## 2 Implementation of CBFCL in PV Systems  
The voltage dip measurement range for different countries is illustrated in Figure 1[5]. The allowable voltage dip values of seven countries from various continents are selected in Table 1. The duration time values of these countries are between 140 ms and 625 ms. The restoration time values of these countries are between 750 ms and 3000 ms. The DC chopper is widely used in the literature for fault current protection systems of grid-connected PVPP systems. The DC chopper circuit is placed between a T-type inverter and a PV panel. The DC chopper topology for the PVPP system is given in Figure 2. A DC chopper circuit includes an IGBT and a very small DC resistor connected in series with it. A DC chopper operates through the gate opening and closing signals of the IGBT. A trigger signal is given to the IGBT to protect the PV panels against damage caused by the fault occurring in the electric power grid. Therefore, the protection circuit is activated and protected from the harmful effects of overcurrent. In this study, a DC chopper control system is defined as an ML algorithm. The DC bus voltage value is measured in real time and is defined as the input of the ML algorithm. A switching signal of the semiconductor switching element in the DC chopper is an output of the ML method. In this study, the output voltage value (\(V_{dc}\)) of the PV panel system is set as 481. The ML algorithm detects the fluctuation in the \(V_{dc}\) voltage value and generates output signals. After the grid fault is cleared, a well-designed procedure is applied to generate PV panel voltage and quickly restart the T-type inverter. A DC chopper circuit is closed by an ML algorithm when the grid voltage returns to a normal level. The design of a DC chopper is illustrated in Figure 2.  
The design of a capacitive bridge fault current limiter with a machine learning technique and a flowchart of the proposed control algorithm are illustrated in Figure 3a,b, respectively. CBFCL is designed to protect the electrical network from the harmful effects of high voltage and current generated during faults in energy transmission and distribution networks. The structure of CBFCL consists of a control system and an electronic circuit. The control system of CBFCL continuously measures the voltage, current, and frequency of the PV system and continuously monitors the operation of the PV system. These control systems detect fault conditions occurring in electric energy systems and then regulate the signals of electronic switching elements. CBFCL's electrical circuit comprises two circuits: \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Grid Code** & **UK** & **Denmark** & **Germany** & **Canada** & **Spain** & **USA** \\ \hline Voltage dip duration time (T\({}_{\text{D}}\)) & 140 ms & 140 ms & 150 ms & 150 ms & 500 ms & 625 ms \\ \hline Minimum voltage level (\%) & 0 & 25 & 0 & 0 & 20 & 15 \\ \hline Voltage restoration time (T\({}_{\text{R}}\)) & 1200 ms & 750 ms & 1500 ms & 1000 ms & 1000 ms & 3000 ms \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The allowable voltage dip values of seven countries. Figure 1: The allowable voltage dip values of six countries from different continents. shunt and bridge. The control system generates the switching signal for the IGBT. The IGBT's switching signal value is 1 when the PV system is operating normally. The system's line current passes via the bridge portion because the semiconductor switch is closed. The IGBT switching signal value is zero when the PV system is operating fautiliy. The semiconductor switch is open, and the system's line current flows through the shunt component. The shunt circuit is made up of impedance-matched resistors and capacitors. As a result, the shunt component controls the high current during the fault time, protecting the PV system from the negative consequences of the high current. In addition, CBFCL reduces voltage fluctuations throughout the fault time.