Electrical Vehicles Effects on Residential Distribution Systems Research Assistant: Paul Haley Research Supervisor: Dr. Leszeck Czarnecki August 31, 2012.

Electrical Vehicles Effects on Residential Distribution Systems

Research Assistant: Paul HaleyResearch Supervisor: Dr. Leszeck Czarnecki

August 31, 2012

Department of Electrical and Computer Engineering

Motivation

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Motivation

• Government and environmental groups endorse EVs.– energy efficiency– dependence on oil– CO2 emissions

• EVs are competitors in the market

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Motivation

• EV battery chargers are large loads.– 2 to 4 kW– Possible reduction of voltage profile

• EVs use AC/DC converters to charge batteries.– Possible increase in voltage harmonic distortion

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Objectives

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Objectives

• Estimate the environmental impact of EVs– Compare energy flow of EVs and GVs– Use efficiency data from best sources accessible

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Objectives

• Evaluate the effects of EV chargers on residential distribution systems– Measure EV battery charging cycle– Model selected residential system

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Objectives

• Research the current state of the EV market– Compile data from various literature

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Conclusions

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Conclusions

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• From an environmental perspective, EVs are beneficial.– The use of EVs is more efficient than GVs. – Use of EVs will reduce burning of carbon-rich fossil

fuels.

Conclusions

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• EVs not likely to cause problems in residential distribution systems in the near future

Conclusions

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• At current prices, EVs cannot compete with GVs, especially hybrids.– Only 0.01% of vehicles in U.S. are EVs.

Environmental Effects of EVs

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Efficiency Comparison

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• Compared efficiencies of the all steps of energy transfer for GVs and EVs.

• Due to many unknown factors the estimated efficiencies are debatable.

Efficiency Comparison

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• Electric car efficiency calculation involves four parts.– Charger and Inverter: 85% each– Battery: 94%– Motor: 90%

• EV energy efficiency: 61%

Efficiency Comparison

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• Final Result– EVs use 74% of the energy used by GVs to do the

same amount of work.

Efficiency and Environmental Impact

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• EVs are more efficient.

• Energy from fossils in U.S. is 69.3%.

• EVs burn 51% of the CO2 producing fossils that GVs consume.

Impact of EV Chargers on Residential Distribution Systems

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Measurements during EV Charging Cycle

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• Low distortion• Nearly unity power factor

Measurements during EV Charging Cycle

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• Current RMS relatively constant

Residential Power System Modeling

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• Expensive neighborhood – more likely to have EVs in the near future

Residential Power System Modeling

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Residential Power System Modeling

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• Computer model run for worst case– 20% current THD per charger– 95% power factor– 100% EV penetration charged simultaneously

Residential Power System Modeling

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• Voltage RMS at end of feeder: 95%• Voltage THD at end of feeder: 6%• Computer modeling repeated for varying

penetration levels– At 60% penetration voltage THD reached 5%.

Residential Power System Modeling

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• These worst case parameters are unlikely.• No problems expected in the near future.

Current EV Market

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EVs & PHEVs on the Market

• Nissan Leaf: 75 miles/charge - $35,200

• Mitsubishi i MiEV:62 miles/charge - $29,125

• Chevy Volt:35 miles/charge - $39,145

• Government incentive: $7,500

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EVs: Consumers Perspective

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• Limited range• Lack of convenient charging infrastructure• Best suited as second car for family• PHEVs more convenient for most consumers

PHEVs: Consumers Perspective

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• Chevy Volt vs. Chevy Cruze– Amortization Time with Incentive:

Government and Political Forces

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• Federal and state incentives not permanent• Future cost of EVs uncertain

– China’s monopoly on lithium and neodymium

Review

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• EVs are environmentally beneficial.– Could reduce burning of fossil fuels by half

• EVs should not cause problems in residential distribution systems in the near future.

• At current prices, EVs cannot compete with GVs.

Thank you!

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