plug-in vehicle drive impacts to the grid

Plug-In Vehicle Drive Impacts to the Grid

Dr. Arindam MaitraElectric Power Research Institute

TRB Environment and Energy Research ConferenceJune 7-9, 2010Raleigh, NC

2© 2010 Electric Power Research Institute, Inc. All rights reserved.

Energy

Annual Residential Electricity Consumption

12231

1890

0

2000

4000

6000

8000

10000

12000

14000

KW

hr US AverageChevy Volt

Adequate Energy Supply to Meet any Realistic Penetration

Opportunity to Alleviate Issues

Related to Nighttime Over

Generation


Peak Demand

Average Peak Summer Demand Per Household (KW)

7.7

6.0

4.6

4.3

3.0

1.4

3.6

7.7

19.2

Springdale, AR

South Bend, IN

Dulles, VA

Hartford, CT

SanFrancisco, CA

PEV (120V@12A)

PEV (240V@15A)

PEV (240V@32A)

Tesla (240V80A)

Feed

ers

PEV Peak Demand Depends on Charging Capacity (Voltage/Amperage)


Planning for PEV Peak Demand

• Unlike transmission systems most distribution system do not have full electrical model to each customer

• There is no wide spread continuous load monitoring system that can detect transformer/cable overload

• In most cases transformer failure is the first indication of overload (example, heat spells)

Regulator

900kvar

900kvar300kvar

900kvar

900kvar

900kvar

Capacitor

Substation

Challenges in Detecting Overload in Distribution System


Electrical Charging Characteristics (Load Diversity)

• Demand will vary spatially across the feeder– Market penetration– System configuration– Socio-economics

• Demand will vary temporally– Driving patterns– Battery size– Electrical connection– Special tariffs


• Build Today’s Infrastructure Today• Infrastructure is expensive

• Focus on Residential– Seamless installations for homeowners– Permits, electricians, inspections– Rates and customer programs

• Workplace– Includes fleet and retail

• Public Charging – as needed– Retail, private, public spaces– Know what drivers need – location, open access, billing – What are the viable business models?

Residential

Workplace

Public

Charging Infrastructure Must Not Become a Barrier to Adoption


Deliver Electricity, Charging Infrastructure to the Vehicle’s Location


Distribution Impact Project

• Multi stage analysis designed to capture and characterize impacts due to PEV load


Hourly Loading Levels

Feeder #1 Feeder #2

Summer peaking Winter peaking Load Factor: 39.6% Load Factor: 64.8%

Peak: 11.4 MW Peak: 8.68 MW


PEV Penetration Levels

Feeder #1 (8%) Feeder #2 (40%)

Higher projected penetration for Feeder #2

~ 333 PEV ~ 2200 PEV


Aggregate Demand at High Penetration (Feeder #2)

40% penetration

Significant changes to evening hour

demands

Base

40%


Sample Study Results – Likelihood of Overload

Assets “closest to the load” are the most likely to the

impacted firstUnlikely impacted assets at

even 20% penetration

Assets at risk at a 2% penetration


Asset Peak-hour Remaining Capacities

Design differences rooted in serving different load types

Feeder #1 Feeder #2


Distribution Load Management Critical

2% Penetration (67)5% Penetration (168)

10% Penetration (336)20% Penetration (672)30% Penetration (1008)

High density regions

Xfmr with available capacity

kVA/cust < 7.2

83 transformers

Transformer upgrades/ planning strategies will be driven by consumer demand+ Risk+ Likelihoods+ Factors

Distribution Investment/Support Requirements Driven by:

•Peak vs. Off Peak Charging

•Types of transformers, loading, customers served (underground, overhead & size)

Smart charging with an integrative view of transformer performance critical


Feeder Loading Analysis: Aggregate Power Demand for Uncontrolled Charging

Aggregate LevelAverage on-peak load for a PEV will be about 500-1100 W

If it’s bigger, it will finish soonerIf it’s smaller, they’ll overlap more


Diversify Off-Peak Coincident Charging

1) Number of PHEVs – Loading increases based on

home arrival time

2) Number of TOU customers– Shifts on-peak load to off-peak– Decrease in On-peak load (A) =

increase in Off-peak load (B)

3) Time when On-peak Rates are enforced

– Base load– Delayed Off-peak charge

(A+C) = (D)

Average Daily Load ShapeBase Load2 PHEV, 0 TOU2 PHEV, 1 TOU2 PHEV, 1 TOU, delayed offpk

Hour of Day

OnPkkW

OffPkOffPk

A BC D


0

0.5

1

1.5

2

2.5

0

0.5

1

1.5

2

2.5

Smart Charging Helps – If Done Right

Charge Power Per Vehicle (kW) Charge Power Per Vehicle (kW)

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

Shifts the charge load to nighttime, but spreads it out relatively evenly over 6 hours

Only shifting the time without evening out the profile can make the situation worse


Transformer Loss of Insulation Life

• Thermal ratings are the strongest indicator of potentially significant impacts– Existing loading conditions– Additional PEV load “Planned Loading

Beyond Nameplate can

account for high peak day aging”


Next Step – Load Monitoring

Planning tool using detail electrical model helps but the real solution to predicting

localized hotspots is load monitoring

Transformer Load Monitoring– Directly– Using AMI (if integrated with

transformer database)


System Compatibility and Power Quality Assessment

• To verify the electrical characteristics of the charger• To characterize the vehicle’s behavior when it is subjected to electrical anomalies


Leveraging Electric Transportation as Distributed Resources

• With potentially hundreds of thousands of plug-in vehicles being deployed in the long term

– Battery to grid for home/PV integration

– V2G for utility services


The Plug-In Vehicle Standards Space

Society of Automotive Engineers• J1772 (Connector)

• J2847/2836/2931 (Communications)

• J2894 (Power Quality)

Infrastructure Working Council• Utility-funded stakeholder group

• Identify and address needs for codes and standards

• Not a standards body

• IEEE 1547 (Grid Tie)

• IEEE P1809 (Electric Trans)

• IEEE P2030 (Smart Grid)

Intl Electrotechnical Comm• TC69 (Charge Infrastructure)

• TC22/ SC3 (Electrical)

National Electric Code• NEC625 (EV Charging Systems)

• Priority Action Plan 11 (Electric Trans)

• Priority Action Plan 15 (Communication)


Smart Charging – How Smart is Smart?

c2010•Charging commands from driver through in-car interface

•Smart phone interface

c2011•Off-line, one-wayutility connectivity, telematics based for DR, pricing signal

•Customer smart phone interface

c2012•Online, bidirectional, AMI and telematicsconnectivity w/ utility DR and pricing signals

•Smart Charging•Customer smart phone interface

c2013•Online, bidirectional, AMI and telematicsconnectivity w/ utility DR and pricing signals

•Smart Charging and Discharging

•Customer smart phone interface

2010-2012 vehicles 2012+ 2014+


Near-Term Steady-State Impacts

• Adequate supply to meet PEV energy need

• PEV clustering impacts most likely on assets– Close to the customer– Low capacity per customer

• Anticipating potential PEV overload impact– Load planning based on detail distribution model– Transformer load monitoring (direct or via AMI)

• Potential adjustments to future distribution planning standards– Transformer sizing, customers served off each transformer, transformer

thermal ratings

plug-in vehicle drive impacts to the grid

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