Power System Level Impacts of Plug-In Hybrid Vehicles (PHEV)

PSERC Webinar, December 18, 2009 –––– Page 1PSERC

Power System Level Impacts of Plug-In Hybrid Vehicles (PHEV)

A .P. MeliopoulosGeorgia Power Distinguished Professor

Jerome MeiselGeorgia Institute of Technology

Thomas J. OverbyeFox Family Professor of ECE

University of Illinois at Urbana-Champaign


The Big Picture

• The annual energy consumption is about 100 Quads. Roughly one third is used for industrial processes, one third in transportation and one third as electric energy.

• Electric Power Uses Diverse Energy Sources (Nuclear, Coal, Gas, Hydro, etc.)

• Transportation is Mainly Petroleum Based. Daily Consumption About 20 Mbarrels (National Issue: Crude Oil Importation at 12 Mb/day)

• Increased Environmental Concerns.


• Can Pluggable Hybrid Vehicle Technology Play a Role in Solving Present Energy Problems (Economically and Environmentally Acceptable).

• What Will be the Impact to the Electric Power System Infrastructure?

• What will be the Impact on Our National Issue of Our Dependence on Oil?

The Big Question

PSERC Webinar, December 18, 2009 –––– Page 4PSERC 4

The Big Picture – Energy in 2007 (US DoE)


Observation

Twenty Years Ago the Energy Consumption in the Form of Electric Power was about 30% of total Energy Consumption.

Presently it stands at 40%.

What will be in the Future? (50% electrification of the transportation industry will bring it to 54%)


The Big Question

Electrification of the Transportation Sector Can be Characterized as:

Transformative Technology

“Alteration of the Energy Picture”


PHEV “Fuel” CostAssumptions:

• Electric range: 40 miles (PHEV40)

• Toyota Prius: 45.0 mpg (avg.) – on Gas

• Total miles driven: 12,000 mi/yr (80% Electric)

• Cost of gasoline: $4.00 / gal ($2.00 / gal)

• Gasoline Car Efficiency: 13% to 20%

• Assume 75% electric and 25% gas driving

• Cost of electric energy: $0.12 / kWhCost of Gas = $270 (66 gallons) ($135)Cost of Electricity = $ 140 (1,170 kWh)

• All Gas Cost = $1,066 ($533)

• Difference: $656 per year ($252)


Power System Level Impacts of PHEV

Infrastructure:Microscopic LevelMacroscopic Level

Fuel UtilizationShift from Petroleum to Utility Mix (Nuclear, Coal, NG, Hydro, etc.)

Impact on EnvironmentGas Based Car Pollutants/Utility Generation Pollutants

Power System Reliability/SecurityV2G in Case of Emergency

Consumer will act on his best interest… Utility must deal with it!


EV, HEV & PHEV

• Tradeoffs in HEV & PHEV designs, and in their benefits in fuel efficiency and emission reductions to consumers and society (EPRI).

• V2G Approach.

• EV Approach.

• Battery Technology Research

• Fuel Cell Powered Vehicles


HEV & PHEV designs

Chapter 3 of the final report provides an analysis of the various designs of HEV and PHEVs and commentary on their benefits/disadvantages in fuel efficiency and other metrics

Standard routes have been developed for the evaluation of PHEV and HEV performance. The standard routes represent typical driving schedules.

Extensive simulations have been performed to establish base parameters and performance metrics for HEV and PHEVs (see chapter 4).


US06 driving schedule of 8 mi, over 600 sec with a peak speed of 80.29 mph, an average speed of 47.96 mph, and 5 stops totaling 45 sec duration.

Electric energy from power grid versus percent of total input energy from battery for a number of driving schedules

Miles per gallons (gasoline) versus percent of total input energy from battery for a number of driving patterns


Potential PHEVsGM: Volt, 2010

TOYOTA: Prius, 2010 they have produced a small quantity for specific customers

INDIA: Available today from small companies (PHEV with Photovoltaic Roof)

AROUND THE GLOBE: Many Third Party Convertors

The GM Volt: Lots of Fanfare – Expectations Low from the Price/Benefit Point of View


Power System Level Impacts of PHEVIntegrated Model


Impact on Distribution System Infrastructure


Impacts of PHEV on Infrastructure

A house consuming 600 kWh per month becomes a 800 to 900 kWh per month with two PHEVs (moderate driving)

Effects on distribution system and transmission system


Integrated electro-thermal models of distribution systems and distribution transformers that include houses, commercial buildings, loads, etc. can be used to investigate impact.

Probabilistic models of electric power demand superimposed to demand for PHEV charging drive the integrated model.

