ELECTRIC VEHICLES ON FAULTED DISTRIBUTION
4.5 PEV Charging load Connected to the Main Feeder at Node 840
The analysis shown above was performed on lateral 832-890; this section has the voltage level of 4.16 kV only which is very low compared to the voltage level of main feeder. To see the impact of PEV charging on fault condition in the system on a section at high voltage level, the same analysis is performed on main feeder of the distribution system having nominal voltage rating of 24.9 kV. For this case, the PEV charging load is connected at node 840 of the distribution system on the main feeder.
4.5.1 Unbalanced Faults
(a) Single line to ground faults
With the PEV charging load connected at node 840 of the distribution system on the main feeder a single line to ground fault is applied to phase A at 0.33 s between node 836 and node 840 of the main feeder and the fault is cleared from the system at 0.42 s. The voltage waveform for faulted phase A for PEV load case and equivalent load case is shown in Fig. 4.9(a) and Fig. 4.9(b) respectively. As can be seen when the electrical vehicle charging load is connected at a node of high voltage main feeder the magnitude of voltage transients observed during the period of reconnection of phase A after the fault is cleared from the system is less as compared to the magnitude of voltage transients when the electric vehicle charging load is connected to the low voltage lateral of the distribution system at node 890.
Similar improvement appears in the current waveform as well. As can be seen in Fig. 4.9(c), no significant rise in magnitude of phase B current during the fault is observed with charging vehicle load connected to node 840 of the main feeder, as compared to the case when PEVs load is connected to node 890 of the lateral.
0.3 0.35 0.4 0.45 0.5 time(s)
(a)Phase A voltage -20
-10 0 10 20
Voltage(kV)
0.3 0.35 0.4 0.45 0.5
time(s) (c)Phase B current -10
-5 0 5 10
Current(A)
0.2 0.3 0.4 0.5 0.6
time(s)
(e)Reactive Power for phase B 0.8
1 2 3
kVAR
0.3 0.35 0.4 0.45 0.5
time(s) (b)Phase A voltage -20
-10 0 10 20
Voltage(kV)
0.3 0.35 0.4 0.45 0.5
time(s) (d)Phase B current -10
-5 0 5 10
Current(A)
0.2 0.3 0.4 0.5 0.6
time(s)
(f)Reactive power for phase B -1
0 1
VAR
For equivalent load For PEV load
Figure 4.9: Impact on voltage, current and reactive power for LG fault at 840 No significant change in the reactive power requirement of phase B is observed during fault when the PEVs charging load is connected to the main feeder as shown in Fig. 4.9(e). Reactive power for the equivalent load case is shown in Fig. 4.9(f).
No significant impact in current, voltage and reactive power is observed at other nodes of the distribution system. Hence, it can be said that the effect of PEV load at the time of fault is limited to the faulted node only, because the clearing of fault by the circuit breaker helps in restricting the effect of PEV load to the faulted node only. These results show that the high voltage level of the distribution line minimizes the negative impacts of PEV load on distribution system during the fault.
(b) Double line to ground fault
Fault analysis results for double line to ground fault case on main feeder for a AB phase fault in line section 836-840 is presented in Fig. 4.10.
0.3 0.35 0.4 0.45 0.5
time(s) (a)Three phase voltage -20
-10 0 10 20
Voltage(kV)
0.3 0.35 0.4 0.45 0.5
time(s) (c)Three phase current -12
-6 0 6 12
Current(A)
0.3 0.35 0.4 0.45 0.5
time(s) (e)Reactive Power 0
0.5 1 1.5
kVAR
phase A phase B phase C
0.3 0.35 0.4 0.45 0.5
time(s) (b)Three phase voltage -20
-10 0 10 20
Voltage(kV)
0.3 0.35 0.4 0.45 0.5
time(s) (d)Three phase current -12
-6 0 6 12
Current(A)
0.3 0.35 0.4 0.45 0.5
time(s) (f)Reactive Power -2
0 0 1 2
VAR
phase A phase B phase C
For PEV load For equivalent load
Figure 4.10: Impact on voltage, current and reactive power for LLG fault No significant change is observed in fault current, voltage and reactive power at the faulted node due to the very high voltage level of the distribution feeder compared to the charging station requirements. Fig. 4.10(a) and Fig. 4.10(b) shows the voltage waveform at node 840 for PEV load case and equivalent load case respectively, here, it can be seen that minor voltage transients appear in the waveform for the PEV load case at the time of reclosing whereas in equivalent load case no such transient appears in the waveform. The fault current and reactive power do not show any significant rise in either case.
