4.2.2. Description of the Meshed 30-Bus Test Systems under Study

The IEEE 30-bus system is considered as a meshed test system in this study to evaluate the proposed approach's efficiency in solving large, meshed networks. As shown in Figure 14, it has 19 lines and 38 DOCRs and it receives power from three distribution substations by bus 1, 6, and 13; each one is represented by a source of 132 MVA, 33 KV as well as with two DG units. The nineteen fault points are labeled as L1 to L19; for each line, there is one fault point as shown in Figure 14. The primary–backup coordination of relays for these fault points and CTI values are illustrated in Table 11 and the optimal TMS, Ip, and A for the meshed 30-bus test system is presented in Table 12. The configurations of the short circuits' current values and more information can be found in ref. [53]. The TMS range is between 1.1 to 1 and for Ip, from 1.4 to 5.9. The minimum value of the CTI is set as 0.3 s.


**Table 10.** Optimal TMS, Ip, and A for the Meshed 9-bus Test System.

**Figure 14.** IEEE 30-Bus MG system (Large-Scale Network).


**Table 11.** CTI for the Meshed 30-bus Test System.

**Table 12.** Optimal TMS, Ip, and A for the Meshed 30-bus Test System.


The optimized values of TMS, Ip, and OTs utilizing NSTCC with the hybrid GSA–SQP algorithm are illustrated in Table 12. It can be noticed from these results that NSTCC is the best approach and achieved the minimum overall OT of all OCRs of 12.231 s compared to 26.826 s and 19.727 s, for the STCC and NSTCC with constant coefficient A, respectively, as it is shown in Table 12. The CTI values calculated from the optimized TMS and Ip are shown in Table 11 and the coordination between primary and backup relays are ensured by the optimal results. Therefore, this signifies that the NSTCC can be efficiently used for solving the OCR coordination problem for the meshed and large-scale power systems.