Simulation of the integrated system provides the operating temperature of distribution transformers as a function of time and loss of transformer life.

Sample results follow.



Transformer Electro-thermal Model• First order electro-thermal

model of the transformer used to compute the temperature of the transformers windings throughout the day

• The dynamics of the transformer winding temperatures are described by the following differential equation

• Trapezoidal integration method used to calculate the solution of the differential equationwith h=10 sec

qh qL1 qL2

Gh,h GL1,L1 GL2,L2

GL1,L2Gh,L1

Gh,L2

Ch,h CL1,L1 CL2,L2

Th TL1 TL2

qGTdtdTC +−=


Simulation Assumptions

• The owners of the first and second house used their 120 V, 15 A garage outlets to charge their cars, while the owner of the third house used a 240 V, 30 A outlet for charging their car.

• Each car needs 18 kWh to be fully charged, has a power factor 0.92 (current lagging), and charging efficiency of 96%.

• For each hour of the simulated day, a random daily load schedule was assumed and the transformer winding currents were calculated for each case (with and without PHEVs).

• The first and second car were charged from 21:00 pm until 8:00 am of the next day (it takes almost 11 hours for the PHEVs to be fully charged with the 120 V, 15 A service). The third car was charged from 0:00 pm to 3:00 pm (it takes 3 hours for the PHEV to be fully charged with the 240 V, 30 A service).



Sample simulation without PHEV.Computed expected life of transformer = 353years

Sample simulation with PHEV40.Computed expected life of transformer = 1.85years

24 ( ( ))

1

BAT

hLOL h e

− +

=

= ⋅∑

Example of 15 kVA Distribution Transformer Feeding Three Houses


0 1 2 3 4 5 6 7 8 9 1011121314151617181920212223240

50

100

150T h (0 C

)

0 1 2 3 4 5 6 7 8 9 1011121314151617181920212223240

50

100

150

T L1 (0 C

)

0 1 2 3 4 5 6 7 8 9 1011121314151617181920212223240

50

100

150

Time (Hours)

T L2 (0 C

)

Impacts of PHEV on InfrastructureReplacement of 15 kVA Transformer with 25 kVA Transformer


Transformer Expected Life Calculation• Loss of life and expected

life of the transformer computed as follows:

• In the 20 0C ambient temperature case, the expected life of the transformer is reduced by approximately 93%

• Additional expected life reduction if the ambient temperature is increased to 30 0C

24

1exp ( )

h h

BLOL AT=

= − +

∑

1365

Expected LifeLOL

=⋅


Increase in percent LOL for Tucson AZ and Fairbanks AK for a varying number of PHEVs included in the distribution system.

Increase in percent LOL for Tucson AZ and Fairbanks AK charging three PHEVs using different transformer sizes.


Impact on Energy Resource UtilizationAnd Pollutants


Impacts of PHEV on Fuel Utilization

Methodology

Probabilistic Production Costing method. Generation is subject to outages and each unit has specific economics. The dispatch procedure is simulated while a probabilistic model of unit availability is used. Model computes expected operational time, expected production (MWh), expected cost by each unit and total. Different scenarios are considered: (a) segregated electric power system operation and gasoline powered cars, and (b) electric power operation with a certain penetration percentage of PHEV.

PHEV Charging Scenario Effective Load Model (PDF of Load)


Primary Energy Source UtilizationPHEV Load

• Additional load due to PHEV shown for the first simulated day

Time

Load

[MW

]

275 MW

Base Case LoadLoad Due To PHEVTotal System Load

The minimum increased 22.10% and 30.66% for the 10% and 20% PHEV penetration scenarios, respectively. And the maximum load increased only 1.75% and 10.78% increase for the 10% and 20% PHEV penetration, respectively. This load leveling is a potential benefit of the semi-controllable load that PHEVs present.


Fuel Heat ContentKcal/Kg

Price$/Kg

Nuclear 19.069 *1013 60,000

Coal 6,000.0 0.05

Petroleum 12,000.0 0.65

Natural Gas

12,800.0 0.35

Example of Probabilistic Production CostingCosting/Reliability Analysis and Outcomes – Example Test System

Primary Fuel Data

Fuel Size [MW] Num.

Units FOR Max. Cap.

Min. Cap.

