## 4 Overcurrent Protection Coordination Results, Analysis and Discussion
### Protection Coordination Results in Scenario 1
\begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**The OCRs**} & \multirow{2}{*}{**50P**} & \multirow{2}{*}{**50G**} & \multirow{2}{*}{**50G**} & \multicolumn{4}{c}{**51P**} & \multicolumn{4}{c}{**51G**} \\ \cline{4-14}  & & & & & **GA** & **GSA** & **PSO-GSA** & & **GA** & **GSA** & **PSO-GSA** \\ \hline \multirow{4}{*}{The 471 Hao-Vo OCR} & \multirow{4}{*}{\(I_{f}\)} & \multirow{4}{*}{20,469 A} & \multirow{4}{*}{\(I_{f}\)} & \multirow{4}{*}{22,340 A} & A & 13.06 & 57.94 & 68.34 & A & 50.75 & 89.14 & 93.49 \\  & & & & & B & 2.14 & 2.44 & 2.49 & B & 2.12 & 2.31 & 2.50 \\  & & & & & C & 1.11 & 0.38 & 1.43 & C & 0.71 & 0.83 & 1.48 \\ \cline{2-14}  & & & & & TDS & 0.41 & 0.33 & 0.21 & TDS & 0.067 & 0.05 & 0.05 \\ \cline{2-14}  & & & & & & & & & & & \\ \cline{2-14}  & \multirow{4}{*}{\(t_{trip}^{defined}\)} & \multirow{4}{*}{0.01 s} & \multirow{4}{*}{\(t_{trip}^{defined}\)} & \multirow{4}{*}{0.01 s} & \multicolumn{4}{c}{The tripping time of the relay for the typical fault at Bus 5:} \\ \cline{4-14}  & & & & & & & & & & & \\ \cline{2-14}  & & & & & & & & & & & \\ \cline{2-14}  & \multirow{4}{*}{\(I_{f}\)} & \multirow{4}{*}{6488 A} & \multirow{4}{*}{\(I_{f}\)} & \multirow{4}{*}{10316 A} & A & 36.23 & 72.58 & 5.81 & A & 78.07 & 74.84 & 13.74 \\  & & & & & B & 1.32 & 2.42 & 2.50 & B & 2.36 & 2.32 & 2.37 \\ \cline{2-14}  & & & & & C & 1.07 & 0.22 & 0.00 & C & 0.25 & 0.53 & 0.00 \\ \cline{2-14}  & & & & & TDS & 0.05 & 0.15 & 2.24 & TDS & 0.03 & 0.03 & 0.17 \\ \cline{2-14}  & \multirow{4}{*}{\(t_{trip}^{defined}\)} & \multirow{4}{*}{0.01 s} & \multirow{4}{*}{\(t_{trip}^{defined}\)} & \multirow{4}{*}{0.01 s} & \multicolumn{4}{c}{The tripping time of the relay for the typical fault at Bus 5:} \\ \cline{4-14}  & & & & & & & & & & & \\ \cline{2-14}  & & & & & & & & & & & \\ \cline{2-14}  & \multirow{4}{*}{\(I_{f}\)} & \multirow{4}{*}{2340 A} & \multirow{4}{*}{\(I_{f}\)} & \multirow{4}{*}{4246 A} & A & 0.036 & 59.36 & 0.01 & A & 3.95 & 59.97 & 0.01 \\ \cline{2-14}  & & & & & B & 2.14 & 2.31 & 0.48 & B & 2.39 & 2.29 & 1.72 \\ \cline{2-14}  & & & & & C & 1.00 & 0.01 & 0.00 & C & 0.3 & 0.72 & 0.01 \\ \cline{2-14}  & \multirow{4}{*}{\(t_{trip}^{defined}\)} & \multirow{4}{*}{0.01 s} & \multirow{4}{*}{\(t_{trip}^{defined}\)} & \multirow{4}{*}{0.01 s} & \multicolumn{4}{c}{TDS} & 0.01 & 0.01 & 1.17 & TDS & 0.01 & 0.01 & 0.01 \\ \cline{2-14}  & & & & & & & & & & & \\ \cline{2-14}  & \multirow{4}{*}{\(t_{trip}\)} & \multirow{4}{*}{0.01 s} & \multirow{4}{*}{\(t_{trip}^{defined}\)} & \multirow{4}{*}{0.01 s} & \multicolumn{4}{c}{The tripping time of the relay for the typical fault at Bus 5:} \\ \cline{4-14}  & & & & & & & & & & & \\ \cline{2-14}  & & & & & & & & & & & \\ \cline{2-14}  & & & & & & & & & & & \\ \cline{2-14}  & & & & & & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Optimal protection coordination results of the OCRs in Scenario 1 and their tripping time when the fault is at Bus 5. Figure 11: Optimal protection characteristic curves of the OC relays in Scenario 1 of the 22 kV distribution system.