Working and reflected active powers of three-phase loads

Unbalanced and/or harmonic generating loads have to be supplied with a working active power, which is higher than the active power measured at the load terminals. Consequently, energy providers of such loads are under paid for the energy delivered. The difference between the working active power and the common active power is referred to as the reflected active power. The reflected active power increases with the decline of the short circuit to load power ratio. Therefore, the reflected active power could be easily visible in weaker power systems, such as micro-grids in islanded mode or on terminals of very high power industrial loads, such as pulsing loads or arc furnaces. The load generated harmonics and/or load imbalance are the causes for the reflected active power. The paper presents results of studies on the dependence of the reflected active power on the relative short circuit power of the supply source.