2.6. Adjustment of the active and reactive power
With the help of power converters, it is possible to adjust the phase displacement φ between the voltage and the current (Figure 2.65), in addition to the frequency and the amplitude of the alternative waves.
Active and reactive powers depend on this phase displacement. It is thus possible to adjust them by controlling the latter. Their expressions in single-phase are as follows:
[2.15a]
[2.15b]
In three-phase: they take the following forms depending on whether we are considering the phase to ground voltages V (of the phase) or the phase-to-phase (of the line) voltages U:
[2.16a]
[2.16b]
A third power, called the apparent power, is defined by the relationship:
[2.17]
We thus define the power triangle, linking P, Q, S and φ (Figure 2.66).
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