Page 252 - Advances in Renewable Energies and Power Technologies

6. Summary 225

(A) (B)
3.5
Available power
Available power ∆P= 200 W
3.0 Power reserve control
PVpowerP pv (kW) 2.0 is activated P pv is activated
2.5 Power reserve control
1.5
1.0
0.5 P pv
0 2 4 6 8 10 12 14 16 18 20 22 24 0 2 4 6 8 10 12 14 16 18 20 22 24
Time (minutes) Time(minutes)
FIGURE 6.18
Photovoltaic (PV) output power of the Power Reserve Control (PRC) strategy under: (A) a
clear-day and (B) a cloudy-day irradiance conditions (with an accelerated test to reduce
the testing time from 24 h to 24 min), where the reference power reserve level DP is
200 W and the PRC strategy is activated when P pv > 2kW.

(A) (B)
∆P (kW) 0.5 ∆P ∆P
0.4
0.3
Reserved power 0.2 ∆P = 0.2 kW PRC MPPT ∆P = 0.2 kW MPPT
*
*
0.1
MPPT
MPPT
0.0
4
2
6
10
12
14
14
8
10
12
0
Time (minutes) 16 18 20 22 24 0 2 4 6 8 Time (minutes) 16 18 20 22 24
FIGURE 6.19
Measured power reserve of the Power Reserve Control (PRC) strategy under: (A) a clear-
day and (B) a cloudy-day irradiance conditions (with an accelerated test to reduce the
testing time from 24 h to 24 min), where the power reserve level DP is 200 W.
6. SUMMARY
In this chapter, the demands for flexible active power control solution have been dis-
cussed. Potential problems associated with a large-scale grid integration of PV sys-
tems, such as overloading of the grid, voltage fluctuation, and limited frequency
regulation capability, have been presented. To address those issues, the power deliv-
ery from PV systems has to be flexible in terms of limiting the maximum feed-in
power, limiting the change rate of the PV power, and providing power reserve during
the operation. Accordingly, three active power control functionalities: PLC, PRRC,
and PRC have been defined in the grid regulations. Among other approaches to
achieve these requirements, modifying the inherent MPPT control algorithm of
the power converter offers a cost-effective solution in terms of no extra component
cost. This approach achieves the flexible power control by continuously regulating
the operating point of the PV system below the MPP following the demand of the
active power control functionality. The operational principle of three flexible power