## 4 Case Studies
### Test System Specification
#### 4.1.2 Jhimpir Wind-Farm-Integrated Substation  
The Jhimpir power substation is a typical wind-farm-integrated substation in the Jamshoro city of Sindh province in Pakistan [56]. The geographical coordinates of this location are latitude = 24.4769 and longitude = 67.9240, and the hub height is 80 m. This wind farm consists of 31 wind turbine generators, \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**WTG Size and Location**} & \multicolumn{2}{c}{**PSO–LP**[55]} & \multicolumn{2}{c}{**HHO–LP**} \\ \cline{2-5}  & \(\mathbf{TOP_{PR}}\) & \(\mathbf{TOP_{BR}}\) & \(\mathbf{TOP_{PR}}\) & \(\mathbf{TOP_{PR}}\) & \(\mathbf{TOP_{BR}}\) \\ \hline
20 WTGs of 1.5 MVA each at bus 3 & 17.17 s & 23.85 s & 15.88 s & 21.36 s \\
15 WTGs of 2.5 MVA each at bus 4 & 15.25 s & 22.44 s & 13.44 s & 19.57 s \\
20 WTGs at bus 3 and 10 WTGs at bus 4 each of 1.5 MVA & 28.17 s & 37.27 s & 24.73 s & 33.16 s \\
15 WTGs at bus 3 and 10 WTGs at bus 6 each of 1.5 MVA & 26.47 s & 35.57 s & 23.93 s & 32.43 s \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Primary and backup relay operation times with variable wind turbine generator (WTG) capacity and location. Figure 14: Primary and backup relay pairs as a function of operation time with a wind speed of 20 m/s and an angle variation of \(10^{\circ}\) using conventional settings and those updated with PSO–LP and HHO–LP. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**WTG Integration**} & \multicolumn{2}{c}{**Conventional Settings**} & \multicolumn{2}{c}{**PSO–LP**[55]} & \multicolumn{2}{c}{**Proposed Approach HHO–LP**} \\
**Bus No.** & **Size (MW)** & **Operation Time (s)** & **Operation Time (s)** & **Time Reduction** & **Operation Time (s)** \\  & \(\Sigma(t_{p}+t_{h})\) & \(\Sigma(t_{p}+t_{h})\) & \(\Sigma(t_{p})\) & \(\Sigma(t_{p}+t_{h})\) & **Time Reduction (\%)** \\ \hline
3 & 30 & 52.14 & 41.02 & 21.327 & 37.24 & 28.577 \\
4 & 37.5 & 48.76 & 37.69 & 22.703 & 33.01 & 32.301 \\
3, 6 & 60, 30 & 72.28 & 62.038 & 14.169 & 56.36 & 22.026 \\
3, 4 & 30, 15 & 76.06 & 65.44 & 13.963 & 57.89 & 23.889 \\
3, 6 & 22.5, 15 & 75.44 & 62.04 & 17.623 & 56.36 & 25.292 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Performance improvement in terms of overall operation time of relay obtained using proposed HHO–LP. Figure 15: CTI obtained with conventional settings and those updated with PSO–LP and HHO–LP for IEEE-8 bus system for all cases. each of capacity 1.6 MW. A doubly fed induction type generator (GE 1.6 MW/103) is installed in the WF. The cut-in, cut-out, and rated wind speed are 3.5 m/s, 25 m/s, and 12 m/s, respectively. The generated voltage is 0.690 kV, which is stepped up to 22 kV. Then, the 22 kV lines are connected to 132 kV lines with a step-up transformer of 22 kV/132 kV, 100 MVA. A one-line diagram of the wind-farm-integrated substation is given in Figure 16. This system has 36 overcurrent relays and there are 35 primary-backup relays pairs, as given in Table 8. The predicted and measured wind speeds for one day in all four seasons are already reflected in Figure 7. It can be seen that wind speed is high during the spring season; thus, it can have a high impact on the variation in fault current level. Therefore, to validate the proposed algorithm in the Jhimpir wind-farm-integrated substation, one hour was selected from the day of the spring season, i.e., 10:00 a.m. to 11:00 a.m. on 15 July of 2019. The minimum and maximum limits of TMS were 0.5 and 1.1, whereas, for \(\mathrm{I_{P}}\), these limits were \(1.1\times\mathrm{I_{Load}}\) and \(1.5\times\mathrm{I_{Load}}\) respectively. The CTI, in this case was set to 0.3. The proposed algorithm was implemented, and the relay settings were updated after every 5 min.