#6 Oil 12 2.4 5 0.02 #2 Oil 20 16 4 0.10 #6 Oil 50 15.2 4 0.04 Coal 76 12.5 3 0.02

Nat. Gas 125 31.25 4 0.08 Nuclear 155 54.25 3 0.10

Coal 197 68.95 1 0.05 Coal 350 140 2 0.08

Nuclear 400 100 1 0.12

Generating Units and Primary Fuel

26

Electric Load (MW)

1.0

Prob

abili

ty (t

/T)

200 400 600 800 1000 1200

0.2

0.4

0.6

0.8

Example Load Model Converted to a “Load Duration Curve”


Probabilistic Production CostingExample Test System

Size [MW] ah bh ch 12 3,330,369 2,550,425 15,047 20 10,080,000 3,150,000 0 50 21,092,334 2,550,425 2,376 76 31,362,044 1,963,834 2,413

100 26,227,189 2,257,130 2,395 155 43,407,948 1,946,828 1,401 197 33,003,505 2,193,793 329 350 81,532,894 1,873,123 822 400 90,962,133 2,244,962 116

NOx CO2 Size [MW] ap bp ap bp

12 20 0.5 6,459 158 20 8 3.8 1,252 626 50 46 0.2 4,733 151 76 180 0.7 37,417 145

100 283 0.9 52 0.2 155 548 1.1 92,849 183 197 374 0.9 123,204 309 350 1,604 3.2 270,004 335 400 0 0 0 0

Generating Units Heat Rates Generating Units Emissions

2 RateHeat PCPBA ⋅+⋅+=


Probabilistic Production CostingExample Results

Primary Energy Source: #6 Oil #2 Oil Coal Nuclear Natural Gas

Total Energy

[GWh/year]

Base Case 62.81 8.14 9171.00 3083.00 665.40

10% PHEV 72.08 9.51 9591.00 3083.00 736.80

20% PHEV 84.56 11.42 9990.00 3084.00 824.00

Percent Change10% PHEV 0.07% 0.01% 3.11% 0.00% 0.53%

20% PHEV 0.16% 0.02% 5.85% 0.01% 1.13%

Figure of Merit: Ave. Cost [¢/kWh]Loss of Load Probability

(LOLP)

Generated Energy

[MWh]

Unserviced Energy

[MWh]

Test System

Base Case 1.27 0.011 12,990,000 15,180

10% PHEV 1.31 0.013 13,490,000 17,960

20% PHEV 1.35 0.015 13,990,000 22,050

Percent

Change

10% PHEV 3.15% 16.98% 3.85% 18.31%

20% PHEV 6.30% 41.09% 7.70% 45.26%


Probabilistic Production CostingExample Results (Pollutants)

NOx CO2

Power System

EAP [kg]

Base Case 47,269,504 7,878,934,800

10% PHEV 48,105,359 8,004,246,500

20% PHEV 49,887,315 8,113,374,100

Percent Change10% PHEV 1.77% 1.59%

20% PHEV 3.36% 2.98%

Energy Normalized EAP [kg/MWh] NOx CO2

Base Case 3.7856 856.5478

10% PHEV 3.6936 811.1942

20% PHEV 3.6022 767.9256


Probabilistic Production CostingExample Results

CO2 [kg] IC Vehicles PHEVsTotal

VehiclesPower System Total

Total Generated

Energy [MWh]

Base Case 3.248E+09 0 3.248E+09 7.879E+09 1.113E+10 12,990,000

90% IC Vehicles, 10% PHEV 2.923E+09 1.590E+07 2.939E+09 8.004E+09 1.094E+10 13,490,000

80% IC Vehicles, 20% PHEV 2.598E+09 3.181E+07 2.630E+09 8.113E+09 1.074E+10 13,990,000

NOx [kg] IC Vehicles PHEVsTotal

Vehicles

Power

SystemTotal

Total Generated

Energy [MWh]

Base Case 1,905,700 0 1,905,700 4.727E+07 4.918E+07 12,990,000

90% IC Vehicles, 10% PHEV 1,715,130 6,717 1,721,847 4.811E+07 4.983E+07 13,490,000

80% IC Vehicles, 20% PHEV 1,524,560 13,435 1,537,995 4.886E+07 5.039E+07 13,990,000


Active Future Distribution Systems (with distributed energy resources – solar, wind, PHEVs, fuel cells,…).

Smart Grid technologies: Distributed Monitoring, Control, Protection and Operations system. Target Speeds 10 times per second

Functions: (a) Optimal operation of the distribution system under normal operating conditions, (b) Emergency management in cases of faults and assist the power grid when needed, (c) Assist Voltage recovery, (d) Assist cold load pickup, (e) Balance Feeder, (f) etc., etc.