(c) Line to line faults
Fault analysis for line to line fault case gives similar results as obtained in the double line to ground fault case. Fig. 4.11(a) and Fig. 4.11(b) shows the three phase voltage recorded at node 840, a transient voltage of small magnitude appears in the faulted phase A and phase B for the PEV load case and no such transients in the faulted phases are observed in the equivalent load case. The three phase current at node 840 for the PEV load case and equivalent load case is shown in Fig. 4.11(c) and Fig. 4.11(d) respectively, the fault current does not show any change and the reactive power for the case 1 and case 2 shown in Fig. 4.11(e) and Fig. 4.11(f) respectively also do not show any significant rise.
0.3 0.35 0.4 0.45 0.5
time(s) (a)Three phase voltage -20
-10 0 10 20
Voltage(kV)
0.3 0.35 0.4 0.45 0.5
time(s) (c)Three phase current -12
-6 0 6 12
Current(A)
0.4 0.45 0.5 0.55 0.6
time(s) (e)Reactive Power 0
0.5 1 1.5
kVAR
phase A phase B phase C
0.3 0.35 0.4 0.45 0.5
time(s) (b)Three phase voltage -20
-10 0 10 20
Voltage(kV)
0.3 0.35 0.4 0.45 0.5
time(s) (d)Three phase current -12
-6 0 6 12
Current(A)
0.3 0.35 0.4 0.45 0.5
time(s) (f)Reactive Power -1
0 1 2
VAR
phase A phase B phase C
For equivalent load For PEV load
Figure 4.11: Impact on voltage, current and reactive power for LL fault at node 840
4.5.2 Balanced Faults
The three phase voltage waveform obtained at node 840 when a three-phase fault is applied at section 836-840 is shown in Fig. 4.12. Fig. 4.12(a) shows the three phase voltage waveform for PEV load case and Fig. 4.12(b) shows three phase voltage waveform for equivalent load case. As can be seen, the magnitude of high- frequency switching transients during the fault recovery time for PEV load case is very low compared to that obtained at node 890 in case of three-phase fault.
Figure 4.12: Impact on three phase voltage for LLL fault at node 840
4.5.3 Open Circuit Faults
The results for open circuit fault on main feeder applied in line section 836-840 are shown in Fig. 4.13. The PEV load does not have any significant effect on the voltage, current and reactive power at the faulted node 840 in comparison to the equivalent load as can be seen in the Fig. 4.13.
0.3 0.35 0.4 0.45 0.5 time(s)
(a)Three phase voltage -20
-10 0 10 20
Voltage(kV)
0.3 0.35 0.4 0.45 0.5
time(s) (c)Three phase current -12
-6 0 6 12
Current(A)
0.3 0.35 0.4 0.45 0.5
time(s) (e)Reactive Power 0
0.5 1 1.5
kVAR
phase A phase B phase C
0.3 0.35 0.4 0.45 0.5
time(s) (b)Three phase voltage -20
-10 0 10 20
Voltage(kV)
0.3 0.35 0.4 0.45 0.5
time(s) (d)Three phase current -12
-6 0 6 12
Current(A)
0.3 0.35 0.4 0.45 0.5
time(s) (f)Reactive Power 0
1 2
VAR
phase A phase B phase C
For PEV load For equivalent load
Figure 4.13: Impact on voltage, current and reactive power for open circuit fault at node 840