Power system fundamentals - Wind Power Integration: Connection and System Operational Aspects - page 33

Note that a capacitive load absorbs negative reactive power, which is equiva-
lent to generating positive reactive power.

2.3.2.2 Summary
The impedances for resistance, inductance and capacitance are therefore as follows:

Component Symbol Impedance

Resistance R R

Inductance L j w L

Capacitance C 1/j w C

2.3.3 Power in AC systems
Consider the voltage and current phasors depicted in Figure 2.10. The current has
been resolved into a real or active component in phase with voltage and a reactive
component lagging the voltage by 90 .
Multiplying the currents in Figure 2.10 by the voltage magnitude results in
active power in phase with the voltage phasor and reactive power lagging the
voltage phasor by 90 , as shown in Figure 2.11. The diagram clarifies the rela-
tionship between active and reactive power, on the one hand, and the apparent

I cos f

f

V

I sin f

I

Figure 2.10 Real and reactive components of current

V I cos f = P

f

V I = VI ∠− f

Figure 2.11 Triangular relationship between active, reactive and apparent power