Realization of Full Benefits Can Be Only Achieved with Smart Grid Technologies


Distribution Management System – New Approach

Real Time Monitoring:

• GPS-Synched Metering

• 3-Phase State Estimation

• Monitoring of XFMR LossOfLife

Real Time Controls:

• Loss Minimization

• Voltage Profile Control

• Emergency Management

• Inertial Controls

• Voltage Stability Control

• Stabilize System transients

• System Reliability

• Increase Operating Limits

Smart Distribution System Technologies


Impact on Power Grid Operations


PHEVSmartmeter

CombinedHeat andPower (CHP)

Distribution System

Transmission System

Reactive-Power-Capable Devices at the Residential Level

Home Monitoring and Control System

PMU

PMU

Mi = Message to provide reactive power amount Qi at Q-C buses i

Manager of Devices ( )in Reactive Support Group

M2M1*

*

*

We Assumed PHEVs to be an Integrated Part of the Grid


PHEV Charging and Wind Generation• How PHEVs are charged can have a significant

impact on grid operations; major synergies with wind for night time charging in midwest

Hourly Wind: August Hourly Wind: April

Source: www.uwig.org/XcelMNDOCwindcharacterization.pdf


Grid Impacts of PHEVs

• Depending upon how quickly the PHEVs could be controlled, they could have a major impact on power system operations– Night time charging when LMPs are low– On a minutes timeframe they can provide post-

contingent controls, and could be used as reactive resources

– On seconds they can provide regulation and frequency response


Transmission System Approach• Study compared SCOPF scenarios without and

with various amounts of PHEVs in the system.• PHEVs were assumed to be able to supply real

power back to the grid with amount of power dependent upon electric outlet configuration– Range from 15 A, 120 V to 40 A, 240 V– PHEV penetration ranged from zero to 25% – Results reported in terms of % of total load that

can be supplied by the PHEVs


Impact of Supply on Percentage of PHEV Load Support


IEEE 24 Bus Test System

1

1

PH PH

PHPH

PH

PHPH

PH PH

PH

PH

PH

PH

PH PH

PH

PH

Bus 1 Bus 2

Bus 3

Bus 4Bus 5

Bus 6

Bus 7Bus 8

Bus 9Bus 10

Bus 11 Bus 12

Bus 13

Bus 14

Bus 15

Bus 16

Bus 17Bus 18

Bus 19Bus 20

Bus 21Bus 22

Bus 23

Bus 24

108 MW 22 Mvar

97 MW 20 Mvar

180 MW 37 Mvar

74 MW 15 Mvar

71 MW 14 Mvar

125 MW 25 Mvar

136 MW 28 Mvar

171 MW 35 Mvar

175 MW 36 Mvar

195 MW 40 Mvar

265 MW 54 Mvar

181 MW 37 Mvar

317 MW 64 Mvar

100 MW 20 Mvar

333 MW 68 Mvar

194 MW 39 Mvar

128 MW 26 Mvar

133 Mvar

-63 Mvar

1.00 pu 1.00 pu

0.95 pu

0.96 pu 0.99 pu

1.00 pu

1.00 pu 0.96 pu

0.96 pu 1.00 pu

0.99 pu 0.98 pu

1.00 pu

1.00 pu

0.99 pu

1.00 pu

1.00 pu 1.00 pu

0.99 pu 0.99 pu

1.00 pu 1.00 pu

1.00 pu

0.96 pu

11 MW 10 MW

13 MW 17 MW

7 MW 7 MW

18 MW

18 MW 0 Mvar

8 MW 0 Mvar

14 MW

32 MW

10 MW 19 MW 18 MW 13 MW

26 MW

33 MW

87%A

Amps

The use of the PHEVs to manage contingencies is a key benefit


IEEE 118 Bus System


IEEE 118 System Contingencies

Using PHEVs to supply energy to the grid requires thatthe infrastructure be available for them to plug in, and thereis sufficient economic incentive for drivers to do so.


Conclusions

• Plug-In Hybrids will drastically impact the electric power grid – mostly favorable impact.

• Local infrastructure issues are manageable

• The power grid may have to be drastically expanded for large penetrations.

• The environmental impact is favorable.

• The impact of system security is favorable


Project: Power System Level Impacts of PHEVSponsor: PSERC

FacultyJerome Meisel, Georgia Institute of TechnologyGeorge Cokkinides, Georgia Institute of TechnologySakis A. P. Meliopoulos, Project Leader, Georgia Institute of TechnologyThomas J. Overbye, University of Illinois, Urbana

Graduate Research AssistantsCurtis Roe, Georgia Institute of TechnologyRenata Revelo Alonso, University of Illinois at Urbana-ChampaignSteven Judd, University of Illinois at Urbana-Champaign

Credits

Documents

Power System Level Impacts of Plug-In Hybrid Vehicles (PHEV)