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3. Energy Management for Photovoltaic Installations  355




                  Table 11.2 Mathematically Cases Based on Three Switches of PV/Battery
                  System
                   Switches                            Powers
                                             Modes
                   K 1      K 2     K 3                P pv     P batt   P load
                   0        0       0        Mode 5    0        0        0
                   0        0       1        Mode 3    0        P batt   P batt
                   0        1       0        Mode 4    P pv     0        P pv
                   0        1       1        Mode 2    P pv     P batt   P pv þ P batt
                   1        0       0        X         X        X        X
                   1        0       1        X         X        X        X
                   1        1       0        Mode 1    P pv     0        P pv
                   1        1       1        X         X        X        X



                  Table 11.3 Simplified Table in the Case of Three Switches (PV/Battery
                  System)
                   Switches                         Powers
                                           Modes
                   K 1      K 2        K 3          P pv      P batt    P load
                   0        0          0   Mode 5   0         0         0
                   0        0          1   Mode 3   0         P batt    P batt
                   0        1          0   Mode 4   P pv      0         P pv
                   0        1          1   Mode 2   P pv      P batt    P pv þ P batt
                   1        1          0   Mode 1   P pv      0         P pv



                  Table 11.4 Real Cases Based on Three Switches of PV/Battery System

                   Modes   Sources     DP    SOC           K1   K2    K3   P load
                   Mode 1  PV            0   SOC < SOC max  1    1    0    P pv
                   Mode 2  PV þ Battery  <0  SOC > SOC min  0    1    1    P pv þ P batt
                   Mode 3  Battery      <0   SOC > SOC min  0    0    1    P batt
                   Mode 4  PV            0   SOC ¼ SOC max  0    1    0    P pv
                   Mode 5  /            <0   SOC ¼ SOC min  0    0    0    0



                     These equations can be minimized to:

                                          P pv ¼ðK 2 þ K 1 Þ$P pv               (11.8)
                                                                                (11.9)
                                          P batt ¼ðK 3 þ K 1 Þ$P batt
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