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3. Energy Management for Photovoltaic Installations 365

P Renew, P load, SOC min, SOC maxP pv,
P load, SOC min, SOC max

Calculate P=P Renew-P load

No Yes
P 0

No Yes
SOC>SOC min
SOC<SOC max
No Yes

Mode 5
P Renew=0
P pv=0 Mode 4 Mode 1
No
Yes

Mode 2 Mode 3

FIGURE 11.9
Energy management strategy of PV/wind system with battery storage.

The different modes depend on the three switches K 1 ,K 2 , and K 3 . Mathemati-
cally, it results in eight cases (Table 11.14).
After simplification, we obtain the Table 11.15:
But only five cases can be exploitable as real cases (Table 11.16)
The different powers can be expressed in terms of the different switches as:

P Renew ¼ K 1 $K 2 $K 3 þ K 1 $K 2 $K 3 þ K 1 $K 2 $K 3 (11.27)
P batt ¼ K 1 $K 2 $K 3 þ K 1 $K 2 $K 3 (11.28)
These equations can be minimized to:

P Renew ¼ K 2 þ K 1 (11.29)
P batt ¼ K 3 (11.30)
Therefore, the load power is given as:
P load ¼ðK 2 þ K 1 Þ$P Renew þ K 3 $P batt (11.31)