4. Integration of renewable energy sources and its interaction with the V2G system
voltage level and load lower than the base load will lead to rise in the voltage level. In other words, valley filling area is increased and the peak shaving area is reduced with the inclusion of renewable energy sources. If the utilisation of EVs in peak and off-peak hours is achieved then the load curve is flattened and the voltage becomes closer to unity.
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0 50 100 150 200 250
Time(hrs)
Power (kW)
Effective load profile of node 3.3 with
renewable Load profile of node 3.3
(without renewable)
Base load Solar + Wind
power
Wind power Solar power
Figure 4.11: CASE I: Load curve of node 3.3 with integration of renewable energy sources
Considering the base load to be 150 kW, ‘power to be compensated’ is shown in Figure 4.12.
X and Y marked regions in the figure represents the amount of power to be compensated (Pcomp). Negative area (Y) is for discharging excess energy to the grid and the positive area (X) is for charging the EVs batteries at the CS. Type A and Type B energy curve is used between 0800 hrs - 1800 hrs and 1800 hrs - 0800 hrs respectively. With the utilization of EVs as a storage, X and Y area can be reduced resulting in the flattening of the node voltage. The voltages of the node with and without integration of the solar and wind energy sources are shown in Figure 4.13. It is observed that voltage of the node diverges from 1 p.u to a higher value with the integration of renewable energy sources.
Now, based on the energy availability at the CS, node voltage and power to be compensated (Figure 4.12), FLC decides the flow of the amount of power between the grid and the CS and it is shown in Figure 4.14. It is observed from this figure that at 0800 hrs, there is a large gap between the FLC output and the power to be compensated. This is due to low energy availability of battery during this time, which is a consequence of the assumption of Gaussian arrival of the EVs at the CS. But after this duration, the difference is very small. Similar scenario is observed at 1800 hrs. The node voltage after the inclusion of the FLC based CS has
4.4 Results and discussion
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−50 0 50 100 150 200 250
Time(hrs)
Power(kW)
Base load Effective load curve with renewable
Y X
Power to be compensated
Type A
Type B Type B
Figure 4.12: CASE I: Power to be compensated at node 3.3 with the integration of solar and wind energy
0300 0600 0900 1200 1500 1800 2100 2400
0.8 0.85 0.9 0.95 1 1.05 1.1
Time(hrs)
Voltage(p.u.)
Voltage at base load
Node Voltage with integration of renewable energy sources
Node Voltage without integration of renewable energy sources
Figure 4.13: CASE I: Voltage of node 3.3 with and without integration of renewable energy sources.
been maintained near to unity due to flattening of the load profile and it is shown in Figure 4.15.
4.4.2 Case II: Industrial load at node 2.3
In this case, the load curve as shown in Figure 4.10 is used to study the interaction of renewable energy sources in the presence of FLC based CS. The analysis will be done only between 0800 hrs and 1800 hrs since, only industrial load is connected at this node and therefore, people working in this area will park their EVs at the CS only during day time. Load curve of node 2.3 with integration of solar and wind power is shown in Figure 4.16. With the integration of renewable energy sources, the effective load has been reduced. Therefore, the valley filling area is increased and the peak shaving area is reduced as shown in the figure.
The ‘power to be compensated’ has been shown in Figure 4.17. ‘X’and ‘Y’marked region TH-1125_09610202
4. Integration of renewable energy sources and its interaction with the V2G system
0300 0600 0900 1200 1500 1800 2100 2400
−50 0 50 100 150 200
Time(hrs)
Power(kW)
Power to be compensated
Type A
Type B
FLC output Effective
load curve with renewable Type B
Figure 4.14: CASE I: FLC power output and the power to be compensated
0300 0600 0900 1200 1500 1800 2100 2400 0.8
0.85 0.9 0.95 1 1.05 1.1
Time(hrs)
Voltage(p.u.)
Node voltage at base load
Node voltage with implementation of FLC
based CS
Figure 4.15: CASE I: Node voltage with implementation of FLC based CS
in the figure represents the amount of power to be compensated. Negative area (Y) is for discharging the excess energy to the grid and positive area (X) is for the charging of EVs batteries at the CS.
The voltage of the node 2.3 (with and without renewable energy sources) is shown in Fig- ure 4.18.
The FLC output is shown in Figure 4.19. In this figure, FLC output is only shown for 0800 hrs to 1800 hrs. It is observed that the proposed controller maintains almost similar curve as that of ‘power to be compensated’. Similarly, the voltage of the node can be shown to be near to unity after the inclusion of FLC based CS.
The energy utilization for the CASE I and CASE II have been shown in Figure 4.20. The positive energy shown in this figure is the required energy and the negative energy is the available energy. These energy curves are different from the curves shown in Figure 4.7 and
4.4 Results and discussion
0400 0700 1000 1300 1600 2000 2400
0 50 100 150 200 250 300
Time(hrs)
Power(kW)
Base load
Load profile of node 2.3 without renewable
Wind power
Solar+Wind power
Solar power Effective load profile of node 2.3 with renewable
Figure 4.16: CASE II: Load curve of node 2.3 with integration of renewable energy sources.
0300 0600 0900 1200 1500 1800 2100 2400
−100 0 100 200 300
Time(hrs)
Power(kW)
Y
X X
Base load
Effective load profile of node 2.3 with renewable Load profile of
node 2.3 without renewable
Type A Power to be compensated
Figure 4.17: CASE II: Power to be compensated at node 2.3 with the integration of solar and wind energy
0300 0600 0900 1200 1500 1800 2100 2400
0.8 0.85 0.9 0.95 1 1.05 1.1
Time(hrs)
Voltage(p.u.) Node voltage without
renewable energy sources Voltage at
base load
Node voltage with renewable energy sources
Figure 4.18: CASE II: Voltage of node 2.3, with and without renewable energy sources
Figure 4.8. It is observed that the energy curve is changing very steeply at certain value of time. This is because EVs arrive/depart every hour. Due to sudden arrival of EVs, the energy level of the CS increases. But, during a certain period, the energy reduces as it is utilised by the grid or by the EVs’ batteries at the CS.
TH-1125_09610202
4. Integration of renewable energy sources and its interaction with the V2G system
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−50 0 50 100 150 200
Time(hrs)
Power(kW) FLC output
Type A Power to be
compensated
Effective load curve with renewable
Figure 4.19: CASE II: FLC power output along with ‘power to be compensated’
0300 0600 0900 1200 1500 1800 2100 2400
−400
−200 0 200 400
Time(hrs)
Energy(kWh)
Energy availability
CASE II CASE I
Energy required
Figure 4.20: Energy utilization of the CS batteries for the CASE I and CASE II