## 4 Simulation Results
### Scenario 2  
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 9. In this study, a voltage dip of 50% is simulated between t = 1 s and 1.1 s, representing the typical voltage dip duration time in grid systems. A 50% voltage dip in an electrical power grid is a medium-severity fault condition. For minimizing the negative impacts of a voltage dip of 50%, 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 50% are given in Figure 9a. When the PVPP system employs the DCch + CBFCL-based SVM approach, its active power peak is 271.34 kW and, after a 50% voltage decrease, its lowest active power value is 137.08 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 50% voltage loss is shown in Figure 9b. 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 + CBFCL-based SVM technique, has a minimum value of 427.03 V and a maximum value of 484.14 V during a 50% 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 9c-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 7 compares the effectiveness of both protection techniques for a 50% voltage dip. The analysis of current waveforms in Figure 9c-f demonstrates the effect of DCch-based Tree and DCch + CBFCL-based SVM methods on current responses during the LVRT process. The q-axis current \(I_{q}\) and d-axis current \(I_{d}\) control the active power and DC-link voltage of the grid-connected PV system, respectively. The DCch + CBFCL-based SVM method reduces the fluctuations in active power value by keeping the \(I_{q}\) current closer to the nominal value during a voltage dip. The DCch + CBFCL-based SVM method reduces the fluctuations in the DC-link voltage value by keeping the Id current close to zero level. The proposed method significantly reduces the fluctuations in DC current (\(I_{dc}\)). It prevents overloading and unstable operation of the inverter by preventing sudden changes in the inverter input current. Diode current is a critical parameter for the protection circuits of an inverter. Long-term hardware problems and thermal stress in the inverter components are avoided by managing excessive diode current. As a result, it helps the system to provide more stable operation by increasing its contribution to the grid during the LVRT process.  
Figure 9: _Cont._