Power values and harmonics
From Electrical Installation Guide
Active power
The active power P of a signal comprising harmonics is the sum of the active powers resulting from the currents and voltages of the same order.
Reactive power
Reactive power is defined exclusively in terms of the fundamental, i.e.
[math]\displaystyle{ Q=U1 \times I1 \times Sin \phi 1 }[/math]
Distortion power
When harmonics are present, the distortion power D is defined as
[math]\displaystyle{ D= \left(S^2 - P^2 -Q^2 \right)^{1/2} }[/math]where S is the apparent power.
