## 4 Simulation Results
### Scenario 3  
For the grid-connected PVPP system, the DCch-based Tree and DCch + CBFCL-based SVM protection techniques are employed separately, with the results shown in Figure 10. In this study, a voltage dip of 25% is simulated between t = 1 s and 1.1 s, representing typical voltage dip duration time in grid systems. A 25% voltage dip is the most common voltage dip type in an electrical power grid. Therefore, it is a more serious situation than other voltage dips. For minimizing the negative impacts of a voltage dip of 25%, the DCch-based Tree and DCch + CBFCL-based SVM protection approaches are employed. The active power fluctuations produced by the PVPP system during a voltage drop of 25% are given in Figure 10a. The PVPP system employs the DCch-based Tree approach, and its active power peak is 243.31 kW. The PVPP system employs the DCch + CBFCL-based SVM approach, and its active power peak is 240.46 kW. The PVPP system employs the \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Signal** & **Method** & **Peak Value** & **Lowest Value** & **Restoration Time (ms)** \\ \hline \multirow{2}{*}{P (kW)} & DCch-based Tree & 298.56 & 131.61 & 164.2 \\ \cline{2-5}  & DCch + CBFCL-based SVM & 271.34 & 137.08 & 126.45 \\ \hline \multirow{2}{*}{DC-link voltage Vdc (V)} & DCch-based Three & 494.99 & 367.98 & 147.83 \\ \cline{2-5}  & DCch + CBFCL-based SVM & 484.14 & 427.03 & 109.26 \\ \hline \multirow{2}{*}{DC current (p.u.)} & DCch-based Tree & 528.06 & 482.28 & 169.09 \\ \cline{2-5}  & DCch + CBFCL-based SVM & 524.46 & 498.69 & 128.49 \\ \hline \multirow{2}{*}{Diode current (A)} & DCch-based Tree & 42.11 & 0.13 & 145.28 \\ \cline{2-5}  & DCch + CBFCL-based SVM & 26.08 & 1.92 & 109.28 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Evaluation of two protection strategies’ tracking effectiveness for a 50% voltage dip in time t = 1 s.  
Figure 9: Dynamic response of the grid-connected PVPP system using the DCch-based Tree and DCch + CBFCL-based SVM protection approaches during voltage dip of 50%: (**a**) active power, (**b**) DC-link voltage, (**c**) q-axis current, (**d**) d-axis current, (**e**) DC current, and (**f**) diode current. DCch-based Tree approach, and its active power is the lowest, at 178.17 kW. The PVPP system employs the DCch + CBFCL-based SVM approach, and its active power is the lowest, at 190.41 kW. The PVPP system, using the DCch + CBFCL-based SVM strategy, has the best peak and lowest active power levels when compared to the results of another protection technique. A PVPP system's DC-link voltage value during a 25% voltage loss is shown in Figure 10b. The PVPP system's DC-link voltage, as determined using the DCch + CBFCL-based SVM technique, has a minimum value of 427.03 V and a maximum value of 484.14 V during a 25% voltage drop. The PVPP system employs the DCch-based Tree technique, and its active power peak is 484.11 V. The PVPP system employs the DCch + CBFCL-based SVM technique, and its DC-link voltage peak is 484.06 V. The PVPP system employs the DCch-based Tree technique, and its DC-link voltage is the lowest, at 452.05 V. The PVPP system employs the DCch + CBFCL-based SVM technique, and its DC-link voltage is the lowest, at 452.99 V. The peak and lowest DC-link voltage levels of the PVPP system using the DCch + CBFCL-based SVM methodology exhibit good values when compared to the outcomes of another protection method. Figure 10c-f show the changes in q-axis current (\(I_{d}\)), d-axis current (\(I_{d}\)), DC current (\(I_{dc}\)), and the diode current (\(I_{dicate}\)) of the PVPP system, respectively. Current values for \(I_{q}\) and \(I_{d}\) are set to 1 and 0, respectively. During normal operation, the PVPP system's nominal DC current is 500 A, and the diode current is 23 A. Table 8 compares the effectiveness of both protection techniques for a 25% voltage dip.