## 5 Conclusions  
The disturbance in protection coordination caused by variations in the fault current level due to wind-speed variation in a wind-farm-integrated power system was investigated in this paper. The proposed algorithm consists of two steps. In the first step, the wind speed is predicted by forecasting it with hybrid ANFIS-SARIMA for a time interval of five minutes, and the fault current level is calculated in advance. Then, to reduce the overall operating times of relays in the second step, the hybrid HHO-LP is proposed for optimal relay coordination by optimizing the relay settings on the basis of the predicted fault current level. These optimal settings are transferred to relays at the start of each interval. If the difference between the actual and predicted value is more than 2%, then the HHO-LP is again run during the interval, and the relay settings are updated, which is a very rare case. The proposed algorithm was tested on a modified IEEE-8 bus system with WTGs and a local wind-farm-integrated substation. The results show that the proposed algorithm provided the optimal relay settings following the variation in fault current level due to wind-speed variation. No miscoordination was seen, and the proper CTI was maintained in all primary-backup relay pairs in all cases for both test benches with a considerable reduction in the overall operation time of relays, which shows the effectiveness of the proposed algorithm. Conceptualization, M.R. and L.H. ; methodology, M.R. and L.H. ; software, M.R. and L.H. ; validation, M.R., L.H., M.S. ([PERSON]), and M.W. ; formal analysis, M.R. and L.H. ; investigation, M.R., L.H., and M.W. ; resources, M.R., L.H., and M.S. ([PERSON]); data curation, S.A., M.W., M.S. ([PERSON]), and M.S. ([PERSON]); writing--original draft preparation, M.R. ; writing--review and editing, M.R., M.S. ([PERSON]), and S.A.; visualization, M.R., S.A., and M.S. ([PERSON]); supervision, L.H. ; project administration, L.H. ; funding acquisition, L.H., M.S. ([PERSON]), and M.S. ([PERSON]). All authors have read and agreed to the published version of the manuscript. \begin{table}
\begin{tabular}{c c c c c c} \hline \multirow{2}{*}{**Interval**} & \multicolumn{2}{c}{**Conventional Settings**} & \multicolumn{2}{c}{**PSO–LP [55]**} & \multicolumn{2}{c}{**Proposed Approach HHO-LP**} \\ \cline{2-6}  & **Operation Time (s)** & **Operation Time (s)** & **Time** & **Operation Time (s)** & **Time** \\  & \(\sum\)(\(t_{p}\)+\(t_{b}\)) & \(\sum\)(\(t_{p}\)+\(t_{b}\)) & **Reduction (\%)** & \(\sum\)(\(t_{p}\)+\(t_{b}\)) & **Reduction (\%)** \\ \hline
1 & 51.248 & 39.515 & 22.894 & 31.860 & 37.831 \\
2 & 48.066 & 37.643 & 21.684 & 32.078 & 33.262 \\
3 & 49.125 & 38.540 & 21.547 & 32.457 & 33.93 \\
4 & 50.864 & 38.632 & 24.048 & 31.638 & 37.799 \\
5 & 51.660 & 39.521 & 23.497 & 31.445 & 39.131 \\
6 & 53.981 & 42.180 & 21.861 & 33.891 & 37.217 \\
7 & 52.112 & 41.919 & 19.559 & 32.514 & 37.607 \\
8 & 55.561 & 43.171 & 22.299 & 34.741 & 37.472 \\
9 & 53.046 & 42.348 & 20.167 & 35.726 & 32.651 \\
10 & 49.220 & 38.790 & 21.933 & 33.189 & 32.57 \\
11 & 58.756 & 47.044 & 19.9332 & 35.210 & 40.074 \\
12 & 52.550 & 41.651 & 20.740 & 32.374 & 38.394 \\ \hline \end{tabular}
\end{table} 
Table 10: Performance improvement in terms of the overall operation time of relays obtained using the proposed HHO-LP. Figure 17: Operation time of primary–backup relays for all relay pairs on 15 July 2019 at **(a)** 10:00 a.m., (b) 10:05 a.m., (c) 10:10 a.m., (d) 10:15 a.m., (e) 10:20 a.m., (f) 10:25 a.m., (g) 10:30 a.m., (h) 10:35 am, (i) 10:40 a.m., (j) 10:454 a.m., (k) 10:50 a.m., and (l) 10:55 a.m.  
**Funding:** This research is funded by the Deanship of Scientific Research at King Saud University through research group No (RG- 1438-089) and in part by the National Natural Science Foundation of China (NNSFC) through grant number 51707034. The authors also thank the Electrical Engineering Department, Southeast University and Lucheng Hong for the support given in conducting the research.