6.1.1. Fault on Node 652

The algorithm was tested for all the faulty events simulated at node 652 and found to be effective for the recognition of these events. Position of this node is critical because there is hybrid combination of line between this node and node 650 (where current and voltage are recorded), which consists of UG cable and OH line sections. At the junction of UG cable and OH line, reflection of the faulty transient, carrying travelling wave may take place, which might affect the performance of algorithm. Results of PG fault simulated on phase A at 0.1 s on node 652 are included in Figure 10. Current and voltage signals captured on node 650 for a period of 0.2 s (12 cycles) are detailed in Figure 10a,b, respectively. Current signals are processed using WDF and WD-index is computed, which is described in Figure 10c. It is observed that WD-index corresponding to phase A has a high magnitude after the incidence of PG fault. However, this index corresponding to the phases B and C has values comparable to the pre-fault values. The ALN-index is computed from the voltage signals and described in Figure 10d. It is concluded that the ALN-index corresponding to all phases sharply increases just after the incidence of PG fault.

Figure 5e describes the FI corresponding to all the phases during the event of PG fault. It can be inferred that FI corresponding to faulty phase (phase A) has a higher magnitude compared to TM after the incidence of PG fault. However, FI corresponding to healthy phases B and C has a lower magnitude compared to TM. Hence, it is established that algorithm is effective for the identification of PG fault and discrimination of the healthy and faulty phases even when there is hybrid combination of UG cable and OH line sections.

**Figure 10.** Recognition of PG fault incident on node 652 of hybrid test system (**a**) current waveform (**b**) voltage waveform (**c**) WD-index (**d**) ALN-index (**e**) FI (f) plot to compute fault recognition time.
