Control and Design of Microgrid Components - Power Systems ...

P-w droop with fixed slope
The values of Pmax=15kW and Δωmin=0.5Hz define range of operating values on the P,ω plane
shown on Figure 6.4.
ω
ω o
ω 1
Unit a
P ao
Unit b
P bo
P a1 P b1
ω min
P
P
max
Figure 6.4 The Active Power versus Frequency Droop.
The value for the fixed slope ‘m’ of the droop is chosen to be corresponding to the value of the
slope obtained for Po=0 when using the fixed slope Eq.3.3 :
ωo
− ω
m = −
P
max o
min
P o
= 0
1
2π
= −
2
15kW
π
= −
15kW
Q-E droop slope and setpoint
The value of Qmax helps to determine the slope for the Q-E droop, once the value of the
maximum excursion expected for the voltage, ΔE, is known. The maximum excursion in voltage
can be thought to be the difference in voltage between the best and worse case scenario.
The best case scenario is represented by the microgrid fully energized from the grid, without
microsources and without any load attached to it. The voltage profile is to be expected to be
absolutely flat, since no current are flowing in, and the voltage equal to the rated voltage of the
system.
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