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Almousawi & Aldair                                                                                                                                               |5
                                                                                              panels in series. This arrangement is used to obtain a power
The maximum #'( , #2*+, , and SOC of BESS obtain the                                          of 5790 W as shown in Fig. (4). The relations between time
optimal reference voltage ("'*() of the PV panel generated by                                 and voltage characteristics of BESS with different current
the control schemes. From these variables, the power                                          discharge is shown in Fig. (5).

coordinate in the PV-BESS-SC hybrid system can be                                             Fig. 4: Output of V-I & V-P Characteristics Under Different
                                                                                                                            Radiation
classified into two employment environments: normal and
                                                                                                Fig. 5: Characteristics of BESS with Different Discharge
SOC regulations. These variables are detailed in the previous                                                                Current.

work [31]. The goal of this control is to minimize the                                        In this paper, the Artificial Bee Colony (ABC) algorithm is
                                                                                              used as an optimization technique to achieve the optimized
charging/discharging stresses on the BESS, thereby raising                                    gains of the five PI controllers with the parameters shown in
                                                                                              Table II [34]. The cost function is represented the saving
the battery's lifetime. Throughout the work, it is assumed that                               operational costs and extending the life span of the HESS
                                                                                              components. The dimension is represented the number of
the SOC of BESS is within acceptable limits.                                                  parameters that required to tune, limit (local optimization) is
                                                                                              represented the number of trails to find the new solution for
vTohletagaeveorfagDeCvlainluke(Vo4*f5V) 4in5      is compared with a reference                each parameter, and a scout production period (global
                                                  this HESS control strategy, and             optimization) is represented another control parameter to
                                                                                              find the new solution randomly. The best cost function
the error is given to the PI controller (PI_1). The total current
EreSqSu.ireTdhi(sI6*I!6*!6 )6
                               is  developed by the   (PI_1) controller from
                               is  divided into high  frequency components

(I785) and low-frequency components (via LPF), yielding a
reference battery current (I9* ). I9* is compared with the actual
BESS current (I9), and the difference is sent to the (PI_2)
controller, which generates PWM to generate switching
pulses for BESS switches (S#, S$). The component with the
high frequency is defined as:-
                                                  = 	 I6*!6 - 	 I9*
BESS  may   not                track  thI7e8I59*  immediately        because  of  the    (1)
                                                                                       slow

dynamics. As a result, the uncompensated BESS power is

given as:-

            P9_;<=!>?@<AB6@C = V. * 0I785 + 	 I9!""	2                                  (2)

SC will compensate for this uncompensated battery power.
                                   P9_;<=!>?@<AB6@C = PD5
                                                                                       (3)

and the difference of power is sent to the (PI_3) controller,

The PI_3 controller, generates PWM to control the SC

switches (S0, S1).

            V. MODELING AND CONTROL DESIGN

Mathematical Models and control designs for the PV panel,

BESS, SC, and DC-DC converters are shown in this section.

TABLE I represented the parameters of the PV-BESS-SC

hybrid system.

                                      TABLE I

            ELECTRICAL SYSTEM PARAMETERS

Design Parameters                                                    value

PV Input Capacitor, 3'(                                              470 µF
PV Inductor, &'(                                                     880 µH
Output Capacitor, 3E", 3E#, 456	3E$                                  1200 µF
Buck Capacitor for BESS, 3"                                          470 µF
Buck Inductor for BESS, &"                                           550 µH
Boost Inductor for BESS, &9                                          880 µH
Buck Capacitor for SC, 3#                                            470 µF
Buck Inductor for SC, &#                                             550 µH
Boost Inductor for BESS, &D5                                         880 µH
DC-Link Voltage, "%&                                                 400 V
Nominal BESS Voltage, ".                                             192 V
Nominal SC Voltage, "-&                                              220 V

The equivalent circuit of a PV panel with an equation was
explained in [32]. Also, the mathematical model for BESS is
described in [31]. The mathematical model for SC is
described in [33]. In this paper, the PV array consists of 4
strings connected in parallel, with each string containing 12
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