6.1.2. Fault on Node 634

The algorithm was tested for all the faulty events simulated on node 634 and found to be effective for the recognition of these events. This node is considered due to the availability of a transformer (TRFF) between nodes 633 and 634. Presence of transformer in the path of travelling wave carrying faulty transients may affect the performance of algorithm as transformer is a magnetically coupled inductive element. Node 634 is operated at voltage of 0.48 kV and node 633 is operated at the voltage of 4.16 kV. Results for PG fault simulated on phase A at 0.1 s on node 634 are illustrated in Figure 11. Current and voltage signals captured at node 650 for a period of 0.2 s (12 cycles) are detailed in Figure 11a,b, respectively. Current signals are processed using WDF and WD-index is computed, which is described in Figure 11c. 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 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 11d. It is concluded that the ALN-index corresponding to all phases sharply increases just after the incidence of PG fault.

Figure 11e details 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 incidence of PG fault. However, FI corresponding to healthy phases B and C has a lower magnitude as 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 a transformer between the faulty point and relay location.

**Figure 11.** Recognition of PG fault incident on node 634 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.

#### *6.2. Fault Impedance Variations*

The nature of fault transients is affected by the fault impedance. Hence, fault impedance might affect the performance of the protection algorithm. In common faulty events, the fault impedance ranges from 0 Ω to 5 Ω. Therefore, the algorithm was tested for the fault impedances of 0 Ω, 5 Ω, 10 Ω, 15 Ω, 20 Ω and 25 Ω for all types of faults. FI magnitude associated with all the phases during the PG fault event incident at node 646 is tabulated in Table 5. It can be observed that FI magnitude is higher compared to TM (5000), corresponds to phase A. Further it is lower as compared to TM, corresponds to phases B and C. It is also observed that FI corresponding to faulty phase decreases with increased fault impedance. Therefore, it is established that PG fault will be effectively detected in hybrid grid with RE penetration and fault impedance up to 25 Ω. Furthermore, the algorithm also works efficiently for all types of faults with fault impedances up to 25 Ω.


**Table 5.** Fault Index During PG Faulty Event with Different Fault Impedance.

#### *6.3. Fault Incidence Angle Variations*

Fault transients may also be affected by the fault incidence angle (FIA), which may result false tripping indication. Hence, performance of the algorithm was tested by simulating the fault at node 646 with incidence angles of 0◦, 30◦, 60◦, 90◦, 120◦ and 150◦ for all types of investigated faults. FI magnitude associated with all the phases during the PG fault event incident at node 646 for different angles is tabulated in Table 6. It can be observed that FI magnitude is higher compared to TM (5000), corresponds to phase A and lower compared to TM, corresponds to phases B and C for all types of fault incidence angles. It is also observed that FI corresponding to faulty phase is maximum for FIA of 90◦. Therefore, it is established that PG fault will be effectively detected in hybrid grid with RE penetration and all types of fault incidence angle with respect to current and voltage waveforms. Furthermore, the algorithm also works efficiently for all types of faults for different FIA.


**Table 6.** Fault Index During PG Faulty Event with Different Fault Incidence Angles.
