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Campus da FEUPRua Dr. Roberto Frias, 3784200 - 465 PortoPortugal
T +351 222 094 000F +351 222 094 050
© 2009
Integração na rede eléctrica de veículos eléctricos
F. J. SoaresF. J. Soares
2009 Julho 29
© 2009
Introduction
• Electric power systems are facing a new challenge: the integration of Electric Vehicles (EVs) in the electricity grids
• Uncertainties related to when and where EVs will charge will become a critical issue for electricity networks operation
• For home charging, 3 different charging approaches can be adopted:
– Dumb charging approach – EVs’ owners are completely free to connect and charge their vehicles whenever they want, being the cost of the electricity constant along the day
– Dual tariff policy – is given the possibility to EVs‘ owners charge their vehicles at a lower price, during valley hours
– Smart charging strategy – a hierarchical control structure manages EVs charging according to grid’s needs
• Electric power systems are facing a new challenge: the integration of Electric Vehicles (EVs) in the electricity grids
• Uncertainties related to when and where EVs will charge will become a critical issue for electricity networks operation
• For home charging, 3 different charging approaches can be adopted:
– Dumb charging approach – EVs’ owners are completely free to connect and charge their vehicles whenever they want, being the cost of the electricity constant along the day
– Dual tariff policy – is given the possibility to EVs‘ owners charge their vehicles at a lower price, during valley hours
– Smart charging strategy – a hierarchical control structure manages EVs charging according to grid’s needs
2Ciência 2009
© 2009
Steady-state case study (MV network)
Residential MV gridResidential MV grid
3Ciência 2009
0
2
4
6
8
10
12
14
16
18
1 5 9 13 17 21
% C
onsu
mpt
ion
Hours
Dumb charging
Dual tariff policy
Smart charging
0
2
4
6
8
10
12
14
16
18
1 5 9 13 17 21
% C
onsu
mpt
ion
Hours
Dumb charging
Dual tariff policy
Smart charging
0
20
40
60
80
100
1 5 9 13 17 21
% C
onsu
mpt
ion
Hours
TOTAL
Household
Commercial
Industrial
0
20
40
60
80
100
1 5 9 13 17 21
% C
on
sum
ptio
n
Hours
TOTAL
Household
Commercial
Industrial
EVs energy demand
EVs energy demand
Regular energy demand
Regular energy demand
© 2009
Steady-state results
4Ciência 2009
– Dumb charging approach - 10% allowable EVs integration
– Dual tariff policy – 14% allowable EVs integration (considering that 25% of the EVs only charge during the cheaper period – valley hours)
– Smart charging strategy – 52% allowable EVs integration (considering that 50% of EVs‘ owners adhered to the smart charging system)
– Dumb charging approach - 10% allowable EVs integration
– Dual tariff policy – 14% allowable EVs integration (considering that 25% of the EVs only charge during the cheaper period – valley hours)
– Smart charging strategy – 52% allowable EVs integration (considering that 50% of EVs‘ owners adhered to the smart charging system)(assuming 1.5 vehicles per household – 12744 vehicles
within the grid)
(assuming 1.5 vehicles per household – 12744 vehicles within the grid)
© 2009
0
5
10
15
20
25
30
No Evs 10% Evs 14% Evs 52% Evs
Loss
es (M
Wh)
No EVs
Dumb charging
Dual tariff policy
Smart charging
Steady-state results
5Ciência 2009
Daily lossesLoad diagrams with 52% EVs
0
5
10
15
20
25
30
35
1 5 9 13 17 21
Load
(MW
)
Hours
Network base load Load with the dumb charging
Load with the dual tariff Load with the smart charging
© 2009
Steady-state results – branches’ congestion levels overview (peak hour)
6Ciência 2009
No EVs Dumb charging – 52% EVs
Dual tariff – 52% EVs Smart charging – 52% EVs
© 2009
Conclusions from the steady-state study
• Low voltages are the limiting factor to further EVs deployment, for all charging strategies.
