On the Definition of Apparent Power

In this paper, the widely recognised apparent power definitions, which are Arithmetic, Vector, IEEE standard, DIN standard apparent power definitions and the apparent power definition of Mayordomo and Usaola, are rigorously reviewed, and their abilities on the measurement of the system’s power transfer efficiency are analysed by using a specially derived apparent power, which is calculated in terms of the total line losses of the system with and without the reactive power compensation. In the analyses, two major compensation strategies, namely the minimum line loss (MLL) and sinusoidal and balanced current (SBC) compensation strategies, are considered to determine the total line loss of the system with the compensation. Therefore, in a representative nonsinusoidal and unbalanced test system, the results are simulated by taking into account unbalance among the resistances of neutral and phase lines. The simulated results show that under nonsinusoidal and unbalanced conditions, the unbalance among the resistances of neutral and phase lines highly affects the system’s power transfer efficiency. Additionally, Mayordomo and Usaola’s apparent power definition can be used for proper measurement of the power transfer efficiency in the nonsinusoidal and unbalanced systems. On the other hand, the accuracies of the rest of the reviewed definitions considerably depends on unbalance among the resistances of neutral and phase lines. It should also be mentioned that the accuracies of the apparent power definitions are considerably not affected by the type of compensation strategy.