## 4 Results and Discussion
### Model Parameters  
The main parameters of the used computational models are presented in this section. Table 1 presents the main parameters of the equivalent main power system to which the ST is connected. Table 2 presents relevant data of the ST.  
\begin{table}
\begin{tabular}{l l} \hline Generation Capacity & 1 GW \\ Total Load & 600 MW/200 MVA \\ Equivalent system Inertia (H) & 2 s \\ Equivalent impedance (seen from MV connection) & 0.02 + j0.232 \(\Omega\) \\ \hline \end{tabular}
\end{table}
Table 1: Main power system: main parameters.  
Figure 17: \(P(f_{LV})\) and \(P(VDC)\) droop controllers incorporated in the controllable AC (**A**) and DC (**B**) DER units connected to the hybrid distribution network.  
Regarding the steady-state conditions for the considered scenarios, the relevant data are presented in Table 3. For the net load scenarios, a total active load of 1.15 MW and a total active generation of 830 kW are considered in the hybrid AC/DC network in steady-state conditions (operation at nominal voltage and frequency). Regarding the net generation scenarios, considering the same conditions, a total active load of 700 kW and a total active generation of 1.1 MW are considered in the hybrid AC/DC network. Regarding the parametrization of the droop controllers for all scenarios, they were set according to Table 4.  
\begin{table}
\begin{tabular}{l l} \hline Nominal Power & 1 MVA \\ Nominal MV AC Voltage (ph-ph) & 15,000 V (RMS) \\ Nominal MV DC link Voltage & 27,000 V \\ Nominal LV DC link Voltage & 720 V \\ Nominal LV AC Voltage (ph-n) & 230 V (RMS) \\ \hline \end{tabular}
\end{table}
Table 2: Smart Transformer: main parameters.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Net load scenario** & & & & \\ \hline
**Z Cables \({}^{\star}\)** & **Load** & **PV Generation \({}^{\star\star}\)** & **EV Charging \({}^{\star\star}\)** & **ESS \({}^{\star\star}\)** \\ \hline \multicolumn{5}{c}{LV AC network} \\ \hline
0.01 + j0.003 \(\Omega\) & 500 kW/220 kvar & \(-\)30 kW (\(-\)30–0 kW) & - & 0 kW (\(\pm\)30 kW) \\ \hline \multicolumn{5}{c}{LV DC network} \\ \hline
0.02\(\Omega\) & 50 kW/- & \(-\)150 kW (\(-\)150–0 kW) & 200 kW (0–300 kW) & - \\ \hline \multicolumn{5}{c}{MV DC network} \\ \hline
0.02\(\Omega\) & 150 kW/- & \(-\)650 kW (\(-\)650–0 kW) & 250 kW (0–400 kW) & - \\ \hline \multicolumn{5}{c}{Smart Transformer} \\ \hline - & 330 kW/0 kvar \({}^{\star\star\star}\) & - & - & 0 kW (\(\pm\)1 MW) \({}^{\star\star\star}\) \\ \hline \multicolumn{5}{c}{**Net Generation Scenario**} \\ \hline
**Z Cables \({}^{\star}\)** & **Load** & **PV Generation \({}^{\star\star}\)** & **EV Charging \({}^{\star\star}\)** & **ESS \({}^{\star\star}\)** \\ \hline \multicolumn{5}{c}{LV AC network} \\ \hline
0.01 + j0.003 \(\Omega\) & 400 kW/220 kvar & \(-\)200 kW (\(-\)200–0 kW) & - & 0 kW (\(\pm\)30 kW) \\ \hline \multicolumn{5}{c}{LV DC network} \\ \hline
0.02\(\Omega\) & 50 kW/- & \(-\)200 kW (\(-\)200–0 kW) & 100 kW (0–300 kW) & - \\ \hline \multicolumn{5}{c}{MV DC network} \\ \hline
0.02\(\Omega\) & 150 kW/- & \(-\)700 kW (\(-\)700–0 kW) & 150 kW (0–400 kW) & - \\ \hline \multicolumn{5}{c}{Smart Transformer} \\ \hline - & \(-\)400 kW / 0 kvar \({}^{\star\star\star}\) & - & - & 0 kW (\(\pm\)1 MW) \({}^{\star\star\star}\) \\ \hline \hline \end{tabular} \({}^{\star\star}\) All cable sections in each sub-network are considered to have the same impedance; \({}^{\star\star}\) the allowable variation range is represented between brackets; \({}^{\star\star\star}\) net load in the ST MV inverter (sum of active load and generation in the hybrid network; \({}^{\star\star\star\star}\) local ESS incorporated in the ST.  
\end{table}
Table 3: Steady-state conditions and operation limits (nominal voltage and frequency).