• The system can handle the penetration of EVs up to 10%, without changes in the electricity network, if a dumb charging approach is used.
• The dual tariff policy improves the integration capability of this grid up to 14%. This value can be higher if a dedicated and dynamic dual tariff is created for EVs.
• The smart charging approach proved to be the most effective one, as by applying a simple set of rules EVs deployment capability was increased to 52%.
• Low voltages are the limiting factor to further EVs deployment, for all charging strategies.
• The system can handle the penetration of EVs up to 10%, without changes in the electricity network, if a dumb charging approach is used.
• The dual tariff policy improves the integration capability of this grid up to 14%. This value can be higher if a dedicated and dynamic dual tariff is created for EVs.
• The smart charging approach proved to be the most effective one, as by applying a simple set of rules EVs deployment capability was increased to 52%.
7Ciência 2009
© 2009
Dynamic stability case study (small island)
8Ciência 2009
• 1 vehicle per household
• 2150 vehicles
• 323 (15%) EVs
Scenario 1 Scenario 2
PTotal load (kW) 2172 2172
Pload (kW) 1770 1770
PEV load (kW) 402 402
PEV available (kW) 851 851
Pwind (kW) 900 1272
Psync1 (kW) 636 450
Psync2 (kW) 636 450
Scenario 1 Scenario 2
PDiesel1,2 (kW) 1500 1500
PDiesel3,4 (kW) 1800 1800
PWind (kW) 1320 1980
PPV (kW) 100 100
Installed powerInstalled power
Valley hour operation (load plus generation dispatch)
Valley hour operation (load plus generation dispatch)
© 2009
Dynamic stability case study – sudden win shortfall
9Ciência 2009
• Sudden shortfall on wind speed may jeopardize current power quality standards under EN 50.160 for isolated systems
• It is a limiting factor to the integration of Intermittent Renewable Energy Sources
• Sudden shortfall on wind speed may jeopardize current power quality standards under EN 50.160 for isolated systems
• It is a limiting factor to the integration of Intermittent Renewable Energy Sources
0 1 2 3 45
6
7
8
9
10
Time (s)
Win
d S
pe
ed
(m
/s)
Disturbance applied to the case study
Disturbance applied to the case study
© 2009
Conclusions from the dynamic stability study
• It is possible to verify that this system improved dramatically its performance when EVs were used for frequency control.
• Electric vehicles interfaced with the grid in a smart way can increase robustness of operation to power system dynamic behaviour.
• The presence of a considerable amount of storage capability connected at the distribution level also allows the operation of isolated distribution grids with large amounts of IRES and/or microgeneration units connected to it.
• It is possible to verify that this system improved dramatically its performance when EVs were used for frequency control.
• Electric vehicles interfaced with the grid in a smart way can increase robustness of operation to power system dynamic behaviour.
• The presence of a considerable amount of storage capability connected at the distribution level also allows the operation of isolated distribution grids with large amounts of IRES and/or microgeneration units connected to it.
10Ciência 2009
0 1 2 3 4 5 6 7 8 9 1049.3
49.4
49.5
49.6
49.7
49.8
49.9
50
50.1
50.2
50.3
Time (s)
Sy
ste
m F
req
ue
nc
y (
Hz)
P
W = 1.3 MW; EV - charge mode
PW
= 1.3 MW; EV - freq. control
PW
= 2.0 MW; EV - freq. control
© 2009
Final remarks
• Smart charging is to charge in the right place at the right time, thus a communication infrastructure will be needed:
– Using smart meters is the most rational option
– 6 millions of smart meters will be deployed in portugal in a near future (InovGrid Project)
• Smart charging is to charge in the right place at the right time, thus a communication infrastructure will be needed:
– Using smart meters is the most rational option
– 6 millions of smart meters will be deployed in portugal in a near future (InovGrid Project)
11Ciência 2009
