## 3 Simulation Results
The voltage drop percentage can be calculated using the following expression:  
\[U\left(\%\right)=\frac{\Delta U_{DC}}{U_{DC}}\times 100 \tag{30}\]  
where \(\Delta U_{DC}=U_{DC2}-U_{DC1}\), and \(U_{DC}\) represents the DC bus voltage. In accordance with Equation (30), the table below shows the voltage drop that occurs as a result of a real load supply in an LVDC distribution. With reference to Table 2, it can be noted that an LVDC distribution's average voltage drop is roughly equal to 0.234%. This average voltage drop is more acceptable than that of other existing works [37]. In an HVDC station, power transformers serve various functions: galvanic isolation between the AC and DC sides, limiting the effect of changes in the AC-side voltage through their tap changer, limiting the short-circuit current, and providing a 30\({}^{\circ}\) phase shift between the pulse bridges. A 250 MVA transformer was used in this novel hybrid test system to \begin{table}
\begin{tabular}{c c c} \hline \hline
**Home Appliances** & **Current (A)** & **Voltage Drops (\%)** \\ \hline EV & 10.63 & 0.187 \\ \hline LED lighting & 0.641 & 0.281 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: LVDC voltage drops. Figure 16: DC load voltage values in the LVDC distribution. supply different loads on the DC side. The load voltage and current of the two DC loads are shown in Figures 17 and 18, respectively. It is noted that the voltage of the HVDC distribution system is always equal to 20 kV as presented in Figures 17 and 18. Additionally, the DC load currents 3 and 4 in this HVDC distribution are 40 A and 67 A, respectively. The transition of the electrical distribution network from LVDC to LVAC distribution is feasible in this study due to the development of electronic power converters. The analyzed LVAC distribution included a 1.5 MW wind turbine and AC loads. The turbine power characteristics are shown in Figure 19. According to Figure 19, MPPT is accomplished by maintaining the tip speed ratio, or the ratio of the turbine speed at the tip of a blade to wind velocity, at its ideal value. This can be accomplished by employing a look-up table to set the optimal rotor speed reference to its corresponding observed wind speed. The variation in the wind speed profile over 24 h is shown in Figure 20 to illustrate the performance of this LVAC distribution system [23]. Figure 19: Wind turbine characteristics. Figure 20: Wind speed profile. Figure 21 shows the voltage and current of the first AC load of the LVAC distribution. Referring to Figure 21, it can be observed that the frequency is always 50 Hz and the load voltage (line to the ground) is always 230 V.  
Total harmonic distortion (THD) is one way to assess the power supply quality. It indicates the number of harmonic components in the voltage and current waveforms and the extent of the waveform distortion resulting from them. Furthermore, THD limits for IEEE 519 systems with rated voltages of less than 1 kV should be no more than 5%. Figure 22 illustrates the THD of the signal shown in Figure 21b. As shown in Figure 22, the THD was lower than 5%, which resulted in a higher power factor, higher efficiency, and lower peak currents. With reference to Figure 22, it is possible to emphasize the LVAC distribution's superior performance in terms of its reduced THD when compared with that of other works. Figure 21: AC load 1 voltage (**a**) and current (**b**) of the LVAC distribution. Figure 22: THD obtained for the AC load 1 current. The voltage drop results of the real AC loads in the LVAC distribution based on Equation (30) with a voltage of type alternative are shown in the table below. Based on Table 3, the LVAC distribution's average voltage drop is almost equal to 1.268%, which is tolerable. Based on Tables 2 and 3, we concluded that the LVDC distribution system performs better than the LVAC distribution system in terms of voltage drops.