## 4 Simulation Results
### Scenario 1  
The Tree classifier is implemented in the control system of the DC chopper protection method (DCch + Tree). The SVM classifier is used in the control system of DC chopper and CBFCL protection method (DCch + CBFCL + SVM). In this study, these methods will be referred to as DCch-based Tree and DCch + CBFCL-based SVM, respectively. For the grid-connected PVPP system, DCch-based Tree and DCch + CBFCL-based SVM protection techniques are employed separately, with the results shown in Figure 8. In this study, a voltage dip of 90% is simulated between t = 1 s and 1.1 s, representing typical voltage dip duration time in grid systems. A voltage dip of 90% in electrical power grids is known as the least frequent type of voltage dip, but it is a serious situation compared to other types of voltage dip. Therefore, it is quite difficult to control this voltage dip during LVRT. For minimizing the negative impacts of a voltage dip of 90%, 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 90% are illustrated in Figure 8a. The active power produced by a PVPP system under normal operating conditions is 237 kW. When the PVPP system employs the DCch-based Tree approach, its active power peak is 284.63 kW and, after a 90% voltage decrease, its lowest active power value is 25.49 kW. When compared to the outcomes of another protection technique, the PVPP system's peak and lower active power values employing the DCch + CBFCL-based SVM approach have the best values. A PVPP system's DC-link voltage value during a 90% voltage loss is shown in Figure 8b. During normal operation, a PVPP system's DC-link voltage is 481 V. The PVPP system's DC-link voltage, as determined using the DCch-based Tree technique, has a maximum value of 495.32 V and a minimum value of 380.85 V during a 90% voltage drop. When compared to the results of another protection method, the PVPP system's peak and lowest DC-link voltage levels utilizing the DCch + CBFCL-based SVM approach have good values. Figure 8c-f show the changes in q-axis current (\(I_{q}\)), d-axis current (\(I_{d}\)), DC current (\(I_{dc}\)), and the diode current (\(I_{diode}\)) 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 6 compares the effectiveness of both protection techniques for a 90% voltage dip. The analysis of the current waveforms in Figure 8c-f demonstrates that the DCch + CBFCL-based SVM approach enhances active power regulation by maintaining the \(I_{q}\) and \(I_{d}\) currents near their nominal values and offers more stable inverter operation by lowering DC current variations. It is observed that the proposed protection method significantly reduces \(I_{dc}\) current fluctuations. As a result, it prevents the inverter from overloading and unstable operation by preventing sudden changes to input current in the inverter. In addition, it is seen that the DCch + CBFCL-based SVM method minimizes the overcurrent conditions and ensures that the inverter protection mechanisms work more effectively when the diode current (\(I_{diode}\)) is analyzed. The simulation results demonstrate that the proposed protection method provides more effective current regulation during LVRT operation. Figure 8: Dynamic response of the grid-connected PVPP system using the DCch-based Tree and DCch + CBFCL-based SVM protection approaches during voltage dip of 90%: (**a**) active power, (**b**) DC-link voltage, (**c**) q-axis current, (**d**) d-axis current, (**e**) DC current, and (**f**) diode current.