## 6 Simulation Results
### Simulation Results of the Line-to-Line Electrical Grid Fault  
In this section, we consider that the phases \"b\" and \"c\" at the PCC at P1 come into accidental contact. Then, the same grid fault is considered at a distance of 45 km from the PCC to the point P2 (Figure 11). Simulation results for this grid fault are shown in Figures 13-15.  
The active powers at the PCC with a short temporary grid fault of two-phase to ground are shown in Figure 14. The reactive powers at the PCC with a short temporary grid fault of two-phase to ground are shown in Figure 15.  
According to Figure 13, which reveals that without the use of D-FACTS systems the voltage at the PCC exceeds the acceptable voltage level 1 pu due to the voltage swell. However, using D-FACTS devices such as D-SVC and the D-STATCOM these undesirable effects are corrected. In addition, voltages at the PCC during a temporary grid fault presented in this figure show that, without the use of D-FACTS and when the grid fault is at the point P1, the voltage at the PCC drops to the value of 0.48 pu, which is less than the acceptable value. Thus, when the grid fault is at the point P2 without D-FACTS, the voltage drops to 0.52 pu. However, with the presence of D-FACTS devices, when this type of grid fault is at point P1, the voltage at the PCC drops to 0.63 with a slight fluctuation. In addition, when the fault is at the point P2 with D-FACTS, the voltage is maintained at 0.71 pu. Moreover, it is noticed that the voltage at the PCC, when using D-STATCOM many oscillations are mitigated compared to using the D-SVC.  
According to Figure 14, which shows that during the occurrence of the same grid fault type in both points P1, P2 and without the presence of D-FACTS systems, no active power is supplied. Then, when the grid fault of 1000 ms duration exceeds the limit (see Figure 2), the wind farm is disconnected from the grid. Moreover, the installation of D-FACTS systems at the PCC guarantees the wind farm commissioning during and after this type of grid fault at these points (P1, P2) without disconnecting from the electrical distribution grid, providing the active power of 10.6 MW. Therefore, in the presence of D-FACTS systems, production of active power by the wind farm is uninterrupted and in the absence of these systems the wind farm is disconnected from the grid by triggering the protection system.  
From Figure 15, it is noticed that in the absence of D-FACTS systems and when the grid fault is located at the points P1 and P2, no exchange of reactive power is provided to the electrical distribution grid. However, in the presence of D-FACTS systems, it provides almost the same amount of reactive power, 7.09 MVAr, when the grid fault is located at point P1 and 8.17 MVAr when the grid fault is located at point P2. Indeed, these injected reactive powers are required for compensation to maintain the stability of the wind farm with the voltage at the PCC around the acceptable value. Therefore, the wind farm is kept in service during and after this type of grid fault without disconnecting from the electrical distribution grid. Thus, the use of D-STATCOM has a capacity to compensate faster than using the D-SVC and the peaks of the injected reactive powers are eliminated.  
Figure 13: (a) Voltage at the PCC during line-to-line electrical grid fault; (b) zoom of voltage at the PCC during line-to-line electrical grid fault.  
Figure 14: **(a)** Active power at the PCC during line-to-line electrical grid fault; (**b**) zoom of active power at the PCC during line-to-line electrical grid fault.