Distribution Capacity Impacts of Plug In Electric Vehicles. Chris Punt, P.E. MIPSYCON 2014

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1 Distribution Capacity Impacts of Plug In Electric Vehicles Chris Punt, P.E. MIPSYCON

2 Outline EV Benefits EV Growth Where are we today? Where are we going? Potential Distribution Capacity Issues Feeder Sub Transformer Service Transformer Other Activities Conclusion 2

3 Benefits of Electric Vehicles Environmental Impacts Can run on renewables Higher conversion efficiency Emissions - Easier to filter pollutants Economics Energy cost is 1/3 compared to gas Can make up for Utility revenue reductions Energy Independence North American Electricity Eliminate Price Volatility Driving Experience Smooth Low noise Instant Torque - Acceleration 3

4 Most Popular U.S. EVs EV Models Nissan Leaf Chevrolet Volt Toyota Prius PHV Tesla Model S Ford Fusion Energi Ford C-Max Energi 4

5 Electric Drive Transportation Association - 5

6 2400 EVs in MN through

7 $/gallon # of EV Inquiries Xcel Energy Area EV Interest and Gas Prices MN Gas Prices XCEL EV Interest Jun- 12 Jul- 12 Aug- 12 Sep- 12 Oct- 12 Nov- 12 Dec- 12 Jan- 13 Feb- 13 Mar- 13 Apr- 13 May- 13 Jun- 13 Jul- 13 Aug- 13 Sep- 13 Oct- 13 Nov- 13 Dec Date 7

8 Where are we today? Minnesota Public Charging 165 electric stations 360 charging outlets ChargePoint Tesla Dealerships Goodwill United States 8,672 electric stations 21,525 charging outlets Department of Energy - 8

9 Where are we going? Initial Xcel Energy Estimates Tesla Charging Stations: 100,000 kwh per year Home Charging: 56,000,000 kwh to date 2014 Legislation in MN EV Charging Tariff All Public Utilities will file an application to the MNPUC by February 1, 2015 Must contain TOD or off-peak rate Must offer customer opportunity to purchase from renewable sources Must be made available to residential class 9

10 Annual Energy 10

11 Charging Level 1 120V 1.1 to 1.8 kw hours for full charge Level 2 240V to 7.7 kw, 19.2 kw 3-8 hours for full charge Level 3 DC Fast Charge Three phase 15 to 240 kw 1/2-2 hours 11

12 Charging Tesla Supercharger 12

13 Amps Chevy Volt Charge Profile Level 1 9 hours Li-ion 13

14 Distribution Capacity Analysis Feeder Substation Transformer Service Transformer 14

15 Feeder Analysis Two St. Paul Feeders served from same substation transformer Typical, indicative of Xcel Energy s planning philosophy Feeder A 36% residential load (multi-family) 77% loaded 13.8kV Feeder B 80% residential load (single family) 65% loaded 13.8kV 15

16 Feeder Analysis Varying Level 2 residential penetration rates 3.3 kw 6.6 kw Assume all charging occurs at peak. Penetration = EV/Residential Customer Assumption: 1 EV per customer Penetrations 0% 1% 2% 5% 10% 15% 25% 35% 50% 75% 16

17 Feeder Analysis Feeder A Feeder "A" Capacity vs 6.6 kw Penetration 170.0% 150.0% 130.0% 110.0% 90.0% 70.0% Feeder "A" Capacity vs 3.3 kw Penetration 0% 10% 20% 30% 40% 50% 60% 70% 80% 120.0% 110.0% 100.0% 90.0% 80.0% 70.0% 0% 10% 20% 30% 40% 50% 60% 70% 80% 17

18 Feeder Analysis Feeder B Feeder "B" Capacity vs 6.6 kw Penetration 160.0% 140.0% 120.0% 100.0% 80.0% 60.0% Feeder "B" Capacity vs 3.3 kw Penetration 0% 10% 20% 30% 40% 50% 60% 70% 80% 120.0% 110.0% 100.0% 90.0% 80.0% 70.0% 60.0% 0% 10% 20% 30% 40% 50% 60% 70% 80% 18

19 Feeder Analysis Takeaways For every 1% penetration we see 0.5% - 1% demand growth on both feeders. Capacity significance starts around the 4% penetration mark. i.e. 2% - 4% demand growth 19

20 Feeder Analysis Takeaways kw per customer 3.3 kw slope Load Normalized 3.3 kw slope Feeder A Feeder B Feeder makeup matters % residential Type of residential Areas with lower kw/customer will see more impact from same penetration levels. 20

21 Sub Transformer Analysis Present Case Penetration 3.3 kw 6.6 kw 0% 46.6% 46.6% 1% 46.9% 47.2% 2% 47.2% 47.9% 5% 48.2% 49.8% 10% 49.9% 53.2% 15% 51.6% 56.5% 25% 55.0% 63.2% 35% 58.4% 69.9% 50% 63.5% 79.9% 75% 72.2% 96.6% Diversity Factor of 81% 21

22 Transformer Analysis Worst Case Penetration 3.3 kw 6.6 kw 0% 57.5% 57.5% 1% 57.9% 58.3% 2% 58.3% 59.1% 5% 59.5% 61.5% 10% 61.6% 65.7% 15% 63.7% 69.8% 25% 67.9% 78.0% 35% 72.1% 86.3% 50% 78.4% 98.6% 75% 89.1% 119.3% Diversity Factor of 100% 22

23 Transformer Analysis Takeaways For every 1% penetration we see 0.3% - 0.8% demand growth. Less raw impact compared to feeders due to diversity Capacity Impact starts at over 5% penetration In most cases feeder limits will be reached before transformer limits (if designed/planned properly) 23

24 kva Service Transformer Load Profile XFMR " " Analysis date: 7/14/ New Peak with Chargers :00 2:00 4:00 6:00 8:00 10:00 12:00 14:00 16:00 18:00 20:00 Time 24

25 Service Transformer Analysis Known Additions Took 46 known EV owner locations and their service transformers Analyzed for addition of Level 2 Charging Peak Load Addition % of Population Overloaded kw charger 4% kw charger 9% 25

26 Service Transformer Analysis All NSPM Additional Peak Load % of Population Overloaded Cost to Replace (M) Penetration kw charger 3% $ % kw charger 5% $ % 4%-5% penetration leads to $2.3M - $4.6M in upgrades Does not account for multiple installations per transformer 26

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28 Projection 2.5% EV share leads to 5% penetration (2024 on low adoption from previous slide) 4% of transformer population overloaded $7M - $10.7M to upgrade (proactive reactive) Revenue far exceeds costs over ten years No significant feeder or sub transformer impact for 10+ years 28

29 PSCo EV Pilot Project Deliverables (early 2015) Determine residential charging characteristics Identify alignment with system peak Distinguish a potential strategy for minimizing distribution impact through control 29

30 EV Project Funded by ECOtality and Department of Energy 13,000 Level 2 Chargers Feeder and EV Peaks don t align Typically EV connected to EVSE 40% - 45% of time but draws power only 8% - 9% of time 30

31 Conclusion EVs are here and growing Impact generally starts occurring at around 5% penetration when peak aligned Service transformers are of biggest concern, especially with multiple EVs Locating Level 2 charging and above necessary Charging at night desired with possibility to control later on 31

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