line losses and the same load (or source) voltage and current. The effective power factor theory gives apparent power a definite physical significance and provides more insights than other definitions in unbalanced circuits. Another merit of the effective power factor definition is that it only involves measurements and computations in the time domain. This study implements the computation of the effective power factor in MATLAB for use in PSCAD/EMTDC. The latter simulates the power system and provides three-phase voltage and current measurements. MATLAB performs the effective power factor computation and sends the results back to PSCAD. A number of simulations are provided in this report to demonstrate the validity and the accuracy of this implementation. / text

Yes / This paper proposes a new index to determine the static voltage stability of the load buses in a power network for certain operating conditions and hence identifies load buses which are close to voltage collapse. The proposed index is formulated from the quadratic equation derived from a two-bus network and is computed using the apparent power and the line impedance. The proposed index shows how far the load buses from their voltage stability limit and hence the most sensitive bus can be identified according to maximum loadability. 14 bus IEEE reliability test system is used to study the performance of the proposed index for its validity. A comparison is also made between proposed index and some other indices found in the literature. The results are discussed and key conclusion drawn.