Effects of Plug-In Electric Vehicles on Electrical Distribution Systems · 2012-05-22 · Electric...

Electric Power Engineering

David Steen Chalmers Energy Conference 2012 1 of 19

Effects of Plug-In Electric Vehicles on Electrical Distribution Systems

David Steen

The work is financed by Göteborg Energi Research Foundation

Chalmers University of Technology

Electrical Power Engineering Energy and Environment



Outline

• Background • Plug in Electric Vehicles (PEVs)

– Drive pattern – Energy consumption

• Distribution systems – Design – Load profiles – Spot price

• Case study results • Conclusions



Background

• Increased interest to reduce the dependency on fossil fuel.

– Plug-in Electric Vehicles (PEVs) have the potential to reduce the fossil fuel usage.

• A large scale introduction of PEVs will increase the usage of electricity. – Increased peak demand?

• Is there a need to control the charging? – How to control the charging most optimal? – How would controlled charging affect the distribution system? – Potential to support renewable electricity production?



Vehicle Usage Data

The figure above is based on a national travel survey conducted by SIKA/TRAFA.

Distance/day commuting 24 km Distance/day leisure 30 km

Energy consumption* 0.2 kWh/km Charge power* 3.68 kVA Power factor* 0.95

Charge efficiency* 88% * Estimated value



Location of the Vehicles

Parked vehicles during the night

The figures above is based on data from the city of Gothenburg and SIKA/TRAFA.

Parked vehicles during the day



A Residential Distribution System in Gothenburg

130/10 kV

= 10/0.4 kVsubstation

SS = Sectionalizing SwitchTS = Tie Switch

SS

SS

TSTS

Normal Operation



A Residential Distribution System in Gothenburg

130/10 kV

= 10/0.4 kVsubstation

SS = Sectionalizing SwitchTS = Tie Switch

SS

SS

TSTS

“Redundancy” Operation



Load Profiles in the Distribution System



Nordpool Electricity Price



Case Study – Charge Strategies

• Uncontrolled charging – The charging is conducted immediately after each journey.

• Loss-optimal charging – The charging is conducted to minimize the losses in the distribution

system.

• Price-optimal charging – The charging is conducted to minimize the electricity cost and

support renewable energy production.



Case Study – Demographical Data

Residential DS Commercial DS No. of vehicles used for leisure journeys

1395 154

No. of vehicles commuting to work in the DS

137 624

No. of vehicles commuting home to the DS

1091 120

• Demographical data has been used to evaluate the

location of the vehicles over the day.

DS = Distribution System



Case Study – Stop Time Vehicles

VW = Vehicles stopping at work VH = Vehicles stopping at home VL = Vehicles stopping after leisure



Case Study – Parked Vehicles

VWP = Vehicles parked at work VHP = Vehicles parked at home VLP = Vehicles parked at home after leisure



Case Study – Load Profile Residential Area Charging only at home

Charging at home and at work



Case Study – Load Profile Commercial Area Charging only at home

Charging at home and at work



• Charging at home

• Charging at home and work

Case Study – Maximum Penetration

Residential Commercial Normal Redund. Normal Redund. Uncontrolled 76% 0% >100% >100% Loss-optimal >100% 0% >100% >100% Price-optimal 49% 0% >100% >100%

Residential Commercial Normal Redund. Normal Redund. Uncontrolled >100% 0% >100% >100% Loss-optimal >100% 0% >100% >100% Loss-optimal 49% 0% >100% >100%



Case Study – Loss, Voltage and Cost

• Residential Area

• Commercial Area

Charging at home Min. voltage [pu] Loss increase [%] Cost [sek/charge] Uncontrolled 0.96 28 7.51 Loss-optimal 0.97 23 6.61 Price-optimal 0.95 33 6.29

Charging at home Min. voltage [pu] Loss increase [%] Cost [sek/charge] Uncontrolled 0.98 3.6 7.51 Loss-optimal 0.98 2.3 6.35 Price-optimal 0.98 2.5 6.29



Conclusions

• PEVs will affect the distribution system.

– Local variation. – Vehicle usage is important.

• By controlling the charging the impact could be reduced. – Formulation of control strategy is important. – Increased number of PEVs can be supported without reinforcing

the distribution system – Decreased total system loss due to PEVs

• Charge cost are reduced by 12-16% for controlled charging compared to uncontrolled charging.



Contact Information

David Steen Division of Electric Power Engineering Department of Energy and Environment Chalmers University of Technology SE-412 96 Göteborg, Sweden

Phone: +46(0)31 - 772 16 63 Mobile: +46(0)739 - 16 95 96 E-mail: [email protected] www.chalmers.se/ee/SV/personal/steen-david

mailto:[email protected]

http://www.chalmers.se/ee/SV/personal/steen-david



Effects of Plug-In Electric Vehicles on Electrical Distribution Systems · 2012-05-22 · Electric...

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